河口微生物污染溯源及其氮循环微生物的响应研究

Microbial source tracking in the estuary and the response of nitrogen-cycling microorganisms

在全球河口氮污染严峻的形势下,关于河口污染来源及其对氮循环微生物影响机理尚不明确.本研究以广东省江门市镇海湾河口为研究区域,采用高通量测序技术,解析不同季节污染源对河口污染的相对贡献,表征河口氮循环微生物群落的生态学特征,探究氮循环微生物与环境因子的关系,并揭示其对不同污染源输入的响应规律.结果表明:(1)在镇海湾河口已知污染来源中,畜禽养殖污染(夏季vs冬季:16.24%vs 37.75%)是河口最大污染来源,其次是沉积物(夏季vs冬季:16.20%vs 26.01%);夏季未知污染来源(51.28%)显著高于冬季(11.03%).(2)反硝化菌主要优势属为贪铜菌属(Cupriavidus)和假单胞菌属(Pseudomonas),固氮菌主要优势属为脱硫单胞菌属(Desulfuromonas)、慢生根瘤菌属(Bradyrhizobium)等,氨氧化菌主要优势属为亚硝化螺菌属(Nitrosospira)和亚硝化单胞菌属(Nitrosomonas);氨氧化菌在反硝化菌、固氮菌和氨氧化菌中α多样性最低(3)T、SAL、pH、TP和TOC是镇海湾河口反硝化、固氮和氨氧化细菌群落共同驱动因素,同时NO_(3)^(-)也是固氮菌群落的驱动因素.(4)镇海湾河口不同污染源输入对反硝化菌、固氮菌与氨氧化菌群落的影响存在较大差异,如反硝化菌群落多样性与沉积物、畜禽养殖污染呈正相关,而与农业、生活污染呈负相关;氨氧化菌群落多样性与农业、生活污染呈正相关,而与畜禽养殖污染呈负相关.本研究的开展深化了对河口污染源输入与氮循环微生物关系的认识,拟为河口富营养化水体的治理对策提供科学依据.

In light of the severe global situation of nitrogen pollution in estuaries,there is a pressing need for a better understanding of pollution sources of the estuary and their impact on the nitrogen-cycling microorganisms.In this study,the estuary of Zhenhai Bay,Jiangmen City,Guangdong Province,was used as the study area.We used high-throughput sequencing technology to resolve the relative contribution of different seasonal pollution sources to estuarine pollution.Additionally,the ecological characteristics of the estuarine nitrogen-cycling microbial community were characterized,and the relationship between estuarine nitrogen-cycling microorganisms and environmental factors was explored.The response pattern of nitrogen-cycling microorganisms to different pollution sources were also investigated.The results showed that:①Among the known sources of pollution in the Zhenhai Bay estuary,livestock(summer vs winter:16.24%vs 37.75%)was the largest source of pollution,followed by sediment(summer vs winter:16.20%vs 26.01%).Unknown sources were significantly higher in summer(51.28%)than in winter(11.03%).②The main dominant genera of denitrifying bacteria were Cupriavidus and Pseudomonas,nitrogen-fixing bacteria were Desulfuromonas,Bradyrhizobium,etc.,and ammonia-oxidizing bacteria were Nitrosospira and Nitrosomonas.Ammonia-oxidizing bacteria had the lowest alpha diversity among three gorups③Environmental factors such as temperature(T),salinity(SAL),pH,total phosphorus(TP),and total organic carbon(TOC)were common drivers of denitrifying bacteria,nitrogenfixing bacteria and ammonia-oxidizing bacteria in the Zhenhai Bay.NO3-was also a driver for nitrogen-fixing bacteria.④The effects of different pollution sources on denitrifying,nitrogen-fixing and ammonia-oxidizing bacterial communities in the Zhenhai Bay varied considerably,e.g.denitrifying bacteria was positively correlated with sediment and livestock,but negatively correlated with agriculture and domestic sources.On the other hand,ammonia-oxidizing bacteria were positively correlated with agriculture and domestic sources,but negatively correlated with livestock.This study deepens our understanding of the relationship between estuarine pollution sources inputs and nitrogen-cycling microorganisms.The findings provide valuable insights for the management measures of eutrophication in estuarie water bodies.By identifying specific pollution sources and their impacts on microbial communities,this research contributes to developing targeted and effective strategies for improving estuarine water quality.