Enzyme Treatment

There are a number of enzymes which hydrolyse Fig. 10.23. Simplified drawing of the Netzsch model LM-20 mill (Rehacek and Schafer, 1977) A, cylidrical grinding vessel with cooling jacket B, agitator with cooled shaft and discs C, annular vibrating slot operator D, variable-speed-drive motor 1 and 2, product inlet and outlet 3 and 4, agitator cooling inlet and outlet 5 and 6, vessel-cooling inlet and outlet. Fig. 10.23. Simplified drawing of the Netzsch model LM-20 mill (Rehacek and Schafer,...

The Multichamber Centrifuge

Ideally, this is a centrifuge for a slurry of up to 5 solids of particle size 0.1 to 200 xm diameter. In the multichamber centrifuge (Fig. 10.18), a series of concentric chambers are mounted within the rotor chamber. The broth enters via the central spindle and then takes a circuitous route through the chambers. Solids collect on the outer faces of each chamber. The smaller particles collect in the outer chambers where they are subjected to greater centrifugal forces (the greater the radial...

Rotary Vacuum Filters

Large rotary vacuum filters are commonly used by industries which produce large volumes of liquid which need continuous processing. The filter consists of a rotating, hollow, segmented drum covered with a fabric or metal filter which is partially immersed in a trough containing the broth to be filtered (Fig. 10.10). The slurry is fed on to the outside of the revolving drum and vacuum pressure is applied internally so that the filtrate is drawn through the filter, into the drum and finally to a...

Pressureretaining Valves

A pressure-retaining valve will maintain pressure in the pipeline upstream of itself, and the valve is designed to open with a rising upstream pressure. It js constructed with a reverse action of the pressure-reducing valve. Safety valves must be incorporated into every air or steam line and vessel which is subject to pressure to ensure that the pressure will never exceed the safe upper limit recommended by the manufacturer or a code of practice and to satisfy government legislation and...

Application of fedbatch culture

The use of fed-batch culture by the fermentation industry takes advantage of the fact that the concentration of the limiting substrate may be maintained at a very low level, thus avoiding the repressive effects of high substrate concentration. Furthermore, the fed-batch system also gives some control over the organisms' growth rate, which is also related to the specific oxygen uptake rate giving some control over the oxygen demand of the fermentation (see Chapter 9). Both variable and fixed...

Chromatography

In many fermentation processes, chromatographic techniques are used to isolate and purily relatively low concentrations of metabolic products. In this context, chromatography will be concerned with the passage and separation of different solutes as liquid is passed through a column, i.e. liquid chromatography. Depending on the mechanism by which the solutes may be differentially held in a column, the techniques can be grouped as follows (b) Ion-exchange chromatography. (c) Gel permeation...

The Selection Of Strains Which Are Tolerant Of Low Oxygen Tension

The provision of oxygen is frequently the limiting factor of many fermentations and it would, therefore, be desirable to select an organism which was capable of producing the product at a lower oxygen tension than normal. This may be achieved by screening for increased production under oxygen limited conditions. For example, Mindlin and Zaitseva (1966) isolated a lysine-producing strain which maintained its productivity under aeration conditions which decreased the parental strain productivity...

Info About Micro Organisms

Primary containment Operation and equipment Work with viable micro-organisms should take place in closed systems (CS), which minimize (m) or prevent (p) the release of cultivated micro-organisms Treatment of exhaust air or gas from CS Sampling from CS Addition of materials to CS, transfer of cultivated cells Removal of material, products and effluents from CS Penetration of CS by agitator shaft and measuring devices Foam-out control to the risk category Changing washing facility Disinfection...

Sterilization Of Liquid Wastes

Process organisms which have been engineered to produce 'foreign' products and therefore contain heterologous genes are subject to strict containment regulations. Thus, waste biomass of such organisms must be sterilized before disposal. Sterilization may be achieved by either batch or continuous means but the whole process must be carried out under contained conditions. Batch sterilization involves the sparging of steam into holding tanks, whereas continuous processes would employ the type of...

Plate And Frame Filters

A plate and frame filter is a pressure filter in which the simplest form consists of plates and frames arranged alternately. The plates are covered with filter cloths Fig. 10.8 or filter pads. The plates and frames are assembled on a horizontal framework and held together by means of a hand screw or hydraulic ram so that there is no leakage between the plates and frames which form a series of liquid-tight compartments. The slurry is fed to the filter frame through the continuous channel formed...

The Static Method Of Gassing

Equation Dissolved Oxygen Probe

In this technique, first described by Wise 1951 , the oxygen concentration of the solution is lowered by gassing the liquid out with nitrogen gas, so that the solution is 'scrubbed' free of oxygen. The deoxygenated liquid is then aerated and agitated and the increase in dissolved oxygen monitored using some form of dissolved oxygen probe. The increase in dissolved oxygen j-'ic 9 5. The increase in dissolved oxygen concentration of a solution over a period of aeration. The oxygen transfer rate...

The Tubularbowl Centrifuge

This is a centrifuge to consider using for particle size ranges of 0.1 to 200 am and up to 10 solids in the in-going slurry. Figure 10.16a shows an arrangement used in a Sharpies Super-Centrifuge. The main component of the centrifuge is a cylindrical bowl or rotor A in Fig. 10.16 , which may be of a variable design de- Fig. JO.15. Diagram of basket centrifuge. pending on application, suspended by a flexible shaft B . driven by an overhead motor or air turbine C . The inlet to the bowl is via a...

