Do bacteria regenerate phosphorus while decomposing seston?

Abstract

The C:P ratio of both seston in suspension and seston collected by sediment traps were systematically higher than the Redfield ratio of 106 : 1 (molar) and decreased significantly with depth in the mesotrophic, phosphorus-limited La Concepción reservoir. An aerobic decomposition experiment of seston at different concentrations by a mixed population of reservoir bacteria was performed in batch cultures to investigate the bacterial role in the changes of the C:P ratio. Dissolved phosphorus was taken up during the bacterial growth phase, while carbon was transformed to CO₂ . Therefore, the C:P ratio of the decomposing seston decreased during this stage, and could partially explain the vertical distribution for the C:P ratio in this reservoir. During the death phase of the bacteria, flagellate grazing caused most of the bacterial phosphorus to be released to the medium.