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PubMed2000

Automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis.

PURPOSE: Contamination of automated surgical equipment is a potential source of postoperative endophthalmitis. The effect of disinfecting the unsterile vacuum control manifold (VCM) on contamination of the aspiration fluid was studied. DESIGN: Comparative prospective microbiologic contamination study. SPECIMENS AND CONTROLS: The 37 aspiration fluid specimens studied or examined consisted of 25 from three automated evacuation systems equipped with an internal VCM (experimental groups) and 12 from one system equipped with a modified external VCM (control group). In addition, the tubings of two internal VCMs were investigated. METHODS: We investigated aspiration fluid specimens from routine cataract and vitrectomy operations performed with automated evacuation systems. After tracing the source of contamination to the internal VCM, the system was modified, creating an external VCM with the possibility for disinfection, and the study was continued. Whereas no sterilizing rinsing procedures were applied to the hidden internal VCM, the modified external VCM was regularly rinsed and filled overnight with 70% isopropanol. All samples were collected under sterile conditions, centrifuged, and cultured for bacterial growth on blood agar and MacConkey agar for 24 to 48 hours at 37 degrees C. The samples of the two internal VCMs were cultured for fungi as well. MAIN OUTCOME MEASURES: Bacterial growth was quantified, and bacteria and fungi were isolated and identified according to standard microbiologic procedures. RESULTS: In all aspiration fluid specimens from internal VCM-systems, 2+ to 4+ bacterial growth was found. Pseudomonas-related genera (Stenotrophomonas maltophilia, 17x; Comamonas acidovorans, 8x; Chryseomonas spp., 3x), Agrobacterium radiobacter (1 3x), Flavobacterium spp. (3x), and Micrococcus luteus (7x) were found most frequently. The tubing of the two VCMs contained biofilms exhibiting several of these bacteria and fungi. All specimens from the modified external VCM-system remained sterile. There was a significant difference with regard to the frequency of contamination of the aspiration fluid between the experimental and control groups (chi-square: P = 0.0001). CONCLUSIONS: The technical modification described herein allows facile hygienic measures, by which contamination of aspiration fluid by the VCM can be eliminated, which otherwise can be a significant source of contamination.

Aqueous Humor↗

PubMed1997

Broviac catheter-related bacteraemias due to unusual pathogens in children with cancer: case reports with literature review.

Among 102 episodes of intravenous catheter related bacteraemias documented between January 1989 and July 1996 in children receiving antineoplastic chemotherapy or bone marrow transplantation at G. Gaslini Children's Hospital, Genoa, Italy, were identified seven episodes due to unusual pathogens: Bacillus circulans, Bacillus licheniformis, Brevibacterium casei, Flavimonas oryzihabitans, Porphyromonas asaccharolytica, Comamonas acidovorans and Agrobacterium radiobacter. Susceptibility to different antibiotics of all strains are reported. In all cases catheter removal was required for culture negativization. All episodes were diagnosed in absence of granulocytopenia.

Bacteremia↗

PubMed2000

Characterization of fungal 17beta-hydroxysteroid dehydrogenases.

