The characteristics of the novel bacterial strain Pseudomonas mendocina isolated from freshwater aquaculture farm.

Plastic contamination can cause damage to the water quality of fish farm ponds, and also affect the quality of the final product. Pseudomonas mendocina was found to biodegrade plastics. Our study aimed to investigate the physicochemical properties and drug resistance of P. mendocina isolated from local freshwater aquaculture farms. Firstly, the strain was isolated from aquaculture water and then identified by matrix-assisted flight mass spectrometry and 16S rDNA sequencing. Then, biochemical and antibiotic resistance analyses were performed, and a microbial high-throughput growth detector was used to assess the growth of the strain. Finally, PCR and proteomics analyses were conducted to determine drug-resistance-related genes/proteins. According to the results of the spectrum diagram and sequencing, the isolated bacteria were identified as P. mendocina, and were positive for reactions of ADH, MTE, LAC, MNE, FRU, CIT, MLT, ONPG, and ACE. P. mendocina was sensitive to most of the antibiotics, and its resistance to CHL, MIN, and TIC/CLA was intermediate. Additionally, gyrB was the resistance gene, and mdtA2, mdtA3, mdaB, and emrK1 were closely related to the drug resistance of P. mendocina. Our results show the biochemical properties of P. mendocina in isolated aquaculture water, and provide a new perspective for P. mendocina involved in the biological removal of plastics or microplastics in freshwater aquaculture farms.

Filling in the Gaps in Metformin Biodegradation: a New Enzyme and a Metabolic Pathway for Guanylurea.

The widely prescribed pharmaceutical metformin and its main metabolite, guanylurea, are currently two of the most common contaminants in surface and wastewater. Guanylurea often accumulates and is poorly, if at all, biodegraded in wastewater treatment plants. This study describes Pseudomonas mendocina strain GU, isolated from a municipal wastewater treatment plant, using guanylurea as its sole nitrogen source. The genome was sequenced with 36-fold coverage and mined to identify guanylurea degradation genes. The gene encoding the enzyme initiating guanylurea metabolism was expressed, and the enzyme was purified and characterized. Guanylurea hydrolase, a newly described enzyme, was shown to transform guanylurea to one equivalent (each) of ammonia and guanidine. Guanidine also supports growth as a sole nitrogen source. Cell yields from growth on limiting concentrations of guanylurea revealed that metabolism releases all four nitrogen atoms. Genes encoding complete metabolic transformation were identified bioinformatically, defining the pathway as follows: guanylurea to guanidine to carboxyguanidine to allophanate to ammonia and carbon dioxide. The first enzyme, guanylurea hydrolase, is a member of the isochorismatase-like hydrolase protein family, which includes biuret hydrolase and triuret hydrolase. Although homologs, the three enzymes show distinct substrate specificities. Pairwise sequence comparisons and the use of sequence similarity networks allowed fine structure discrimination between the three homologous enzymes and provided insights into the evolutionary origins of guanylurea hydrolase.IMPORTANCE Metformin is a pharmaceutical most prescribed for type 2 diabetes and is now being examined for potential benefits to COVID-19 patients. People taking the drug pass it largely unchanged, and it subsequently enters wastewater treatment plants. Metformin has been known to be metabolized to guanylurea. The levels of guanylurea often exceed that of metformin, leading to the former being considered a "dead-end" metabolite. Metformin and guanylurea are water pollutants of emerging concern, as they persist to reach nontarget aquatic life and humans, the latter if it remains in treated water. The present study has identified a Pseudomonas mendocina strain that completely degrades guanylurea. The genome was sequenced, and the genes involved in guanylurea metabolism were identified in three widely separated genomic regions. This knowledge advances the idea that guanylurea is not a dead-end product and will allow for bioinformatic identification of the relevant genes in wastewater treatment plant microbiomes and other environments subjected to metagenomic sequencing.

Bacteria involved in biodegradation of creosote PAH - A case study of long-term contaminated industrial area.

Polycyclic aromatic hydrocarbons (PAH) contained in creosote oil are particularly difficult to remove from the soil environment. Their hydrophobic character and low bioavailability to soil microorganisms affects their rate of biodegradation. This study was performed on samples of soil that were (for over forty years) subjected to contamination with creosote oil, and their metagenome and physicochemical properties were characterized. Moreover, the study was undertaken to evaluate the biodegradation of PAHs by autochthonous consortia as well as by selected bacteria strains isolated from long-term contaminated industrial soil. From among the isolated microorganisms, the most effective in biodegrading the contaminants were the strains Pseudomonas mendocina and Brevundimonas olei. They were able to degrade more than 60% of the total content of PAHs during a 28-day test. The biodegradation of these compounds using AT7 dispersant was enhanced only by Serratia marcescens strain. Moreover, the addition of AT7 improved the effectiveness of fluorene and acenaphthene biodegradation by Serratia marcescens 6-fold. Our results indicated that long-term contact with aromatic compounds induced the bacterial strains to use the PAHs as a source of carbon and energy. We observed that supplementation with surfactants does not increase the efficiency of hydrocarbon biodegradation.

