尼克酰胺与核黄素提高红串红球菌USTB-03对4,6-二甲基二苯并噻吩脱硫活性研究

主要考察了尼克酰胺和核黄素提高红串红球菌USTB-03对4,6-二甲基二苯并噻吩(4,6-DMDBT)脱硫活性的效应。研究结果表明,在培养基中添加初始浓度为10 mmol/L的尼克酰胺,脱硫比活性由原来302.4 mmol 4,6-DMDBT/(kg细胞干重·h)增加到476.4 mmol 4,6-DMDBT/(kg细胞干重·h),提高了57.5%。添加初始浓度为25μmol/L的核黄素,脱硫比活性增加到了465.8 mmol 4,6-DMDBT/(kg细胞干重·h),提高了54%。无论是采用微量的尼克酰胺或核黄素都可以大幅度提高红串红球菌USTB-03对4,6-DMDBT的脱硫活性,在此研究领域尚未发现有研究报道。尼克酰胺和核黄素分别是NAD和FMN的主要成分,可以促进脱硫关键辅酶FMNH_2的生物合成,因此,大幅度提高了红串红球菌USTB-03对4,6-DMDBT的脱硫活性。     

Investigation of the Organic Solvent Resistance Mechanisms in Rhodococcus and Lysinibacillus Using Several Molecular Forensic Tools

Rhodococcus erythropolis IBB_Po5 (KM405337) and Lysinibacillus xylanilyticus IBB_Po7 (KM405338) showed good tolerance to 5% (v/v) organic solvents (alkanes, aromatics). However, 5% (v/v) alkanes (i.e., cyclohexane, n-hexane, n-decane) were less toxic for R. erythropolis IBB_Po5 and L. xylanilyticus IBB_Po7 cells, compared with 5% (v/v) aromatics (i.e., toluene, o-xylene, ethylbenzene). The high organic solvent tolerance of these two Gram-positive bacteria could be due to the presence in their genome of some catabolic (alkB1, todM, xylM) and trehalose-6-phosphate synthase (otsA1) genes. R. erythropolis IBB_Po5 possesses three catabolic genes (i.e., alkB1, todM, xylM), while L. xylanilyticus IBB_Po7 possesses only one catabolic gene (i.e., alkB1). Numerous adaptations involved in organic solvents tolerance were depicted in R. erythropolis IBB_Po5 and L. xylanilyticus IBB_Po7 cells exposed to 5% (v/v) alkanes and aromatics (i.e., changes in the cell growth rate, membrane permeability, cell morphology, biosurfactant emulsification index, carotenoids profile, DNA fingerprinting). Therefore, microbiological, biochemical, and DNA fingerprinting studies of the bacteria isolated from polluted environments could provide valuable information that may complement or supplement other forensic investigations.     

Bioremediation of DSO contaminated soil

Seven strains isolated from DSO (disulfide oil) contaminated soils. Among them, two strains had high potential to remove DSO from contaminated soils. These strains identified as Paenibacillus (a gram positive, nitrogen fixing spore, spore forming bacillus) and Rhodococcus (a gram positive, catalase positive, acid fast forming bacteria), by preliminary tests. The optimal conditions for DSO removal from contaminated soils were determined. The biotic depletion for Paenibacillus pre-grown in nutrient broth was 24.3% and for Rhodococcus was 19.3%. Bioremediation of DSO in soil was investigated by gas chromatography and UV–vis absorption spectroscopy techniques. The results showed that addition of water (20 μl/g soil) to soil is necessary for DSO removal by both strains and none of the strains could remove DSO in concentrations more than 30 μg/g soil. The results also showed that none of these strains could degrade DSO under anaerobic condition.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

烷烃降解菌的筛选、鉴定及优势菌株的降解特性

以正庚烷为唯一碳源,从长期受到石油污染的土壤中筛选获得可利用正庚烷的微生物14株.通过形态观察和16S rDNA序列比对,鉴定G2、G9、G14为红球菌属,G3、G27为人苍白杆菌属,G4、G7为芽孢杆菌属,G5、G10、G15、G25为节杆菌属,G16为缺陷短波单胞菌,G17、G22为嗜麦芽寡养单胞菌属.通过考察其降解烷烃的能力,确定Rhodococcus sp.G2为烷烃降解优势菌株.该菌株可代谢庚烷获得最大菌体浓度D600 nm=7.51.同时该菌对不同碳链长度的烷烃,如十二烷、十六烷、煤油和二甲苯均具有较强的降解能力,以十二烷为碳源的最大比生长速率为0.37 h-1,最高菌体浓度为D600 nm=12.00,在正十六烷中生长,最大比生长速率为0.23 h-1,在煤油中生长,最大比生长速率为0.14 h-1,在以二甲苯为唯一碳源时,D600 nm也可达到1.00左右.研究表明该菌株对于石油污染土壤的生物修复有很大的应用前景.图6表2参9     