Mechanically Agitated Reactors

The effect of air flow rate on KLa values in conventional agitated systems is illustrated in Fig. 9.12. The quantitative relationships between aeration and KLa for agitated vessels are considered in the subsequent Volumetric air flow rate volume of air volume1 medium min 1 Fig. 9.12. The effect of air-flow rate on the KLa of an agitated, aerated vessel. Volumetric air flow rate volume of air volume1 medium min 1 Fig. 9.12. The effect of air-flow rate on the KLa of an agitated, aerated vessel....

Trickling Filters

Trickling Filter Schematic

The term filter in this unit operation is a misnomer, as the action of a trickling filter is not one of filtration, but rather it is a fixed film bio-reactor. Settled effluent to be treated is passed down through a packed bed counter-current to a flow of air. Micro-organisms ad hering to the packing matrix adsorb oxygen from the upflowing air and organic matter from the downflowing effluent the latter is then metabolized and the effluent stream's BOD reduced. A conventional trickling filter...

Anaerobic Digestion

Multistage Oxygen Aeration System

Large volumes of wet sludge which are produced in primary and secondary sedimentation tanks may have to be reduced in volume before disposal. This volume of sludge can be reduced by anaerobic digestion. In sludges containing 20,000-60,000 mg dm3 solid matter, 80 of the degradable matter may be digested, which will reduce the solids content by 50 . During anaerobic digestion acid fermenting bacteria degrade the waste to free volatile fatty acids, mainly acetic and propionic acid, which are then...

Activated Sludge Processes

The basic activated-sludge process Fig. 11.4 consists of aerating and agitating the effluent in the presence of a flocculated suspension of micro-organisms on particulate organic matter the activated sludge. This process was first reported by Arden and Lockett 1914 and is now the most widely used biological treatment process for both domestic and industrial wastewaters. The raw effluent enters a primary sedimentation tank where coarse solids are removed. The partially clarified effluent passes...

Cmo

Foam sensing and control unit. vices which have been manufactured include horizontal rotating shafts, centrifugal separators and jets spraying on to deflector plates Hall et al., 1973 Viesturs et al., 1982 . Unfortunately most of these devices have to be used in conjunction with an antifoam. A load cell offers a convenient method of determining the weight of a fermenter or feed vessel. This is done by placing compression load cells in or at the foot of the vessel supports. When...

Co

Prochem Hydrofoil Impellers

The effect of P nicillium chrysogenum mycelium on KLa in a stirred fermenter Deindoerfer and Gaden, 1955 . Fig. 9.17. The effect of P nicillium chrysogenum mycelium on KLa in a stirred fermenter Deindoerfer and Gaden, 1955 . niveus novobiocin fermentation and demonstrated that high dissolved oxygen levels 60-80 occurred in oxygen-limited cultures. It was concluded that, although oxygen was being transferred into solution, the dissolved gas was not reaching a large proportion of the...

Whole Broth Processing

Whole Broth Processing

The concept of recovering a metabolite directly from an unfiltered fermentation broth is of considerable interest because of its simplicity, the reduction in process stages and the potential cost savings. It may also be possible to remove the desired fermentation product continuously from a broth during fermentation so that inhibitory effects due to product formation and product degradation can be minimized throughout the production phase Roffler et al., 1984 Diaz, 1988 . Bartels et al. 1958...

Solid Shear

Pressure extrusion of frozen micro-organisms at around -25 C through a small orifice is a well established technique at a laboratory scale using a Hughes press or an X-press to obtain small samples of enzymes or microbial cell walls. Disruption is due to a combination of liquid shear through a narrow orifice and the presence of ice crystals. Magnusson and Edebo 1976 developed a semi-continuous X-press operating with a sample temperature of - 35 C and an X-press temperature of - 20 C. It was...

Liquid Shear

Disc Bowl Centrifuge Diagram

Liquid shear is the method which has been most widely used in large scale enzyme purification procedures Scawen et al., 1980 . High-pressure homogenizes used in the processing of milk and other products in the food industry have proved to be very effective for microbial cell disruption. One machine, the APV-Man-ton Gaulin-homogenizer The APV Co. Ltd, Crawley, Surrey, U.K. , which is a high-pressure positive displacement pump, incorporates an adjustable valve with a restricted orifice Fig. 10.21...

Valves And Steam Traps

Valves attached to fermenters and ancillary equipment are used for controlling the flow of liquids and gases in a variety of ways. The valves may be 1. Simple ON OFF valves which are either fully open or fully closed. 2. Valves which provide coarse control of flow rates. 3. Valves which may be adjusted very precisely so that flow rates may be accurately controlled. 4. Safety valves which are constructed in such a way that liquids or gases will flow in only one direction. When making the...

Various Approaches To Scale Up And Scale Down Methods

Bubble columns and air-lift vessels tend to be scaled-up on the basis of geometric similarity and constant gas velocity Scragg, 1991 . Under these conditions the KLa and shear rate in the two scales will be similar. The major difference will be the height of the vessels resulting in increased pressure at the base of the larger vessel. This would result in higher oxygen and carbon dioxide solubility which would give a higher KLa but might result in carbon dioxide inhibition. The other problem in...

Centrifugation

Micro-organisms and other similar sized particles can be removed from a broth by using a centrifuge when filtration is not a satisfactory separation method. Although a centrifuge may be expensive when compared with a filter it may be essential when 1. Filtration is slow and difficult. 2. The cells or other suspended matter must be obtained free of filter aids. 3. Continuous separation to a high standard of hygiene is required. Non-continuous centrifuges are of extremely limited capacity and...

References

E, and Millis, N. 1973 Biochemical Engineering. Academic Press, London. Banks, G. T. 1977 Aeration of moulds and streptomycete culture fluids. Topics in Enzyme and Fermentation Biotechnology, Vol. 1, pp. 72-110 Editor Wiseman, A. . Ellis Horwood, Chichester. q f 1979 Scale-up of fermentation processes. Topin Enzyme and Fermentation Biotechnology, Vol. 3, pp. 170-267 Editor Wiseman, A. . Ellis Horwood, Chich- niOMEW W. H. 1960 Scale-up of submerged fermentations. Adv. App....

