Synthesis and production of poly(3-hydroxyvaleric acid) homopolyester by Chromobacterium violaceum

Chromobacterium violaceum DSM 30191 accumulated a homopolyester of 3-hydroxyvaleric acid (3HV) up to 65% of the cellular dry matter during cultivation in fed-batch cultures with valeric acid as sole carbon source and during cell starvation of the nitrogen source. From fructose, gluconate, propionate or hexanoate a homopolyester of 3-hydroxybutyrate (3HB) was accumulated. Poly(3HV) homopolyster was also accumulated by two different strains of C. violaceum, whereas two other strains of C. violaceum and three strains of Janthinobacterium lividum accumulated poly(3HB-co-3HV) copolyesters from valerate. The composition of the biosynthetic poly(3HV) was confirmed by various nuclear magnetic resonance spectroscopic methods. Differential scanning calorimetry analysis of four poly(3HV) samples that were isolated from different batches of cells revealed glass transition temperatures between –10 and –12°C and melting points between 107 and 112°C. Viscosity measurements gave intrinsic viscosities between 62.5 and 124.8 × 10^–2 dl/g for these samples, indicating approximate relative molecular masses between 60 000 and 145 000 of the biosynthetic poly(3HV). Correspondence to: A. Steinbüchel     

Identification of Chromobacterium violaceum genes with potential biotechnological application in environmental detoxification

Chromobacterium violaceum is a Gram-negative bacterium found in a wide variety of tropical and subtropical ecosystems. The complete genome sequence of C. violaceum ATCC 12472 is now available, and it has considerable biotechnological potential for various applications, such as environmental detoxification, as well as medical and agricultural use. We examined the biotechnological potential of C. violaceum for environmental detoxification. Three operons, comprising the ars operon, involved in arsenic resistance, the cyn operon, involved in cyanate detoxification, and the hcn operon, encoding a cyanase, responsible for biogenic production of cyanide, as well as an open reading frame, encoding an acid dehalogenase, were analyzed in detail. Probable catalytic mechanisms for the enzymes were determined, based on amino acid sequence comparisons and on published structural information for these types of proteins.     

紫色色杆菌感染小熊猫引起肺炎的临床调查

本文报道了福州大熊猫研究中心小熊猫感染紫色色杆菌引起肺炎的群发病例。7 只小熊猫中,出现以呼吸衰竭为主要临床症状的3 只小熊猫在发病3 d内全部死亡,病死率100% 。死亡的小熊猫解剖病变为气管内有白色泡沫样分泌物,肺有化脓性坏死并严重淤血;胸腔,心包积液且胸水浑浊;肝脏呈弥漫性空泡变性,淤血和散在局灶性坏死。通过流行病学调查,病理解剖观察,细菌分离培养和鉴定及动物回归试验,诊断为紫色色杆菌无色变种感染。根据GenBank 数据库提供的紫色色杆菌16S RNA 基因序列,设计一对引物(5’GAG CAAACA GGA TTA GAT ACC 3’;5’TTA CGG TTA CCT TGT TAC GAC 3’),获得目的基因片段739 bp,将核苷酸序列测定的结果与GenBank 数据库提供的7 株紫色色杆菌进行同源性比较。分离的菌株(FJ08A) 与CV09 株、ESBV4400株同源性均为98.8% ,与AY117554 株、EAV2 株、AJ871127 株、LMG3953 株、JS1 株同源性分别为98. 2% 、98.0% 、94.9%、93.1% 、92.8% 。依据调查结果和药物敏感试验,对其余4 只未发病的小熊猫采取肌
肉注射头孢哌酮钠和口服复方新诺明进行预防性治疗,效果良好,未有新病发生。结果表明:(1)紫色色杆菌是革兰氏阴性菌,致病性强,致死率高,腹腔注射分离的紫色色杆菌菌液导致接种小白鼠在2 ～3 d 内全部死亡。小熊猫感染后,发病迅速,致死率高,应引起重视;(2)紫色色杆菌是一种条件致病菌,外伤感染是主要致病因素。     

Comparison of seven structurally related coumarins on the inhibition of Quorum sensing of Pseudomonas aeruginosa and Chromobacterium violaceum

Quorum sensing (QS) is a cell-to-cell signaling communication system that controls the virulence behavior of a broad spectrum of bacterial pathogens, participating also in the development of biofilms, responsible of the antibiotic ineffectiveness in many infections. Therefore, QS system is an attractive target for antimicrobial therapy. In this study, we compare the effect of seven structurally related coumarins against bacterial growth, biofilm formation and elastase activity of Pseudomonas aeruginosa. In addition, the anti-pathogenic capacity of the seven coumarins was evaluated on the wild type and the biosensor strain of Chromobacterium violaceum.The comparative study of coumarins showed that molecules with hydroxyl groups on the aromatic ring displayed higher activity on the inhibition of biofilm formation of P. aeruginosa over coumarins with substituents in positions 3 and 4 or without the double 3,4-bond. These 3 or 4-hydroxylated positions caused a decrease in the anti-biofilm activity obtained for coumarin. However, the hydroxyl group in position 3 of the pyrone ring was important for the inhibition of C. violaceum QS and elastolytic activity of P. aeruginosa. The effects observed were active independently of any effect on growth. According to our results, coumarin and its hydroxylated derivatives represent an interesting group of compounds to use as anti-virulence agents against the human pathogen P. aeruginosa.     

