Micro-organisms as a Source

Different subspecies have been shown to be active against different orders of insect. Although the method of insect death is the same, the different endotoxins either have different binding regimes or are activated by the gut enzymes of different insect species and this leads to the differences in activity spectrum. There is evidence, however, that different insect orders act upon the delta-endotoxins in different ways. Treatment of a pro-toxin with lepidopteran gut juice leads to a toxin that is active against Lepidoptera whereas treatment with dipteran gut juice produces 

Bt israelensis (Bti) Cry4A, Cry4B, Cry4C Cry4D Diptera 

As these toxins are proteins it is possible to isolate the genes that code for them and use these genes to transform crop plants and thereby render them insecticidal. This is discussed briefly under Transgenic Crops (Section 6). 

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In this chapter we examine the processes that have been developed to produce micro-organisms as a source of food protein. We will examine the reasons why micro-organisms have been considered as alternative protein sources, the substrates on which they have been grown, the various process technologies developed and the comparative economics of these processes. One process will be examined in depth, to illustrate how a team composed of such diverse people as microbiologists, process engineers, patent lawyers and cost analysts work together to develop a marketable product. 

Looking at the biological function, the primary extractives are necessary for maintaining the metabolism and supply of the components for the biosynthesis of the secondary substances. Typical primary substances include carbohydrates (sugars), which can be found for example as monosaccharides, disaccharides and as starch as well as fats and proteins. As sapwood is responsible for the constant water and nutrient supply of the whole tree, mainly primary extractives are involved, which are also used by various micro-organisms as a source of food. 

You may be wondering why anyone should ever have considered using micro-organisms as a protein source. Let us consider why this should have been. 

The efficacy of chemical and photochemical decolourization of dyes in the effluent of textile factories has been proved many times. However, in the majority of cases these methods are relatively expensive and the solid catalysator used for the oxidation sometimes presents a new problem for environmental protection. Microbiological methods are less expensive, the dyes are decomposed to small organic and inorganic molecules which can be taken up by micro-organisms as carbon and nitrogen sources. Also, in the case of microbiological decomposition of dyes, liquid chromatographic techniques can be... 

One of the limitations of milk as a raw material is its perishability - it is an excellent source of nutrients for micro-organisms as well as for humans. However, this perishability is readily overcome by a well-organized, efficient dairy industry. 

Micro-organisms form a very important source of fouling various authors [66,67] report a strong decline in flux, even as much as 70% of the original value, in the presence of micro organisms. 

Sulphur is found widely in nature. Inorganic sulphates can be reduced via sulphide to be incorporated into amino acids. Some micro-organisms can use hydrogen sulphide as a source of sulphur, organo-sulphur compounds may also provide microbial sulphur. 

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