Protein made from bugs

Press, 2 May 1981, Page 14

Protein made from bugs

Single-cell protein (SCP) was one of the technologies of the 1970 s that flopped. Now it looks as if something may be salvaged from the wreckage, especially in countries rich in either oil or waste carbo-hy-drates. -SCP consists of one-celled microbes, such as bacteria and yeast, whose body weight is high in protein. The original idea was to grow millions of tonnes of these microbes, to be sold to farmers as a cheap food supplement for livestock. But the bugs were to be grown on an oil-based diet. Rises in oil prices knocked one big hole in the economics of SCP. Regulators knocked another hole, as concern arose — albeit sometimes on dubious scientific evidence — about the safety of meat from animals fed on oilbased feedstuffs. Apart from the Soviet Ministry for Microbiological Industry, Britain’s ICI was the only large organisation to persevere with SCP. Its first commercial plant is now producing 4000

From “The Economist,” London

tonnes of bacterial protein* a month. But the price of natural gas, from which methanol " is derived to feed the bacteria, is still rising and IGI needs to -. make its process more efficient, if it is to justify a larger; , second-generation plant, pro- > ducing 250,000 tonnes a year or . more, that it has under consid- ; oration. Still, the company is _ gaining experience of operating “ ' in sterile conditions which ' could be of value in launching other products most likely in the .pharmaceutical field. ■ In Arab countries, on the other hand, the arithmetic of SCP looks much more promis-’ ing. There, natural gas is being wastefully flared, : while demand for meat is rising and grazing land for livestock is in short suppl}’. SCP is an obvious means of matching this supply of gas to the demand forprotein and several Arab countries are now developing their own SCP technology, designing plants with enough capacity-to meet the needs of an Arab

a ' country's livestock: 50,000 - 1 100,000 , tonnes a year. The s .Arabs are pushing ahead with s'.;' their technology partly with o’.-help from scientists made re- - dundant by closures of Western SGP programmes. . Other countries are looking r at how to produce SCP without [- ■ 'oil: or gas,-using carbohydrates.! s Carbohydrates are 'the natural g foodstuff of many types of h microbe and can be obtained g fairly cheaply wherever there n:. is either surplus land or unutilised., crop wastes. Because carbohydrates .come in many , forms, each source is likely to [■ -need its own process technology.- West Hoechst »;•. is “involved in adjoint project ’ , with the Indonesian .Governp : ment to' develop • SCP! produc- ) tion from cassava. Finland is 5 looking -at SCP from sulphite z liquor, a waste product of pulp r ..'.';and . paper . mills. Straw, j .i' ■ sajvdust . and fast-growing [■. woody plants', are also good < candidates for SGP production, y Drawbacks of Chemical pro- , cesses using carbohydrates include the seasonality of crops and the high transport costs involved in collecting crops over wide areas. • But Brazil’s ethanol-from-sugar programme — intended to produce gasohol for cars rather than SCP — shows that these drawbacks of • , carbohydrates can be over- * come. To minimise transport costs, each ethanol plant will i gather sugar cane from an area only 25 kilometres in diameter, sufficient to produce 30,000 tonnes of ethanol a year. To extend the harvest season to seven months a year, Brazil is planting a mix of cane varieties that will be ready for harvesting at different seasons. Interestingly, Brazil plans to make chemicals, as well as gasohol, from sugar. By 1985, it will convert 15 per cent (1.2 M tonnes) of its ethanol produc- , tion into ethylene and other chemical derivatives. It is dei veloping economic technology 1 for plants producing 20,000I 40,000 tonnes of • ethylene a ’year. Meanwhile, ethanol is being < used in the United States in 1 one small SCP project. The [ ethanol is fed to yeast and the yeast used as an additive to -• human foods. This SCP is being i sold not for its nutritive value ■ but for its functional proper- ) ties. Addition of small quantities of yeast to processed foods can aid fat binding, gel formation. whippability, etc. Pure > Culture Products, a Chicagobased company, is producing .5000 tonnes of yeast a year for . such purposes. It is now thinking of setting up a plant in Europe.