High Phosphate Concentrations Accelerate Bacterial Peptide Decomposition in Hypoxic Bottom Waters of the Northern Gulf of Mexico

作者：Liu Zhanfei; Liu Shuting^*

来源：Environmental Science & Technology, 2016, 50(2): 676-684.

DOI：10.1021/acs.est5b03039

Despite extensive studies of the development and dynamics of hypoxia in coastal oceans, factors controlling the decomposition rates and pathways of labile organic matter (OM) in hypoxic waters are not well understood. Here we investigate peptide decomposition in a stratified water column in the hypoxic region of the northern Gulf of Mexico by conducting on-deck incubation experiments amended with tetrapeptide ala-val-phe-ala (AVFA), a fragment of RuBisCO. Our results show that decomposition efficiency of AVFA was limited by the availability of soluble reactive phosphorus (P-i) in the surface water (<0.3 mu M), as it was greatly enhanced after P-i addition to the incubation water. In contrast, peptide decomposition rate in the subsurface water, enriched with P-i (0.4-1.2 mu M), was twice as high as that in the surface water, concomitant with the development of fast-growing bacteria during the incubation. Consistent with the Growth Rate Hypothesis, these results indicate that a high level of P-i is crucial in stimulating the growth of bacterial strains with high RNA contents and thus faster OM decomposition in marine environments. This high decomposition potential of OM in subsurface hypoxic waters presents a positive feedback on hypoxia formation in P-i-enriched coastal subsurface waters, as a higher OM decomposition rate leads to rapid consumption of dissolved oxygen (DO).

• 出版日期2016-1-19