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首页> 外文期刊>Applied Microbiology >Functionally Redundant Cellobiose-Degrading Soil Bacteria Respond Differentially to Oxygen
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Functionally Redundant Cellobiose-Degrading Soil Bacteria Respond Differentially to Oxygen

机译：功能冗余的降解纤维二糖的土壤细菌对氧气的响应不同。

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The availability of oxygen (O_(2)) in aerated (i.e., water-unsaturated) soils affects the metabolic activities of aerobic and anaerobic soil prokaryotes that degrade plant-derived saccharides. Fluctuating availabilities of O_(2) were imposed on agricultural soil slurries supplemented with cellobiose. Slurries were subjected to oxic conditions (48 h), followed by an anoxic period (120 h) and a final oxic period (24 h). Redox potential was stable at 500 mV during oxic periods but decreased rapidly (within 10 h) under anoxic conditions to ?330 mV. The consumption of cellobiose occurred without apparent delay at all redox potentials. The metabolic activities of seven previously identified saccharolytic family-level taxa of the investigated soil were measured with newly designed quantitative PCR assays targeting the 16S rRNA. Four taxa responded to the experimental conditions. The amounts of rRNAs of Micrococcaceae and Cellulomonadaceae ( Actinobacteria ) increased under oxic conditions. In contrast, the RNA contents of Clostridiaceae (cluster I, Firmicutes ) and two uncultured family-level-taxa, i.e., “Cellu” and “Sphingo” (both Bacteroidetes ) increased under anoxic conditions. That the degradation of cellobiose was independent of the availability of O_(2) and that redox potentials decreased in response to anaerobic activities indicated that the degradation of cellobiose was linked to functionally redundant cellobiose-degrading taxa capable of altering redox conditions.
机译：加气（即水不饱和）土壤中氧气的可用性（O_（2））影响需氧和厌氧土壤原核生物的代谢活性，这些原核生物降解植物来源的糖类。 O_（2）的波动性被施加到补充了纤维二糖的农业土壤泥浆上。使浆料经受有氧条件（48h），随后是缺氧时间（120h）和最终有氧时间（24h）。氧化期间，氧化还原电位稳定在500 mV，但在缺氧条件下（10小时内）迅速下降至约330 mV。纤维二糖的消耗在所有氧化还原电位下都没有明显延迟。使用针对16S rRNA的新设计的定量PCR测定法测量了先前研究的土壤中七个糖化酶家族水平分类单元的代谢活性。四个分类单元响应了实验条件。在有氧条件下，微球菌科和纤维单胞菌科（放线菌）的rRNA数量增加。相反，在缺氧条件下，梭菌科（类I，硬毛菌）和两个未培养的家族水平的类群，即“ Cellu”和“ Sphingo”（均为拟杆菌属）的RNA含量增加。纤维二糖的降解与O_（2）的可用性无关，并且氧化还原电位响应厌氧活动而下降表明，纤维二糖的降解与功能上多余的纤维二糖降解类群有关，能够改变氧化还原条件。

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