甲烷利用细菌降解三氯乙烯的研究

GYJ3菌株细胞微细结构的电镜观察结果表明：它具有Ⅱ型甲烷利用细菌的特征,应归属于Ⅱ型菌。考察了Cu2+浓度、培养气相中甲烷浓度对菌株细胞中甲烷单加氧酶（EC1．14．13．25,简称MMO）活性的影响。结果表明,培养液中Cu2+浓度为1．5μmol／L,培养气相中甲烷：空气比为2∶1时,可溶性甲烷单加氧酶占细胞中MMO总量的95％。研究了GYJ3菌株细胞悬浮液降解三氯乙烯过程。实验结果表明,GYJ3菌株能够降解不同浓度的三氯乙烯,较高浓度的三氯乙烯对降解反应没有明最的抑制作用。加入甲酸盐作为电子给体能够提高三氯乙烯降解反应速率。实验中观察到GYJ3菌株降解三氯乙烯过程中反应速率随着反应的进行而下降,在三氯乙烯降解过程中三氯乙烯氧化产物是导致细胞失活的主要原因。实验室中测定了GYJ3菌株单位重量细胞降解三氯乙烯极限量,它可作为评价细菌降解三氯乙烯能力的重要指标。     

聚乙烯醇高效降解菌的筛选及降解特性研究

以聚乙烯醇为唯一碳源从环境中筛选获得了高效降解聚乙烯醇的微生物菌株XT11,初步鉴定为假单胞菌属(Pseudomonas sp.).对菌株Pseudomonas XT11的生长过程及PVA降解过程进行了研究,发现该菌株在54 h内可将1 g/L的聚乙烯醇(PVA)降解.同时研究了温度、pH值及酵母膏浓度对该菌株降解PVA的影响,结果表明其最适温度、pH值和酵母膏浓度分别为30℃、7.0和0.5 g/L.研究了PVA浓度对PVA降解率的影响,发现随着PVA浓度的增大,PVA的降解率降低.     

一个甲烷氧化菌株的分离、鉴定及其特性研究

实验室自行设计方案分离多株以甲烷为唯一碳源的菌株,对其中的1株QJ16进行了研究,根据该菌株形态特征与16S rDNA序列的同源性分析,证实该菌株是一个与其最近的甲基单胞菌属各成员都不相同的菌株.对该菌株的培养条件和利用甲烷的特性进行研究结果表明,氮源以氯化铵和硝酸钾共同作用最好,碳源以甲烷最佳,最佳生长温度为30℃,最佳生长pH为6～7;在批式实验时菌株利用甲烷的最适pH为6.5左右,微量元素Cu2 的浓度为15 μmol/L.     

一株DDT降解菌的筛选、鉴定及降解特性的初步研究

从DDT污染的土壤中筛选具有DDT降解能力的细菌,经过富集培养、分离纯化得到56株细菌,将其接种到基础盐酵母培养基,7d后用紫外分光光度计法初筛得到降解率较高的一株菌,编号为D-1.通过16S rDNA序列分析结合传统分类学方法确定该菌为寡养单胞菌属(Stenotrophomonas sp.)的一株茵.对菌体降解DDT的特性的研究表明,在培养温度为3℃,底物质量浓度为40 mg/L, pH 7.0,摇床转速为200 r/min的条件下,该菌株对DDT降解10d的降解率为69.0%.     

一株纤维化纤维微细菌的生物学特性及其对几种苯环类化合物的利用研究

本文针对一株纤维化纤维微细菌Cellulosimicrobium cellulans Ha8菌株开展了生物学特性和苯环类物质代谢能力研究.该菌株革兰氏阳性,长杆状,培养后期逐渐变为短杆状;能固氮,水解蛋白质,液化明胶,利用淀粉、纤维素和果胶,分解几丁质;在pH 6.0～9.0和20℃～40℃范围内生长较好;能利用苯甲酸、苯酚、二甲苯、苯丙烯酸和二苯胺为唯一碳源进行生长,对这几种苯环类物质浓度的耐受范围分别为0 mmol/L～30 mmol/L、0 mmol/L～8 mmol/L、0 mmol/L～30 mmol/L、0 mmol/L～15 mmol/L和0 mmol/L～40 mmol/L,但不能利用2,4-二硝基苯酚、邻硝基酚、邻甲氧基酚、氨基苯磺酸、邻苯二酚和邻菲罗啉为唯一碳源生长.     

高效氯氰菊酯降解菌JCN13的分离鉴定及降解特性研究

从生产高效氯氰菊酯的农药厂污水曝气池中,分离到一株能降解高效氯氰菊酯并以之为唯一碳源进行生长的细菌JCN13.经生理生化试验和16S rDNA分析,鉴定菌株JCN13为沙雷菌属(Serratia sp.).气相色谱检测,菌株JCN13在4 d内对100 mg/L高效氯氰菊酯的降解率为89%,8 d内基本降解完全.经气质联用检测,发现高效氯氰菊酯在被菌株JCN13降解的过程中存在异构体的转化.     

