Biomedical subjects

Richard Villemur

Publications and source records attributed to Richard Villemur.

At least 19 recordsLinked to original sources

PubMed2006

Long-term storage conditions for carriers with denitrifying biomass of the fluidized, methanol-fed denitrification reactor of the Montreal Biodome, and the impact on denitrifying activity and bacterial population.

The Montreal Biodome has a denitrification system to stabilize the nitrate concentration in its 3 million liter seawater aquarium. However, this microbial process has failed periodically due to various technical problems. The system can take several weeks to recover its full denitrification capacity. In order to provide the denitrification system with a backup of active biomass, different freezing conditions for the denitrifying biomass were tested. The biomass was conserved for 1 week-17 months at -20 degrees C with and without glycerol or at -80 degrees C with and without glycerol, and the denitrifying activity was tested in batch culture for 140 h periods at various intervals. Our results showed that glycerol was required for fast recovery of the microbial community's denitrifying activity. The -20 degrees C and -80 degrees C conservation temperatures with glycerol gave similar results although there was a short period of nitrite accumulation in the -20 degrees C sample. There were no substantial changes in the microbial community of any of the frozen samples after 17 months of conservation as monitored by denaturing gradient gel electrophoresis. This is the first report on the long-term conservation of a complex denitrifying population by freezing.

Biomass↗

PubMed2006

The Desulfitobacterium genus.

Desulfitobacterium spp. are strictly anaerobic bacteria that were first isolated from environments contaminated by halogenated organic compounds. They are very versatile microorganisms that can use a wide variety of electron acceptors, such as nitrate, sulfite, metals, humic acids, and man-made or naturally occurring halogenated organic compounds. Most of the Desulfitobacterium strains can dehalogenate halogenated organic compounds by mechanisms of reductive dehalogenation, although the substrate spectrum of halogenated organic compounds varies substantially from one strain to another, even with strains belonging to the same species. A number of reductive dehalogenases and their corresponding gene loci have been isolated from these strains. Some of these loci are flanked by transposition sequences, suggesting that they can be transmitted by horizontal transfer via a catabolic transposon. Desulfitobacterium spp. can use H2 as electron donor below the threshold concentration that would allow sulfate reduction and methanogenesis. Furthermore, there is some evidence that syntrophic relationships occur between Desulfitobacterium spp. and sulfate-reducing bacteria, from which the Desulfitobacterium cells acquire their electrons by interspecies hydrogen transfer, and it is believed that this relationship also occurs in a methanogenic consortium. Because of their versatility, desulfitobacteria can be excellent candidates for the development of anaerobic bioremediation processes. The release of the complete genome of Desulfitobacterium hafniense strain Y51 and information from the partial genome sequence of D. hafniense strain DCB-2 will certainly help in predicting how desulfitobacteria interact with their environments and other microorganisms, and the mechanisms of actions related to reductive dehalogenation.

Biodegradation, Environmental↗

PubMed2006

Occurrence and expression of crdA and cprA5 encoding chloroaromatic reductive dehalogenases in Desulfitobacterium strains.

Desulfitobacterium hafniense PCP-1 (formerly frappieri PCP-1) has two reductive dehalogenases (RDases) that have been characterized. One is a membrane-associated 2,4,6-trichlorophenol RDase, which is encoded by crdA, and the other is a 3,5-dichlorophenol RDase encoded by cprA5. In this report, we determined the occurrence of these two RDase genes in seven other Desulfitobacterium strains. The presence or absence of these two RDases may explain the differences in the spectrum of halogenated compounds by these Desulfitobacterium strains. crdA gene sequences were found in all of the tested strains. It was expressed in strain PCP-1 regardless of the absence or presence of chlorophenols in the culture medium. crdA was also expressed in D. hafniense strains DCB-2 and TCE-1. cprA5 was detected only in D. hafniense strains PCP-1, TCP-A, and DCB-2. In these strains, cprA5 transcripts were detected only in the presence of chlorophenols. We also examined the expression of putative cprA RDases (cprA2, cprA3, and cprA4) that were shown to exist in the D. hafniense DCB-2 genome. RT-PCR experiments showed that cprA2, cprA3, and cprA4 were expressed in D. hafniense strains PCP-1, DCB-2, and TCP-A in the presence of chlorophenols. However, contrary to cprA5, these three genes were also expressed in the absence of halogenated compounds in the culture medium.

