基于宏转录组研究蔬菜秸秆发酵体系细菌群落

Bacterial community of vegetable straw fermentation system based on metatranscriptomics

分析蔬菜秸秆快速好氧发酵过程中活性细菌群落丰度、组成、多样性的演变规律,为进一步挖掘微生物资源,调节发酵工艺提供理论参考依据。依托罐式有机物料快速腐解设备,选取发酵过程中4个不同发酵时期(升温期、高温期、降温期和腐熟期)的有机物料为研究对象,提取微生物总RNA、反转录cDNA,以16S rRNA基因为分子标靶,借助qPCR技术和Illumina Miseq高通量测序平台,研究不同发酵时期细菌群落丰度、组成、多样性的变化及群落组成与物料理化因子偶联分析,揭示群落与理化因子之间的相关性。不同发酵时期物料的pH发生了显著的变化,升温期物料pH为6.26,而到了高温期乃至腐熟期pH均在8.0以上;发芽指数随着发酵进程推移达到94%以上。高温期的细菌数量显著高于其他3个时期。各个时期的活性细菌α多样性指数,除Simpson指数外,其余差异不显著。不同时期的优势菌门均是厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria),但相对丰度变化较大;不同时期菌群属组成和相对丰度之间存在显著差异,升温期存在其他时期检测不到的菌属。通过CCA分析可知pH是影响微生物群落结构的主要因子。

In this study,the changes,including the abundance,diversity,and patterns,in an active bacterial community structure were identified during the rapid aerobic fermentation of vegetable straw.Samples were collected in four different phases during the rapid aerobic fermentation of vegetable straw:the heating,thermophilic,cooling,and maturation phases.Total RNA was extracted from the samples and subjected to reverse transcription to obtain cDNA.The 16S rRNA gene was used as the target gene for Illumina Miseq sequencing and quantitative polymerase chain reaction(PCR).The bacterial abundances,diversity,and compositions were analyzed.The relationships among the physicochemical factors and bacterial community were determined.The pH value changed significantly during the different fermentation periods,where the pH was 6.26 in the heating phase but above 8.0 in all of the other phases.The germination index increased with the fermentation time,exceeding 94%.The abundance of the 16S rRNA gene was significantly higher in the thermophilic phase than the other three phases.Excluding Simpson′s index,the active bacterialα-diversity indexes did not differ significantly among the phases.The dominant phyla in the different phases were Firmicutes,Proteobacteria,and Actinobacteria but their relative abundances varied greatly.There were significant differences in the compositions and relative abundances of various genera during different periods.Some bacteria could be detected in the heating phase but not in the other periods.According to the canonical correspondence analysis,pH was the main factor that affected the microbial community structure.