低温高效苯酚降解菌的分离与降解特性

从哈尔滨太平污水厂活性污泥中筛选到7株高效苯酚降解菌,可利用苯酚作为唯一碳源和能源。通过对这7株菌在不同温度、pH值、以及不同苯酚浓度下生长和苯酚降解情况的考察,确定了这7株菌的最适生长温度为10°C,最适pH值为7.5,最大可降解苯酚浓度为3000mg/L。通过对这7株苯酚降解菌降解性能的研究表明:其具有较强的苯酚降解能力,在10°C、pH值为7.5、装液量为50mL、接种量15%、摇床振荡速度160r/min的条件下,反应48h后可使500mg/L的苯酚降解率达90%以上。葡萄糖对菌体的生长及苯酚降解能力均有一定的影响,当葡萄糖浓度是500mg/L时,该菌对苯酚的降解率仍在80%以上。该研究对处理含有其它碳源的含酚废水具有一定的意义。通过DGGE图谱条带的分析表明,其亮度可以说明这些菌在各个系统中均表现为优势菌,且在污水环境中表现出较强的活性,其优势地位能够稳定地存在。其中2、4、24、28条带丰富,表现出它们在污水环境系统中的多样性。     

阿特拉津降解菌SA1的分离鉴定及其降解特性研究

为进行阿特拉津(AT)污染的生物修复,从AT降解混合菌群中,经长期的交替液体摇瓶培养和平板划线分离,筛选到一株能完全降解AT的菌株SA1。经生理生化特征及16S rDNA序列分析,将该菌鉴定为假单胞菌属(Pseudomonas sp.)。与已报道的AT降解菌Pseudomonas sp.ADP不同,SA1能以AT为唯一碳源、氮源和能源生长,培养基中添加铵盐不抑制SA1的降解功能,而添加葡萄糖时,累积的氰尿酸会被快速降解。SA1生长的最适温度为37℃,最适pH值为7.0。SA1的静息细胞在10℃~40℃或pH值4~11时均能高效降解AT,比ADP降解具有更广的pH和温度范围,表明SA1降解菌株具有广阔的应用前景。SA1中AT降解基因为保守的atzABCD,并含有IS1071的tnpA基因片段,传代过程中降解基因会以一定频率丢失。     

互营烃降解菌系M82的脂肪酸降解特性

【目的】通过分子生态学手段筛选适合互营烃降解菌Syntrophus sp.生长的非烃碳源。【方法】利用实验室驯化获得的正十六烷烃降解产甲烷菌系M82为接种物,添加不同碳源(正十二烷二元酸、正十四烷二元酸、正十六烷烃、十六烷酸钠、乳酸钠和丙酸钠)传代培养,通过PCR-DGGE和qPCR技术研究不同碳源条件下Syntrophaceae科细菌的丰度与变化趋势;利用T-RFLP方法分析古菌群落结构。【结果】菌系M82可以利用多种脂肪酸生长并产生甲烷,但是细菌群落结构发生了变化,只在添加正十二烷二元酸和正十四烷二元酸的培养液中检测到了代表Syntrophaceae细菌的条带,并且每毫升菌液中Syntrophaceae细菌的log丰度分别达到7.4和7.6,比添加其它几种非烃碳源的实验组丰度高2-3个单位。古菌群落结构主要由乙酸营养型产甲烷古菌(Methanosaeta)和氢营养型产甲烷古菌(Methanoculleus)组成。【结论】Syntrophus sp.细菌可以利用正十二烷二元酸和正十四烷二元酸这两种非烃碳源生长,这为我们定向分离互营烃降解菌和研究起始烃降解机制和代谢机理提供了依据。     

长链烷烃降解菌的降解特性

对长链烷烃降解菌的降解能力和摄取模式进行了研究。评价14株烃降解菌利用中长链烃生长的能力,发现只有少数烃降解菌能够获得良好生长,其中Mycobacterium fortuitum514,Pseudomonas aeruginosa1785和Pseudomonas marginata766等3株菌能够高效降解C20到C33的长链烷烃。辛烷不能支持这些长链烷烃降解菌的生长,说明其烃氧化酶与Pseudomonas oleovorans的OCT质粒编码的单氧酶不同。此外,M.fortuitum不产胞外表面活性剂,而P.aeruginosa和P.marginata则是表面活性剂产生菌,然而三者在以烃为碳源生长时均显示出很高的细胞表面疏水性。根据生长现象分析3株菌采用了不同的烷烃摄取模式。     