Bacterial Proteins↗

PubMed2005

Design optimization of a self-cleaning moving-bed bioreactor for seawater denitrification.

The hydrodynamic behavior and denitrification capacity of a down flow self-cleaning moving bed bioreactor (MBBR) using floating packed-bed carriers were investigated. Water mixing in the MBBR was determined by tracer studies, which showed a completely stirred tank reactor. Eleven different types of patented plastic packed-bed carriers were selected based on their density, shape and specific surface area. Video studies of the carriers were used to determine operating conditions and select the Cascade 1A and Tri-Pack 1 carriers for denitrification experiments. Both carriers showed a similar performance level in terms of the denitrification capacity of the resulting MBBR. The improvement in liquid circulation is thought to explain the high denitrification rates that reached 27 gNm(-2)d(-1) and the maintenance of a thin biofilm. Increasing the overall liquid velocity profile led to an increase of up to 30% in the denitrification rate in conditions with a 1-month-old biofilm. This MBBR design seemed to control biofilm development and could easily be scaled up to denitrify seawater or freshwater systems.

Biofilms↗

PubMed2005

Conditions for effective removal of pyrene from an artificially contaminated soil using Pseudomonas aeruginosa 57SJ rhamnolipids.

The efficacy of a new rhamnolipid biosurfactants mixture to enhance the removal of pyrene from a soil artificially contaminated was investigated. The molar solubilization ratio (MSR) and the partition coefficient between the micelles and water (log K(m)) were found to be 7.5 x 10(-3) and 5.7, respectively. From soil column studies, the pyrene removal increased linearly with the concentration of the injected biosurfactants solution above the effective critical micellar concentration (0.4 g L(-1)). Flushing with a 5.0 g L(-1) biosurfactants solution increased the pyrene concentration in the effluent by 178 times. At high biosurfactants' concentrations (2.5 and 5.0 g L(-1)), the cumulative pyrene recovery reached 70%. This pyrene remobilization takes place independently of the soil organic carbon solubilization. This study provides a combination of batch and column experiments in order to find the conditions for effective soil remediation using a new rhamnolipids mixture.

Biodegradation, Environmental↗

PubMed2005

Seawater denitrification in a closed mesocosm by a submerged moving bed biofilm reactor.

The performance of a submerged moving bed biofilm reactor (MBBR) for the denitrification of seawater in a 3.25 million closed circuit mesocosm was investigated at pilot scale, using methanol as a carbon source at various C/N ratios. Nitrate accumulation in closed systems where water changes are expensive and problematic may cause toxicity problems to marine life. Seawater was pretreated in a recirculated fixed bed to remove oxygen prior to the denitrification step. The 110l MBBR was partly filled (25%) with spherical positively buoyant polyethylene carriers with an effective surface area of approximately 100 m2 m(-3), which represents 35% of the total surface area. Carriers were maintained submerged by a conical grid and circulated by the downflow jet of an eductor. The MBBR mixing system was designed to prevent dead mixing zones and carrier fouling to avoid sulfate reduction while treating seawater containing as high as 2150 mg SO4-Sl(-1). NO3-N reduction from 53 to as low as 1.7+/-0.7 mg l(-1) and a maximum denitrification rate of 17.7+/-1.4 g Nm(-2) d(-1) were achieved at 4.2-4.3 applied COD/N (w/w) ratio. Methanol consumption corresponded to denitrification stoichiometric values, indicating the absence of sulfate reduction. Denitrification rates and effluent residual dissolved organic carbon were proportional to the C/N ratio. Such reactors could be scaled up in closed systems where water changes must be minimized.

Biofilms↗

PubMed2005

Cryptanaerobacter phenolicus gen. nov., sp. nov., an anaerobe that transforms phenol into benzoate via 4-hydroxybenzoate.

