Effect on Oxidation-Reduction Potential on Microbes

The oxidation-reduction potential is an indication of the oxidation and reducing power of the substrate.

The oxidation-reduction potential is normally expressed as Eh and measured in millivolt units, is defined as the tendency to yield electrons (become oxidized) or to capture electrons (become reduced). The value of Eh at which microorganisms grow determines whether they are aerobic or anaerobic.

The greater the degree in which a substance is oxidized, the more highly positive will be its Eh value, and the greater the degree to which a substance is reduced, the more highly negative will be its Eh value.

In general, aerobes require a substrate having a positive Eh, means that aerobic microorganisms grow rapidly under a high oxidation-reduction potential.

For anaerobes it requires a substrate having a negative Eh.

The optimum Eh values for the growth of microbes vary with species.

Yeats and molds require higher oxidation-reduction potential Eh values than most bacteria, generally 200 to 400 millivolt.
Effect on Oxidation-Reduction Potential on Microbes

Nutritional Requirements of Microbes

Microorganism , especially bacteria, vary greatly in nutritional requirements from species to species.

Nutrition supplies the basic cell building requirements. Nutrition not only provides energy but also acts as precursor for growth of microorganism.

Some microbes have an unconditional need for preformed complex organic compounds while others can thrive with just a few inorganic substance as their sole nutritional requirements.

Some bacteria can utilize the nitrogen in air to form proteins and carbon dioxide in air to obtain energy or to form compounds from which they can then obtain energy.

Others can utilities simple inorganic, such as nitrates, as a source of nitrogen and relatively simple organic compounds such as lactates, as a source of energy.

Most of microbial species utilize simple monomeric substrates such as monosaccharides and amino acids, whereas others digest complex proteins and polysaccharides.

In nature, microbial populations are capable of growth on a variety of substrates.

Nearly all yeast can derive all their nitrogen from lysine, and amino acid.

Some bacteria may require complex organic compounds for growth, including amino acids, vitamin and traces of certain minerals.

Molds and yeast like bacteria, may require basic elements – carbon, hydrogen, nitrogen, phosphorous, sulphur, oxygen and other metal ions as well as vitamin and other organic compound.

Carbon is the prime requirement of any organism Based on the source of carbon, microorganisms can be either autotrophs or heterotrophs. Autotrophs use carbon dioxide of the atmosphere as their source of carbon.
Nutritional Requirements of Microbes