【不同生物能源作物对土壤中细菌和古菌群落N循环的影响】Yuejian Mao Anthony C. Yannarell Sarah C. Davis Roderick I. Mackie. Impact of different bioenergy crops on N-cycling bacterial and archaeal communities in soil. Environmental Microbiology Special Issue: Plant–Microbe Interactions
Abstract
Biomass production for bioenergy may change soil microbes and influence ecosystem properties. To explore the impact of different bioenergy cropping systems on soil microorganisms the compositions and quantities of soil microbial communities (16S rRNA gene) and N-cycling functional groups (nifH bacterial amoA archaeal amoA and nosZ genes) were assessed under maize switchgrass and Miscanthus x giganteus at seven sites representing a climate gradient (precipitation and temperature) in Illinois USA. Overall the site-to-site variation in community composition surpassed the variation due to plant type and microbial communities under each crop did not converge on a ‘typical’ species assemblage. Fewer than 5% of archaeal amoA bacterial amoA nifH and nosZ OTUs were significantly different among these crops but the largest differences observed at each site were found between maize and the two perennial grasses. Quantitative PCR revealed that the abundance of the nifH gene was significantly higher in the perennial grasses than in maize and we also found significantly higher total N in the perennial grass soils than in maize. Thus we conclude that cultivation of these perennial grasses instead of maize as bioenergy feedstocks can improve soil ecosystem nitrogen sustainability by increasing the population size of N-fixing bacteria.
【高纬北极泥炭土壤中有机碳的转化】Alexander Tveit Rainer Schwacke Mette M Svenning and Tim Urich. Organic carbon transformations in high-Arctic peat soils: key functions and microorganisms. The ISME Journal (2013) 7 299–311; doi:10.1038-ismej.2012.99
Abstract
A substantial part of the Earths’ soil organic carbon (SOC) is stored in Arctic permafrost peatlands which represent large potential sources for increased emissions of the greenhouse gases CH4 and CO2 in a warming climate. The microbial communities and their genetic repertoire involved in the breakdown and mineralisation of SOC in these soils are however poorly understood. In this study we applied a combined metagenomic and metatranscriptomic approach on two Arctic peat soils to investigate the identity and the gene pool of the microbiota driving the SOC degradation in the seasonally thawed active layers. A large and diverse set of genes encoding plant polymer-degrading enzymes was found comparable to microbiotas from temperate and subtropical soils. This indicates that the metabolic potential for SOC degradation in Arctic peat is not different from that of other climatic zones. The majority of these genes were assigned to three bacterial phyla Actinobacteria Verrucomicrobia and Bacteroidetes. Anaerobic metabolic pathways and the fraction of methanogenic archaea increased with peat depth evident for a gradual transi