球形红细菌厌氧降解邻二氯苯及其机理研究

研究分析光合细菌球形红细菌在厌氧光照条件下降解邻二氯苯的条件和机理。结果表明, 在厌氧光照条件下球形红细菌的最佳生长和对邻二氯苯的最佳降解条件为：pH 7.0, 温度为30℃, 接种量10％。在最佳条件下, 邻二氯苯的去除率可达90％以上; 其降解中间产物主要有氯苯、4-羟基苯甲酸; 根据降解产物的分析, 推断球形红细菌降解邻二氯苯的机理主要是按照先脱掉一个氯原子生成氯苯, 然后氯苯进一步脱氯并通过4-羟基苯甲酸的代谢途径开环进行。     

球形红细菌厌氧降解2,4-二硝基甲苯

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30 °C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始pH 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

球形红细菌污泥颗粒化及降解氯苯

投加絮凝剂是促使微生物快速形成污泥颗粒的一种有效手段,通过研究在不同絮凝剂下生成的生物絮体的形态和沉降性能,推荐选用聚合氯化铝(PAC)作为促进光合细菌球形红细菌形成污泥颗粒的絮凝剂。PAC的最佳投加量范围为140-160mg/L,其中,PAC投加量150mg/L时,促进污泥颗粒化的效果最好。考察球形红细菌污泥颗粒降解氯苯的环境条件,结果表明球形红细菌污泥颗粒降解氯苯的最佳条件为好氧、pH7.0、30°C。     

Non-reciprocal regulation of Rhodobacter capsulatus and Rhodobacter sphaeroides recA genes expression

Abstract The Rhodobacter capsulatus recA gene has been isolated and sequenced. Its deduced amino acid sequence showed the closest identity with the Rhodobacter sphaeroides RecA protein (91% identity). However, the promoter regions of both R. capsulatus and R. sphaeroides recA genes are only 64% similar. An Escherichia coli -like LexA binding site was not present in the upstream region of the R. capsulatus recA gene. Nevertheless, the R. capsulatus recA gene is inducible by DNA damage in both hetero- and phototrophically growing conditions. The R. capsulatus recA gene is poorly induced when inserted into the chromosome of R. sphaeroides , indicating that the recA gene of both bacteria possess different control sequences despite their phylogenetically close relationship.     

球形红杆菌L2的生物学特性及其应用

从淀粉废水中分离获得一株光合细菌,经形态特征,培养特征,生理生化特征及Ｇ＋Ｃｍｏｌ％含量等生物学特性分析,确定为球形红杆菌（Ｒｈｏｄｏｂａｃｔｅｒｓｐｈａｅｒｏｉｄｅｓ）Ｌ２。该菌应用于淀粉废水处理,ＣＯＤ去除率达９５．７％发酵产类胡萝卜素,产量达２９５ｍｇ／Ｌ;作为饲料添加剂进行肉鸡饲喂,增重１６．４０％。     

Chromate reduction by Rhodobacter sphaeroides

Rhodobacter sphaeroides grew in the presence of up to 43 μM chromate and reduced hexavalent chromium to the trivalent form under both aerobic and anaerobic conditions. Reduced chromium remained in the external medium. Reductase activity was present in cells of R. sphaeroides independent of whether chromate was present or not in the growth medium. The reducing activity was found in the cytoplasmic cell fraction and was dependent on NADH. The chromate-reducing enzyme was purified by anion exchange, hydroxyapatite and hydrophobic interaction chromatography, and gel filtration. The molecular weight of the enzyme was 42 kDa as determined by gel filtration. The optimum of the reaction is at pH 7.0 and 30°C. The enzyme activity showed a hyperbolic dependence on the concentrations of both substrates, NADH and chromate, with a maximum velocity at 0.15 mM NADH. A K _m of 15±1.3 μM CrO₄ ²⁻ and a V _max of 420±50 μmol min⁻¹ mg protein⁻¹ was determined for the enzyme isolated from anaerobically grown cells and 29±6.4 μM CrO₄ ²⁻ and 100±9.6 μmol CrO₄ ²⁻ min⁻¹ mg protein⁻¹ for the one from aerobically grown ones. Journal of Industrial Microbiology & Biotechnology (2000) 25, 198–203. Received 05 January 2000/ Accepted in revised form 27 May 2000     

Nucleotide and deduced amino acid sequence of the Rhodobacter sphaeroides gene encoding form II ribulose-1,5-bisphosphate carboxylase/oxygenase and comparison with other deduced form I and II sequences

The nucleotide sequence for the Rhodobacter sphaeroides form II ribulose 1,5-bisphosphate carboxylase/oxygenase was determined. The deduced product is highly homologous with the form II-like enzyme of Rhodospirillum rubrum , but appears to be more distantly related to the large subunit of the L₈S₈ enzyme found in autotrophic bacteria, cyanobacteria and higher plants. Several regions highly conserved among L₈S₈ and L_X enzymes correspond with regions previously implicated in catalytic activity and subunit interactions. An imperfect palindrome and a stem loop structure were identified in the 5' and 3' flanking sequences, respectively, of R. sphaeroides rbpL .     

类球红细菌发酵生产类胡萝卜素条件优化

本文对类球红细菌3757产类胡萝卜素进行了发酵条件优化,结果得到了较优的培养基组成:葡萄糖2%,苹果酸钠0.5%,酵母浸粉1.3%,硫酸铵0.9%,磷酸氢二钾0.09%,磷酸二氢钾0.06%,生长因子溶液1%,p H 8.0;其中,生长因子溶液配方:维生素B1 0.1%,烟酰胺(VPP)0.1%,生物素0.0016%。较优培养条件为:接种量5%,转速200 r/min,种龄24 h,发酵温度32℃,发酵时间40 h。优化后类胡萝卜素产率较优化前提高了76.2%。     

Identification and characterization of a GroEL homologue in Rhodobacter sphaeroides

A protein closely related to the Escherichia coli GroEL protein has been isolated from Rhodobacter sphaeroides. Native and SDS-polyacrylamide gel electrophoresis of this protein have shown that it is present in the cell as a multimeric complex of Mr 670,000 which is composed of a monomer of Mr 58,000. Antisera raised against the Mr 58,000 polypeptide have been shown to cross-react with GroEL and the alpha subunit of the pea plastid chaperonin. The N-terminal amino acid sequence of the Mr 58,000 polypeptide is identical to that of GroEL at 15 of 19 residues and is also closely related to the alpha subunit of the pea plastid chaperonin, though less so to the beta subunit.