Removal Of Microbial Cells And Other Solid Matter

Schematic flow diagram for foam fractionation Wane and Sinskey, 1970 . Microbial cells and other insoluble materials are normally separated from the harvested broth by filtration or centrifugation. Because of the small size of many microbial cells it will be necessary to consider the use of filter aids to improve filtration rates, while heat and fiocculation treatments are employed as techniques for increasing sedimentation rates in centrifugation. The methods of cell and cell debris...

Info

A typical power curve for a baffled vessel agitated by a flat-blade turbine. Reynolds number so that the value of x is zero ,nd the value of the Reynolds number is in ,f the values of the exponent, are substituted into M1 9 21 for the zones of viscous and turbulent hm.'l'licn the following terms are given For viscous flow P c xN2D3. 9.22 For turbulent flow P cpN3D5. 9.23 I mi dic-e equations it may be seen that power con-sU ,piion is dependent only on the viscosity of the liquid in...

Auxotrophic Mutant Lysine And Penicillin Share Same Pathway

That they were capable of secreting a range of enzymes and, thus, the strains were presumed to be modified in their secretion mechanisms. It is interesting to note that an improved secreter of a heterologous protein has been isolated using a traditional mutation and selection approach which has been miniaturized and automated. In several cases the examination of randomly selected high-yielding mutants has indicated that their superiority may have been due to modifications of their control...

Plastic Rheology

Bingham Plastic

A rheogram of a Newtonian fluid. Iig. 9.10. A rheogram of a Newtonian fluid. shear rate, for a Newtonian fluid, would produce a straight line, the slope of which would equal the viscosity. Such a plot is termed a rheogram as shown in Fig. 9.10 . Thus, a Newtonian liquid has a constant viscosity regardless of shear, so that the viscosity of a Newtonian fermentation broth will not vary with agitation rate. However, a non-Newtonian liquid does not obey Newton's law of viscous flow and...

Medium Optimization

At this stage it is important to consider the optimization of a medium such that it meets as many as possible of the seven criteria given in the introduction to this chapter. The meaning of optimization in this context does need careful consideration Winkler, 1991 . When considering the biomass growth phase in isolation it must be recognized that efficiently grown biomass produced by an 'optimized' high productivity growth phase is not necessarily best suited for its ultimate purpose, such as...

Medium Formulation

Medium formulation is an essential stage in the design of successful laboratory experiments, pilot-scale development and manufacturing processes. The constituents of a medium must satisfy the elemental requirements for cell biomass and metabolite production and there must be an adequate supply of energy for biosynthesis and cell maintenance. The first step to consider is an equation based on the stoichiometry for growth and product formation. Thus for an aerobic fermentation carbon nitrogen Oz...

Proportional Plus Derivative Control

If proportional plus derivative control is used, the output response to an error will lead to reduced deviations, faster stabilization and a reduced offset Fig. 8.17 compared with proportional control alone. Because the derivative component has a rapid stabilizing influence, the controller can cope with rapid load changes. PROPORTIONAL PLUS INTEGRAL PLUS DERI VATlVr CONTROL The combination of proportional plus integral plUs derivative normally provides the best control possibilities Fig. 8.17 ....

Spiral Cooler

Labile Affect

Flow diagram of a typical continuous sterilization system employing spiral heat exchangers Alfa-Laval Engineering Ltd., Brentford, Middlesex . process is that temperature may be used as a variable in scaling up a continuous process so that the increased V factor may be achieved whilst maintaining the nutrient quality constant. Deindoerfer and Humphrey 1961 attempted to rationalize the choice of time-temperature regime by the use of a Nutrient Quality Criterion Q , based on similar...

H

Culture effluent to effluent collection or to subsequent stages advantageous in the utilization of multiple carbon sources and in the production of secondary metabolites. Harte and Webb 1967 demonstrated that when Klebsiella aerogenes was grown on a mixture of glucose and maltose only the glucose was utilized in the first stage and maltose in the second. Secondary metabolism may occur in the second stage of a dual system in which the second stage acts as a holding tank where the growth rate is...

Sterile Barrier In Fermenter

Industrial Steam Jacketed Vessel Diagram

Finally the steam supply to the steam jacket is stopped. Valve D is closed and valve E opened, thus introducing sterile air into the fermenter to achieve a slight positive pressure in the vessel. Sterilization of the exhaust gas from a fermenter Sterilization of the exhaust gas can be achieved by 0.2-fim filters on the outlet pipe Fig. 5.21 . Under normal operation aerosol formation may occur in the fermenter and moisture and solid matter may then plug the filter. To ensure...

Medium Rheology

Fermentation media frequently contain starch as a carbon source which may render the medium non-Newtonian and relatively viscous. However, as the organism grows it will degrade the starch and thus modify the rheology of the medium and reduce its viscosity. Such a situation was described by Tuffile and Pinho 1970 in their study of the growth of Streptomyces aureofaciens on a starch-containing medium. Before inoculation, the medium displayed Bingham plastic characteristics with a well-defined...

Magnetic Drives

Double Mechanical Seal

The problems of providing a satisfactory seal when the impeller shaft passes through the top or bottom plate of the fermenter may be solved by the use of a magnetic drive in which the impeller shaft does not ponents 1, flexible coupling 2, stirrer shaft 3, bearing housing 4, ball journal fit on mating parts 5, two slots for gland leaks, only one shown 6, 'O'-ring seal 7, seal body 8, stationary counter-face sealed to body with square-section gasket 9, exit port for condensate, fitted with...

