【摘要】 利用厌氧微生物分离技术,对深度为1.2 m的海南红树林湿地沉积物钻孔样品进行了分离培养,共获得11株厌氧sulfate-reducing bacteria（SRB）菌株。经显微观察和16S rDNA序列分析,可归纳为6个属,其中已经报道有芽孢杆菌属（Bacillus）、弧菌属（Vibrio）和梭状芽胞杆菌属（Clostridium）,另外3个属分别为伯克霍尔德菌属（Burkholderia）、希瓦氏菌属（Shewanella）和海杆菌属（Marinobacterium）。不同属的细菌对硫酸盐还原的速率最低为14.71%,最高可达56.78%,并且以上6属11株菌都能将+6价的硫还原生成-2价硫,并与培养基中的Fe²⁺结合生成黑包FeS沉淀,而这些无定形FeS沉淀是生成黄铁矿的前体。红树林湿地SRB种群数量随沉积物深度的增加而降低,结合沉积物的地球化学分析测试结果表明,表层（0cm）水界面的沉积物由于处于氧化-还原界面,氧气的周期性输入在一定程度上抑制了SRB的生长;随着深度增加（10-40 cm）,充足的有机质、偏中性的pH值以及厌氧环境的增强,使得SRB种类和数量明显增加;而60 cm以下沉积物中因TOC含量降低,减少了微生物可利用的碳源,pH值明显降低,Na⁺和Ca²⁺离子浓度明显增加,这些因素都抑制了SRB的生长,使得深部沉积物中SRB的种类和数量显著减少。更多还原

【Abstract】 Utilizing an anaerobic method of isolating microorganisms,we identified and cultured a total of 11 strains of anaerobic sulfate-reducing bacteria（SRB） from sediment samples collected from 1.2 m-deep mangrove swamps in Hainan.These SRB were classified into 6 genera based on their morphology that was observed under a microscopy and through sequence analysis of their 16 S ribosomal DNA（16S rDNA）.These include three reported genera:Bacillus,Vibrio,and Clostridium.They also include three newly discovered genera:Burkholderia,Shewanella,and Marinobacterium.The minimum rate of sulfate reduction of these bacteria was 14.71%,and the maximum rate was 56.78%.Moreover,all the 11 strains were able to reduce sulfur S⁶⁺ to S^2-,which was subsequently bound with iron(Fe²⁺) to produce black iron（Ⅱ） monosulfide（FeS） precipitate.FeS precipitate is the precursor of pyrite.The population of SRB in the mangrove swamps decreased with depth.Geochemical analysis of the sediments reveal that the oxidation and reduction interface was located at interface of sediment and water（0 cm）,and the periodic input of oxygen partially inhibited the growth of SRB.In contrast,as the depth of sediment increased（10-40 cm）,an adequate supply of organic matter,a near-neutral pH,and an enhanced anaerobic environment led to a significant increase in both the number of SRB strains and the population of SRB.However,at depths greater than 60 cm,the total organic carbon（TOC） content in the sediment decreased,which reduced the carbon source available for microorganisms.In addition,both a significant reduction in pH levels and significant increases in sodium cation（Na⁺） and calcium cation(Ca²⁺) concentrations inhibited SRB growth,greatly decreasing the number of SRB strains and the total SRB population in the deep sediments.The geochemical characteristics of the sediments were the main factors affecting vertical distribution of SRB species in the mangrove swamp samples.更多还原