Pseudomonas Mendocina Bacteremia: A Case Study and Review of Literature.

BACKGROUND Pseudomonas mendocina is a Gram-negative, aerobic, rod-shaped bacterium belonging to the family Pseudomonadaceae. In nature, P. mendocina has been isolated from water and soil samples. The species rarely causes disease in humans though severe infections resulting in hospitalization and intensive care have been documented. This case is perhaps the second reported case in the United States of a P. mendocina related infection. In this case report, we analyze the clinical and laboratory features of P. mendocina infection in a severely immunocompromised acquired immunodeficiency syndrome (AIDS) patient and review the available literature. CASE REPORT A 64-year-old white male with past medical history significant for human immunodeficiency virus (HIV)/AIDS (CD4 count on admission <10 cells/mm³) diagnosed in 1988 and on antiretroviral therapy since 1992, was admitted to our facility for acute management of a suspected invasive mold infection. On hospital day 20 the patient developed a fever of 39.9°C, had an elevated lactate of 2.6 mmol/L and absolute neutrophil count greater than 1000 cells/mm³. On hospital day 22, both blood culture sets were positive for Pseudomonas mendocina. Antibiotic therapy was de-escalated to ceftazidime and after a total treatment course of 10 days the was successfully discharged. CONCLUSIONS There have been 14 reported cases of P. mendocina in the world. Four cases presented with meningitis and 5 with endocarditis. Beyond typical anti-pseudomonal agents, 2 of the reported cases show susceptibility of P. mendocina antibiotics such as sulfamethoxazole/trimethoprim and ceftriaxone. All documented case reports of P. mendocina infection resulted in successful treatment with antibiotics and survival of the patient.

Cyanotrophic and arsenic oxidizing activities of Pseudomonas mendocina P6115 isolated from mine tailings containing high cyanide concentration.

Mine tailings and wastewater generate man-made environments with several selective pressures, including the presence of heavy metals, arsenic and high cyanide concentrations, but severe nutritional limitations. Some oligotrophic and pioneer bacteria can colonise and grow in mine wastes containing a low concentration of organic matter and combined nitrogen sources. In this study, Pseudomonas mendocina P6115 was isolated from mine tailings in Durango, Mexico, and identified through a phylogenetic approach of 16S rRNA, gyrB, rpoB, and rpoD genes. Cell growth, cyanide consumption, and ammonia production kinetics in a medium with cyanide as sole nitrogen source showed that at the beginning, the strain grew assimilating cyanide, when cyanide was removed, ammonium was produced and accumulated in the culture medium. However, no clear stoichiometric relationship between both nitrogen sources was observed. Also, cyanide complexes were assimilated as nitrogen sources. Other phenotypic tasks that contribute to the strain's adaptation to a mine tailing environment included siderophores production in media with moderate amounts of heavy metals, arsenite and arsenate tolerance, and the capacity of oxidizing arsenite. P. mendocina P6115 harbours cioA/cioB and aoxB genes encoding for a cyanide-insensitive oxidase and an arsenite oxidase, respectively. This is the first report where P. mendocina is described as a cyanotrophic and arsenic oxidizing species. Genotypic and phenotypic tasks of P. mendocina P6115 autochthonous from mine wastes are potentially relevant for biological treatment of residues contaminated with cyanide and arsenic.

Pseudomonas mendocina: the first case of peritonitis on peritoneal dialysis / Pseudomonas mendocina: el primer caso de peritonitis en diálisis peritoneal

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The isolation and functional identification on producing cellulase of Pseudomonas mendocina.

