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Immobilization and mineralization of dissolved free amino acids by stream‐bed biofilms
Author(s) -
FIEBIG DOUGLAS M.,
MARXSEN JORGEN
Publication year - 1992
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1992.tb00568.x
Subject(s) - mineralization (soil science) , chemistry , environmental chemistry , amino acid , glycine , biofilm , trophic level , dissolved organic carbon , abiotic component , chromatography , nitrogen , ecology , organic chemistry , biology , biochemistry , bacteria , genetics
SUMMARY 1. Radiolabelled ( 14 C) amino acids were used to investigate the influence of sediment size as well as dissolved free amino acid (DFAA) concentration and composition on immobilization and mineralization of DFAAs by biofilms from a first‐order stream. 2. Over time (240 min), biofilms on stony substrata immobilized a DFAA mixture more effectively than those on sandy substrata, however proportional mineralization of immobilized DFAAs was higher for sandy substrata (36 v 20%). 3. Using stony substrata, the DFAA mixture was immobilized more rapidly than glycine alone at ‘near‐natural’ amino acid concentrations (c. 37 μgl −1 ), as well as enriched concentrations (1 and 100 mg 1‐ −1 ). Instantaneous rates of glycine immobilization and mineralization were not saturated at glycine enrichments of up to 980 mgl −1 . 4. With both the amino acid mixture and glycine alone, proportional mineralization of the immobilized amino acids increased on enrichment to Img 1‐ −1 (DFAA mixture: from 25 to 37%; glycine alone: from 50 to 54%), but then fell on further enrichment to 100mgl −1 (DFAA mixture: 11%; glycine alone: 7%). 5. Results are discussed in terms of the potential trophic utility of immobilized DFAAs as well as the apparent roles of biotic and abiotic immobilization mechanisms. Immobilization and mineralization responses to variables investigated in this study give an insight into potential variability of carbon immobilization and retention in stream‐bed sediments. This is fundamental to an understanding of how DOC may become available to higher trophic levels.