一株降解苯酚的酵母菌的分离与特性

从炼油厂消化污泥中分离到一株酵母菌(Saccharomyces sp.)。该菌能在以苯酚为唯一碳源的培养基上生长。菌落较小,表面不光滑四周呈树枝状,生长的温度范围为25～35℃,生长的pH范围为6—9。在以苯酚为唯一碳源时,能生长的最高酚浓度为1850ppm,蛋白胨、酵母粉能促进酵母菌的生长和降解,且能使酵母菌的耐酚浓度提高到2400ppm。葡萄糖能促进酵母菌的生长。但抑制苯酚的降解。此酵母菌还能利用苯甲酸钠、间苯二酚和油酸。     

低温石油降解菌LHB16的筛选及降解特性研究

目的:筛选、鉴定低温石油降解菌并对其降解特性进行研究.方法:富集分离低温石油降解菌;采用形态学、生理生化实验和分子生物学方法进行菌种鉴定;紫外分光光度法和GC-MS检测石油降解特性.结果:自盘锦油田低温环境土样中分离到1株低温菌,命名为LHB16,该菌能以石油烃为惟一碳源和能源.经鉴定为嗜麦芽窄食单胞菌(Stenotrophomonas maltophilia).该菌生长温度范围0℃～35℃,最适生长温度15℃.在接种量为2%(V/V),原油浓度为0.5%(W/V),振荡培养10 d时,降解率可达80.16%.石油中长链烷烃C15～C32被完全降解.传代培养数代,降解率为81.06%,降解性能稳定.结论:菌株LHB16在低温地区石油污染的生物治理中有良好的应用前景.     

敌敌畏降解菌的分离鉴定及降解特性研究

目的:从受有机磷农药污染的土壤中分离能降解DDVP的菌株,对其进行鉴定和降解特性研究.方法:采用DDVP为惟一碳源和能源的无机盐培养基,通过富集培养、平板划线分离得到一株优势菌,编号为DDW-1,采用形态学、生理生化和16S-rDNA序列分析对其进行鉴定,采用气相色谱测定菌株DDW-1对DDVP的降解能力,并进行底物广谱性测试和降解酶定位实验.结果:该菌株鉴定为甲基杆菌属(Methylobacterium sp.).降解特性试验结果表明,其最佳生长条件为温度28℃,初始pH为7.0,在该条件下,500mg·L-> DDVP经过DDW-1菌株代谢3d后,降解率达63.7%.结论:菌株DDW-1能降解DDVP,该菌株产胞内酶.     

高效芘降解菌N12的分离鉴定与降解特性

以芘为目标降解物,利用选择性富集培养方法,从沈抚灌区污染土壤中分离到一株高效芘降解菌N12,经生理生化试验和16S rDNA测序分析,该菌被鉴定为分枝杆菌属（Mycobacterium sp.）.菌株N12能以菲、苊、芴和芘为唯一碳源和能源生长,不能以蒽、萘和苯并芘为唯一碳源和能源生长.在菲和芘共同存在的情况下菌株N12可降解苯并芘,9 d内对苯并芘降解率可达79.0%.摇瓶降解试验表明,菌株N12可在7 d内将100 mg·L^-1的芘降解94.4%,14 d内将其完全降解;可将600 mg·L^-1的芘在7 d内降解56.1%,14 d内降解95.5%.添加葡萄糖可促进N12对芘的降解.菌株N12是一株优良的多环芳烃降解菌,可作为多环芳烃污染土壤生物修复的菌种资源.     

两株真降解菜籽饼中植酸的研究

利用选择性培养基从土壤中分离到两株能降解植酸的丝状真菌。这些菌株能利用肌醇作为唯一的碳源和能源而生长。在液态发酵中植权的降解率分别为７４．４％和９５．０％;在固太发酵中植酸的降解率为４０％左右。某些金属离子对菌株的降解率的提高具有一定的促进作用。对温度、ｐＨ和水分等影响因了也进行了初步的探讨。经初步鉴定,这两株菌中有一株为拟青霉（Ｐａｅｃｉｌｏｍｙｃｅｓ ｓｐ）,另一株为青霉（Ｐｅｎｉｃｉｌｌｉｕ     

一株毒死蜱降解新菌株Sphingopyxis terrae R17的分离鉴定及降解特性

从农药厂排污沟污泥中分离到一株能降解毒死蜱的新菌株,命名为R17,经生理生化和16S rDNA序列同源性分析,鉴定为Sphingopyxis terrae.R17可以利用毒死蜱作为唯一碳源生长,该菌株的最适生长温度为35℃、最适pH为7～8,在此条件下培养28 h后,菌落浓度达9.18×108cfu/mL.研究了该菌在...     