An anaerobic bacterium that transforms phenol and 4-hydroxybenzoate (4-OHB) into benzoate, strain LR7.2T, was isolated from a culture originating from a mixture of swamp water, sewage sludge, swine waste and soil. Cells of strain LR7.2T are Gram-positive short rods (1 x 2 microm) that are electron-dense when observed by electron microscopy. The optimum pH and temperature for growth and transformation activity of 4-OHB are 7.5-8.0 and 30-37 degrees C, respectively. The bacterium does not use sulphate, thiosulphate, nitrate, nitrite, FeCl3, fumarate or arsenate as an electron acceptor. It does not normally use sulphite, although stimulation of growth and 4-OHB transformation activity at a low concentration (up to 2 mM) has been reported previously under different culture conditions. The presence of 4-OHB or phenol is essential for growth; transformation of 4-OHB or phenol into benzoate is used to produce energy for growth. Using [6D]-phenol, 4-OHB was shown to be an intermediate in the transformation of phenol into benzoate. No spore was observed. The bacterium has a DNA G+C content of 51 mol% and its major membrane fatty acid is anteiso-C(15 : 0). The 16S rRNA gene sequence of strain LR7.2T shows only 90 % similarity to its closest relative (Pelotomaculum thermopropionicum). From these results, a new taxon is proposed: Cryptanaerobacter phenolicus gen. nov., sp. nov. The type strain is LR7.2T (=ATCC BAA-820T=DSM 15808T).

Anaerobiosis↗

PubMed2004

Use of eukaryotic mitochondrial DNA to differentiate human, bovine, porcine and ovine sources in fecally contaminated surface water.

A molecular method based on the detection of mitochondrial DNA from various animal species was developed to track the origin of surface water pollutions, and to differentiate human and animal sources. Mitochondrial DNA sequences were used to design PCR primers specific for human, bovine, ovine and porcine DNA using single, multiplex and nested PCR protocols. The primers were tested with DNA extracted from untreated domestic sewage, agricultural soils run-off, swine farm effluents and water from two rivers with known pollution sources. At least one of the four species was detected in most of these samples. The limit of detection in wastewater was 10(3)-10(4) cells L(-1) with a multiplex PCR protocol. This is the first report of a method using eukaryotic genetic DNA to detect and differentiate animal DNA from fecal sources in water. This innovative method is simple and could be used to quickly differentiate sources of pollution in a watershed.

Agriculture↗

PubMed2004

Burkholderia cepacia infections associated with intrinsically contaminated ultrasound gel: the role of microbial degradation of parabens.

OBJECTIVE: To describe an outbreak of serious nosocomial Burkholderia cepacia infections occurring after transrectal prostate biopsy associated with ultrasound gel intrinsically contaminated with paraben-degrading microorganisms. METHODS: A retrospective chart review prompted by a blood culture isolate of B. cepacia. Identification of microorganisms in ultrasound gel in two Canadian centers and characterization by pulsed-field gel electrophoresis and assays for paraben degradation. SETTING: Two Canadian university-affiliated, tertiary-care centers in Newfoundland and Alberta. RESULTS: Six serious B. cepacia infections were identified at the two centers. Isolates of B. cepacia recovered from the blood of patients from both centers and the ultrasound gel used during the procedures were identical, confirming intrinsic contamination. Strains of Enterobacter cloacae isolated from ultrasound gel at the two centers were also identical. The ability to degrade parabens was proven for both B. cepacia and E. cloacae strains recovered from the ultrasound gel. CONCLUSIONS: Ultrasound gel is a potential source of infection. Contamination occurs at the time of manufacture, with organisms that degrade parabens, which are commonly used as stabilizing agents. There are far-reaching implications for the infection control community.

Aged↗

PubMed2004

Nitratireductor aquibiodomus gen. nov., sp. nov., a novel alpha-proteobacterium from the marine denitrification system of the Montreal Biodome (Canada).

