Methane production from rice straw carbon in five different methanogenic rice soils:rates,quantities and microbial communities

The input of organic substances(e.g.,rice straw)in rice field soils usually stimulates the production and emission of the greenhouse gas methane(CH4).However,the amount of CH4 derived from the applied rice straw,as well as the response of bacterial and archaeal communities during the methanogenic phase,are poorly understood for different rice field soils.In this study,samples of five different rice soils were amended with 13^C-labeled rice straw(RS)under methanogenic conditions.Immediately after RS addition,the RS-derived CH4 production rates were higher in soils(Uruguay,Fuyang)that possessed a stronger inherent CH4 production potential compared with other soils with lower inherent potentials(Changsha,the Philippines,Vercelli).However,soils with higher inherent potential did not necessarily produce higher amounts of CH4 from the RS applied,or vice versa.Quantitative PCR showed copy numbers of both bacteria and methanogens increased in straw-amended soils.High-throughput sequencing of 16 S rRNA genes showed distinct bacterial communities among the unamended soil samples,which also changed differently in response to RS addition.Nevertheless,RS addition generally resulted in all the rice field soils in a relative increase of primary fermenters belonging to Anaerolineaceae and Ruminococcaceae.Meanwhile,RS addition also generally resulted in a relative increase of Methanosarcinaceae and/or Methanocellaceae.Our results suggest that after RS addition the total amounts of RSderived CH4 are distinct in different rice field soils under methanogenic conditions.Meanwhile,there are potential core bacterial populations that are often involved in primary fermentation of RS under methanogenic conditions.

Community assemblage of free-living diazotrophs along the elevational gradient of Mount Gongga

Mountain systems are unique for studying the responses of species distribution and diversity to environmental changes along elevational gradients.It is well known that free-living diazotrophic microorganisms are important to nitrogen cycling in mountain systems.However,the elevational patterns of free-living diazotrophs and the underlying ecological processes in controlling their turnover along broader gradients are less well documented.Here,we investigated the pattern of diazotrophic diversity along the elevational gradient(1800 m-4100 m)in Mount Gongga of China.The results showed that the α-diversity of diazotrophs did not change with the elevation from 1800 m to 2800 m,but decreased at elevations above 3000 m.Such diversity pattern was driven mainly by soil total carbon,nitrogen,and plant richness.Various diazotrophic taxa showed differential abundance-elevation relationships.Ecological processes determining diazotrophic community assemblage shift along the elevations.Deterministic processes were relatively stronger at both low and high elevations,whereas stochastic processes were stronger at the middle elevation.This study also suggested a strong relationship among aboveground plants and diazotrophs,highlighting their potential interactions,even for free-living diazotrophs.

Ambient temperature alters body size and gut microbiota of Xenopus tropicalis

Temperature is important to determine physiological status of ectotherms. However, it is still not fully understood how amphibians and their symbiotic microbiota acclimate to ambient temperature. In this study, we investigated the changes of gut microbiota of Xenopus tropicalis at different temperatures under controlled laboratory conditions. The results showed that microbial communities were distinct and shared only a small overlap among froglet guts, culture water and food samples.Furthermore, the dominant taxa harbored in the gut exhibited low relative abundance in water and food. It indicates that bacterial taxa selected by amphibian gut were generally of low abundance in the external environment. Temperature could affect betadiversity of gut microbiota in terms of phylogenetic distance, but it did not affect alpha diversity. The composition of gut microbiota was similar in warm and cool treatments. However, signature taxa in different temperature environments were identified. The relationships between temperature, gut microbiota and morphology traits of X. tropicalis revealed in this study help us to predict the consequences of environmental changes on ectothermic animals.

Response of bacterial communities to short-term pyrene exposure in red soil

分核，代表性的多不的芳香的烃(哼) 主要从石块燃料的不完全的燃烧生产的化合物，对生态系统健康危险。然而，长期的暴露研究没在土壤微生物上检测分核的任何重要效果。在这研究，短期的缩影实验被进行在土壤上识别分核的立即的效果细菌的社区。freshlycollected 太古的红土壤在 0， 10， 100， 200，和 500 mg