Possible degradative process of cholecystokinin analogs in rabbit jejunum brush-border membrane vesicles

Our recent work on the intestinal metabolism and absorption of cholecystokinin analogs, sulfated C-terminal octapeptide (CCK8; Asp-Tyr(SO(3)H)-Met-Gly-Trp-Met-Asp-Phe(NH(2)) = DY(SO(3)H)MGWMDF(NH(2))) and tetrapeptide (CCK4; Trp-Met-Asp-Phe(NH(2)) = WMDF(NH(2))), was extended to investigate the degradative process of these analogs using rabbit jejunum brush-border membrane vesicles and to find a better enzyme-inhibitor system for intestinal absorption of peptide drugs. Various enzyme inhibitors and a lower pH buffer were applied to discover the major enzyme(s) involved in each process. Metabolic pathways showing degradative processes were proposed for both analogs. The major cleavage site occurs at the W(1)-M(2) for CCK4. At least three metabolic pathways occur independently for CCK8 and appear at peptides bonds between G(4)-W(5), M(6)-D(7), and D(7)-F(NH(2))(8). Many different enzymes of aminopeptidase, endopeptidase, angiotensin-converting enzyme, metalloenzyme, and others were involved in each process. Identification of more specific yet safe enzyme inhibitors and co-administration of various these inhibitors may lead to further enhancement in intestinal peptide absorption when administered orally.     

Molecular characteristics of xenobiotic-degrading sphingomonads

The genus Sphingomonas (sensu latu) belongs to the α-Proteobacteria and comprises strictly aerobic chemoheterotrophic bacteria that are widespread in various aquatic and terrestrial environments. The members of this genus are often isolated and studied because of their ability to degrade recalcitrant natural and anthropogenic compounds, such as (substituted) biphenyl(s) and naphthalene(s), fluorene, (substituted) phenanthrene(s), pyrene, (chlorinated) diphenylether(s), (chlorinated) furan(s), (chlorinated) dibenzo-p-dioxin(s), carbazole, estradiol, polyethylene glycols, chlorinated phenols, nonylphenols, and different herbicides and pesticides. The metabolic versatility of these organisms suggests that they have evolved mechanisms to adapt quicker and/or more efficiently to the degradation of novel compounds in the environment than members of other bacterial genera. Comparative analyses demonstrate that sphingomonads generally use similar degradative pathways as other groups of microorganisms but deviate from competing microorganisms by the existence of multiple hydroxylating oxygenases and the conservation of specific gene clusters. Furthermore, there is increasing evidence for the existence of plasmids that only can be disseminated among sphingomonads and which undergo after conjugative transfer pronounced rearrangements.     

Proteome analysis of fungal and bacterial involvement in leaf litter decomposition

Fungi and bacteria are key players in the decomposition of leaf litter, but their individual contributions to the process and their interactions are still poorly known. We combined semi‐quantitative proteome analyses (1‐D PAGE‐LC‐MS/MS) with qualitative and quantitative analyses of extracellular degradative enzyme activities to unravel the respective roles of a fungus and a bacterium during litter decomposition. Two model organisms, a mesophilic Gram‐negative bacterium (Pectobacterium carotovorum) and an ascomycete (Aspergillus nidulans), were grown in both, pure culture and co‐culture on minimal medium containing either glucose or beech leaf litter as sole carbon source. P. carotovorum grew best in co‐culture with the fungus, whereas growth of A. nidulans was significantly reduced when the bacterium was present. This observation suggests that P. carotovorum has only limited capabilities to degrade leaf litter and profits from the degradation products of A. nidulans at the expense of fungal growth. In accordance with this interpretation, our proteome analysis revealed that most of the extracellular biodegradative enzymes (i.e. proteases, pectinases, and cellulases) in the cultures with beech litter were expressed by the fungus, the bacterium producing only low levels of pectinases.     