To promote understanding of the evolution of the steroid hormone signalling and hydroxysteroid dehydrogenases (HSDs), comparative characterization of fungal 17beta-HSDs was performed. Constitutive 17beta-HSD activity was determined in cytosols of the fungi: Cochliobolus lunatus, Pleospora herbarum, Fusarium lini, Trichoderma viride, Mucor spinosus, Rhizopus nigricans and Pleurotus ostreatus. The reaction equilibrium in all species except P. ostreatus was shifted towards reduction. The preferential coenzyme for reduction of androstenedione was NADPH, while for oxidation of testosterone, NAD4 was preferred. The highest enzyme activities were found in the Ascomycete C. lunatus (152.4 nmol mg(-1) h(-1)) and in the Basidiomycete P. ostreatus (69.1 nmol mg(-1) h(-1)). No similarities on the protein and mRNA level between fungal 17beta-HSDs and the purified enzyme from C. lunatus were observed. To investigate the nature of these enzymes, 17beta-HSD was purified from P. ostreatus using ammonium sulphate precipitation, hydrophobic interaction chromatography, and affinity chromatography. The purified enzyme has an apparent molecular mass of approximately 35 kDa and is probably a dimer as determined by gel filtration. Chemical modifications exposed Lys, His and Tyr as important for enzyme activity. Additionally, no similarities of C. lunatus and P. ostreatus enzymes were found to bacterial 3alpha,20beta-HSD from Streptomyces hydrogenans, 3beta,17beta-HSD from Comamonas testosteroni and mammalian 17beta-HSD types 1 and 4. The results thus suggest that there are most probably different enzymes responsible for 17beta-HSD activity in filamentous fungi.

17-Hydroxysteroid Dehydrogenases↗

PubMed2004

An extra large insertion in the polyhydroxyalkanoate synthase from Delftia acidovorans DS-17: its deletion effects and relation to cellular proteolysis.

The polyhydroxyalkanoate (PHA) synthase (PhaC(Da)) from Delftia acidovorans DS-17 (formerly Comamonas acidovorans) has a unique large insertion consisting of 40 amino acid residues in the alpha/beta hydrolase fold region. In order to examine whether this insertion is necessary for enzyme function, we generated a mutant gene where the nucleotides encoding the insertion sequence were deleted [phaC(Da)del(342-381)]. The ability of the mutant PhaC(Da) lacking the insertion sequence to produce PHA in recombinant Escherichia coli JM109 was compared with that of wild-type PhaC(Da). The results revealed that the mutant enzyme had approximately one fourth the activity of the wild-type enzyme. However, there was no significant difference in PHA content accumulated in cells harboring either the mutant PhaC(Da) or wild-type PhaC(Da) nor were there any differences in the molecular masses of the produced polymers. Therefore, we have concluded that the characteristic insertion is not indispensable for PHA synthesis. Also, slight cellular proteolysis in E. coli was found specifically for wild-type PhaC(Da) by Western blot analysis. This result prompted us to further examine the proteolytic stability of PhaC(Da) in D. acidovorans. Consequently, it has been suggested that the insertion region of PhaC(Da) is susceptible to cellular proteolysis during accumulation of PHA.

Acyltransferases↗

PubMed1997

Porin from the halophilic species Ectothiorhodospira vacuolata: cloning, structure of the gene and comparison with other porins.

The gene coding for the anion-specific porin of the halophilic eubacterium Ectothiorhodospira (Ect.) vacuolata was cloned and sequenced, the first such gene so analyzed from a purple sulfur bacterium. It encodes a precursor protein consisting of 374 amino acid (aa)-residues including a signal peptide of 22-aa residues. Comparison with aa sequences of porins from several other members of the Proteobacteria revealed little homology. Only two regions showed local homology with the previously sequenced porins of Neisseria species, Comamonas acidovorans, Bordetella pertussis, Alcaligenes eutrophus, and Burkholderia cepacia. Genomic Southern blot hybridization studies were carried out with a probe derived from the 5' end of the gene coding for the porin of Ect. vacuolata. Two related species, Ect. haloalkaliphila and Ect. shaposhnikovii, exhibited a clear signal, while the extremely halophilic bacterium Halorhodospira (Hlr.) halophila (formerly Ect. halophila) did not show any cross-hybridization even at low stringency. This result is in good accordance with a recently proposed reassignment within the family Ectothiorhodospiraceae, which included the separation of the extremely halophilic species into the new genus Halorhodospira.

Amino Acid Sequence↗

PubMedDate not supplied

Polychlorinated biphenyl degradation activities and hybridization analyses of fifteen aerobic strains isolated from a PCB-contaminated site.

