Pyrosequencing Analysis Of Soil Microbial Diversity And Structure After Polylactic Acid Degradation In Different Soil Environments

Because of the increasing scarcity of petroleum re-sources coupled with the continual worsening of global “white pollution”,the study of biodegradable bio-based materials has become an important focus for researchers around the world.Polylactic acid(PLA)is a biodegradable aliphatic polyester that can be produced by fermentation of renewable resources such ascorn,cassava,potato and sugarcane.PLA can be completely degraded into CO2 and H2 O in microbial environment.However,the degradation rate is slow in the natural environment,how to improve the degradation rate has become one of the hotspots in the current research.In this articl,three types of soil(swamp,orchard and farmland)were selected to evaluate the biodegradation of PLA.During a four-month burial time course in soil,residual degraded samples were regularly sampled,and biodegradation was investigated by performing scanning electron microscopy(SEM)and by assessing tensile strength and elongation at break.PLA nonwovens biodegradation was also evaluated by measuring CO2 generation.The abundance,diversity and community structure of the environmental microorganisms present in the three soil types were determined by performing pyrosequencing to identify dominant PLA-degrading microbes.At the same time,PLA was used as the sole carbon source to acclimate microorganisms in swamp soils and analysis by performing pyrosequencing.The main results are as follows:1.PLA can be degraded under soil conditions.The best degradation effect of PLA was found in swamp soil and the worst degradation effect of PLA was found in farmland soil.2.The Infrared Spectroscopy(IR)analysis display: The degradation process of PLA in natural environment is aerobic degradation process.3.The higher diversity and richness of soil bacteria,the better degradation of PLA.4.The number of O TU in 3 types of soil(swamp,orchard and farmland)were 11110,811236 and 8848,respectively.All bacteria were grouped into 9 different phyla and 16 different families.Proteobacteria and Bacteroidetes were the two most dominant PLA-degrading microbial phyla.Flavobacteriaceae,Comamonadaceae and Cytophagaceae were the three most dominant PLA-degrading families.5.The number of OTU in Gen1,Gen3,Gen6 were 1619,1014 and 945,respectively.All bacteria were grouped into7 different phyla and 6 different families.Consistent with the conclusion 4,Proteobacteria and Bacteroidetes were the two most dominant PLA-degrading microbial phyla.