Temperature is a critical variable in enclosed solid-state fermentation(ESSF)systems and profoundly influences microbial survival.However,the spatial temperature variation within the ESSF environment and its impact on...Temperature is a critical variable in enclosed solid-state fermentation(ESSF)systems and profoundly influences microbial survival.However,the spatial temperature variation within the ESSF environment and its impact on microbial community assembly remain underexplored.This study investigated the assembly and functional divergence of abundant and rare microbial subcommunities in first-turn Daqu under varying temperature con-ditions.The results showed that the temperature distribution of Daqu in the fermentation chamber followed a Weibull distribution,with three distinct thermal zones formed based on spatial positioning.The microbial community structure of the first-turn Daqu exhibited characteristics of a transitional phase between that of the raw materials and mature Daqu.Although no significant differences were observed in the overall microbial community structure across different temperature zones,the community structure in the low-temperature zone showed greater dispersion in similarity,whereas the high-temperature zone tended towards consistency and stability.The assembly of the abundant subcommunity was influenced by temperature and reducing sugars,while the rare subcommunity was primarily shaped by reducing sugars,moisture content,and acidity.In response to high-temperature stress,the abundant and rare subcommunities adopted different adaptive strate-gies,forming“distributed networks”and“centralized networks,”respectively.Furthermore,the selection of stress-response metabolic pathways showed differing emphases on“resource conservation”and“stress defense,”contributing to the functional differentiation of Daqu.This study provides insights into how spatial temperature variation in ESSF systems affects microbial community structure and functional specialization,critical for optimizing fermentation and improving Daqu’s microbial stability in Baijiu production.展开更多
Biological nitrogen fixation(BNF)facilitated by diazotrophs,which convert N2 to ammonia,plays a key role in nutrient supply of terrestrial ecosystems.However,the differential contributions of rare versus abundant subc...Biological nitrogen fixation(BNF)facilitated by diazotrophs,which convert N2 to ammonia,plays a key role in nutrient supply of terrestrial ecosystems.However,the differential contributions of rare versus abundant subcommunities to nitrogen fixation dynamics remain poorly characterized,especially in alpine ecosystem.This study examined BNF changes and shifts in abundant and rare soil diazotrophic taxa along an aridity gradient(arid,semi-arid,semi-humid,and humid)across the Tibetan Plateau.We found a significantly higher N fixation rate,vegetation coverage and biomass,nifH gene abundance,and diazotroph diversity in semi-arid and arid habitats than in semi-humid and humid habitats.Rare subcommunity composition explained more of the variation in N fixation rates than did the abundant subcommunities,suggesting greater roles of diazotrophic rare taxa in supplying nitrogen availability in alpine grasslands.The main influence factors of nitrogen fixation are aridity,plant coverage and soil C:N ratio.Structural equation modeling indicated that soil factors(e.g.,bulk density,C:N ratio)and climatic factors(aridity and temperature)affected the composition of rare subcommunity through altering plant coverage and biomass,consequently affecting soil nitrogen fixation.This study establishes rare diazotrophs as critical regulators of soil nitrogen fixation and deciphers their mediation in climate-altered N-cycling processes in alpine ecosystems.展开更多
基金supported by grants from the Guizhou Science and Technology Support Program(grant number Qiankehe Platform Talent-ZDSYS[2023]007).
文摘Temperature is a critical variable in enclosed solid-state fermentation(ESSF)systems and profoundly influences microbial survival.However,the spatial temperature variation within the ESSF environment and its impact on microbial community assembly remain underexplored.This study investigated the assembly and functional divergence of abundant and rare microbial subcommunities in first-turn Daqu under varying temperature con-ditions.The results showed that the temperature distribution of Daqu in the fermentation chamber followed a Weibull distribution,with three distinct thermal zones formed based on spatial positioning.The microbial community structure of the first-turn Daqu exhibited characteristics of a transitional phase between that of the raw materials and mature Daqu.Although no significant differences were observed in the overall microbial community structure across different temperature zones,the community structure in the low-temperature zone showed greater dispersion in similarity,whereas the high-temperature zone tended towards consistency and stability.The assembly of the abundant subcommunity was influenced by temperature and reducing sugars,while the rare subcommunity was primarily shaped by reducing sugars,moisture content,and acidity.In response to high-temperature stress,the abundant and rare subcommunities adopted different adaptive strate-gies,forming“distributed networks”and“centralized networks,”respectively.Furthermore,the selection of stress-response metabolic pathways showed differing emphases on“resource conservation”and“stress defense,”contributing to the functional differentiation of Daqu.This study provides insights into how spatial temperature variation in ESSF systems affects microbial community structure and functional specialization,critical for optimizing fermentation and improving Daqu’s microbial stability in Baijiu production.
基金supported by the National Natural Sciences Foundation of China(Grant No.42177449)the National Natural Sciences Foundation of China(Grant No.42130717)Shaanxi Provincial Science Fund for Distinguished Young Scholars(Grant No.2024JC-JCQN-35).
文摘Biological nitrogen fixation(BNF)facilitated by diazotrophs,which convert N2 to ammonia,plays a key role in nutrient supply of terrestrial ecosystems.However,the differential contributions of rare versus abundant subcommunities to nitrogen fixation dynamics remain poorly characterized,especially in alpine ecosystem.This study examined BNF changes and shifts in abundant and rare soil diazotrophic taxa along an aridity gradient(arid,semi-arid,semi-humid,and humid)across the Tibetan Plateau.We found a significantly higher N fixation rate,vegetation coverage and biomass,nifH gene abundance,and diazotroph diversity in semi-arid and arid habitats than in semi-humid and humid habitats.Rare subcommunity composition explained more of the variation in N fixation rates than did the abundant subcommunities,suggesting greater roles of diazotrophic rare taxa in supplying nitrogen availability in alpine grasslands.The main influence factors of nitrogen fixation are aridity,plant coverage and soil C:N ratio.Structural equation modeling indicated that soil factors(e.g.,bulk density,C:N ratio)and climatic factors(aridity and temperature)affected the composition of rare subcommunity through altering plant coverage and biomass,consequently affecting soil nitrogen fixation.This study establishes rare diazotrophs as critical regulators of soil nitrogen fixation and deciphers their mediation in climate-altered N-cycling processes in alpine ecosystems.
