【摘要】 目的:研究从厦门近岸海域沉积物样品中分离筛选出的芽孢八叠球菌属菌株Sporosarcina saromensis M52在含不同浓度六价铬[Cr（Ⅵ）]培养基中的生长情况,定位Cr（Ⅵ）还原酶,探讨金属离子和小分子物质对耐Cr（Ⅵ）菌株M52还原能力的影响。方法:将M52菌株的种子液接种于含不同浓度(0～600mg·L^-1)Cr（Ⅵ）LB培养基中,培养0～48h后用紫外分光光度法测量600nm处M52菌液的吸光度（A）值,观察M52菌株在含0、50、100、200、400和600mg·L^-1 Cr（Ⅵ）的LB培养基中的生长情况。将M52菌液超声破碎前、破碎后后离心所得胞内和胞外活性物质与对照组M52菌液在37℃、pH 7.5条件下培养0、12、24和48h,用二苯碳酰二肼分光光度法分别测定溶液中Cr（Ⅵ）的浓度,计算各时间点胞内和胞外活性物质中Cr（Ⅵ）的还原率。在LB培养基中分别加入0.2 mmol·L^-1的Mn²⁺、Fe²⁺和Cu²⁺,1 mmol·L^-1 SDS、1%Triton X-100和吐温80作为处理组,以未作处理的LB液体培养基为对照组,将种子液以4%浓度接种于处理组和对照组,计算M52菌株在0、6、12、24、36和48h对Cr（Ⅵ）的还原率,分析金属离子和小分子物质处理组中M52菌株对Cr（Ⅵ）还原率的变化。结果:当Cr（Ⅵ）浓度低于100mg·L^-1时,随浓度增加菌株生长加快;当100mg·L^-1≤Cr（Ⅵ）浓度<600mg·L^-1时,随浓度增加菌株生长受到抑制;当Cr（Ⅵ）浓度高于600mg·L^-1时,M52菌株几乎不生长。与对照组比较,M52菌株对Cr（Ⅵ）的还原率在细胞内外均升高（P<0.05）,胞内Cr（Ⅵ）的还原率最高。与对照组比较,Cu²⁺和Fe²⁺存在情况下M52菌株对Cr（Ⅵ）的还原率升高（P<0.05）,且Cu²⁺>Fe²⁺,Mn²⁺存在情况下M52菌株对Cr（Ⅵ）的还原率降低（P<0.05）;与对照组比较,小分子物质SDS、Triton X-100和吐温80存在时,M52菌株对Cr（Ⅵ）的还原率降低（P<0.05）,且SDS>Triton X-100>吐温80。结论:低浓度Cr（Ⅵ）可以促进M52菌株生长,高浓度Cr（Ⅵ）则会抑制菌株生长,M52菌株对Cr（Ⅵ）的还原主要发生在胞内,Cu²⁺和Fe²⁺可促进M52菌株还原Cr（Ⅵ）,吐温80、Triton X-100和SDS可抑制M52菌株还原Cr（Ⅵ）。更多还原

【Abstract】 Objective:To investigate the growth of Sporosarcina saromensis M52o btained from the sediment samples in Xiamen,to locate the Cr（Ⅵ）reduetase,and to study the effects of metal ions and small molecules on the reducing ability of Cr（Ⅵ）resisistant strain M52.Methods:The seed solution of M52 strain was inoculatedinto the LB medium containing different concentrations(0-600 mg·L^-1)of Cr（Ⅵ）.After cultivating for 0-48h,the absorbance（A）value of M52 strain liquid at 600nm was measured by UV spectrophotometry.The growth of M52strain in LB medium containing 0,50,100,200,400,and 600 mg·L^-1 Cr（Ⅵ）was observed.The intracellular and extracellular active substances obtained by centrifugation of M52bacteria solution before and after sonication and the M52 in control group were cultured at 37℃and pH 7.5,respectively.Using diphenylcarbazide spectrophotometry,the concentrations of Cr（Ⅵ）in the solution at 0,12,24,and 48hwere measured,and the reduction rates of Cr（Ⅵ）in intracellular and extracellular active substances at each time point were calculated.0.2mmol·L^-1 Mn²⁺,Fe²⁺and Cu²⁺,1mmol·L^-1SDS and 1%Triton X-100,Tween 80were added to the LB medium as treatment groups,and the untreated LB liquid medium was used as control group.The seed solution was inoculated in treatment groups and control group at 4%concentration.The reduction rates of Cr（Ⅵ）by M52 at 0,6,12,24,36,and 48hwere calculated.The changes of the reduction rates of Cr（Ⅵ）by M52in metal ion and small molecule treatment groups were investigated.Results:When the concentration of Cr（Ⅵ）was lower than 100mg·L^-1,the growth of strain was promoted with the increase of concentration;when the concentration of Cr（Ⅵ）was higher than 100mg·L^-1,the growth of the strain was inhibited with the increase of concentration;when the concentration of Cr（Ⅵ）was higher than 600mg·L^-1,the M52 strain hardly grew.Compared with control group,the reduction rates of Cr（Ⅵ）by M52occurred both inside and outside the cells were increased（P<0.05）,and the intracellular Cr（Ⅵ）had the highest reduction rate.Compared with control group,the reduction rates of Cr（Ⅵ）by M52were increased in the presence of Cu²⁺and Fe²⁺（P<0.05）,and Cu²⁺>Fe²⁺;the reduction rate was reduced in the presence of Mn²⁺（P<0.05）.Compared with control group,the reduction rates of Cr（Ⅵ）by M52were reduced in the presence of small molecules SDS,Triton X-100,and Tween80,and SDS>Triton X-100>Tween 80.Conclusion:Low concentration of Cr（Ⅵ）can promote the growth of the M52strain,and high concentration of Cr（Ⅵ）can inhibit the growth of the strain.The reduction of Cr（Ⅵ）by M52 mainly occurs in the cells.Cu²⁺and Fe²⁺can promote the reduction of Cr（Ⅵ）by M52.Tween 80,Triton X-100,and SDS can inhibit the reduction of Cr（Ⅵ）by M52.更多还原