Single cell protein

SINGLE CELL PROTEIN (SCP)

Some microorganisms like bacteria, blue green algae, yeasts and filamentous algae are used as food and are called SCP.

They are processed to remove excess nucleic acid.

The raw materials for single cell protein production include whey, sulphite waste liquours, hydrocarbon waste from petroleum industry, waste water containing starch from potato processing plants, straw, molasses and animal manure.

The microorganisms are grown in large fermenting tanks with forced aeration for vigorous cell growth. Microorganisms which can be explored for obtaining SCP are:

(i) Algae : Spirulina, Scenedesmus, Chlorella

(ii) Fungi : Fusarium graminearum, Candida utilis, Trichoderma viride

(iii) Bacteria : Achromobacter, Cellulomonas, Methylophilus methylotrophus (Source of Pruteen) : 250 g of this microorganism can be expected to produce 25 tonnes of protein per day.

GREEN MANURE

It is a manure prepared from young, green crop plants by ploughing them back into soil.

Usually, young leguminous crops are used for green manuring because they also increase the nitrogen fertility of the soil.

The plants commonly used for green manuring in India are : Sunn Hemp (Crotolaria juncea), Dhaincha (Sesbania aculeata), Cluster Bean (Cyamopsis tetragonoloba), Sweet Clover (Melilotus parviflora), Cowpea (Vigna sinensis), Horse Gram (Dolichos uniflorus), Egyptian clover (Berseem, Trifolium alexandrinum), Lentil (Lens esculenta).

The plants are rich in nitrogenous compounds because of the presence of nodules on the roots. Sesbania rostrata possesses such nodules on the stem (caulinary nodules) as well.

The plants are slowly converted into manure through the activity of microorganisms. Green manures have all the benefits of farmyard manure.

Additionally, they increase nitrogenous content of the soil, reduce alkalinity and prevent soil erosion.

It is found that green manures increases crop yield by 30-50% as compared to farmyard manure.

ENERGY CROPS

In the face of rising prices and shortage of fossil fuel, attempts are being made to use alcohol for running automobiles.

Both ethanol (ethyl alcohol) and methanol (methyl alcohol) can be used for this purpose.

Proalcohol programme of Brazil envisages the complete replacement of petrol or gasoline with alcohol.

Gasohol programme of U.S.A. contemplates 10-15% blend of alcohol with petrol. While Brazil is concentrating on preparing alcohol from Sugarcane, U.S.A. is experimenting with Maize.

Besides Sugarcane and Maize, other crops which can be used for production of alcohol are Potato, Sugar beet, Tapioca and molasses of sugar industry.

Growing crops for production of alcohol and other fuels is known as energy cropping.

The existing gasoline engines require only little modification for using gasohol or pure alcohol.

One problem with employing alcohol as fuel is the cost of production. Another problem is the reduction in agricultural land.

This will reduce the amount of food available for feeding human population.

PETROLEUM PLANTS

Nobel Laureate, Melvin Calvin, suggested that the shortage of petrol can be overcome by extracting them from certain plants popularly called petroleum plants.

The plants produce a large amount of latex. Latex contain long chained liquid hydrocarbons.

These long chained hydrocarbons can be used directly or broken to hydrocarbons of chain length similar to the ones present in petrol.

Petroleum plants belong to families Euphorbiaceae, Asclepiadaceae, Apocyanaceae and Asteraceae.

The two plants investigated for petroleum products are Euphorbia lathyrus (family Euphorbiaceae) and Brickellia species (family Asteraceae).

Other useful plants are - Jatropha curcas and Pongamia pinnata. Limitation : Commercial exploitation of petroleum plants seems to be not yet feasible because the product would be too expensive.