Oxidation of isoeugenol by Nocardia iowensis

Isoeugenol is a starting material for both the synthetic and biotechnological production of vanillin and vanillic acid. Nocardia iowensis DSM 45197 (formerly Nocardia species NRRL 5646) resting cells catalyze the conversion of isoeugenol to vanillic acid, vanillin, vanillyl alcohol and guaiacol. The present study used a variety of chemical, microbial and enzymatic approaches to probe the pathways used by N. iowensis in the oxidation of isoeugenol to these products. Of three possible pathways considered, initial side-chain olefin epoxidation, epoxide hydrolysis to a vicinal diol, and diol cleavage to vanillin and subsequently further oxidation to vanillic acid appears as the most likely route. Isoeugenol was not oxidized to ferulic acid, a well-known microbial transformation precursor for vanillin and vanillic acid. ¹⁸O-Labeled oxygen (one atom) and water (two oxygen atoms) were incorporated into vanillic acid during the whole-cell biotransformation reaction with isoeugenol indicating the likely involvement of oxygenase and hydrolase systems in the bioconversion reaction. Vanillin was converted to singly labeled vanillic acid in the presence of H₂¹⁸O suggesting the presence of an aldehyde oxidase. Cell extracts achieved the conversion of isoeugenol to vanillic acid and vanillin without cofactors. Partial fractionation of two enzyme activities supported the presence of isoeugenol monooxygenase and vanillin oxidase activities in N. iowensis.     

Microbiological resolution of chiral arylethyl carbinols by Nocardia corallina

Whole cells of Nocardia corallina B-276 oxidized enantioselectively racemates of arylethyl carbinols, at 0.5 mM, to give ketones in yields from 4 to 97% (w/w) and the unreacted alcohols showing enantiomeric excess ranging from 5 to > 99%. The configuration of the resulting alcohol is (R).     

类胡萝卜素产生菌№5205的分类鉴定

从江苏省如东沿海滩涂淤泥中分离到 1株产类胡萝卜素的诺卡氏菌形放线菌№ 5 2 0 5 ,其基丝形成横隔并断裂成短杆状 ,细胞壁化学组分IV型 ,糖类型A ,含枝菌酸 ,磷酸类脂类型PII(PE) ,甲基萘醌主要成分为MK 8(H4 ) ,属于诺卡氏菌属 (Nocardia)。经形态、生理生化、化学分类特性等鉴定为藤黄诺卡氏菌桔橙变种 (Nocardialuteavar.aurantiacan .var .)。     

产腈水合酶菌Nocardia sp.HD9611的发酵条件优化的研究

探讨了种龄、接种量、搅拌转速、pH及补料等因素对Nocardia sp.HD9611产腈水合酶的影响.结果表明,最佳种龄为20h;接种量对酶活的提高没有明显影响,但7.5%时最佳;当搅拌转速低于400r/min时,溶解氧将成为细胞生长的限制因子;发酵过程中pH调节对细胞量及酶活的提高有积极的作用;补料对细胞密度及酶的产生有积极影响,总糖为80g/L时,细胞量31.88g/L,提高了120.8%,酶活为7100U,提高了107.6%.此研究为制定最佳控制策略提供了参考.     

诺卡氏菌烈性噬菌体vB_Ncarnea_KYD1的分离纯化与基因组分析

【背景】诺卡氏菌是一种广泛分布的好氧放线菌,可在人体内引起局部或播散性感染,尤其是在免疫功能低下的个体中。诺卡氏菌感染在临床上较难鉴定,而且不断有新型诺卡氏菌种被发现。不同类型、不同地域的诺卡氏菌具有流行差异和抗生素敏感性差异,阻碍了适当治疗方式的选择。利用病灶处的宿主菌分离得到噬菌体来控制诺卡氏菌感染的这种方法在近年来受到了各界的关注。【目的】尝试从环境中分离出能够用于临床治疗的针对诺卡氏菌的烈性噬菌体,并研究其基因组学特征。【方法】利用双层平板法分离得到目标噬菌体,观察其噬菌斑形态,并对噬菌体进行分离纯化,在透射电镜下鉴定其特征。提取噬菌体DNA进行全基因组测序与注释,并与数据库内已知噬菌体基因组进行比较,同时构建系统进化树以进行遗传进化分析。【结果】本文以肉色诺卡氏菌为宿主,从环境样本中分离出一株烈性噬菌体vB_Ncarnea_KYD1,在双层平板上可形成直径<2 mm的透亮均匀的噬菌斑。基因组分析表明,vB_Ncarnea_KYD1DNA为环状,大小为66 621 bp,共发现102个蛋白质编码区(coding sequence,CDS)及一个tRNA-Ser编码序列。透射电镜观察与系统进化树综合分析可以确定,vB_Ncarnea_KYD1为长尾噬菌体科的一个新属。其在进化过程中经历了复杂的基因重组过程。暂未发现毒力因子相关基因与抗性基因,具备实用价值。【结论】从环境水体中分离出一株烈性肉色诺卡氏菌噬菌体vB_Ncarnea_KYD1,通过电镜观察与基因组分析可知,此株噬菌体为长尾噬菌体,基因组中暂未发现不利于临床应用的相关基因,是一株相对安全的烈性诺卡氏菌噬菌体。研究结果丰富了国内噬菌体资源库,并为后续诺卡氏菌感染疾病的治疗提供支持。     

