Single Cell Protein SCP Process,Carbon Source,Chlorella, Scenedesmus, Spirulina,N-Alkanes, Gaseous Hydrocarbons, Methanol, Ethanol,Saccharomycopsis Lipolytica,Alkaline Hydrolysis, Chemical Extraction

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	Single Cell Protein SCP Process - Regardless of the type of substrate or organism employed, the production of SCP involves following basic steps: (i) preparation of suitable medium with suitable carbon source; (ii) prevention of contamination of medium and the plant; (iii) production of the desired micro organism; (iv) separation of microbial biomass and its processing. The medium for SCP production varies according to the micro organism. Among other things, the medium must contain a carbon source for cultivating the heterotrophic micro organisms, although green algae (Chlorella, Scenedesmus, Spirulina, etc.) can be cultivated autographically without a dissolved carbon source.
The carbon sources for heterotrophic organisms can be divided into two groups, namely fossil and renewable. Fossil carbon sources include n-alkanes, gaseous hydrocarbons, methanol, ethanol, etc. and the renewable sources include CO2 molasses, whey, polysaccharide hydrolysates, effluents (of breweries, distilleries, confectioneries industries, potato and canning industries and wood pulp industries) or other solid substrates. In most of the industrial establishments, n-alkanes appear to be preferred carbon source. In addition to the alkane fraction, salts of pol-, K+, Mi+, Mn2+, Zn2+, Fe2+ and gaseous ammonia (as source of nitrogen) are also added for cultivating many microorganisms including Saccharomycopsis lipolytica.
Production of mushrooms (fruiting bodies of higher fungi) has also acquired importance in several countries in recent years, since it is considered to be a delicacy for human food. These are cultured on solid substrates which range from straw and composted straw to pieces of wood and sawdust. World production of the common type of mushroom exceeds 106 tonnes per year. At the University of Waterloo (Canada), success has been achieved in initiating a new project where the fungus Chaetomium cellulyticum is cultured on a variety of agricultural and forestry wastes. In most of the industrial systems for biomass production, it is desirable to keep the medium and the plant free from contamination. The circulating air and the gaseous components of the medium (NH3' CO2, etc.) are sterilized by passing through filters. Other components are sterilized by steam, in most cases. The fermentation equipment is also sterilized.
The desired microorganism is cultured on the medium under dean conditions. The organism to be cultured on the medium must have the following basic properties: (i) it should be non pathogenic to plants, animals and to humans; (ii) it should have good nutritional value; (iii) it should be usable as food or feed; (iv)it should not contain any toxic compound; (v) its production cost should be low.
	The choice of the fermenter (cultivation vessel) depends upon the microorganisms. Aeration is an important operation in the cultivation. Heat is generated during cultivation, and it is to be removed by using a cooling device. The production is usually continued for indefinite period for maximum economy. Using such a fermenter, it is possible to produce about 4-30gIl of microbial biomass at 38-40°C and pH 6.8. The microbial biomass can be harvested by a variety of methods. Single cell organisms like yeast and bacteria are normally recovered by centrifugation. Filamentous organisms are recovered by filtration. It is important to recover as much water as possible prior to final drying. The whole operation is to be done under clean and hygienic conditions to keep the product and the broth, that leaves the Plant free of bacterial contamination. The final dried products are normally bacteriologically stable.

if handled properly. In some cases, an after treatment of the biomass is desirable to reduce the unwanted compounds in the product or to isolate the protein. One of the important tasks is to reduce nucleic acid content, which is high in microorganisms (4-6% in algae, 10-16% in bacteria, 6-10% in yeasts and 2.5-6% in fungi) and can be hazardous to health.

Some of the methods employed for reducing nucleic acid content in microbial biomass are, alkaline hydrolysis, chemical extraction, and activation of endogenous nucleases during final stage of microbial biomass production.