生物炭-牛粪堆肥中产β-葡聚糖苷酶微生物群落应答碳代谢抑制效应

Beta-glucosidase-producing microbial community in response to the carbon catabolite repression during the composting of cattle manure with biochar

摘要:

【背景】在高浓度葡萄糖引起的碳代谢抑制效应下，产β-葡聚糖苷酶(β-glucosidase)功能微生物群落为适应碳代谢压力的变化，会差异化表达糖耐受和非糖耐受的功能基因。在堆肥中添加生物炭可以改变微生物生存的环境，进而影响微生物群落的组成与功能。【目的】分析在不同碳代谢压力下添加生物炭对产β-葡聚糖苷酶功能微生物群落的结构组成与功能的影响。【方法】在生物炭牛粪-稻草堆肥中添加葡萄糖、纤维二糖及β-葡聚糖苷酶抑制剂，构建不同的碳代谢压力。以细菌来源GH1家族的β-葡聚糖苷酶基因为分子标记基因构建基因克隆文库。同时测定羧甲基纤维素酶酶活和β-葡聚糖苷酶酶活。【结果】放线菌、变形菌和拟杆菌是功能微生物群落中的优势菌群。其中，CL处理组变形菌数量有所下降，在添加了抑制剂的处理组中，拟杆菌的数量明显上升。高浓度葡萄糖显著抑制了羧甲基纤维素酶酶活，但对β-葡聚糖苷酶酶活影响不大，其中低浓度纤维二糖的处理可以显著诱导β-葡聚糖苷酶活性。GHCH处理组中β-葡聚糖苷酶表现出高浓度葡萄糖激活特性。【结论】添加生物炭未明显影响参与纤维素降解的功能微生物群落对碳代谢抑制效应的应答。与自然堆肥相比，在添加了生物炭的堆肥中，产β-葡聚糖苷酶的微生物群落对添加了高浓度葡萄糖引起的碳代谢抑制效应或添加了低浓度纤维二糖的诱导效应更敏感。

Abstract:

[Background] High concentration of glucose will cause carbon catabolite repression, and the functional microbial community producing β-glucosidase adapts to such pressure by differentially regulating the expression of glucose-tolerant and non-glucose tolerant β-glucosidases. Adding biochar in compost can change the environment where microorganisms live and affect the composition and function of the microbial community. [Objective] The effects of biochar addition on the structure and function of β-glucosidase-producing microbial community were analyzed under different carbon metabolism pressures. [Methods] Different carbon metabolism pressures were constructed by adding glucose, cellobiose, and β-glucosidase inhibitor into the biochar-cattle manure-maize straw compost. We used the β-glucosidase gene of the GH1 family derived from bacteria as a molecular marker to construct a gene clone library and measured the activities of carboxymethylc ellulase (CMCase) and β-glucosidase. [Results] Actinobacteria, Proteobacteria, and Bacteroidetes were dominant in the functional microbial community. The relative abundance of Proteobacteria was lower in the low-concentration cellobiose group, and that of Bacteroidetes was significantly higher in the groups with the addition of inhibitor. High glucose significantly inhibited CMCase activity while had little effect on β-glucosidase activity, and low cellobiose markedly induced β-glucosidase activity. The β-glucosidase was activated by high glucose in the high-concentration glucose+high-concentration cellobiose group. [Conclusion] The addition of biochar did not significantly affect the response of the functional microbial community involved in cellulose degradation to carbon catabolite repression. Compared with the natural compost, the addition of biochar in the compost increased the sensitivity of β-glucosidase-producing microbial community to the carbon catabolite repression induced by high concentrations of glucose and to the inductive effect of low-concentration cellobiose.