9株鱼源鰤诺卡氏菌生物学特征和致病性比较

【背景】鰤诺卡氏菌(Nocardia seriolae)是一种革兰氏阳性好氧菌,易引起鲈形目鱼类结节病发生,近几年对大口黑鲈、杂交鳢等名优鱼类的危害越来越大。【目的】比较分析9株不同年份、不同地区患结节病的不同淡水鱼品种分离的鰤诺卡氏菌的种间同源关系、生长特性、致病性以及药物敏感性差异,为进一步研究制定相应的防控与治疗措施提供基础数据和科学依据。【方法】在9株试验菌生理生化实验鉴定结果基础上,采用16SrRNA基因序列比对、限制性片段长度多样性比较菌株间的同源性;扩增看家基因secA1基因序列进行不同来源菌株种内相似度比对;通过体外培养比较不同菌株的生长情况;人工注射感染分析9株试验菌对大口黑鲈的致病性差异;采用微量肉汤二倍稀释法测试9株试验菌对13种抗菌药物的最小抑菌浓度;运用PCR技术检测菌株携带毒力基因和耐药基因的情况。【结果】生理生化结果显示9株试验菌与鰤诺卡氏菌的基本理化特征相符;9株试验菌聚类分析聚为一类,种内相似度高,限制性片段长度多样性酶切图谱相同,生长特性无明显差异;9株试验菌对大口黑鲈致病性无显著差异,但毒力基因携带情况略有不同,其均携带mce1A、mig和pup基因,而dop和whiB3只在部分菌株检出;9株试验菌均对氟甲喹和氨苄西林耐药,除NS1外,都对磺胺间甲氧嘧啶耐药,对大部分抗菌药物敏感,主要携带blaTEM和sul1耐药基因。【结论】不同时间、不同地区及不同宿主分离的9株鰤诺卡氏菌在生物学特性、致病性和药物敏感性等方面无明显差异;同源性相近,提示华南地区感染淡水鱼的鰤诺卡氏菌可能为同一流行株型。研究结果为鰤诺卡氏菌的发病机制及防控技术的进一步研究奠定了基础。     

Microbial Oxidation of Allylic Alcohols

A new method for the oxidation of primary ad secondary allylic alcohols to the corresponding aldehydes/acids and ketones respectively is described utilizing Nocardia corallina B-276. In contrast, Pseudomonas oleovorans TF4-1L oxidized only the primary allylic alcohols but not the secondary allylic alcohols.     

Clinical usefulness of continuous administration ofNocardia rubra cell wall skeleton (N-CWS) in diffuse panbronchiolitis (DPB)

Eight patients with diffuse panbronchiolitis (DPB) who had repeated intractable airway infections were continuously treated withNocardia rubra cell wall skeleton (N-CWS), a biological response modifier. As a result, subjective symptoms were reduced in 6 patients. Antibiotics therapy could be discontinued completely in two patients and the dose of antibiotics could be reduced considerably in two other patients. No adverse reactions in relation to N-CWS were observed. These results suggest that N-CWS is effective in treating erythromycin-resistant DPB.Abbreviations BRM Biological response modifier - DPB Diffuse panbronchiolitis - EM erythromycin - N-CWS Nocardia rubra cell wall skeleton     

Structural aspects of the soluble NAD-dependent hydrogenase isolated from Alcaligenes eutrophus H16 and from Nocardia opaca 1b

The soluble NAD-dependent hydrogenase (hydrogen-NAD oxidoreductase, EC 1.12.1.2), consisting of four non-identical subunits, was isolated from Alcaligenes eutrophus H16 and from Nocardia opaca 1b and analyzed by a HPLC gel permeation technique and electron microscopy. The tetrameric enzyme particles from both origins, as determined from negatively stained electron microscopic samples, were found to be elongated and very similar in shape and size. The A. eutrophus enzyme was measured in more detail. It exhibited dimensions of 12.7 nm by 5.5 nm (axial ratio 2.3:1). Dissociation into smaller particles and unspecific aggregation combined with partial inactivation were observed in the presence of the inhibitor NADH. Kept in buffer without added nickel, the enzyme was partially dissociated. Reassociation of tetramers without restored enzyme activity was achieved by addition of 0.5 mM NiCl₂. A working model for the structural organization of the tetrameric enzyme particle is presented.     

Biosynthesis of vitamin B12

Radioactivity from [1-¹⁴C]riboflavin was incorporated into the 5,6-dimethylbenzimidazole moiety of Vitamin B₁₂ in the aerobes Bacillus megaterium, Nocardia rugosa and Streptomyces sp. as well as in the aerotolerant anaerobe Propionibacterium freudenreichii, but not in the anaerobe Eubacterium limosum.As recently published for E. limosum, also in the anaerobe Clostridium barkeri radioactivity from [1-¹⁴C]glycine and [2-¹⁴C]glycine was found in the 5,6-dimethylbenzimidazole moiety, but not in the corrin moiety. The addition of l-[methyl-¹⁴C]methionine to C. barkeri led to the labeling of the corrin moiety and the 5,6-dimethylbenzimidazole moiety, showing that the seven extra methyl groups in the corrin ring as well as the two methyl groups of the base part originate from this precursor.In Clostridium thermoaceticum, forming the vitamin B₁₂ analog 5-methoxybenzimidazolylcobamide, [1-¹⁴C]glycine and [2-¹⁴C]glycine were also incorporated into the 5-methoxybenzimidazole moiety, but not into the corrin ring.In E. limosum l-[U-¹⁴C]glutamate led to the labeling of the corrin ring of vitamin B₁₂, but not of its base moiety.There results together with data from the literature indicate that a common biosynthetic pathway might exist for the corrinoid biosynthesis in aerobic microorganisms, and in those aerotolerant anaerobes like the Propionibacteria, which form the 5,6-dimethylbenzimidazole moiety of vitamin B₁₂ only under aerobic conditions. They also show that this pathway differs from the pathway found in anaerobic bacteria.