基于稳定性同位素核酸探针技术的红壤微生物底物利用策略研究

外源活性碳底物输入强烈影响土壤微生物的生长，但是在系统发育分类水平上，细菌和真菌对活性底物的动态响应及利用特征和微生物群落组成的关系仍不清楚。以红壤为研究对象，采用¹³C标记葡萄糖为底物进行模拟培养并定期取样，利用稳定性同位素核酸探针(DNA-based stable isotope probing,DNA-SIP)和高通量测序技术分析活性的真菌和细菌类群，并探讨不同微生物利用葡萄糖来源碳的动态特征。研究发现，微生物群落对葡萄糖的利用符合从细菌向真菌演替的r/K选择策略。在细菌群落中，隶属于富营养菌的变形菌门(Proteobacteria)和放线菌门(Actinobacteria)对活性底物的利用能力显著高于寡营养菌的酸杆菌门(Acidobacteria)和绿弯菌门(Chloroflexi)。和细菌的底物利用策略不同，真菌子囊菌门(Ascomycota)和担子菌门(Basidiomycota)在整个培养期间均可以利用葡萄糖和土壤原有组分。因此，葡萄糖的连续加入并未改变不同营养类型细菌的底物利用策略，而真菌对底物的利用具有广谱性特征，活性底物可诱导真菌对土壤原有组分...

Strategies for soil microbes utilizing exogenous substrates in Ultisol based on nucleic acid stable isotope probing technique

【Objective】The input of exogenous active carbon(C) substrate strongly affects the growth of soil microorganisms.However, so far little knowledge is available about dynamic responses of soil microorganisms(bacteria and fungi) to the input of exogenous active carbon substrate and functional traits of the microorganisms in utilizing the substrate and their relationships with community structure of the microorganisms.【Method】Hence, an experiment was carried out using;C-glucose as substrate in Ultisol for incubation of soil microorganisms(bacteria and fungi), which were sampled periodically for analysis with the aid of DNA-based stable isotope probing and high-throughput pyrosequencing techniques to explore dynamic traits of the microorganisms utilizing the carbon of glucose relative to species. 【Result】It was found that in utilizing the substrate, the bacterial and fungal communities followed the r/K selection strategy in evolution from bacteria to fungi. Among the bacterial community, copiotrophic bacteria, like Proteobacteria and Actinobacteria, were higher than oligotrophic phyla, like Acidobacteria and Chloroflexi, in activated substrate utilization capacity. Different from bacteria in utilization of substrates, fungi, like Ascomycota and Basidiomycota, were low in selectivity and able to utilize both labile C and native soil organic matter.【Conclusion】Hence, bacteria retain their intrinsic life-history strategies controlled by their copiotrophic or oligotrophic natures,regardless of increase in C availability. Fungi can utilize a wide range of substrates and labile C input can induce copiotrophic Ascomycota to utilize heterogeneous recalcitrant C, thus accelerating decomposition of native soil C.