Measurements of sulfur, phosphorus and other ions in microbial biomass: influence on correct determination of elemental composition and degree of reduction

The elemental compn. of microorganisms varies widely with respect to the N, S, P, and ash content as well as many trace elements depending on microorganism and growth conditions. As a consequence, the mass of 1 C-mol of biomass can differ considerably from 1 microorganism to another. S is completely volatilized during combustion, so that the calcn. of the mass fraction of O is affected when S is not measured. However, its neglect does not seriously affect the elemental compn. and the degree of redn. of biomass. P is found in ash after combustion at the same degree of redn. as in biomass. Therefore, O bound to it should be included in the elemental formula, so that the degree of redn. of biomass remains unchanged by inclusion of P into elemental formula. No external O is incorporated into biomass during combustion and thus the measured ash fraction is correct. [on SciFinder (R)]