The Montreal Biodome operates a methanol-fed denitrification system that treats the water in its three million litre marine mesocosm. An unknown bacterium, named strain NL21T, was isolated from this system on TSA and R2A agar. The organism is a Gram-negative, rod-shaped (1x3 microm) facultative aerobe. Optimal growth conditions on R2A agar are 30-35 degrees C, pH 7-7.5 and 1% (w/w) NaCl. Phylogenetic analysis of the 16S rDNA sequence reveals that strain NL21T forms a novel lineage in the family 'Phyllobacteriaceae' within the alpha2 subgroup of the Proteobacteria. The closest related genera are Aminobacter, Pseudaminobacter, Mesorhizobium and Defluvibacter. Major cellular fatty acids are C(18:1)omega7c (75%), C(19:0)omega8c cyclopropane (9.4%) and C(18:0) (4.2%). The DNA G+C content of strain NL21T (57 mol%) differs from those of all other described members of the 'Phyllobacteriaceae' (60-64 mol%). Strain NL21T reduces nitrate to nitrite, but does not reduce nitrite to nitrogen gas. Only a few sugars and amino acids can serve as carbon sources. Strain NL21T is able to grow without salt and tolerates up to 5% NaCl. Phylogenetic analysis, as well as physiological and biochemical tests, showed that strain NL21T was different from all other members of the 'Phyllobacteriaceae' with validly published names. Strain NL21T therefore represents a novel genus, for which the name Nitratireductor aquibiodomus gen. nov., sp. nov. is proposed, with the type strain NL21T (=DSM 15645T=ATCC BAA-762T).

Alphaproteobacteria↗

PubMed2004

Purification, cloning, and sequencing of a 3,5-dichlorophenol reductive dehalogenase from Desulfitobacterium frappieri PCP-1.

A membrane-associated 3,5-dichlorophenol reductive dehalogenase was isolated from Desulfitobacterium frappieri PCP-1. The highest dehalogenase activity was observed with the biomass cultured at 22 degrees C, compared to 30 and 37 degrees C, where the cell suspensions were 2.2 and 9.6 times less active, respectively. The reductive dehalogenase was purified 12.7-fold to apparent homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 57 kDa. Its dechlorinating activity was not inhibited by sulfate and nitrate but was completely inhibited by 2.5 mM sulfite and 10 mM KCN. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activities, suggesting the involvement of a corrinoid cofactor. Several polychlorophenols were dechlorinated at the meta and para positions. The apparent K(m) for 3,5-dicholorophenol was 49.3 +/- 3.1 microM at a methyl viologen concentration of 2 mM. Six internal tryptic peptides were sequenced by mass spectrometry. One open reading frame (ORF) was found in the Desulfitobacterium hafniense genome containing these peptide sequences. This ORF corresponds to a gene coding for a CprA-type reductive dehalogenase. The corresponding ORF (named cprA5) in D. frappieri PCP-1 was cloned and sequenced. The cprA5 gene codes for a 548-amino-acid protein that contains a twin-arginine-type signal for secretion. The gene product has a cobalamin binding site motif and two iron-sulfur binding motifs and shows 66% identity (76 to 77% similarity) with some tetrachloroethene reductive dehalogenases. This is the first CprA-type reductive dehalogenase that can dechlorinate chlorophenols at the meta and para positions.

Amino Acid Sequence↗

PubMed2003

Purification, cloning and sequencing of an enzyme mediating the reductive dechlorination of 2,4,6-trichlorophenol from Desulfitobacterium frappieri PCP-1.

A new membrane-associated 2,4,6-trichlorophenol reductive dehalogenase from Desulfitobacterium frappieri PCP-1 was isolated. Initial characterization of the crude preparation showed that the dechlorinating activity was sensitive to oxygen, and its optimum pH was 7.0. Its dechlorinating activity was not inhibited by sulphate, was completely inhibited by 1 mM sulphite, and partially inhibited by 5 mM sodium azide and by more than 5 mM nitrate. Several polychlorophenols were dechlorinated in the ortho position with respect to the hydroxy group. A dehalogenase was purified to apparent homogeneity. SDS gel electrophoresis revealed a single protein band with a molecular mass of 37 kDa. However, after two-dimensional gel electrophoresis, this band was composed of three isoforms. MS analyses showed that the three isoforms were from the same protein and the molecular mass of the most abundant isoform is 33800 Da. A mixture of iodopropane and titanium citrate caused a light-reversible inhibition of the dechlorinating activity, suggesting the involvement of a corrinoid cofactor. The apparent K(m) value for 2,4,6-trichlorophenol and pentachlorophenol were 18.3+/-2.8 microM and 26.8+/-2.9 microM respectively, at a methyl viologen concentration of 2 mM. The N-terminal amino acid sequence and an internal tryptic peptide sequence were determined. One open reading frame (ORF) was found in the Desulfitobacterium hafniense genome containing these peptides sequences. The corresponding ORF in D. frappieri PCP-1 was cloned and sequenced. This ORF, that we designated crdA, showed no homology with any known dehalogenase, suggesting a distinct reductive dehalogenase.

