108 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
Table 20.— Estimated Annual Yeast Production, 1977 
(dry tonnes) 
Baker’s yeast 
Dried yeast' 
Europe 
74,000b 
160,000b 
North America 
73,000 
53,000 
The Orient 
15,000 
25,000 
United Kingdom 
15,500 
n 
South America 
7,500 
2,000 
Africa 
2,700 
2,500 
Totals 187,700 242,500 
®Dried yeast includes food and fodder yeasts: data for petroleum-grown yeasts 
are not available. 
*i*Production figures for U.S.S.R. not reported. 
'-None reported. 
SOURCE: H. J. Peppier and D. Perlman (eds.), Microbial Technoiogy, vol. 1 (Lo,’- 
don: Academic Press, 1979), p. 159. 
Table 21.— Classification of Yeast-Related 
U.S. Patents (1970 to July 1977) 
Category Number issued 
Yeast technology (apparatus, processing) .... 22 
Growth on hydrocarbons 28 
Growth on alcohols, acids, wastes 22 
Production of chemicals 14 
Use of baking and pasta products 24 
Condiments and flavor enhancers 18 
Reduced RNA 11 
Yeast modification of food products 13 
Isolated protein 5 
Texturized yeast protein 7 
Lysates and ruptured cells 7 
Animal feed supplements 12 
Total 183 
SOURCE; H. J. Peppier, “Yeast,” Annual Report on Fermentation Processes, D. 
Perlman (ed.), vol. 2 (London: Academic Press, 1978), pp. 191-200. 
several factors. For each bacterial, yeast, or 
algal strain used, technological problems (from 
the choice of micro-organisms to the use of cor- 
responding raw material) and logistical prob- 
lems of construction and location of plants have 
arisen. But the primary limitation so far has 
been the cost of production compared with the 
costs of competing sources of protein. (The com- 
parative price ranges in 1979 for selected 
microbial, plant, and animal protein products 
are shown in table 22.) 
Table 22.— Comparison of Selling Price Ranges 
for Selected Microbial, Plant, and Animal 
Protein Products 
Product, substrate, and quality 
Crude 
protein 
content 
Price range 
1979 U.S. 
dollars/kg 
Single-cell proteins 
Candida utilis, ethanol, food grade 
52 
1.32-1.35 
Kluyveromyces fragilis, cheese 
whey, food grade 
54 
1.32 
Saccharomyces cerevisiae: 
Brewer’s, debittered, food grade 
52 
1.00-1.20 
Feed grade 
52 
0.39-0.50 
Plant proteins 
Alfalfa (dehydrated) 
17 
0.12-0.13 
Soybean meal, defatted 
49 
0.20-0.22 
Soy protein concentrate 
70-72 
0.90-1.14 
Soy protein isolate 
90-92 
1.96-2.20 
Animal proteins 
Fishmeal (Peruvian) 
65 
0.41 -0.45 
Meat and bonemeal 
50 
0.24-0.25 
Dry skim milk 
37 
0.88-1.00 
SOURCE: Office of Technology Assessment. 
Agriculture (USDA), total domestic and e.xport 
supply for U.S. soybeans will gi'ow 7.1 pcM’cent 
by 1985. 
Soybeans are primarily consumed as animal 
feed. But while only 4 pei'cent of their annual 
production are directly consumed by humans, 
the market is growing significantly. The in- 
troduction of improved te.xtured soy proU'in in 
cereals, in meat substitutes and e.xtendei's, and 
in dairy substitutes has incrc^a.sed the us(' of .soy 
products. Nevertheless, the markc't does not de- 
mand soy products in particular’ hut pi’otein 
supplements, vegetable oils, feed gr ain supple- 
ments, and meat extendcM's in gcMKM’al. Otlier 
protein and oil sources could r-eplace sox heans 
if the economics were attr’actii'e enough. Fish- 
meal, di'v beans, SCP, and cer’eals ar-e all jioten- 
tial competitor's. As long as a suhstilule can 
meet the nutritional, fla\'or', toxicity, and r’cgula- 
tory standards, competition will h(> pr'imar’ily 
based on price. 
The costs of manufacturing SCP for animal 
feed in the United States are high, particularly 
relative to its major competing protein source, 
soybeans, which can be produced with little fer- 
tilizer and minimal processing. The easy avail- 
ability of this legume severely limits microbial 
SCP production for animal feed or human food. 
In fact, according to the U.S. Department of 
The competition between .soylx'ans and S( P 
illustrates one ol the par'adoxes of genetic engi- 
neering. While signifi('ant rr'sear’ch is attempt- 
ing the genetic impr’o\'ement of .soybeans, ge- 
netic techniques ar'e also lu'irig explor-ed to in- 
crease the production of SCI’. C()nse(|uently, the 
same tool— genetic engiiK'eiing— encourages 
competition between the two commoditii's 
