Composition and bacterial utilization of free amino acids in tropical mangrove sediments |
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| Affiliation: | 1. MSc in Biotecnology from the University of São Paulo (USP), PhD in Biotechnology, Federal University of São Paulo (UNIFESP), São José dos Campos, SP, Brazil, Rua Talim, 330, Vila Nair, São José dos Campos, SP CEP: 04021-001, Brazil;2. MSc in Metrology and Quality from the National Institute of Metrology, Quality and Technology (Inmetro), Laboratory of Tissue Bioengineering, Directory of Metrology Applied to Life Sciences, National Institute of Metrology, Quality and Technology (Inmetro), Avenida Nossa Senhora das Graças, 50, Duque de Caxias, RJ CEP: 25250-020, Brazil;3. Researcher at the Laboratory of Tissue Bioengineering, Directory of Metrology Applied to Life Sciences, National Institute of Metrology, Quality and Technology (Inmetro), Avenida Nossa Senhora das Graças, 50, Duque de Caxias, RJ CEP: 25250-020, Brazil;4. Post-doctoral Fellow at the Laboratory of Tissue Bioengineering, Directory of Metrology Applied to Life Sciences, National Institute of Metrology, Quality and Technology (Inmetro), Avenida Nossa Senhora das Graças, 50, prédio 6, 2° andar, Duque de Caxias, RJ CEP: 25250-020, Brazil;5. Associated Researcher at the Laboratory of Tissue Bioengineering, Directory of Metrology Applied to Life Sciences, National Institute of Metrology, Quality and Technology (Inmetro), Avenida Nossa Senhora das Graças, 50, Duque de Caxias, RJ CEP: 25250-020, Brazil;6. Professor of the Department of Science and Technology, Science and Technology Institute, Federal University of São Paulo (UNIFESP), São José dos Campos, SP, Brazil, Rua Talim, 330, Vila Nair, São José dos Campos, SP CEP: 04021-001, Brazil;1. Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;2. University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The composition and bacterial utilization of dissolved free amino acids (DFAA) in tropical mangrove sediments was examined. Amino acid concentrations (300–900 ng total DFAA ml−1) and composition were similar to that of other organic-rich, anaerobic sediments with lowest and highest concentrations in the low and mid intertidal zones, respectively. The non-protein amino acid, β-glutamic acid, rarely reported in previous studies, was found as a major component of the interstitial DFAA pool. Intracellular amino acids from some cultured strains of sulphate-reducing bacteria (e.g. Desulfobacter app) showed the presence of β-glutamic acid as a major cellular constituent suggesting that these bacteria may be a source of this amino acid in mangrove pore waters. In high intertidal sediments, bacterial growth rates (μ) correlated significantly with total DFAA concentrations with depth.Amino acid concentrations and composition differed significantly between sediments and overlying tidal waters. Flux chamber experiments showed negligible amino acid flux out of the sediments in untreated chambers, but rates of amino acid flux ranged from 27 to 69 mgN m−2 day−1 (= 81–207 mg C.m−2 day−1) in chambers where poisons were applied to the sediment surface. Such fluxes could account for between 9–38% and 5–19% of the nitrogen and carbon required to support the levels of bacterial productivity measured in surface (0–1 cm) sediments. These experiments suggest that bacterial populations in surface sediments are capable of utilizing all of the amino acid flux to the sediment-water interface in tropical mangroves. |
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