Nonmechanically Agitated Reactors

Bubble columns and air-lift reactors are not mechanically agitated and, therefore, rely on the passage of air to both mix and aerate. The flow pattern of bubbles through a bubble column reactor is dependent on the gas superficial velocity cm second 1 . At gas velocities of below 1-4 cm second the bubbles will rise uniformly through the medium Van't Riet and Tramper, 1991 and the only mixing will be that created in the bubble wake. This type of flow is referrred to as homogeneous. At higher gas...

The Improvement Of Industrial Microorganisms

Natural isolates usually produce commercially important products in very low concentrations and there fore every attempt is made to increase the productivity of the chosen organism. Increased yields may be achieved by optimizing the culture medium and growth conditions, but this approach will be limited by the organism's maximum ability to synthesize the product. The potential productivity of the organism is controlled by its genome and, therefore, the genome must be modified to increase the...

Fermentations

Although a consideration of the stoichiometry of respiration gives an appreciation of the problem of oxygen supply, it gives no indication of an organism's true oxygen demand as it does not take into account the carbon that is converted into biomass and products. A number of workers have considered the overall stoichiometry of the conversion of oxygen, a source of carbon and a source of nitrogen into biomass and have used such relationships to predict the oxygen demand of a fermentation. A...

P N D

Where VRc is the Reynolds number and PL is the liquid viscosity. Yet another dimensionless number, termed the Froude number, relates inertial force to gravitational force and is given the term g is the gravitational force. Rushton et al. 1950 demonstrated that the power number was related to the Reynolds and Froude numbers by the general expression where c is a constant dependent on vessel geometry but independent of vessel size, x and y are exponents. Examples of the values of c, x and y are...

Lc

A vessel for the batch sterilization of liquid waste from a contained fermentation Jansson et al, 1990 . Extremely small particles suspended in a fluid are subject to Brownian motion which is random movement due to collisions with fluid molecules. Thus, such small particles tend to deviate from the fluid flow pattern and may become impacted upon the filter fibres. Diffusion is more significant in the filtration of gases than in the filtration of liquids. Charged particles may be...

The Range Of Fermentation Processes

There are five major groups of commercially important fermentations i Those that produce microbial cells or biomass as the product. ii Those that produce microbial enzymes. iii Those that produce microbial metabolites. iv Those that produce recombinant products. v Those that modify a compound which is added to the fermentation the transformation process. The historical development of these processes will be considered in a later section of this chapter, but it is first necessary to include a...

External Feedback

A diagrammatic representation of an external feedback system is shown in Fig. 2.8b. The effluent froni -the fermenter is fed through a separator, such as a continuous centrifuge or filter, which produces two effluent streams a concentrated biomass stream and a dilute one. A fraction of the concentrated stream is then returned to the vessel. The flow rate from the medium reservoir is F dm3 h 1 the flow rate of the effluent upstream of the separator is Fs dm3 h ' and the concentration of biomass...

The Effect Of Microbial Products On Aeration

Generally speaking, the product of a fermentation contributes relatively little to the viscosity of the cul ture broth. However, the exception is the production of bacterial polysaccharides, where the broths tend to be highly viscous 30,000 cp, Sutherland and Ellwood, 1979 and non-Newtonian. Charles 1978 demonstrated that the bacterial cells in a polysaccharide fermentation made a minimal contribution to the high culture viscosity which was due primarily to the polysaccharide product. Normally,...

Scaleup And Scaledown

Aeration And Agitation Fermentation

Scale-up means increasing the scale of a fermentation, for example from the laboratory scale to the pilot plant scale or from the pilot plant scale to the production scale. Increase in scale means an increase in volume and the problems of process scale-up are due to the different ways in which process parameters are affected by the size of the unit. It is the task of the fermentation technologist to increase the scale of a fermentation without a decrease in yield or, if a yield reduction...

Demand

Both the demand for oxygen by a micro-organism and the supply to the organism by the fermenter have been considered in this chapter. This section attempts to bring these two aspects together and considers how processes may be designed such that the oxygen uptake rate of the culture does not exceed the oxygen transfer rate of the fermenter. The volumetric oxygen uptake rate of a culture is described by the term, Qqx, where Qn is the specific oxygen uptake rate mmoles 02 g1 biomass h ' and x is...

Chronological Development Of Fermentation Industry

AN INTRODUCTION TO FERMENTATION PROCESSES 1 The range of fermentation processes 1 The chronological development of the fermentation industry 5 The component parts of a fermentation process 9 References 2. MICROBIAL GROWTH KINETICS 13 Comparison of batch and continuous culture in industrial processes 21 Continuous culture and biomass production 25 Comparison of batch and continuous culture as investigative tools 26 Variable volume fed-batch culture 27 Fixed volume fed-batch culture 28...

Batch Sterilization

Batch And Continuous Sterilization

0 10 30 50 70 90 Duration of sterilization min Fig. 5.5. The effect of the time of sterilization on the yield of a subsequent fermentation Richards, 1966 . The thermal destruction of essential media components conforms approximately with first order reaction kinetics and, therefore, may be described by equations similar to those derived for the destruction of bacteria where xt is the concentration of nutrient after a heat treatment period, t, x0 is the original concentration of nutrient at the...

The Development Of Inocula For Bacterial Processes

The main objective of inoculum development for traditional bacterial fermentations is to produce an active inoculum which will give as short a lag phase as possible in subsequent culture. A long lag phase is disadvantageous in that not only is time wasted but also medium is consumed in maintaining a viable culture prior to growth. The length of the lag phase is affected by the size of the inoculum and its physiological condition Meyrath and Suchanek, 1972 . As already stated, the inoculum size...