A mechanistic perspective on bacterial metabolism of chlorinated methanes

Chlorinated methanes are important environmental pollutants, which can be metabolized by bacteria. The biotransformation of chlorinated methanes by bacteria has been shown to be due either to gratuitous metabolism (cometabolism) or their use as a source of carbon and energy. The reactions which result in carbon-halogen bond cleavage include substitutive, reductive, oxygenative, and gem-elimination mechanisms. Certain methylotrophic bacteria can use dichloromethane as a source of carbon and energy. Dichloromethane dehalogenase catalyzes the first substitutive reaction in this metabolism. The enzyme shows a 10¹⁰-fold rate enhancement over the reaction of the bisulfide anion with dichloromethane in water. Pseudomonas putida G786 synthesizes cytochrome P-450_CAM which catalyzes the gratuitous reduction of chlorinated methanes. These studies with purified enzymes are beginning to reveal more detailed mechanistic features of bacterial chlorinated methane metabolism.Abbreviations DNA deoxyribonucleic acid - k_cat catalytic first order rate constant for an enzyme catalyzed reaction - K_M Michaelis constant for an enzyme catalyzed reaction - MNDO modified neglect of diatomic overlap - PIMA pattern induced multialignment - DCMD dichloromethane dehalogenase     

L-serine deaminating enzymes in Escherichia coli crude extracts

(a) The measured L-serine deaminating activity of a crude bacterial extract may originate from L-serine deaminase, from biosynthetic L-threonine deaminase, or from degradative L-serine deaminase. Nevertheless, the contribution of the individual enzymes can be determined.(b) About a half of the L-serine deaminating activity of wild type E. coli bacteria, grown in synthetic minimal medium, originates from L-serine deaminase and about half from biosynthetic L-threonine deaminase.(c) Ninety percent of L-serine deaminating activity of wild type E. coli bacteria, grown in yeast extract-tryptone medium, originates from L-serine deaminase, and the remainging ten percent from the degradative L-threonine deaminase.(d) Conditions have been established in which threonine deaminases are eliminated and the activity of L-serine deaminase alone could be measured, even in crude extracts.     

Dehalogenation of dichloromethane by dichloromethane dehalogenase/glutathione S-transferase leads to formation of DNA adducts

Formation of DNA adducts following conversion of dichloromethane by bacterial dichloromethane dehalogenase/glutathione S-transferase was demonstrated. Adducts included dichloromethane carbon and glutathione sulfur atoms. A reaction with DNA occurred preferentially at guanine bases. Increased DNA degradation in a polA mutant of Methylobacterium dichloromethanicum DM4 grown with dichloromethane confirmed the genotoxicity associated with dichloromethane degradation, suggesting an important role of DNA repair in the metabolism of halogenated, DNA-alkylating compounds by bacteria.     

甲基对硫磷降解菌假单胞菌WBC-3的筛选及其降解性能的研究

从农药污染土样中分离出的一株细菌具有彻底降解甲基对硫磷的能力。该菌经生理生化特性分析和16S rDNA序列同源性分析,鉴定为假单胞菌属,命名为Pseudomonas sp.WBC\|3。该菌在pH7～8、温度23℃～30℃范围内均生长良好,对甲基对硫磷的耐受浓度在单纯无机盐培养基中可达到800mg/L,在含有01%葡萄糖的培养基中可达到2000mg/L。该菌能够以甲基对硫磷作为唯一碳源、氮源,将其彻底降解作为生长基质,对于300mg/L甲基对硫磷的降解速度达15mg/L\5h,于22h后达到其稳定生长期。该菌对于多种有机磷农药及部分芳烃类化合物具有生化代谢能力。从该菌的细胞周质组分中纯化出的有机磷水解酶在SDSPAGE胶上显示为分子量约为33.5×103的条带。     

A novel dichloromethane-degrading <Emphasis Type="Italic">Lysinibacillus sphaericus</Emphasis> strain wh22 and its degradative plasmid

Dichloromethane (DCM)-degrading bacterium strain wh22 (GenBank accession number FJ418643) was isolated and identified as Lysinibacillus sphaericus based on standard morphological and physiological properties, cellular fatty acid composition, mole percent guanine–cytosine content, and nucleotide sequence analysis of enzymatically amplified 16S ribosomal deoxyribonucleic acid. The strain also grew on many other halocarbons found in the waste gases of industrial effluents, such as 1,2-dichloroethane, chlorobromomethane, methylene bromide, 1,1,1-trichloroethane, trichloroethylene, and hexachlorobenzene. The strain harbored a novel degradative plasmid, pRC11 (48.8 kb). The genes coding for the metabolism of DCM were found to be plasmid-borne, and a physical map of the plasmid has been established. The purified plasmid was transformed to dcm ⁻ Escherichia coli DH5 at a rate of 1.65 × 10⁵. The transformed cells were able to grow on DCM at a concentration of 5–16 mM and can be further used as an excellent source for genetic manipulations leading to the construction of genetically modified microbial strains or genetically engineered microorganisms.