Spatio-temporal Distribution Of Microbial Communities In Full-scale System Treating Soy Sauce Brewing Wastewater And Analysis Of Related Environmental Factors

Industrial production of soy sauce has resulted in large quantities of effluents,representing an important source of pollution.Currently,anaerobic-anoxic-aerobic membrane bioreactor process（A₂O-MBR）is the most commonly applied for treatment of soy sauce brewing wastewater.Highly diverse microorganisms within activated sludge are functionally important for pollutants removal,whose spatio-temporal distribution are related to the rates of contaminants removal and influenced by environmental factors.Nevertheless,still comparatively little is known about the spatio-temporal distribution of microbial communities in the soy sauce brewing wastewater treatment process and related environmental factors.Microbial community structures and metabolic activity in the A₂O-MBR system treating soy sauce-producing wastewater were studied using 16S rRNA gene and rRNA high-throughput sequencing.At DNA and RNA level,microbial communities harbored distinct biodiversity.Proteobacteria was the most abundant and active phylum in activated sludge.Abundant Megasphaera,Thauera and Azoarcus were in slow metabolism,while Psychrobacter with low abundance had the highest potential for activity in the anaerobic tank.As for archaea,Cenarchaeales was the most abundant and active order and a large amount of hydrogenotrophic methanogens kept syntrophic with Megasphaera.The rare taxa,such as Methanosarcinales and Nitrosopumilales,had a high potential for activity in the anoxic tank.Furthermore,the total and active microbes were quantified via DNA and RNA-based qPCR and the 16S rRNA:rRNA gene ratios of bacteria and archaea decreased along with the treatment process.Next,spatio-temporal distribution of microbial communities and related environmental factors in the A₂O-MBR system treating soy sauce-producing wastewater were investigated using 16S rRNA gene and rRNA high-throughput sequencing.Distinct from the archaeal community,the total and active bacteria were seasonally clustered.Firmicutes and Planctomycetes increased their abundance in summer and autumn,while Thaumarchaeota decreased.In winter,Prevotella₉ and Lactobacillus shifted to be more metabolically active.qPCR results showed that the biomass of the total bacteria significantly increased in winter and high temperature facilitated the dynamic changes of archaeal biomass.Temperature,pH,chemical oxygen demand（COD）,total ammonia nitrogen（TAN）and nitrate nitrogen（NO₃^--N）were major factors influencing the structure of microbial communities.Firmicutes and Bacteroidetes were positively correlated with COD and TAN,while Proteobacteria negatively correlated.SM1A02 increased its abundance in summer and autumn and positively correlated with temperature.Methanomicrobiales was positively correlated with total ammonia nitrogen,highly affiliative with ammonia.Furthermore,the biomass of the total bacteria significantly increased in winter and high temperature facilitated the dynamic changes of microbial biomass.FAPROTAX predicted that the main metabolic functions of taxa were chemoheterotrophy,aerobic chemoheterotrophy,fermentation,nitrate reduction and nitrogen respiration with no significant seasonal differences.Altogether,this study investigated the spatio-temporal distribution of microbial communities and related environmental factors during the soy sauce brewing wastewater treatment process,and provided theoretical basis and data support for treatment of soy sauce brewing wastewater.