Nwu

The occurrence of oxygen limitation during the dynamic gassing out of a fermentation. Tuffile and Pinho 1970 compared a number of methods for the determination of Kta values in viscous streptomycete fermentations. The techniques used were static gassing-out, dynamic gassing-out and the oxygen-balance method. Tuffile and Pinho did not make it clear whether non-respiring mycelium was present during their static gassing-out procedure, but from their results it would appear that it was...

Metabolite Productivity

Theoretically, a fermentation to produce a metabolite should also be more productive in continuous culture than in batch because a continuous culture may be operated at the dilution rate which maintains product output at its maximum, whereas in batch culture product formation may be a transient phenomenon during the fermentation. The kinetics of product formation in continuous culture have been reviewed by Pirt 1975 and Trilli 1990 . Product formation in a chemostat may be described as Change...

T

A feedback control loop Rolf and Lim, 1985 . ture changes from the set point on the thermometer, the operative will take appropriate action and adjust the steam valve to correct the temperature deviation. Should the temperature not return to the set point within a reasonable time, further action may be necessary. Much depends on the skill of individual operatives in knowing when and how much adjustment to make. This approach with manual control may be very costly in terms of labour...

The Dynamic Method Of Gassing

Taguchi and Humphrey 1966 utilized the respiratory activity of a growing culture in the fermenter to lower the oxygen level prior to aeration. Therefore, the estimation has the advantage of being carried out during a fermentation which should give a more realistic assessment of the fermenter's efficiency. Because of the complex nature of fermentation broths the probe used to monitor the change in dissolved oxygen concentration must be of the membrane-covered type which may necessitate the use...

Sterilization Of The Feeds

A variety of additives may be administered to a fermentation during the process and it is essential that these materials are sterile. The sterilization method depends on the nature of the additive, and the volume and feed rate at which it is administered. If the additive is fed in large quantities then continuous sterilization may be desirable, for example, Aunstrup et al. 1979 cited the use of continuous heat sterilization for the feed medium of microbial enzyme fermentations. Aunstrup et al....

Lin j 10111 V cereuimuc

Lr, i , The cyclic fed-batch process gave Jrcc tun'- llu- hirudin activity of a continuous fermen- truiwripiion .,I though a genetic explanation of the . ulisoHilJ not be offered. ' penicillin lei mentation provides an excellent exam-nle of the use of feed systems in the production of a secondary metabolite. The fermentation may be divided into two phases the 'rapid-growth' phase, during which the culture grows at imax, and the 'slow-growth' or -production' phase. Glucose feeds may be used to...

Oxygen Requirements

It is sometimes forgotten that oxygen, although not added to an initial medium as such, is nevertheless a very important component of the medium in many processes, and its availability can be extremely important in controlling growth rate and metabolite production. This will be discussed in detail in Chapter 9. The medium may influence the oxygen availability in a number of ways including the following 1. Fast metabolism. The culture may become oxygen limited because sufficient oxygen cannot be...

X

Sites of the defective enzymes Biosynthetic route Feedback inhibition Feedback repression Control defective Fig. 3.18. The control of the synthesis of purine nucleotides in a mutant defective m adenylosuccinate synthase and IMP dehydrogenase activities. . -,f auxotrophic mutants has resulted m the ' K,',on of nianv microbial products in large concen-proJiK obviOUsly, such mutants are not suitable lrilUS' xnihesis of products which control their own '' . sis' independently. A hypothetical...

Liquids

The flow of non-sterile liquids can be monitored by a number of techniques Howe et al., 1969 , but measurement of flow rates of sterile liquids presents a number of problems which have to be overcome. On a laboratory scale flow rates may be measured manually using a sterile burette connected to the feed pipe and timing the exit of a measured volume. The possible use of rotameters has already been mentioned in the previous section. A more expensive method is to use an electrical flow transducer...

Deep Jet Fermenter

Schematic diagram of 20 m3 bubble column fermenter fitted with internal cooling coil Carrington et al., 1992 . pH and DO indicate positions of pH and oxygen electrodes. and mixing in the middle compartment were found to be comparable with those obtained with conventional internal loop air-lift vessels, although some tangential liquid flow was observed in this compartment. Some designs of continuous culture fermenter achieve the necessary mechanical power input with a pump to...

Pressurereduction Valves

Thermostatic Traps

Pressure-reduction valves are incorporated into pipelines when it is necessary to reduce from a higher to a lower pressure, and be able to maintain the lower Fig. 7.38. Section of a safety valve Kemplay, 1980 . Fig. 7.38. Section of a safety valve Kemplay, 1980 . liquid. Once the pressure falls below the value set by the tensioned spring, the spindle should return to its original position. However, the valve may stick open if waste material lodges on the valve seat and plant operators may...

Technology

Fermentors Line Analyzers

Since the initial use of computers in the 1960s for modelling fermentation processes Yamashita and Mu-rao, 1978 and in process control for production of glutamic acid Yamashita et al., 1969 and penicillin Grayson, 1969 , there have been numerous publications on computer applications in fermentation technology Rolf and Lim, 1985 Bushell, 1988 Whiteside and Morgan, 1989 Fish et al., 1990 . Initially, the use of large computers was restricted because of their cost but reductions in costs and the...

Modification Of The Permeability

Glutamate Synthesis Glutamicum

The best example of the modification of the permeability of a micro-organism is provided by the glutamic acid fermentation. Kinoshita et al. 1957a isolated a biotin-requiring, glutamate-producing organism, subsequently named Corynebacterium glutamicum, the permeability of which could be modified by the level of biotin. Provided that the level of biotin in the production medium was below 5 ig dm3 then the organism would excrete glutamate, but at concentrations of biotin optimum for growth the...