Fifteen bacterial strains using biphenyl as sole carbon and energy source, obtained from different positions and depths of a polychlorinated biphenyl (PCB)-contaminated area, were analyzed for their basic metabolic phenotypes and subjected to genomic DNA hybridization screening for the presence of well characterized bph operons such as those of Pseudomonas pseudoalcaligenes KF707 and Rhodococcus globerulus P6. Most of the isolates belonged to the gamma-subdivision (Pseudomonas stutzeri, P. plutida, P. fluorescens and Vibrio logei species) and to the beta-subdivision (genera Alcaligenes, Comamonas, Ralstonia) of the Proteobacteria. All the isolates were able to cometabolize different low chlorinated PCB congeners. Among the dichlorinated biphenyls tested, a lower degradation capacity was observed for the di-ortho substituted congeners, whereas high levels of degradation were observed for the di-meta and di-para isomers, whether they were chlorinated on one or on both rings. The PCB congeners nonsubstituted in the 2,3 or 2,3 and 3,4 positions were also degraded by most of the isolated strains, which were, however, unable to significantly metabolize PCBs with more than 3 chlorine atoms. Five of the isolated strains were also able to degrade some of the tri- and tetrachlorobiphenyls tested. Southern hybridization analysis showed a strong homology between four of the fifteen isolated strains and the bph operon obtained from P. pseudoalcaligenes strain KF707. Conversely, none of the isolates here examined showed homology with the bph operon of R. globerulus strain P6. In line with this, the KF707 bph probe strongly hybridized with DNA of a significant number of bacterial colonies obtained from selected locations in the contaminated area using biphenyl-supplemented minimal medium agar plates.

Bacteria, Aerobic↗

PubMed2003

The ethanol oxidation system and its regulation in Pseudomonas aeruginosa.

Pseudomonas aeruginosa ATCC 17933, when growing on ethanol, uses a pyrroloquinoline quinone (PQQ)-dependent ethanol oxidation system. The genes coding for the ethanol oxidizing enzyme, a quinoprotein ethanol dehydrogenase (QEDH), cytochrome c(550), which is an essential component of the electron transport chain and accepts the electrons from QEDH, and an NAD-dependent acetaldehyde dehydrogenase form the exaABC gene cluster. Downstream of the exaBC genes the pqqABCDE gene cluster is found, which codes for proteins essential for biosynthesis of the cofactor PQQ. Also essential for growth on ethanol are an acetyl-CoA synthetase encoded by the acsA gene and a malate:quinone oxidoreductase encoded by the mqo gene. The X-ray structure of the soluble QEDH from P. aeruginosa was solved. It is a homodimeric enzyme and, aside from differences in some loops, the folding of QEDH is very similar to the large subunit of the soluble methanol dehydrogenase of methylotrophs, and the PQQ domain of the quinohemoprotein alcohol dehydrogenase from Comamonas testosteroni and P. fluorescens. Transcription from the QEDH (exaA) promoter is regulated by a two component system: a histidine sensor kinase (ExaD), which is presumably located in the cytoplasm, and a response regulator (ExaE). The phenotypic characterization and transcription studies with six regulatory mutants indicate that seven different genes in an hierarchical organization may be involved in regulating the transcription of the ethanol oxidation system and components of acetate metabolism in P. aeruginosa.

Alcohol Oxidoreductases↗

PubMed2003

The quinohaemoprotein lupanine hydroxylase from Pseudomonas putida.

