不同冻融阶段表层季节冻土细菌群落结构和功能解析OA北大核心CHSSCDCSTPCD

Microorganisms in frozen soil play a crucial role in predicting the potential mechanism of response between the frozen soil and climate.This study was envisaged to reveal the influence of different stages of the soil freeze-thaw process on the bacterial community in frozen soil and analyze the response of the bacterial community to the dynamics of the frozen soil properties.We determined the physiochemical properties of the topsoil from typical seasonally frozen ground in Heilongjiang Province.16s rRNA high-throughput sequencing was performed to analyze the bacterial community structure and function.The correlation between the physicochemical properties of the soil and the bacterial community structure and function were investigated using redundancy analysis.The results showed that:(1)Different stages of the soil freeze-thaw process exhibited an insignificant impact on the soil pH and total phosphorus.The soil organic matter and total nitrogen during complete freezing were significantly higher than those during the transition stage(P＜0.05).(2)A total of 985111 reads were obtained and clustered into operational taxonomic units(OTUs)belonging to 42 phyla.Among the dominant phyla,the relative abundance of Actinobacteria during the complete thaw was significantly higher than that during the transition and complete freezing stages(P＜0.05).The relative abundance of Proteobacteria,Acidobacteria,and Chloroflexi did not differ significantly across the stages of the freeze-thaw process.The alpha diversity and beta diversity of the bacterial community varied significantly in the different stages of the freeze-thaw process.The bacterial community diversity was considerably increased during the transition stage,while the β-diversity changed dramatically during complete freezing,compared with other stages.Furthermore,complete freezing had a greater impact on the positive correlation between the abundance of the bacterial phyla and the bacterial community stability.(3)A total of 5418 pathways of the bacterial community were identified and clustered into 6 categories.It was observed that the metabolic pathways accounted for the greatest proportion,that is,over 75％on average in all stages of the freeze-thaw process.All of the primary pathways varied significantly between the complete freezing and the complete thaw stages(P＜0.05).Nearly all of the significantly differential primary pathways varied dramatically between the complete freezing and the complete thaw stages(P＜0.05).(4)Soil organic carbon(SOC),total nitrogen(STN)and total phosphorus(STP)were found to be the major environmental factors influencing the bacterial community composition and structure,while soil pH had an insignificant effect.To conclude,different stages of the freeze-thaw process(especially the complete freezing stage)had a significant influence on the bacterial community structure and function.The intensity of influence was either positively or negatively correlated with the soil physicochemical properties,such as SOC,STN,and STP.The findings provide valuable clues to understand the response mechanism of the bacterial community in seasonally frozen ground in Heilongjiang in the context of global warming.