K

Rotating-disc contactors have been used in effluent treatment Chapter 11 . They utilize a growing microbial film on slow rotating discs to oxidize the effluent. Anderson and Blain 1980 have used the same principle to construct small fermenters of up to 40-dm3 working volume. A range of filamentous fungi, including species of Aspergillus, Rhizopus, Mucor and Penicil-liurrt, could be grown on the polypropylene discs. It has been possible to obtain yields of 80 g dm-3 of citric acid from A. niger...

Continuous Culture And Biomass Production

Microbial biomass which is produced for human or animal consumption is referred to as single cell protein SCP . Although yeast was produced as food on a large scale in Germany during the First World War Laskin, 1977 the concept of utilizing microbial biomass as food was not thoroughly investigated until the 1960s. Since the 1960s, a large number of industrial companies have explored the potential of producing SCP from a wide range of carbon sources. Almost without exception, these...

Cyclic fedbatch culture

Where G is the substrate feed rate g dm-3 h ' and Y is the yield factor. Hut d.i dt fxx, thus substituting for dx dt in equation 2.34 gives l'unidcd that GY x does not exceed u,max then the limning substrate will be consumed as soon as it enters the fermenter and ds dt 0. However, dx dt may not he equated to zero, as in the case of variable okiine fed-batch, because the biomass concentration, as well as the total amount of biomass in the fer-mciik-i. will increase with time. Biomass...

The Mechanical Seal

Stirrer Gland Bearing Fermenter

The mechanical seal assembly Figs 7.14 and 7.15 is now commonly used in both small and large fermenters. The seal is composed of two parts, one part is stationary in the bearing housing, the other rotates on the shaft, and the two components are pressed together by springs or expanding bellows. The two meeting surfaces have to be precision machined, the moving surface normally consists of a carbon-faced unit while the stationary unit is of stellite-faced stainless steel. Steam condensate is...

Ho

Fig. 3.34. a Structure of actinorhodin, b structure of medermycin, c structure of mederrhodin Hunter and Baumberg, 1989 . Fig. 3.34. a Structure of actinorhodin, b structure of medermycin, c structure of mederrhodin Hunter and Baumberg, 1989 . the subsequent modification reactions which occur after cyclization. McDaniel et al. 1993 have constructed plasmids coding for recombinant PKSs and achieved expression in Streptomyces coelicolor. Five novel polyketides were synthesized and the system...

Cyclone Fermenter

Cyclone Column Fermenter

Three-compartment multiple air-lift loop fermenter Bakker et al., 1993 . Cross-sectional side and top view. form large air bubbles which are dispersed by the shear of the water jet. In an ejector the liquid jet enters into a larger converging-diverging nozzle and entrains the gas around the jet. The gas which is sucked into the converging-diverging jet is dispersed in that zone. One of the industrial-scale fermenters using the ejector design is marketed by Vogelbusch Vogelbusch AG,...

Continuous Culture

Continuous Culture Microorganisms

Exponential growth in batch culture may be prolonged by the addition of fresh medium to the vessel Provided that the medium has been designed such that growth is substrate limited i.e. by some component of the medium , and not toxin limited, exponential growth will proceed until the additional substrate is exhausted This exercise may be repeated until the vessel is full However, if an overflow device were fitted to the fermenter such that the added medium displaced an equal volume of culture...

Paramagnetic Oxygen Analyser

Paramagnetic Oxygen Analyser

A deflection-type paramagnetic oxygen analyser Brown et at., 1969 . Fig. 8.8. A deflection-type paramagnetic oxygen analyser Brown et at., 1969 . The measurement and recording of the inlet and or exit gas composition is important in many fermentation studies. By observing the concentrations of carbon dioxide and oxygen in the entry and exit gases in the fermenter and knowing the gas flow rate it is possible to determine the oxygen uptake of the system, the carbon dioxide evolution...

Bourdon Tube Pressure Gauge

Aquarium Diaphragm Pump

A cut-away view of a short-form magnetic flowmeter Howe et al., 1969 . the increases and decreases in weight of the various vessels at regular time intervals. Provided the specific gravities of the liquids are known it is possible to estimate flow rates fairly accurately in different feed pipes. This is another technique which may be used with particulate suspensions. Another indirect method of measuring flow rates aseptically is to use a metering pump which pumps liquid continuously...

The Selection Of Nonfoaming Strains

Foaming during a fermentation may result in the loss of broth, cells and product via the air outlet as well nutting the fermentation at risk from contamination see Chapter 9 . Thus, foaming is normally controlled hv cither chemical or mechanical means see Chapters 4 and 7 , hut this task may be made easier if a non-foaming strain of the commercial organism can be developed. Foaming which occurs early in the fermentation is usually due to a component in the medium whereas foaming late in the...

Xj

Aseptic Sampling Werner 1992

An alternative simple sample port. the sample port and the exterior is a condensed flow of steam between valves C and D, valves A and B being closed. Valve D is connected to a steam trap to avoid condensate accumulation. To sterilize valve B prior to sampling, valve C is partially closed, valve D completely closed and valve B partially opened to allow a slow stream of steam and condensate out of the sampling port. Valve A is opened briefly to cool the pipe and the broth is discarded....

V7

Steam Sterilizable Feed Ports Fermentor

Containment sampling unit for Chapter 2 Werner, 1992 . Fig. 7.2S. Containment sampling unit for Chapter 2 Werner, 1992 . At Containment levels 2 and B3 4, probes are fitted with triple 'O'-ring seals Hambleton et al., 1991 . Although double 'O'-ring seals with steam tracing have been described they are not normally considered to be feasible Leaver and Hambleton, 1992 . The use of pre-inserted back-up probes is recommended as a means for dealing with probe failure rather than using a...