Amino Acid Sequence↗

PubMed2003

Addition of trace metals increases denitrification rate in closed marine systems.

We investigated the effect of trace metals (Fe, Mn, Cu, Zn and Mo) on the denitrification unit at the Montreal Biodome. Two dosages of the five trace metals were tested on a denitrifying bacterial population which was extracted from the denitrification unit and cultured in 250 mL chemostats with artificial seawater. The low dosage showed a 20% increase in the denitrification rate whereas the high dosage had a more pronounced effect with a 250% increase. No increase in bacterial growth was observed, suggesting that the trace metals had an effect on the denitrification activity. When the trace metals were tested separately, only iron had a significant effect similar to the increase in the denitrification rate observed when the five trace metals were added. The combination of Fe and Mn caused a small but significant increase compared to the five trace metals. We then tested the effect of adding Fe, Mn and Cu to the denitrification unit at the Montreal Biodome. A high dosage of these trace metals showed a 250% increase in the denitrification rate, which went from 200 to 700 g NO(x)-N/d. Our results showed that the addition of trace metals is crucial for denitrification activities.

Ecosystem↗

PubMed2003

Improving the biotreatment of hydrocarbons-contaminated soils by addition of activated sludge taken from the wastewater treatment facilities of an oil refinery.

Addition of activated sludge taken from the wastewater treatment facilities of an oil refinery to a soil contaminated with oily sludge stimulated hydrocarbon biodegradation in microcosms, bioreactors and biopile. Microcosms containing 50 g of soil to which 0.07% (w/w) of activated sludge was added presented a higher degradation of alkanes (80% vs 24%) and polycyclic aromatic hydrocarbons (PAHs) (77% vs 49%) as compared to the one receiving only water, after 30 days of incubation at room temperature. Addition of ammonium nitrate or sterile sludge filtrate instead of activated sludge resulted in a similar removal of PAHs but not of alkanes suggesting that the nitrogen contained in the activated sludge plays a major role in the degradation of PAHs while microorganisms of the sludge are active against alkanes. Addition of sludge also stimulated hydrocarbon biodegradation in 10-kg bioreactors operated during 60 days and in a 50-m3 biopile operated during 126 days. This biopile treatment allowed the use of the soil for industrial purpose based on provincial regulation ("C" criteria). In contrast, the soil of the control biopile that received only water still exceeded C criteria for C10-C50 hydrocarbons, total PAHs, chrysene and benzo[a]anthracene. The stimulation effect of sludge was stronger on the 4-rings than on 2-rings PAHs. The soil of the biopile that received sludge was 4-5 times less toxic than the control. These results suggest that this particular type of activated sludge could be used to increase the efficiency of the treatment of hydrocarbon-contaminated soils in a biopile.

Alkanes↗

PubMed2003

rhlA is required for the production of a novel biosurfactant promoting swarming motility in Pseudomonas aeruginosa: 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs), the precursors of rhamnolipids.

Pseudomonas aeruginosa produces extracellular glycolipids composed of L-rhamnose and 3-hydroxyalkanoic acid called rhamnolipids. Although these compounds are usually regarded as biosurfactants or haemolysins, their exact physiological function is not well understood. Rhamnolipids are synthesized by a rhamnosyltransferase, encoded by the rhlAB operon, which catalyses the transfer of TDP-L-rhamnose to 3-(3-hydroxyalkanoyloxy)alkanoic acid (HAA) moieties of various lengths. RhlB is the catalytic protein of the rhamnosyltransferase. rhlA is indispensable for rhamnolipid synthesis, but its function is unknown. Using a liquid chromatography/mass spectrometry method, the production of extracellular HAAs by P. aeruginosa was detected previously and it was demonstrated that they are the actual precursors of rhamnolipid biosynthesis. In this report, evidence is presented indicating that rhlA is required for production of HAAs and that these HAAs display potent surface-active properties. P. aeruginosa can colonize surfaces by swarming motility, a form of organized translocation requiring the production of wetting agents. Using rhlA and rhlB mutants it was observed that swarming requires the expression of the rhlA gene but does not necessitate rhamnolipid production, as HAAs act as surfactants. Finally, it was shown that the use of ammonium instead of nitrate as source of nitrogen and an excess of available iron both decrease rhlA expression and swarming motility.