一株降氰细菌的筛选及其转化特性初步研究

从污染土壤中分离一株高效降氰菌株DN25,经表型分析和16SrDNA分析,初步判断为产碱杆菌(Alcaligenes sp．)。该菌株耐氰能力强,能在氰浓度达1,000mg／L的环境中生长。其生长和转化的最佳温度和pH分别为30％和8．0,10h对氰浓度为500mg／L的溶液转化率可达到99％。同时菌株也可有效转化亚铁氰化钾,对于氰浓度相当于500mg／L的亚铁氰化钾液,12h的转化率可达到96％。     

Degradation of phenol and toxicity of phenolic compounds: a comparison of cold-tolerant<Emphasis Type="Italic"> Arthrobacter</Emphasis> sp. and mesophilic<Emphasis Type="Italic"> Pseudomonas putida</Emphasis>

Phenol degradation efficiency of cold-tolerant Arthrobacter sp. AG31 and mesophilic Pseudomonas putida DSM6414 was compared. The cold-tolerant strain was cultivated at 10°C, while the mesophile was grown at 25°C. Both strains degraded 200 mg and 400 mg phenol/l within 48–72 h of cultivation, but the cold-tolerant strain produced more biomass than the mesophile. Both strains oxidized catechol by the ortho type of ring fission. Catechol 1,2 dioxygenase (C1,2D) activity was found intra- and extracellularly in the absence and in the presence of phenol. In the presence of 200 mg phenol/l, C1,2D activity of the mesophile was about 1.5- to 2-fold higher than that of the cold-tolerant strain. However, an initial phenol concentration of 400 mg/l resulted in a comparable enzyme activity of the cold-tolerant and the mesophilic strain. The two strains differed significantly in their toxicity pattern towards 12 aromatic (mostly phenolic) compounds at different growth temperatures, which was determined via growth inhibition in the presence of nutrients and toxicants. For the cold-tolerant strain, toxicity was significantly lower at 10°C than at 25°C. The mesophile showed a significantly lower susceptibility to high hydrocarbon concentrations when grown at 25°C compared to 10°C.Communicated by K. Horikoshi     

Biodegradation of phenol and 4-chlorophenol by the yeast <Emphasis Type="Italic">Candida tropicalis</Emphasis>

Biodegradation of phenol and 4-chlorophenol (4-cp) using a pure culture of Candida tropicalis was studied. The results showed that C. tropicalis could degrade 2,000 mg l⁻¹ phenol alone and 350 mg l⁻¹ 4-cp alone within 66 and 55 h, respectively. The capacity of the strain to degrade phenol was obviously higher than that to degrade 4-cp. In the dual-substrate system, 4-cp intensely inhibited phenol biodegradation. Phenol beyond 800 mg l⁻¹ could not be degraded in the presence of 350 mg l⁻¹ 4-cp. Comparatively, low-concentration phenol from 100 to 600 mg l⁻¹ supplied a sole carbon and energy source for C. tropicalis in the initial phase of biodegradation and accelerated the assimilation of 4-cp, which resulted in the fact that 4-cp biodegradation velocity was higher than that without phenol. And the capacity of C. tropicalis to degrade 4-cp was increased up to 420 mg l⁻¹ with the presence of 100–160 mg l⁻¹ phenol. In addition, the intrinsic kinetics of cell growth and substrate degradation were investigated with phenol and 4-cp as single and mixed substrates in batch cultures. The results illustrated that the models proposed adequately described the dynamic behaviors of biodegradation by C. tropicalis.     

Degradation of the antibiotics norfloxacin and ciprofloxacin by a white-rot fungus and identification of degradation products

More than 90% of the antibiotics ciprofloxacin (CIPRO) and norfloxacin (NOR) at 2 mg L⁻¹ were degraded by Trametes versicolor after 7 days of incubation in malt extract liquid medium. In in vitro assays with purified laccase (16.7 nkat mL⁻¹), an extracellular enzyme excreted constitutively by this fungus, 16% of CIPRO was removed after 20 h. The addition of the laccase mediator 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt led to 97.7% and 33.7% degradation of CIPRO and NOR, respectively. Inhibition of CIPRO and NOR degradation by the cytochrome P450 inhibitor 1-aminobenzotriazole suggests that the P450 system also plays a role in the degradation of the two antibiotics. Transformation products of CIPRO and NOR were monitored at different incubation times by triple-quadrupole and quadrupole time-of-flight mass spectrometry, and can be assigned to three different reaction pathways: (i) oxidation of the piperazinyl substituent, (ii) monohydroxylation, and (iii) formation of dimeric products.     