Lupanine hydroxylase catalyses the first reaction in the catabolism of the alkaloid lupanine by Pseudomonas putida. It dehydrogenates the substrate, which can then be hydrated. It is a monomeric protein of M(r) 72,000 and contains a covalently bound haem and a molecule of PQQ. The gene for this enzyme has been cloned and sequenced and the derived protein sequence has a 26 amino acid signal sequence at the N-terminal for translocation of the protein to the periplasm. Many of the features seen in the sequence of lupanine hydroxylase are common with other quinoproteins including the W-motifs that are characteristic of the eight-bladed propeller structure of methanol dehydrogenase. However, the unusual disulfide bridge between adjacent cysteines that is present in some PQQ-containing enzymes is absent in lupanine hydroxylase. The C-terminal domain contains characteristics of a cytochrome c and overall the sequence shows similarities with that of the quinohaemoprotein, alcohol dehydrogenase from Comamonas testosteroni. The gene coding for lupanine hydroxylase has been successfully expressed in Escherichia coli and a procedure has been developed to renature and reactivate the enzyme, which was found to be associated with the inclusion bodies. Reactivation required addition of PQQ and was dependent on calcium ions.

Amino Acid Sequence↗

PubMed2005

Multiarray sensors with pattern recognition for the detection, classification, and differentiation of bacteria at subspecies and strain levels.

This work describes the integration of a fully autonomous electrochemical biosensor with pattern recognition techniques for the detection and classification of bacteria at subspecies and strain level. The system provides a continuous, real-time monitoring of bacteria activity upon exposure to antibiotics. The system utilizes 96-well-type electrodes array (DOX-dissolved oxygen sensor) with principal component analysis (PCA) for rapid and routine classification of different classes of bacteria and related strains. A representative sample of a section of the bacteria kingdom has been analyzed and classified using the proposed DOX-PCA system, including the following: Corynebacterium glutamicum, Micrococcus luteus, Staphylococcus epidermidis, Yersinia ruckeri, Escherichia adecarboxylata, Comamonas acidovorans, Alcaligenes odorans, Bacillus globigii, and three strains of Escherichia coli (K12, SM10, ATCC 25922). The new classification scheme is based on the hypothesis that, under identical experimental conditions, various bacteria consume oxygen at different rates and are affected in different ways by selected antibiotics. Thus, the response of the individual electrode in the array is indirectly altered, compared to that of cells growing on medium, by the addition of the antibiotic. By using three different antibiotics in separate wells, a unique fingerprint can be created for a specific bacterium. With the proposed DOX-PCA system, classification of bacteria was achieved at subspecies and strain level in real time. This study represents a basic research tool that may allow researchers to rapidly detect, quantify, and classify bacteria type at subspecies and strain levels.

Ampicillin↗

PubMed1997

Active site directed mutagenesis of 3 beta/17 beta-hydroxysteroid dehydrogenase establishes differential effects on short-chain dehydrogenase/reductase reactions.

Mutagenetic replacements of conserved residues within the active site of the short-chain dehydrogenase/reductase (SDR) superfamily were studied using prokaryotic 3 beta/17 beta-hydroxysteroid dehydrogenase (3 beta/17 beta-HSD) from Comamonas testosteroni as a model system. The results provide novel data to establish Ser 138 as a member of a catalytically important "triad" of residues also involving Tyr151 and Lys155. A Ser-->Ala exchange at position 138 results in an almost complete (> 99.9%) loss of enzymatic activity, which is not observed with a Ser-->Thr replacement. This indicates that an essential factor for catalysis is the ability of side chain 138 to form hydrogen bond interactions. Mutations in the NAD(H) binding region, in strands beta A, beta D, and adjacent turns, reveal two additional residues, Thr12 and Asn87, which are important for correct binding of the coenzyme and with a differential effect on the reactions catalyzed. Thus, mutation of Thr12 to Ala results in a complete loss of the 3 beta-dehydrogenase activity, whereas the 3-oxoreductase activity remains unchanged. On the other hand, a T12S substitution yields a protein with unaltered catalytic constants for both reactions, revealing that a specific hydrogen bond is critical for the dehydrogenase activity. Our interpretation of the available crystal structure of 3 alpha/20 beta-HSD from Streptomyces hydrogenans suggests a hydrogen bond in that enzyme between the Thr12 side chain and the backbone NH of Asn87 rather than the coenzyme, indicating that this hydrogen bond to the beta D strand might determine a crucial difference between the reductive and the oxidative reaction types. Similarly, mutation of Asn87 to Ala results in an 80% reduction of kcat/Km in the dehydrogenase direction but also unchanged 3-oxoreductase properties. It appears that the binding of NAD+ to the protein is influenced by local structural changes involving strand beta D and turn beta A to alpha B.

