砷输入对河口沉积物微生物厌氧发酵的影响

Effect of arsenic input on microbial anaerobic fermentation of estuarine sediments

为探究外源五价砷(arsenate,As(Ⅴ))输入对砷污染环境沉积物原位微生物厌氧发酵和群落结构影响,阐释As(Ⅴ)与砷污染河口沉积物微生物群落结构互作效应,本研究以辽宁省葫芦岛市某锌厂排污口下游高砷污染的五里河河口沉积物为对象,通过外源添加As(Ⅴ)(1、10、60 mg·L^(-1))进行富集培养,测定产氢产酸、pH与碳源消耗等理化参数,结合高通量测序技术检测沉积物中微生物群落组成变化;同时采用平板稀释涂布方法筛选高浓度As(Ⅴ)富集菌液中优势菌株。结果表明,富集培养过程中,所有处理组的砷形态都发生了转化,其中在60 mg·L^(-1)外源As(Ⅴ)投加下,约43%的As(Ⅴ)转化为三价砷(tarsenite,As(Ⅲ));微生物群落组成自原始沉积物的11个门转为单一厚壁菌门(Firmicutes),优势菌属狭义梭菌属1(Clostridium_sensu_stricto_1)占据优势生态位。自60 mg·L^(-1)的As(Ⅴ)输入的富集菌群中,筛选分离出一株厌氧发酵丁酸梭菌(Clostridium butyricum CXL⁃1),该菌株具有较高的As(Ⅲ)耐受性(≥200 mg·L^(-1)),并能利用葡萄糖发酵代谢产生有机酸和H2等发酵产物,为硫酸盐还原菌、产甲烷古菌等提供氢气和碳源。本研究结果可为砷污染环境微生物厌氧矿化修复提供参考。

The effect of exogenous arsenate(As(Ⅴ))input on the anaerobic fermentation and community structure in situ in arsenic(As)⁃contaminated sediments was investigated to elucidate the interaction between As(V)and microbial community composition in the arseniccontaminated estuarine sediments.The Ascontaminated sedi⁃ments were collected from the Wuli River in Huludao City,Liaoning Province,China.The sediment samples were incubated after adding As(V)(i.e.,1,10,60 mg·L^(-1),respectively).Physicochemical parameters(e.g.,hydrogen production,acid production,pH,and carbon consumption)and microbial community composition were measured during incubation.The dominant strains were isolated from culture solution with high As(V)concentration using plate dilution method.During the enrichment culture,transformation of arsenic form was observed in all treatments.Among them,about 43%of As(V)was converted to arsenite(As(Ⅲ))in the treatment with 60 mg·L^(-1) As(V).At the end of the incubation,the phylum number in the original sediment decreased from eleven to one(Firmicutes),and the dominant genus Clostridium_sensu_stricto_1 occupied the dominant ecological niche.An an⁃aerobic fermentative Clostridium butyricum CXL⁃1 with the high As(Ⅲ)tolerance(≥200 mg·L^(-1))was isolated from the treatment with the addition of 60 mg·L^(-1) As(V),which showed the capacity to produce fermentation products such as organic acids and H2 by glucose fermentation metabolism,thereby providing hydrogen and carbon sources for sulfatereducing bacteria and methanogens.Our results can provide reference for the anaerobic mineralization remediation of Ascontaminated environments by microorganisms.