Q

the heat transfer surface available, m2, the heat transferred, W, the overall heat transfer coefficient, W m2K, A 7 the temperature difference between the heating or cooling agent and the mass itself, K. The coefficient U represents the conductivity of the system and it depends on the vessel geometry, fluid properties, flow velocity, wall material and thickness Scragg, 1991 . 1 U is the overall resistance to heat transfer analogous to 1 K for gas-liquid transfer Chapter 9 . It is the...

The Elimination Of Undesirable Products From A Production Strain

Athough an industrial micro-organism may produce large quantities of a desirable metabolite it may also produce a large amount of a metabolite which is not required, is toxic or may interfere with the extraction process. Thus, in these circumstances it would be an advantage to alter the strain such that the undesirable product is no longer produced. An example in the penicillin-producing strains is the elimination of the production of the yellow pigment, chrysogenein, by the selection of...

Xxas1122

Where xn is the original biomass concentration, x, is the biomass concentration after the time interval, t hours, e is the base of the natural logarithm. Fig. 2.1. Growth of a typical microbial culture in batch conditions. Fig. 2.1. Growth of a typical microbial culture in batch conditions. On taking natural logarithms, equation 2.2 becomes Thus, a plot of the natural logarithm of biomass concentration against time should yield a straight line, the slope of which would equal fx,. During the...

Aseptic Operation And Containment

Aseptic operation involves protection against contamination and it is a well established and understood concept in the fermentation industries, whereas con tainment involves prevention of escape of viable cells from a fermenter or downstream equipment and is much more recent in origin. Containment guidelines were initiated during the 1970s East et al, 1984 Flickinger and Sansone, 1984 . To establish the appropriate degree of containment which will be necessary to grow a micro-organism, it, and...

Fc Valves Bonnet

Cross Section View Ball Valve

Sectional view of a two-piece gate valve British Valve Manufacturers Association, 1972 . Will the valve serve its chosen purpose Is it suitable for aseptic operation or contained processes, and of the correct dimensions Is the pressure drop across the valve tolerable Will the valve withstand the rigours of the process The materials used to construct the valve should be suited to the process. It is also important to know whether corrosive liquids are used or synthesized during the...

The Isolation Of Mutants Which Do Not Produce Feedback Inhibitors Or Repressors

Mutants which do not produce certain feedback inhibitors or repressors may be useful for the production of intermediates of unbranched pathways and intermediates and end products of branched pathways. Demain 1972 presented several 'blue-prints' of hypothetical mutants producing intermediates and end products of biosynthetic pathways and these are illustrated in Fig. 3.12. The mutants illustrated in Fig. 3.12 do not produce some of the inhibitors or repressors of the pathways considered and,...

The Application Of The Parasexual Cycle

Parasexualism Croosing Over

Many industrially important fungi do not possess a sexual stage and therefore it would appear difficult to achieve recombination in these organisms. However, Pontecorvo et al. 1953 demonstrated that nuclear fusion and gene segregation could take place outside, or in the absence of, the sexual organs. The process was termed the parasexual cycle and has been demonstrated in the imperfect fungi, A. niger and P. chrysogenum, as well as the sexual fungus A. nidulans. In order for parasexual...

Other Fermentation Vessels

Antifoam Baffle Fermented Design

Some of the other forms of fermentation vesels will now be considered. These vessels have more limited applications and have been developed for specific purposes or closely related processes. Some are historical developments, such as the earliest forms of packed tower, others were being developed in parallel with the standard mechanically stirred fermenter during the 1940s, while other approaches are more recent. Aspects of this topic have been reviewed by Prokop and Votruba 1976 , Katinger...

Porous Sparger

Parts Porous Sparger

The porous sparger of sintered glass, ceramics or metal, has been used primarily on a laboratory scale in Fig. 7.16. Diagram of magnetically coupled top stirrer assembly Applikon Dependable Instruments, Schiedam, Netherlands . Retaining nut 6 Bottom end cap j ' Agitator shaft - Fig. 7.16. Diagram of magnetically coupled top stirrer assembly Applikon Dependable Instruments, Schiedam, Netherlands . rj Ball bearing 3 Spacing washer Seal rj Ball bearing 3 Spacing washer Seal Fig. 7.17. Diagram of...

Microbial metabolites

Primary And Secondary Metabolites

The growth of a microbial culture can be divided into a number of stages, as discussed in Chapter 2. After the inoculation of a culture into a nutrient medium there is a period during which growth does not appear to occur this period is referred to as the lag phase and may be considered as a time of adaptation. Following a period during which the growth rate of the cells gradually increases the cells grow at a constant, maximum rate and this period is known as the log, or exponential, phase....

Microbial enzymes

Enzymes have been produced commercially from plant, animal and microbial sources. However, microbial enzymes have the enormous advantage of being able to be produced in large quantities by established fermentation techniques. Also, it is infinitely easier to improve the productivity of a microbial system compared with a plant or animal one. Furthermore, the advent of recombinant DNA technology has enabled enzymes of animal origin to be synthesized by microorganisms see Chapter 3 . The uses to...

Fedbatch Culture

Yoshida et al. 1973 introduced the term fed-batch culture to describe batch cultures which are fed continuously, or sequentially, with medium, without the removal of culture fluid. A fed-batch culture is established initially in batch mode and is then fed according to one of the following feed strategies i The same medium used to establish the batch culture is added, resulting in an increase in volume. ii A solution of the limiting substrate at the same concentration as that in the initial...