17-Hydroxysteroid Dehydrogenases↗

PubMedDate not supplied

Mixed culture bioconversion of 16-dehydropregnenolone acetate to androsta-1,4-diene-3,17-dione: optimization of parameters.

Bioconversion of 16-dehydropregnenolone acetate (16-DPA) to androsta-1,4-diene-3,17-dione (ADD), an intermediate for the production of female sex hormones, by mixed culture of Pseudomonas diminuta MTCC 3361 and Comamonas acidovorans MTCC 3362 is reported. Various physicochemical parameters for the bioconversion of 16-DPA to ADD have been optimized in shake flask cultures. Nutrient broth inoculated with actively growing co-culture proved ideal for bacterial growth and bioconversion. A temperature range of 35-40 degrees C was most suitable; higher or lower temperatures adversely affected the bioconversion. Dimethylformamide below 2% concentration was the most suitable carrier solvent. Maximum conversion was recorded at 0.5 mg mL(-1) 16-DPA. A pH of 5.0 yielded a peak conversion of 62 mol % in 120 h incubation period. Addition of 9alpha-hydroxylase inhibitors failed to prevent further breakdown of ADD to nonsteroidal products. 16-DPA conversion in a 5 L fermenter followed a similar trend.

Androstadienes↗

PubMed2002

Relative dominance of physical versus chemical effects on the transport of adhesion-deficient bacteria in intact cores from South Oyster, Virginia.

Bacterial transport experiments were conducted using intact sediment cores collected from sites on the Delmarva Peninsula near South Oyster, VA, to delineate the relative importance of physical and chemical heterogeneity in controlling transport of an adhesion-deficient bacterial strain. Electron microscopy revealed that the sediments consisted of quartz and feldspar with a variable amount of clay and iron and aluminum hydroxide coatings on the grains. A nonmotile, gram-negative indigenous groundwater strain, designated as Comamonas sp. DA001, was injected into the cores along with a conservative tracer bromide (Br). DA001 cells were 1.2 x 0.6 microm in size with a hydrophilic surface and a slightly negative surface charge. Bacterial breakthrough preceded that of Br. This differential advection phenomenon can be accounted for by reduction of the effective porosity for the bacteria relative to Br. The distribution of cells remaining in the core as determined by scintillation counting and phosphor imaging techniques was variable, ranging from nearly uniform concentrations throughout the core to exponentially decreasing concentrations with distance from the point of injection. The fraction of bacterial retention in the core was positively correlated with the abundance of the metal hydroxides and negatively correlated with grain size. Because grain size was inversely correlated with the abundance of the metal hydroxide coatings, it was necessary to separate the effects of grain size and mineralogy. The fraction of the bacterial retention accounting for the effect of grain size, the collision efficiency, exhibited no correlation with the abundance of the metal hydroxides, indicating that the bacterial retention was primarily controlled by grain size. Reasons for the lack of influence of mineralogy on bacterial transport include (i) the slightly negatively charged bacterial surfaces; (ii) an insufficient heterogeneity of sediment surface properties; and (iii) the masking of the positive charge of the metal hydroxide surfaces by adsorbed organic carbon (up to 1180 ppm). This study demonstrates that the laboratory-based bacterial transport experiments are effective in delineating physical versus chemical controlling factors and provide an important link to field-based bacterial transport studies.

Bacteria↗

PubMed1999

A ColE1-compatible expression vector for the production of His-tagged fusion proteins.