Quorum Sensing Inhibition in Chromobacterium violaceum by Amikacin Combination with Activated Charcoal or Small Plant-Derived Molecules (Pyrogallol and Coumarin)

Microbiology - The study was aimed at effective inhibition of quorum sensing (QS) in the model bacterium Chromobacterium violaceum ATCC 31532 by combinations of compounds with different anti-QS...     

Cloning, molecular analysis, and expression of the polyhydroxyalkanoic acid synthase (phaC) gene from Chromobacterium violaceum.

The polyhydroxyalkanoic acid synthase gene from Chromobacterium violaceum (phaC(Cv)) was cloned and characterized. A 6.3-kb BamHI fragment was found to contain both phaC(Cv) and the polyhydroxyalkanoic acid (PHA)-specific 3-ketothiolase (phaA(Cv)). Escherichia coli strains harboring this fragment produced significant levels of PHA synthase and 3-ketothiolase, as judged by their activities. While C. violaceum accumulated poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when grown on a fatty acid carbon source, Klebsiella aerogenes and Ralstonia eutropha (formerly Alcaligenes eutrophus), harboring phaC(Cv), accumulated the above-mentioned polymers and, additionally, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) when even-chain-length fatty acids were utilized as the carbon source. This finding suggests that the metabolic environments of these organisms are sufficiently different to alter the product range of the C. violaceum PHA synthase. Neither recombinant E. coli nor recombinant Pseudomonas putida harboring phaC(Cv) accumulated significant levels of PHA. Sequence analysis of the phaC(Cv) product shows homology with several PHA synthases, most notably a 48% identity with that of Alcaligenes latus (GenBank accession no. AAD10274).     

Determination of gaps by contig alignment with telomere-mediated chromosomal fragmentation in Candida albicans

We have adopted a method of telomere-mediated chromosome fragmentation in order to demonstrate the alignment of contigs and determination of gaps. We established the order and orientation of four contigs of Candida albicans chromosome 5 and determined the sizes of three gaps between these contigs. We confirmed this proposed alignment of contigs, as well as gap sizes, by sequencing one gap and analyzing three mega deletions of approximately 41 kbp, 58 kbp, and 77 kbp, which covered two other gaps. These gaps could be also conveniently sequenced, which is an important step in establishing a complete sequence. The combined length of contigs and gaps covered approximately 422 kbp, which is one third of chromosome 5. Telomere-mediated chromosome fragmentation, used here for the first time to align the contigs of C. albicans and determine the gaps, proved to be a reliable method. The method could be helpful in sequencing projects of other diploid organisms, in particular those in which centromeres have not been identified. In addition, our approach can be used to assign any contig to a chromosome, or to induce the loss of a specific chromosome.     

Competitive interaction of thymol with cviR inhibits quorum sensing and associated biofilm formation in Chromobacterium violaceum

International Microbiology - Biofilm formation associated with quorum sensing (QS) is a community behaviour displayed by many gram-negative pathogenic bacteria that provide survival advantages in...     

Quorum Sensing in Chromobacterium subtsugae (Formerly,C. violaceum) Is Inhibited by Gamma-Lactones,the Minor Components of Eucalyptus Leaf Extract

Microbiology - The goal of the study was to investigate the mechanism of quorum sensing (QS) inhibition in the model bacterium Chromobacterium subtsugae 026 (formerly, C. violaceum 026) by...     

Genetic diversity study of Chromobacterium violaceum isolated from Kolli Hills by amplified ribosomal DNA restriction analysis (ARDRA) and random amplified polymorphic DNA (RAPD)

Aim: Chromobacterium are saprophytes that cause highly fatal opportunistic infections. Identification and strain differentiation were performed to identify the strain variability among the environmental samples. We have evaluated the suitability of individual and combined methods to detect the strain variations of the samples collected in different seasons. Methods and Results: Amplified ribosomal DNA restriction analysis (ARDRA) and random amplified polymorphic DNA (RAPD) profiles were obtained using four different restriction enzyme digestions (AluI, HaeIII, MspI and RsaI) and five random primers. A matrix of dice similarity coefficients was calculated and used to compare these restriction patterns. ARDRA showed rapid differentiation of strains based on 16S rDNA, but the combined RAPD and ARDRA gave a more reliable differentiation than when either of them was analysed individually. Conclusion: A high level of genetic diversity was observed, which indicates that the Kolli Hills’C. violaceum isolates would fall into at least three new clusters. Significance and Impact of the Study: Results showed a noteworthy bacterial variation and genetic diversity of C. violaceum in the unexplored, virgin forest area.     

Trichophyton violaceum infection of the scalp in Poona (India)

Summary A report of thirty-four cases of ringworm of the scalp caused byT. violaceum studied at Sassoon Hospitals, Poona, India, is presented. The infections were found to be more common in children of the ages between 5 to 15 during the months of February to June. Majority of the affected individuals were undernourished. Symptomatologically the cases fall into five groups.