Abstract — Dissolved organic matter (DOM) release by anoxygenic phototrophic bacteria belonging to diverse taxonomic groups is a ubiquitous process, resulting in 5–20% of the CO 2 fixed by photosynthesis leaving the cell. The green photosynthetic bacterium Chlorobaculum limnaeum releases ~10% of the carbon assimilated during autotrophic СО 2 fixation. Extracellular DOM release by Cba. limnaeum is a normal function of living cells, since it does not occur in the dark and is inhibited by fluoroacetate, an inhibitor of СО 2 fixation via the reducing TCA acids cycle, which is used for CO 2 assimilation in this bacterium. In the presence of acetate or pyruvate in the medium, DOM release increases to 30 and 60%, respectively. Nitrogen limitation stimulates DOM release by Cba. limnaeum up to 60% of assimilated СО 2 . Under these conditions, addition of acetate results in DOM release increasing up to 100%. Therefore, the extracellular release of DOC by anoxygenic phototrophic bacteria can be considered as an important source of substrates for the growth of heterotrophic bacteria in oxygen-free aquatic ecosystems.

中文翻译：

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缺氧光养细菌将光合固定碳作为溶解有机物释放

摘要 — 属于不同分类群的无氧光养细菌释放溶解有机物 (DOM) 是一个普遍存在的过程，导致 5-20% 的通过光合作用固定的 CO 2 离开细胞。绿色光合细菌 Chlorobaculum limnaeum 释放约 10% 在自养 СО 2 固定过程中吸收的碳。Cba 释放细胞外 DOM。limnaeum 是活细胞的正常功能，因为它不会在黑暗中发生，并且被氟乙酸盐抑制，氟乙酸盐是一种通过还原性 TCA 酸循环固定 СО 2 的抑制剂，用于该细菌中的 CO 2 同化。在培养基中存在醋酸盐或丙酮酸盐时，DOM 释放量分别增加到 30% 和 60%。氮限制刺激 Cba 释放 DOM。limnaeum 高达 60% 的同化 СО 2 。在这些条件下，添加醋酸盐导致 DOM 释放增加至 100%。因此，无氧光养细菌细胞外释放DOC可被认为是无氧水生生态系统中异养细菌生长的重要底物来源。