Plasmid pDB31 is a ColE1-compatible expression vector based on the p15A origin of replication. It is designed to express His-tagged fusion proteins in cells co-hosting a compatible expression vector. It was constructed by assembling the operator/promoter region plus the 6xHis and the multiple cloning site of pQE31 (QIAGEN) with the p15A origin of replication plus KanR of pGP1-2. The plasmid was found to be stable in Escherichia coli strains BL21 and DH11S. It was used to produce and purify the ferredoxin reductase component of Comamonas testosteroni B-356 biphenyl dioxygenase inside a clone hosting the remaining dioxygenase genes on a compatible plasmid.

DNA, Recombinant↗

PubMed1977

A novel mechanism of enzymic ester hydrolysis. Inversion of configuration and carbon-oxygen bond cleavage by secondary alkylsulphohydrolases from detergent-degrading micro-organisms.

The hydrolysis was studied of potassium (+)-octan-2-yl sulphate by two analogous, optically stereospecific, secondary alkylsulphohydrolases purified from two detergent-degrading micro-organisms, Comamonas terrigena and Pseudomonas C12B. Polarimetry studies have shown that (+)-octan-2-yl sulphate prepared from (+)-octan-2-ol is hydrolysed by both enzymes to yield (-)-octan-2-ol. This inversion of configuration implies that the enzymes are catalysing the scission of the C-O bond of the C-O-S linkage, a type of bond scission apparently not hitherto encountered among hydrolytic enzymes acting on ester bonds. Enzymic hydrolysis of potassium (+)-octan-2-yl sulphate in the presence of H218O and analysis of hydrolysis products for the presence of 18O has confirmed that C-O bond scission (and not O-S bond scission) occurs with both enzymes.

Arylsulfatases↗

PubMed1977

Preparation and characterization of substrates suitable for the study of stereospecific secondary alkylsulphohydrolases of detergent-degrading micro-organisms.

During the course of the purification of novel stereospecific secondary aklylsulphohydrolases present in certain detergent-degrading micro-organisms, it became apparent that substrates prepared by sulphating secondary alcohols with H2SO4 are heterogeneous. Apart from the racemization that occurs if resolved alcohols are sulphated, evidence is provided to show that other isomers are produced in which the position of the ester sulphate group on the alkyl chain has been altered. These changes can be avoided if pyridine/SO3 reagent (prepared with SO3) is substituted as sulphating agent. Experiments in which secondary alkyl sulphates prepared by both methods were tested as potential substrates for the two secondary alkylsulphohydrolase enzymes of Comamonas terrigena have provided initial information about the specificity of the enzymes.

Alcohols↗

PubMed1978

Purification and properties of the S1 secondary alkylsulphohydrolase of the detergent-degrading micro-organism, Pseudomonas C12B.

The S1 secondary alkylsulphohydrolase of the detergent-degrading micro-organism, Pseudomonas C12B, was separated from other alkylsulphohydrolases and purified to homogeneity. Under the experimental conditions used the enzyme completely hydrolysed d-octan-2-yl sulphate (d-1-methylheptyl sulphate), but showed no activity towards the corresponding l-isomer. Additional evidence has been obtained to indicate that it is probably optically stereospecific for d-secondary alkyl sulphate esters with the ester sulphate group at C-2 and with a chain length of at least seven carbon atoms. Enzyme activity towards racemic samples of heptan-2-yl sulphate (1-methylhexyl sulphate), octan-2-yl sulphate and decan-2-yl sulphate (1-methylnonyl sulphate) increased with increasing chain length. l-Octan-2-yl sulphate is a competitive inhibitor of the enzyme, as are certain primary alkyl sulphates and primary alkanesulphonates. Inhibition by each of the last two types of compounds is characteristic of the behaviour of an homologous series. Inhibition increases with increasing chain length and plots of log K(i) values against the number of carbon atoms in each alkyl chain show the expected linear relationship. A crude preparation of the S2 secondary alkylsulphohydrolase was used to show that this particular enzyme hydrolyses l-octan-2-yl sulphate, but is probably inactive towards the corresponding d-isomer. The similarity of the S1 and S2 enzymes to the CS2 and CS1 enzymes respectively of Comamonas terrigena was established, and some comments have been made on the possible roles of these and other alkylsulphohydrolases in the biodegradation of detergents.