Cometabolic turnover of aniline,phenol and some of their monochlorinated derivatives by the Rhodococcus mutant strain AM 144

One-step conversion of aniline, phenol and some of their monochlorinated derivatives into the corresponding catechols by resting pre-adapted cells of the Rhodococcus mutant strain AM 144 (defective in synthesis of catechol 1,2-dioxygenase) was shown to depend on the availability of an additional metabolizable carbon substrate, e.g. glucose or acetate. A stoichiometric relation existed between the amount of the latter compounds added and the amount of aniline (or phenol, respectively) converted into catechol suggesting that the primary function of the cosubstrates was to provide reducing power to the oxygenative transformation reaction. The observed cosubstrate-dependence generally parallels that seen in previous studies on turnover of different monochloroaromatic non-growth substrates by aromatics-utilizing Rhodococcus wildtype-strains. Cell cultures of strain AM 144 growing at the expense of acetate also proved able to convert aniline into catechol. Typically, growth of the cells was retarded during the phase of aniline transformation as compared to the respective control cultures. Based on the results of these model experiments, it was concluded that (i) in natural microbial communities cometabolically active bacteria would hardly enrich under cometabolic conditions over fast-growing non-cometabolizing bacteria if the latter organisms will tolerate the particular non-growth substrate, and (ii) cometabolizing bacteria would have a selective advantage only if the non-growth substrate to be transformed is a toxic one or if it can serve as a potential nutrient source (e.g., of nitrogen or sulfur).Abbreviations MCA monochloroaniline - MCP monochlorophenol - MCC monochlorocatechol - TLC thin-layer chromatography - MS mass spectrometry - GLC gas-liquid chromatography - UV ultraviolet (range of the spectrum)     

烟嘧磺隆降解菌Chryseobacterium sp.LAM-M5的分离、鉴定及其降解机理研究

为获得更丰富的烟嘧磺隆降解菌资源,以合肥某烟嘧磺隆生产厂活性污泥为研究对象,从中分离并筛选得到一株能以葡萄糖为唯一碳源、烟嘧磺隆为唯一氮源生长的菌株,根据其表型特征、16S rRNA序列相似性、DNA-DNA杂交值(DDH)和平均核苷酸一致性(ANI)的分析结果,将其鉴定为Chryseobacterium lacus ...     

Degradation of lignin and lignin model compounds by various mutants of the white-rot fungus Sporotrichum pulverulentum

In order to better understand which enzyme are of importance in lignin degradation, new cellulase deficient strains from Sporotrichum pulverulentum have been isolated by spontaneous and induced mutations from both wild type and from the earlier studied cellulase deficient strain 44. These new strains are xylanase positive (Xyl⁺), and produce considerably higher amounts of phenol oxidases (Pox) than either parent type. The new strains have been compared with the wild type and strain 44 with respect to their ability to release ¹⁴CO₂ from a) vanillic acid labelled in the carboxyl, methoxyl and ring carbons; b) the dimer (4-methoxy-¹⁴C)-veratryl-glycerol--guaiacyl ether; c) ¹⁴C-ring-labelled DHP and ¹⁴C[-carbon side chain] labelled DHP.The new strains, the wild type and strain 44 were compared with respect to their ability to cause weight losses in wood blocks and to delignify wood. One of the new strains, 63-2, caused a higher weight loss in wood than either the wild type or strain 44. Another strain, 44-2, produced a higher weight loss than strain 44. An increase in acid-soluble lignin was observed in wood blocks treated for two weeks with the two new mutant strains and wild type. After prolonged incubation for 6 and 8 weeks the amount of acid-soluble lignin decreased.Abbreviations DHP Dehydrogenation polymerizate - DMS 2,2-dimethylsuccinic acid     

Characterization of the Deubiquitinating Activity of USP19 and Its Role in Endoplasmic Reticulum-associated Degradation

Deubiquitinating enzymes (DUBs) regulate various cellular processes ranging from protein degradation to cellular signaling. USP19, the only DUB containing a carboxyl-terminal transmembrane domain, was proposed to function in endoplasmic reticulum-associated degradation (ERAD). Here we characterize the function and regulation of USP19. We identify Hsp90 as a specific partner that binds the catalytic domain of USP19 to promote substrate association. Intriguingly, although overexpressed USP19 interacts with Derlin-1 and other ERAD machinery factors in the membrane, endogenous USP19 is mostly in the cytosol where it binds Hsp90. Accordingly, we detect neither interaction of endogenous USP19 with Derlin-1 nor significant effect on ERAD by USP19 depletion. The USP19 transmembrane domain appears to be partially stabilized in the cytosol by an interaction with its own catalytic domain, resulting in auto-inhibition of its deubiquitinating activity. These results clarify the role of USP19 in ERAD and suggest a novel DUB regulation that involves chaperone association and membrane integration. Moreover, our study indicates that the localization of tail-anchored membrane proteins can be subject to regulation in cells.