A method to determine the contribution of bacteria to phosphate uptake by aerobic freshwater sediment

Abstract

An extraction method to determine the contribution of bacterial processes to phosphate uptake of aerobic freshwater sediment was tested on Fe hydroxyphosphate that was either synthesized or formed under in situ conditions and a pure culture of Acinetobacter 210A. A mild extraction with H 2 SO 4 solubilized the entire Fe hydroxyphosphate fraction but did not extract bacterial phosphate. Phosphate uptake of randomly sampled surface layers of the sediment of Lake Loosdrecht was considerable, ranging from 11 to 138 µ mol g −1 on a dry weight basis. The contribution of bacterial processes ranged from 12 to 32%. Addition of an easily degradable substrate, such as acetate, to the sediment stimulated the uptake of phosphate and augmented the biologically bound phosphate fraction. The results indicated that growing bacteria play a considerable role in phosphate uptake by aerobic sediment.