高效复合菌对多菌灵的生物降解

将多菌灵降解菌Alcaligenes sp.和Rhodococcua sp.(编号为A和R)按不同比例进行复配,并采用三波长校正法和HPLC法测定不同复配降解体系中多菌灵的残留量,比较了纯培养和复合菌群对多菌灵的降解效果,最后对高效复合菌的降解条件进行了优化.试验结果表明,得到的高效降解复合菌群AR5(A∶R复配比例1...     

氟铃脲降解菌FLN-1的分离鉴定及降解特性

从农药厂废水处理池的活性污泥中分离到1株能降解氟铃脲的菌株,命名为FLN-1.根据表型特征、生理生化特性及16S rDNA序列同源性分析,将FLN-1初步归类为红球菌属(Rhodococcus sp.).研究结果表明.该菌能在含氟铃脲(50mg·L-1)的基础盐液体培养基中降解氟铃脲,5d降解率达85%,降解最适pH为6.0～9.0,最适温度为25～40℃,降解速率随初始接种量的增加而增大;100mg·L-1的葡萄糖、酵母膏和蛋白胨对菌株降解氟铃脲具有促进作用.酶的定域试验表明,降解氟铃脲的酶为胞内酶.     

二苯并噻吩脱硫微生物菌种的筛选与活性

从被石油污染的土壤中筛选出1株能对二苯并噻吩(DBT)进行高效脱硫的微生物菌种,初步鉴定为红串红球菌USTB-03(RhodococcuserythropolisUSTB-03).该菌种可以按特异性脱硫途径(简称4S途径)将DBT转化为2-羟基联苯(2HBP)和亚硫酸作为最终脱硫产物.在葡萄糖、甘油和乙醇分别作为微生物生长的唯一碳源时,葡萄糖是支持该菌生长和提高其脱硫比活性的较好碳源,使培养出的微生物对DBT的脱硫比活性达到了68.63mmol2HBP/(kg·h).该菌株还可以对4,6-二甲基二苯并噻吩(4,6-DMDBT)进行脱硫.     

降解DBP菌株CQ0302的分离鉴定及其降解特性

从垃圾填埋场的土壤中分离到一株降解邻苯二甲酸二丁酯(DBP)的细菌 CQ0302.经过对其形态特征、生理生化以及 16S rRNA 序列分析,该菌株初步鉴定为深红红球菌(Rhodococcus ruber).该细菌利用 DBP 生长的最适温度为 30.0～35.0℃,最适 pH 值为 7.0～8.5. DBP 浓度低于 1500mg/L 时的降解动力学方程为 ln C=-0.02735t+A,半衰期为 25.34h.菌株全细胞蛋白 SDS-聚丙烯酰胺电泳结果显示,菌株在 DBP 诱导前后的全细胞蛋白组成有明显的差异.测定了降解途径中相关酶的活性,表明芳环的裂解是由邻苯二酚 1,2-双加氧酶催化的.     

一株溶藻细菌的溶藻特性及其鉴定

从海绵固定化微生物系统中分离获得1株溶藻细菌P15,对其溶解铜绿微囊藻(Microcystisaeruginosa)、栅藻(Scenedesmus)及小球藻(Chlorella)的效果、溶藻方式进行了研究,并利用16SrDNA序列分析法进行了鉴定.结果表明,初始菌浓度大于2.4×10⁷个/mL时,P15菌具有理想的溶藻效果,48h后铜绿微囊藻去除率可达到65.84%,栅藻及小球藻也能很好地去除.P15菌革兰氏染色阳性,可运动;能利用乳酸胺等32种常见碳源.P15菌株与多株红球菌的16SrDNA核苷酸序列的同源性均在99.7%以上,归属于红球菌属.