The Effect Of Microbial Diversity And Carbon Sources On Soil Mineralization

At present,most studies on biodiversity and protection are pay attention to the value and importance of large creature,however,less attention has been on microbe.Microorganisms play important roles in ecosystem service due to microbe with fast propagation rate and much biomass.It is well known that soil is the largest carbon cool of terrestrial ecosystem and carbon mineralization of soil organic occupies the important position in the global carbon cycle,which control the carbon balance of the atmosphere.There were different microbes involve in the process of carbon mineralization.Therefore,it is very essential to study the effect of soil microbial diversity on soil carbon mineralization.In order to study the effect of microbial diversity on soil carbon metabolism,we adopted serial dilution method to produce 10^-1?D1?,10^-3?D3?and 10^-5?D5?dilution soil suspension and then inoculated into the sterile soil.After six weeks pre-incubation,different carbon sources?glucose,cellulose and biochar?were added and continually cultured for four weeks.During culture period,the rate carbon mineralization,the abundance and composition of microbe and the pattern of carbon source utilization were studied by titration,real-time PCR,16S rDNA high-throughput sequencing,Biolog ECO,respectively.The study shows that there were no significantly change of biomass between different treatments after pre-incubate 6 weeks,which indicated that microbial biomass of different samples reached the new balance after 6weeks and the effect of microbial biomass on carbon mineralization could be ignored.The utilization strength of carbon source,average well color development?AWCD?and functional diversity index?Shannon,McIntosh and richness index?of D1 were significantly higher than D5 treatment.The correlation analysis demonstrated that functional diversity significantly correlated with the utilization strength of carbon source and AWCD.Meanwhile,principal component analysis and One-Way ANOVA also indicated that pattern of carbon source utilization of microbial community had difference in different treatments.Soil bacterial compositions after the pre-culture were detected by the high throughput sequencing,and we found that microbial species diversity indices of the D1 treatment were all higher than D3 and D5 treatment in addition to ACE index,and D1 significantly higher than D5 treatment,even though there were not differences on microbial biomass among different treatments.Moreover,the correlation analysis showed that species diversity had very significant positive correlation with the utilization strength of carbon source,which indicated that the loss of microbial diversity would affect the utilization strength of carbon source,pattern of carbon source utilization,and function in terrestrial ecosystem.The precultured samples added different carbon sources?glucose,cellulose and biochar?were cultured 28 days.We found that under the same dilution gradient,the pattern of carbon source utilization of microbial community demonstrated significant differences among different carbon sources.On the other hand,under the same carbon source condition,pattern of carbon source utilization of microbial community was also significantly different.In conclusion,there were strong effects of both microbial diversity and carbon source on the soil carbon mineralization.Therefore,it is important that soil microbial diversity would be for the function of forest ecosystem.