Seasonal Changes Of Bacterial Community Structure And Function In Cellar Water And Their Interactive Responses To Water Quality Factors

The surface and groundwater resources are extremely scarce in the villages and towns of Northwest China,where hills and gullies are the main landforms.There has been a long-term drinking water safety crisis for people and animals,and rainwater which is usually collected and stored in cellar,cellar water is the only potential water resource.However,the quality of cellar water is generally polluted and the situation of water safety is not very encouraging,which has become one of the main factors encumbering the economic and social development of the region and the further improvement of people's living standards.It was found that cellar water had significant self-purification during storage.The self-purification exists in the degradation of various pollutants by microorganisms in the water.In the process of water self-purification,the seasonal variation of microbial community is a complex ecological process involving many factors.The composition of microbial community is closely related to the environmental factors in its habitat.There are also obvious interactive responses between environmental factors and microbial community.These interactions are strong effects on water self-purification.The ecological characteristics of microorganisms can be divided into structural and functional characteristics,which is an effective starting point for understanding and solving environmental problems.However,no scholars have studied the structure and function diversity of microbial community,the interaction between bacterial community and water quality factors.In order to elucidate the interaction between bacterial community and water quality factors in the process of self-purification of cellar water,the 16 S rRNA gene-high-throughput sequencing technology combined with bioinformatics analysis methods,tools and databases such as PCA,PCoA,RDA,PICRUSt bioinformatics online platform and KEGG,were used to systematically study the seasonal variation characteristics of the structure and function of bacterial community,and the interaction between the structure and function diversity of bacterial community and water quality factors.The main conclusions are followings:(1)Microorganisms in cellar water have high taxonomic diversity,and the structure and composition of microbial community are different in different time series.Microbial community shows a large number of rare species and a few common species of species abundance distribution pattern,that is,a small number of dominant bacteria with relatively high abundance constitute micro-organisms at different taxonomic levels.The difference of the basic community structure of organisms is mainly reflected in the change of dominant flora status and relative abundance,while the composition and abundance of many non-dominant bacteria with low relative abundance are different in each sample,and some non-dominant bacteria appear in specific cellar water samples.(2)The microbial community in cellar water has a high diversity of functional genes,including a variety of functional genes encoding enzymes involved in the cycling and degradation of carbon,nitrogen and phosphorus.A large number of functional genes encoding enzymes related to the degradation and metabolism of fatty acids,starch and sucrose,nitrogen and phosphorus in microbial communities are characterized by high functional diversity and quantitative dominance,although there are differences among the samples.There was a significant positive correlation with the water quality factors polluted by reactive nitrogen,phosphorus and organic matter,indicating that there were a large number of microorganisms with relatively specific ecological functions in the cellar water carrying out a lot of metabolic activities related to carbon,nitrogen and phosphorus.The diversity and abundance of functional genes encoding corresponding enzymes in each sample reflect the distribution characteristics of microbial communities with specific ecological functions in each sample of cellar water.(3)The dynamic change and succession of microbial communities at different taxonomic levels in cellar water with time is a complex ecological process regulated by multiple factors.The key factors affecting the growth,composition and change of bacterial community in cellar water were the different interaction,mode and intensity between bacteria and bacteria,bacteria and water quality factors.The key microbial groups that play an important role in the process of cellar water self-purification mainly include:Proteobacteria at phylum level,Acidimicrobiia,Chloroflexi,?-proteobacteria,Opitutae,Anaerolineae at class level,with the Acidimicrobiia being main key microbial groups.At order level,Accidimicrobiales,[Saprospirales],Alteromonadales,Nitrosomonadales,Bacteroidales,[Roseiflexales] were the main microbial groups,among which Nitrosomonadales was the most important one.Desulfobulbaceae,[Acidaminobacteraceae],Methanoregulaceae,Pirellulaceae,Brucellaceae were the main microorganisms at the family level,among which Desulfobulbaceae was important.Herbiconiux,Carnobacterium,Paenibacillus,Polaromonas,Leptothrix were the main microorganisms at genus level,among which Herbiconiux was important.The relationship between bacterial communities in cellar water is more cooperative than competitive,and the relationship between bacterial communities with positive correlation is obviously closer than that between bacterial communities with negative correlation,which makes them tend to cooperate with each other(such as mutualism)or have similar niche preferences,and show corresponding relationship.The bacterial community with chemotaxis in cellar water has a relatively objective function.The positive and negative correlation between bacterial community and environment is probably related to the chemotaxis of bacterial community.The research is very important for understanding the migration and transformation of pollutants in cellar water under the action of bacterial community,revealing the specific ecological function of bacteria,and further developing the management and maintenance of water quality in cellar water,and developing suitable bioremediation technology for water pollution in cellar water.