Environmental drivers of soil microbial activity and diversity along an elevational gradient

Microbial functional and structural patterns and drivers along elevational gradients have recently received increasing attention.In this study,we examined soil bacterial and fungal community diversity,compositions,and microbial activities(i.e.,soil basal respiration and extracellular enzyme activities)across an elevational gradient from 1148 m to 2080 m(consists of six elevations)in the Yuanmou dry-hot valley located in Southwest China.Environmental factors,including soil temperature,moisture content,pH,soil organic carbon(SOC),total nitrogen(TN),the C/N ratio,total phosphorus(TP),and aboveground plant biomass were also determined.The results showed that soil bacterial alpha diversity(Shannon index)was unaffected by elevation,whereas fungal alpha diversity firstly increased significantly from 1148 m to 1539 m but did not increase further at higher elevations.Bacterial Shannon index was significantly correlated with SOC,whereas fungal Shannon index was remarkably associated with soil temperature.Microbial activity,beta diversities and community composition varied with elevation,but none of them showed a consistent trend.Monte Carlo test revealed that soil moisture followed by temperature,and pH,were the primary drivers of bacterial community composition.Soil fungal community composition significantly depended on soil moisture.Overall,our study suggested bacterial diversity and composition were determined by climatic(moisture and temperature)and edaphic properties(SOC and pH),while fungal diversity and composition were structured mainly by climatic factors.These findings may contribute to a better understanding of microbial responses along elevational gradients in this semi-arid region.

Metagenomic Analysis of Mangshan Pit Viper (Protobothrops mangshanensis) Gut Microbiota Reveals Differences among Wild and Captive Individuals Linked to Hibernating Behaviors

Gut microbiota play important roles in the immunity,digestion,and energy meta bolism of their reptile hosts.Mangshan pit viper(Protobothrops mangshanensis)is a critically endangered snake species that is a Class I national protected species in China.Little is known regarding the relationship between P.mangshanensis and their gut microbial communities.In this study,the gut microbiota of wild P.mangshanensis individuals,artificially hiberna ting captive individuals,and non-hibernating captive individuals were compared across nine samples.Comparative shotgun metagenomic analysis was used to investigate the taxonomic composition,diversity,and function of P.mangshanensis gut microbial communities and assess whether their gut microbiomes were affected by their living environments and captivity conditions.The dominant phyla within P.mangshanensis gut microbial communities were Proteobacteria(65.55%),Bacteroidetes(15.97%),and Firmicutes(8.11%).Enriched functional pathways within the gut microbiota included meta bolism(54.9%),environmental information processing(9.67%),and genetic information processing(9.37%).Wild snake gut communities exhibited higher microbial diversity than the other two groups.The gut microbiomes of wild and hibernating captive snakes may be more reflective of healthy intestinal homeostasis than that in nonhibernating snakes.Specifically,non-hibernating snakes exhibited increased levelsof potentially pathogenic populations and functional specialization within gut microbial communities.Thus,different livingenvironments and captivitymethodsmay correspond to major shifts in microbiota composition,diversity,and function within P.mangshanensis.This study provides important insights to help guide the conservation of P.mangshanensis,while also carrying broad implications for our understanding of the effects of living environments and non-hibernating captivity conditions on the gut microbiota of snakes.

Fecal microbiota reveal adaptation of herbivores to the extreme environment of the Qinghai–Tibet Plateau

Background:Gut microbiota is pivotal in regulating hosts'biological processes and maintaining homeostasis,but knowledge about its role in wild herbivores in extreme environments remains limited.Methods:Gut bacteria and fungi were sequenced in ruminant(Chiru and Yak)and nonruminant(Kiang)herbivores on the Qinghai–Tibet Plateau,and their community structure,co-occurrence networks,functions,and assembly mechanisms were investigated using multivariate ecological and statistical methods.Results:Kiang had lower gut microbial diversity than Chiru and Yak.Bacterial host-specific exclusivity was greater than that of fungi.In addition to the evidence of glycan biosynthesis and carbohydrate metabolism,Chiru had a high Firmicutes/Bacteroidetes ratio and low animal pathogen abundance,suggesting better adaptation to the plateau's harsh environment.Additionally,members of gut microbiota tended to co-occur rather than co-exclude in all herbivores.Different network complexity and stability patterns were observed between bacterial and fungal communities.Furthermore,gut bacterial assembly was primarily controlled by stochastic dispersal limitation and drift,whereas fungal assembly was primarily controlled by deterministic homogeneous selection except in Chiru.Conclusions:On the Qinghai–Tibet Plateau,Chiru and Yak exhibit more diverse gut microbiota and more diverse metabolic functions than Kiang,and gut bacteria are more divergent than gut fungi in these herbivores.