The Isolation Of Resistant Mutants

The isolation of analogue-resistant mutants has already been discussed in the field of primary metabolism, where the rationale was that a mutant resistant to the inhibitory effects of an analogue, which mimics the control characteristics of the natural metabolite, may overproduce the natural metabolite. This approach has been adopted, or may be adopted, in a number of guises in the field of secondary metabolism. i Mutants may be isolated which are resistant to the analogues of primary metabolic...

The Chronological Development Of The Fermentation Industry

The chronological development of the fermentation industry may be represented as five overlapping stages microbial cells such that the recipients are capable of synthesizing 'foreign' or heterologous proteins. A wide range of microbial cells have been used as hosts for such systems including Escherichia coli, Saccharomyces cerevisiae and filamentous fungi. Products produced by such genetically engineered organisms include interferon, insulin, human serum albumin, factors VIII and IX, epidermal...

Gmcsf

Cancer chemotherapy Bone marrow transplantation Haemophilia Cancers, hepatitis B, leukaemia Cancers, amyotrophic lateral sclerosis, genital warts Cancers, AIDS-related complex, sidered Ward et al., 1990 Dunn-Coleman el al., 1991 . Bovine chymosin is an aspartyl protease extracted from the abomasum of unweaned calves and is used as a milk-clotting agent in the manufacture of cheese. Its natural source means that the enzyme is available only in limited quantities which made the possibility of...

The Isolation Preservation and Improvement of Industrially Important Microorganisms

THE ISOLATION OF INDUSTRIALLY straints of the process. Bull et al. 1979 cited a number IMPORTANT MICRO-ORGANISMS of criteria as being important in the choice of organism The most publicized advances in biotechnology over the last ten years have been those in recombinant DNA technology. Whilst these advances have resulted in the development of extremely valuable new commercial processes and have improved many others, it is worthwhile reiterating Buckland's 1992 comment that the combined sales of...

The Preservation Of Industrially Important Microorganisms

The isolation of a suitable organism for a commercial process may be a long and very expensive procedure and it is therefore essential that it retains the desirable characteristics that led to its selection. Also, the culture used to initiate an industrial fermentation must be viable and free from contamination. Thus, industrial cultures must be stored in such way as to eliminate genetic change, protect against contamination and retain viability. An organism may be kept viable by repeated...

The Isolation Of Revertant Mutants

As discussed in the section on primary metabolites, a mutant may revert to the phenotype of its 'parent', but the genotype of the revertant may not, necessarily, be the same as the original 'parent'. Some revertant aux-otrophs have been demonstrated to accumulate primary metabolites Shiio and Sano, 1969 and attempts have been made to apply the technique to the isolation of mutants overproducing secondary metabolites. Two approaches have been used in the field of secondary metabolites with...

Introduction

Detailed investigation is needed to establish the most suitable medium for an individual fermentation process, but certain basic requirements must be met by any such medium. All micro-organisms require water, sources of energy, carbon, nitrogen, mineral elements and possibly vitamins plus oxygen if aerobic. On a small scale it is relatively simple to devise a medium containing pure compounds, but the resulting medium, although supporting satisfactory growth, may be unsuitable for use in a large...

Aeration And Agitation

Aeration and agitation will be considered in detail in Chapter 9. In this chapter it should be stated that the primary purpose of aeration is to provide microorganisms in submerged culture with sufficient oxygen for metabolic requirements, while agitation should ensure that a uniform suspension of microbial cells is achieved in a homogeneous nutrient medium. The type of aeration-agitation system used in a particular fermenter depends on the characteristics of the fermentation process under...

Orifice Sparger

Various arrangements of perforated pipes have been tried in different types of fermentation vessel with or without impellers. In small stirred fermenters the perforated pipes were arranged below the impeller in the form of crosses or rings ring sparger , approximately three-quarters of the impeller diameter. In most designs the air holes were drilled on the under surfaces of the tubes making up the ring or cross. Walker and Holdsworth 1958 commented that in production vessels, sparger holes...

Filter Sterilization

Suspended solids may be separated from a fluid during filtration by the following mechanisms iii Electrostatic attraction. Suspended particles in a fluid stream have momentum. The fluid in which the particles are suspended will flow through the filter by the route of least resistance. However, the particles, because of their momentum, tend to travel in straight lines and may therefore become impacted upon the fibres where they may then remain. Inertial impaction is more significant in the...

Alfa Laval Spiral Heat Exchanger

System Engineering Process Spiral

The design of continuous sterilization cycles may be approached in exactly the same way as for batch sterilization systems. The continuous system includes a time period during which the medium is heated to the sterilization temperature, a holding time at the desired temperature and a cooling period to restore the medium to the fermentation temperature. The temperature of the medium is elevated in a continuous heat exchanger and is then maintained in an insulated serpentine holding coil for the...

Sandwich Technique Auxotroph

The use of the penicillin selection method for the isolation of auxotrophic mutants of C. glutamicum Abe, 1972 . medium only the prototrophs will germinate and subsequent treatment of the spore suspension with a suitable compound would kill the germinated prototrophic spores but leave the ungerminated auxotrophic spores unharmed. The auxotrophic spores may then be isolated by washing, to remove the inhibitor, and cultured on supplemented medium. Ganju and Iyengar 1968 developed a...

Examples Of The Use Of Auxotrophs For The Production Of Primary Metabolites

Lysine Biosynthesis Glutamicum

Many auxotrophic mutants have been produced from C. glutamicum for the synthesis of both amino acids and nucleotide related compounds. C. glutamicum is a biotin-requiring organism which will produce glutamic acid under biotin-limited conditions but it is important to remember that mutants of this organism, employed for the production of other amino acids, must be supplied with levels of biotin optimum for growth. Biotin-limited conditions will result in these mutants producing glutamate and not...