Effects of substrate concentration, growth state, and oxygen availability on relationships among bacterial carbon, nitrogen and phospholipid phosphorus content

J. Brinch‐Iversen, Aarhus Universitet
G. M. King


Abstract The utility of phospholipid phosphorus (Plip‐P) concentrations as a measure of microbial biomass is dependent upon the accuracy of the conversion factors used for relating Plip‐P to cell carbon, nitrogen or weight. Mixed cultures enriched from marine sediments have been used to evaluate the reliability of these relationships as a function of substrate concentration, growth state and the presence of oxygen. Ratios of Plip‐P to carbon and nitrogen were independent of growth state and substrate level but were sensitive to oxygen status. For aerobic incubations, average ratios of 190 and 730 μmol Plip‐P/g carbon and nitrogen were obtained, respectively. Average ratios of 100 and 350 μmol Plip‐P/g carbon and nitrogen were obtained from anaerobic incubations. As a result, it is not likely that a single conversion factor can be applied to samples from both aerobic and anaerobic systems. In addition, a limited survey of algal Plip‐P, carbon and nitrogen concentrations indicates that the presence of a significant algal biomass can result in erroneous estimates of bacterial abundance. Copyright © 1990, Wiley Blackwell. All rights reserved