Casey John R, Ferrón Sara, Karl David M
Center for Microbial Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, United States.
Front Microbiol. 2017 Nov 16;8:2157. doi: 10.3389/fmicb.2017.02157. eCollection 2017.
Molecular evidence for proteorhodopsin- and bacteriochlorophyll-based photoheterotrophy is widespread in oligotrophic marine microbial community metagenomes, and has been implicated in light-enhanced growth rates, substrate uptake rates, and anapleurotic carbon fixation, thus complicating the web of interactions within the 'microbial loop.' We quantified photoheterotrophic metabolism of the oxidized organic acid glycolate, a fast-turnover and exclusively phytoplankton-derived substrate at an oligotrophic site in the subtropical North Pacific Ocean. As expected, concentration-dependent changes in uptake rates were observed over the diel cycle, with maxima occurring at midday. Although no light-enhanced substrate uptake rates were observed, samples exposed to light altered the balance between assimilation and respiration, resulting in an approximately four-fold increase in glycolate-specific assimilation efficiency. Energy demand for such a metabolic adjustment was linearly related to light, consistent with photoheterotrophy.
基于视紫红质和细菌叶绿素的光异养的分子证据在贫营养海洋微生物群落宏基因组中广泛存在，并与光增强的生长速率、底物摄取速率和回补性碳固定有关，从而使“微生物环”内的相互作用网络变得复杂。我们量化了亚热带北太平洋贫营养站点中氧化有机酸盐乙醇酸（一种快速周转且仅来源于浮游植物的底物）的光异养代谢。正如预期的那样，在昼夜循环中观察到摄取速率随浓度的变化，最大值出现在中午。虽然未观察到光增强的底物摄取速率，但暴露于光下的样品改变了同化和呼吸之间的平衡，导致乙醇酸特异性同化效率增加了约四倍。这种代谢调整的能量需求与光呈线性相关，这与光异养一致。