Alkanesulfonates↗

PubMed2001

Resistance to antibiotics and biocides among non-fermenting Gram-negative bacteria.

OBJECTIVE: To investigate the antibiotic and biocide susceptibilities of clinical isolates of rarely encountered Gram-negative, non-fermenting bacteria. METHODS: Thirty Gram-negative non-fermenting bacterial strains were isolated from blood cultures of oncology patients. These were studied for their resistance to 11 antibiotics. Their susceptibilities to seven biocides used in hospitals were also examined. RESULTS: Isolates of Stenotrophomonas maltophilia and Ochrobactrum anthropi were generally resistant to at least five of the antibiotics, whereas isolates of Comamonas acidivorans, Flavobacterium oryzihabitans, Aeromonas hydrophila, Sphingobacterium spiritivorum, Acinetobacter junii and Acinetobacter lwoffi were generally sensitive to at least nine of the antibiotics. Trovafloxacin and trimethoprim-sulfamethoxazole were the most effective antibacterial agents tested, with 0% and 7%, respectively, of isolates being resistant, whereas 63% of isolates were resistant to aztreonam. Some isolates, sensitive to meropenem and/or ceftazidime in vitro, possessed very high MBC/MIC ratios for these beta-lactams. Two out of three biocides used in hospital pharmacies showed lethal activity towards all strains tested when used at less than one-third of their recommended in-use concentration. Proceine 40 failed to give a 5 log reduction in bacterial cell number for the isolates tested when used at its "in-use" concentration. A concentration of > 500 mg/L chlorhexidine was required to achieve a 5 log reduction for the same isolates. CONCLUSIONS: We have examined the antibiotic susceptibilities of non-fermenting Gram-negative bacterial strains isolated from immunocompromised patients. Despite being sensitive to certain antibiotics in vitro, some isolates were still able to cause serious bacteremia. We have also reported for the first time the susceptibilities of non-fermenting Gram-negative bacteria to common biocides used in hospital infection control, and have shown that some strains are able to persist at the "in-use" concentration of particular biocides. It is therefore important to study further this particular group of organisms, and, in particular, to examine whether there exists a link between resistance to antibiotics and resistance to biocides.

Anti-Bacterial Agents↗

PubMed2002

Bioconversion of 3 beta-acetoxypregna-5,16-diene-20-one to androsta-1,4-diene-3,17-dione by mixed bacterial culture.

AIMS: To isolate a bacterium capable of degrading 3 beta-acetoxypregna-5,16-diene-20-one (16-DPA) to androsta-1,4-diene-3,17-dione (ADD) and to decipher the biodegradation pathway. METHODS AND RESULTS: Isolation on mineral salt agar containing 16-DPA as sole carbon source yielded two bacteria identified as Pseudomonas diminuta and Comamonas acidovorons. These bacteria failed to degrade 16-DPA individually in pure cultures but converted 16-DPA to ADD in a mixed culture. The intermediates accumulated during the bioconversion were identified as pregna-4,16-diene-3,20-dione and pregna-1,4,16-triene-3,20-dione. CONCLUSIONS: The degradation pattern of 16-DPA by mixed bacterial culture revealed the reaction sequence as (i) cleavage of C-3 acetyl function, (ii) dehydrogenation at C-1 and C-2 positions and (iii) cleavage of C-17 side-chain. SIGNIFICANCE AND IMPACT OF THE STUDY: The present work opens a new approach towards the production of a female sex hormone precursor and elucidates the biodegradation pathway of 16-DPA by mixed bacterial culture.

Androstadienes↗