天津北大港水库水质存在咸化问题，水质咸化可能会导致微生物群落组成和多样性发生显著变化。为探究 水质咸化条件下水库微生物群落组成的空间分布特征，于 2021 年 12 月在北大港水库采集表层、中层和底层的水 样，利用高通量测序技术，对北大港水库不同深度及上下游的微生物群落组成及多样性进行分析，并探究溶解性 总固体与微生物群落的关系。结果表明：北大港水库的溶解性总固体（total?dissolved?solids,?TDS）质量浓度在表层、 中层和底层存在差异，下游高于上游。微生物的主要优势菌门为变形菌门、拟杆菌门和放线菌门，变形菌门的相 对丰度均超过 50%。优势菌属是 Clade_III 未定属（相对丰度 1.10％～72.72?％）和黄杆菌属（Flavobacterium?相对丰 度 0.32％～20.09?％），Clade_III 未定属的相对丰度上游高于下游，黄杆菌属的相对丰度表层高于中层和底层。上 游水体表层的微生物群落组成与中层、底层的微生物群落组成存在显著差异，下游在不同深度微生物群落组成差 异不显著，中层和底层的微生物群落组成存在相似性。Chao1 和 Shannon 指数表现出表层<中层<底层，下游略高 于上游，微生物 Alpha 多样性指数随 TDS 质量浓度的增大而减小。在科水平上，Clade_Ⅲ能够耐受较高的盐度，但 当 TDS 质量浓度>3?000?mg/L 时其丰度降低。

Beidagang?Reservoir?has?the?function?of?water?supply?in?the?utilization?of?water?resources.?The?reservoir can?provide?local?residents?with?drinking?water?and?irrigation?water.?There?is?a?problem?of?salting?in?the?water quality?in?the?Beidagang?Reservoir.?The?salting?law?and?mechanism?of?Beidagang?Reservoir?were?mainly?studied, and ?the ?microbial ?community ?structure ?was ?less ?studied. ?Salinization ?of ?water ?quality ?may ?lead ?to ?significant changes?in?microbial?community?composition?and?diversity.?The?reservoir?mainly?focuses?on?the?exploration?of?the diversity ?of ?microbial ?communities. ?There ?is ?a ?lack ?of ?comparative ?studies ?of ?reservoirs ?between ?different microorganisms ?at ?different ?water ?depths. ?The ?microbial ?communities ?of ?coastal ?reservoirs ?have ?been ?poorly studied.?Microorganisms?are?sensitive?indicators?of?salinity.?The?spatial?distribution?characteristics?of?microbial community?composition?under?salinization?of?water?quality?in?reservoirs?are?still?unclear.?It?is?of?great?significance to?study?the?community?distribution?of?microorganisms?in?salty?reservoirs.?It?can?not?only?understand?the?structural composition?of?microbial?communities?and?the?relationship?between?salinity,?but?also?provide?a?theoretical?basis?for bioremediation?of?high?salt?water?treatment.?It?provides?basic?data?and?scientific?basis?for?Beidagang?Reservoir?to play?the?function?of?water?supply?and?water?resource?utilization.?In ?order ?to ?explore ?the ?salinization ?and ?the ?spatial ?distribution ?characteristics ?of ?microbial ?communities, Beidagang?Reservoir?was?chosen?as?our?research?area.?The?water?samples?from?the?surface,?middle?and?bottom layers ?of ?Beidagang ?Reservoir ?were ?collected ?in ?December ?2021. ?The ?composition ?and ?diversity ?of ?microbial communities?at?different?depths?and?upstream?and?downstream?of?Beidagang?Reservoir?were?analyzed?by?high- throughput?sequencing?technology?to?understand?the?spatial?distribution?characteristics?of?the?microbial?community composition ?structure ?of ?Beidagang ?Reservoir. ?The ?relationship ?between ?dissolved ?total ?solids ?and ?microbial communities?was?explored.?The?influence?of?reservoir?salty?water?on?microbial?community?structure?was?explored. ??????The?results?show?that?there?are?differences?in?the?surface,?middle?and?bottom?layers?of?dissolved?total?solids (TDS)?mass?concentration?in?Beidagang?Reservoir,?and?the?downstream?is?higher?than?that?in?the?upstream.?The main ?dominant ?phylums ?of ?microorganisms ?are?Proteobacteria,?Bacteroidetes?and?Actinobacteria, ?and ?the abundance?of?Proteobacteria?is?more?than?50%.?The?dominant?genera?are?Clade_III?undetermined?genus?(1.10%- 72.72%)?and?Flavobacterium?(0.32%-20.09%),?the?abundance?of?upstream?Clade_III?undetermined?genera?is?higher than?that?of?the?downstream,?and?the?abundance?of?surface?Flavobacterium?is?higher?than?that?of?the?middle?and bottom ?layers. ?There ?were ?significant ?differences ?between ?the ?microbial ?community ?composition ?of ?the ?upper surface ?layer ?and ?the ?middle ?and ?bottom ?microbial ?community ?composition, ?while ?the ?downstream ?microbial community?composition?at?different?depths?was?not?significant,?and?the?composition?of?the?middle?and?bottom microbial?communities?was?similar.?The?Chao1?and?Shannon?indices?showed?that?the?surface?3?000?mg/L),?which?may?inhibit?their?growth. ??????This?study?can?provide?a?theoretical?basis?for?bioremediation?of?salty?water?in?reservoirs.?Therefore,?the?role?of salt-tolerant?microorganisms?on?water?purification?can?be?studied?in?depth.