The fermentation technologist should be aware of the problem of assessing market potential, although he/she may not be primarily involved in collating or assessing the necessary data. Some aspects have been considered by MacLennan (1976), Hepner (1977), Law-son and Sutherland (1978) and Keim and Venkatasub-ramanian (1989).
Four categories of microbial product can be recognized economically and it is important to consider to which category a compound belongs:
1. Low price bulk chemicals, e.g. solvents, biomass high fructose syrups (US$102-103 tonne
2. Mid price chemicals, e.g. organic acids, amino acids, bipolymers ($103-105 tonne"1).
3. High price microbial and animal-cell products, e.g. enzymes, vitamins, antibiotics, corticosteroids, vaccines, etc. ($105-107 tonne"1'.
4. Very high-price animal-cell products, e.g. mono-clonals, tissue plasminogen activator, etc. ($107-109 tonne"1).
The third and fourth groups can normally be produced only by a microbial or animal-cell based process and therefore do not have to compete with an alternative chemical process which is usually much cheaper. This includes compounds which have complicated structures, are chemically or thermally unstable or for which a multi-stage chemical synthesis would be expensive. Many microbial products are not exploited because cheaper synthetic processes are available.
Hepner (1977, 1978) has examined the factors that determine the feasibility of large-scale ethanol production by fermentation. He considered that ethanol produced by fermentation would only be competitive with synthetic ethanol from crude oil if the fermentation plant was in an area where cheap supplies of carbohydrate were available. In an example based on 1977 costs, if crude oil cost $100 tonne"1, fermentation produced ethanol would be financially viable only if raw-sugar feedstock cost less than $109 tonne"1 or molasses cost less than $75 tonne" KHepner, 1978). In Brazil in 1975, an ethanol production programme using sugar-cane as a substrate was started so that the petroleum imports could be reduced. During 1977, 7 X 108 dm3 of ethanol were produced and it was hoped to have increased production to 1.5 X 109 dm3 during 1979. The ethanol, although subsidized by the Brazilian government, was selling at $1 per 4.5 dm3, which was more than the cost of petrol refined from imported oil (Hammond, 1978). Other aspects of potential ethanol production have been discussed by Bu'Lock (1979).
It is necessary to estimate the size of the present and potential market and the increase in demand for a compound. This type of exercise was undertaken for single-cell protein (MacLennan, 1976; Taylor and Senior, 1978). Taylor and Senior (1978) gave summaries of major single-cell protein plants which were operational or planned, estimates of single-cell protein production in 1980 and 1985 and predicted world supply and demand for high-quality protein meal. It was estimated that by 1985 there would be a market of 5 X 106
Table 12.2. Criteria for strain improvement (Schwab, 1988)
Impact on process or product
Improvement of titre and/or specific production rate
General decrease of production costs, improved exploitation of reactor capacity, lower investment costs, increased efficiency in downstream processing steps
Improvement of yield
Lower costs for substrates, decreased production of heat and C02, lower cooling costs, less waste and pollution
Use of more favourable substrates (less expensive, better availability, etc.), omission of pretreatment steps (e.g. enzymatic hydrolysis of polysaccharides).
Improvement of technological features of micro-organisms (e.g. flocculation behaviour, structure of mycelium, sporulation, foaming, strain stability, etc.)
Improvement of product quality
Decreased production of specific by-products (fewer impurities), prevention of product degradation (e.g. pectinases)
Improvement of solubility in extraction solvents (e.g. addition of specific side chains), increased thermic stability of altered enzymatic properties of proteins
Changing of the locus of product accumulation (e.g. intra cellular to extra-cellular)
Improved product recovery (e.g. omission of cell disruption), correct products (e.g. fully processed proteins).
tonnes annum for single-cell protein world wide, whereas production would only be 2.9 X 106 tonnes annum '. Such predictions supported the establishment of a process by ICI pic. Unfortunately the product which was marketed as an animal protein feed during the 1980s could not compete for price with soya beans and the manufacturing plant was closed down (Sharp, 1989).
Ratafia (1987) estimated the world markets in 1991
for products that can be made by mammalian cell culture to be as follows ($ X 106): diagnostics 6500, vaccines 5200, hormones 4900, lymphokines 1750, monoclonal antibodies 1700, other products 3040. The largest market for a cell culture product was indentified for tissue plasminogen activator (tPA) which was being used in clinical trials and proving effective in dissolving several forms of blood clots. Datar et al. (1993) have estimated the potential number of patients in the
Table 12.3 Panlab's penicillin strain-development programme, P-line, showing yields in units cm~3 from data supplied by Panlabs Inc.
(Queener and Swartz, 1979)
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