Bacterial Proteins↗

PubMed2002

Liquid chromatographic/mass spectrometric detection of the 3-(3-hydroxyalkanoyloxy) alkanoic acid precursors of rhamnolipids in Pseudomonas aeruginosa cultures.

A series of pseudomolecular and fragment ions attributed to 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) were detected by liquid chromatography/mass spectrometry among the rhamnolipids observed in a Pseudomonas aeruginosa strain 57RP supernatant. The fragmentation mechanism leading to the formation of the fragment ions was determined by a deuterium exchange experiment and by using a standard HAA mixture obtained from the mild acidic hydrolysis of rhamnolipids of known composition. The structure and the response factor of these free HAAs were determined. The HAAs relative composition differs between free HAAs and those present in rhamnolipids, the former being enriched in lower molecular mass congeners and depleted in the heavier ones. Within an isomeric pair, the isomer with the shortest 3-hydroxyalkaloyl residue at the hydroxyl end was more abundant than the one with the heavier 3-hydroxyalkaloyl acid at this position, and the ratios of their relative abundances were similar for free HAAs and those in rhamnolipids. Experiments with deuterium-labeled rhamnolipids demonstrated that free HAAs are part of a pool used for rhamnolipid biosynthesis and are not rhamnolipid degradation products.

Chromatography, Liquid↗

PubMed2002

Rapid antimicrobial susceptibility testing of urinary tract isolates and samples by flow cytometry.

A multiparametric flow cytometry antimicrobial susceptibility test was developed and its performance was evaluated on clinical urine isolates and samples in comparison with standard methods. Alterations in cytoplasmic membrane integrity were monitored by propidium iodide, and the anionic probe bis-(1,3-dibutylbarbituric acid) trimethine oxonol (DiBAC4(3)) was used to measure changes in membrane potential. Microbial size and cellular content were analysed by light scattering. Twelve antibiotics were tested on 6 ATCC control strains, 22 urine isolates and 19 clinical urine samples, variously containing Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Staphylococcus aureus, S. saprophyticus and S. epidermidis. Agreement between the flow cytometry results, broth microdilution and disk diffusion tests was 93.9% (n = 328 tests). Of the 20 discrepancies observed, 18 were for species other than E. coli. Perfect correlation was obtained with five antibiotics, whereas norfloxacin, nitrofurantoin and tetracycline were responsible for 13(65%) of the 20 discrepancies.

Anti-Bacterial Agents↗

PubMed2002

prbA, a gene coding for an esterase hydrolyzing parabens in enterobacter cloacae and Enterobacter gergoviae strains.

The new gene prbA encodes an esterase responsible for the hydrolysis of the ester bond of parabens in Enterobacter cloacae strain EM. This gene is located on the chromosome of strain EM and was cloned by several PCR approaches. The prbA gene codes for an immature protein of 533 amino acids, the first 31 of which represent a proposed signal peptide yielding a mature protein of a putative molecular mass of 54.6 kDa. This enzyme presents analogies with other type B carboxylesterases, mainly of eukaryotic origin. The cloning and expression of the prbA gene in a strain of Escherichia coli previously unable to hydrolyze parabens resulted in the acquisition of a hydrolytic capacity comparable to the original activity of strain EM, along with an increased resistance of the transformed strain to methyl paraben. The presence of homologues of prbA was tested in additional ubiquitous bacteria, which may be causative factors in opportunistic infections, including Enterobacter gergoviae, Enterobacter aerogenes, Pseudomonas agglomerans, E. coli, Pseudomonas aeruginosa, and Burkholderia cepacia. Among the 41 total strains tested, 2 strains of E. gergoviae and 1 strain of Burkholderia cepacia were able to degrade almost completely 800 mg of methyl paraben liter(-1). Two strains of E. gergoviae, named G1 and G12, contained a gene that showed high homology to the prbA gene of E. cloacae and demonstrated comparable paraben esterase activities. The significant geographical distance between the locations of the isolated E. cloacae and E. gergoviae strains suggests the possibility of an efficient transfer mechanism of the prbA gene, conferring additional resistance to parabens in ubiquitous bacteria that represent a common source of opportunistic infections.

Amino Acid Sequence↗