Microbial cells fungi

Single cell protein, normally called simply SCP, is the term used to describe microbial cells, or proteins from them, which are used as food (food for humans) or feed (food for farm animals or fish). Although the term micro-organisms covers viruses, bacteria, fungi, algae and protozoa, viruses and protozoa are not considered suitable for SCP production. 

Micro-organisms are rich in protein. Microbial cells can contain as much protein as conventional foods. Bacteria can contain 60-65% (as a % of dry weight) protein whereas fungi and algae contain about 40%. In addition, microbial cells can be a rich source of fibre, unsaturated fats, minerals and vitamins. They are low in saturated fats and sodium. 

The air that we breathe is full of microbial cells and spores of bacteria and fungi. Because they are extremely light they are readily are carried by wind currents. In hot weather soil, a rich source of all types of microbes, turns to dust and increases the airborne microbial population... 

Most of the antibiotics commercially available nowadays are derivatives of natural compounds produced by bacteria or fungi. It is widely accepted that in nature these secondary metabolites can act as weapons for microbial cell defence, inhibiting the growth of competitors. However, it seems that antibiotics have, in nature, more sophisticated and complex functions [1-3]. Many environmental bacteria can not only cope with natural antimicrobial substances but also benefit from their presence. For instance, the use of antibiotics by bacteria as biochemical signals, modulators of metabolic activity or even carbon sources has been demonstrated [1, 2, 4]. In other cases, antibiotics can be tolerated because they have structures similar to the natural substrates of bacterial housekeeping enzymes and thus are inactivated, leading to a natural form of resistance [2]. These are just some... 

Source. Enzymes for food applications come from all three kingdoms plant, animal, and microbial. Traditionally used plant and animal enzymes are the plant proteases such as papain, ficin and bromelain, plant amylases from malt, and animal rennin which is used in cheese manufacture. Microbial cells are the usual and most promising future source of industrial enzymes. Estimates of the number of microorganisms in the world tested as potential sources of enzymes fall around 2% with only about 25 organisms, including a dozen or so fungi, currently used for industrial enzymes. 

Non-enzymatic attack In non-enzymatic attack of minerals by microbes, reactive products of microbial metabolism come into play. The microbial enzymes responsible for metabolic product formation are located below the cell envelope, in the cytoplasm of prokaryotes (Bacteria and Archaea) and in cell organelles and/or the cytoplasm of eukaryotes (e.g. fungi, algae, lichens). In these instances of microbial attack, physical contact of the microbial cells with the surface of a mineral being attacked is not essential. The reactive metabolic products are formed intracellularly and are then excreted into the bulk phase where they are able to interact chemically, i.e. non-enzymatically, with a susceptible mineral. Depending on the type of metabolic product and mineral, the interaction with the mineral may result in mineral dissolution or mineral diagenesis by oxidation or reduction or acid or base attack. Mineral dissolution or diagenesis may also be the result of complexation by a microbial metabolic product with that capacity. In some instances mineral attack may involve a combination of some of these reactions. 

Cell walls are biochemically rather inert with reduced digestibility to many organisms because of their complex cellulose, pectin, and lignin molecules. Callose and lignin are often accumulated at the site of infection or wounding (6,7) and form a penetration barrier. Synthesis of inhibitory proteins (e.g., lectins, protease inhibitors) or enzymes (e.g., chitinase, lysozyme, hydrolases, nucleases) that could degrade microbial cell walls or other microbial constituents would be protective, as well as synthesis of peroxidase and phe-nolase, which could help inactivate phytotoxins produced by many bacteria and fungi. These proteins are either stored in the vacuole... 

Joosten, V., Lokman, C., Hondel, C., Punt, P.J., The production of antibody fragments and antibody fusion proteins by yeasts and filamentous fungi. Microbial Cell Factories 2003, 2, 1-15. 

Release of compound from intracellular milieu/cell mass and removal of bulk of biomass. Most of the bulk of the biomass (plants or microbes) exists as fairly inert, insoluble, and often polymeric material, such as the cellulose of plants or fungi and the microbial cell wall. The first step of the extraction is to release and... 

On the surface of the soil, residues are attacked by bacteria, fungi and animals. In the soil the conditions for further decay are more favourable to microorganisms. The carbon in the residues is oxidized to carbon dioxide, incorporated in microbial cells and the reminder is incorporated into humus. Humus can be further decomposed by soil microflora. 

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