Microbial ecological associations in the surface sediments of Bohai Strait

Microbial communities play key roles in the marine ecosystem. Despite a few studies on marine microbial communities in deep straits, ecological associations among microbial communities in the sediments of shallow straits have not been fully investigated. The Bohai Strait in northern China(average depth less than 20 m) separates the Bohai Sea from the Yellow Sea and has organic-rich sediments. In this study, in the summer of 2014, six stations across the strait were selected to explore the taxonomic composition of microbial communities and their ecological associations. The four most abundant classes were Gammaproteobacteria, Deltaproteobacteria, Bacilli and Flavobacteriia. Temperature, total carbon, depth, nitrate, fishery breeding and cold water masses influenced the microbial communities, as suggested by representational dif ference and composition analyses. Network analysis of microbial associations revealed that key families included Flavobacteriaceae, Pirellulaceae and Piscirickettsiaceae. Our findings suggest that the families with high phylogenetic diversity are key populations in the microbial association network that ensure the stability of microbial ecosystems. Our study contributes to a better understanding of microbial ecology in complex hydrological environments.

Effects of cow manure ratios on methane production and microbial community evolution in anaerobic co-digestion with different crop wastes

The present study investigated the effects of cow manure ratios mixed with maize stover,rice straw,and wheat stalk at 3,2,1(total solid based,TS-based),respectively,on methane production and microbial community structure during the anaerobic co-digestion process.Results showed cow manure co-digested with maize stover,wheat stalk,and rice straw at ratios of 2,1,and 3 had the highest cumulative methane yields(272.99,153.22167.73 mL/g volatile solid(VS),respectively)and better stability(e.g.pH,volatile fatty acids(VFAs)and their component).The main microbe evolution had a similar trend which was Petrimonas and Methanosaeta in the early digestion process(Days 0-7)and then evolved into Longilinea,Ruminofilibacter,and Methanosarcina with the progress of digestion,but the relative abundance of these microbes in each reactor was different.It was worth noting that Caldicoprobacter in cow manure to maize stover ratio of 2,and to rice straw ratio of three reactors had a relatively higher proportion than reactor of cow manure to wheat stalk ratio of 1,and Hydrogenophaga was the specific bacterium in cow manure to wheat stalk ratio of 1 reactor.In addition,Petrimonas showed positive relationship with VFAs and Longilinea was the opposite.Methanosaeta and Methanobacterium contributed the most during the peak period of methane production in cow manure and maize stover co-digested reactor,and showed positive relationship with acetic acid.However,Methanosarcina and Methanospirillum made a great contribution during the peak period of methane production in cow manure co-digested with wheat stalk and rice straw reactors.These findings could provide further information on the application of cow manure co-digested with crop wastes.

Tectonomicrobiology:A new paradigm for geobiological research

Geomicrobiology is a sub-discipline of geobiology and emphasizes the interaction between microorganisms and their environment on Earth. There is a need to explicitly emphasize the biogeochemical processes performed by microorganisms associated with Earth's tectonic activities, especially under the framework of the modern theory of plate tectonics. Tectonomicrobiology aims to create a better synergy between microbial and active tectonic processes. This explicit synergy should also foster better communications between solid Earth scientists and life scientists in terms of holistic Earth system dynamics at both tectonic and micro-scales.