The straw can be degraded efficiently into humus by powerful enzymes from microorganisms, resulting in the accelerated circulation of N,P,K and other effective elements in ecological system. We isolated a strain through screening the straw degradation strains from natural humic straw in the low temperature area in northeast of china, which can produce cellulase efficiently. The strain was identified as Pseudomonas mendocina by using morphological, physiological, biochemical test, and molecular biological test, with the functional clarification on producing cellulase for Pseudomonas mendocina for the first time. The enzyme force constant Km and the maximum reaction rate (Vmax) of the strain were 0.3261 g/L and 0.1525 mg/(min.L) through the enzyme activity detection, and the molecular weight of the enzyme produced by the strain were 42.4 kD and 20.4 kD based on SDS-PAGE. The effects of various ecological factors such as temperature, pH and nematodes on the enzyme produced by the strain in the micro ecosystem in plant roots were evaluated. The result showed that the optimum temperature was 28°C, and the best pH was 7.4∼7.8, the impact heavy metal was Pb2+ and the enzyme activity and biomass of Pseudomonas mendocina increased the movement and predation of nematodes.

Pseudomonas mendocina native valve infective endocarditis: a case report.

BACKGROUND: Gram-negative microorganisms are uncommon pathogens responsible for infective endocarditis. Pseudomonas mendocina, a Gram-negative water-borne and soil-borne bacterium, was first reported to cause human infection in 1992. Since then, it has rarely been reported as a human pathogen in the literature. We describe the first case of native valve infective endocarditis due to P. mendocina in the USA. CASE PRESENTATION: A 57-year-old white man presented with bilateral large leg ulcers, fever, and marked leukocytosis. His past medical history included gout and chronic alcohol use. P. mendocina was isolated from his blood cultures. A comprehensive review of P. mendocina infection in the literature was performed. A total of eight cases of P. mendocina infection were reported in the literature. More than two-thirds of the cases of P. mendocina septicemia were associated with native valve infective endocarditis. Thus, an echocardiogram was performed and demonstrated mitral valve endocarditis with mild mitral insufficiency. His leg wounds were debrided and were probably the source of P. mendocina bacteremia. Unlike Pseudomonas aeruginosa, P. mendocina is susceptible to third-generation cephalosporins. Our patient received a 6-week course of antimicrobial therapy with a favorable clinical outcome. CONCLUSIONS: Our reported case and literature review illuminates a rare bacterial cause of infective endocarditis secondary to P. mendocina pathogen. Native cardiac valves were affected in all reported cases of infective endocarditis, and a majority of affected heart valves were left-sided. The antibiotics active against P. mendocina are different from those that are active against P. aeruginosa, and they notably include third-generation cephalosporins. The outcome of all reported cases of P. mendocina was favorable and no mortality was described.

Calcium-mediated modulation of Pseudomonas mendocina NR802 biofilm influences the phenanthrene degradation.

A potential biofilm forming and phenanthrene utilizing marine bacterium Pseudomonas mendocina NR802 was isolated from Rushukulya, Odisha, East Coast of India. The effect of Ca(2+) and Mg(2+) on biofilm growth and phenanthrene degradation was evaluated. Among the various tested concentrations, 20 mM of Ca(2+) and Mg(2+) showed a significant enhancement in biofilm production by the bacterium. The SEM-EDAX study showed that the elemental composition of the biofilm varied significantly when grown in the presence of Ca(2+) and Mg(2+). The CSLM analysis of biofilms grown in the presence of 20 mM Ca(2+) and Mg(2+) reveal the critical role of these ions on biofilm architectural parameters such as total biomass, biofilm thickness, roughness coefficient and surface to biovolume ratio. Ca(2+) was found to enhance the extracellular polymeric substances (EPS) production and phenanthrene degradation. Ca(2+) enhanced the biofilm growth in a dose dependent manner, whereas Mg(2+) significantly increased the cell growth in biofilm. More than 15% increase in phenanthrene degradation was observed when biofilm was grown in the presence of an additional 20 mM Ca(2+). This study also supports the fundamental role of Ca(2+) in biofilm growth, architecture as well as biofilm-mediated pollutant degradation.

Association with soil bacteria enhances p38-dependent infection resistance in Caenorhabditis elegans.

The importance of our inner microbial communities for proper immune responses against invading pathogens is now well accepted, but the mechanisms underlying this protection are largely unknown. In this study, we used Caenorhabditis elegans to investigate such mechanisms. Since very little is known about the microbes interacting with C. elegans in its natural environment, we began by taking the first steps to characterize the C. elegans microbiota. We established a natural-like environment in which initially germfree, wild-type larvae were grown on enriched soil. Bacterial members of the adult C. elegans microbiota were isolated by culture and identified using 16S rRNA gene sequencing. Using pure cultures of bacterial isolates as food, we identified two, Bacillus megaterium and Pseudomonas mendocina, that enhanced resistance to a subsequent infection with the Gram-negative pathogen Pseudomonas aeruginosa. Whereas protection by B. megaterium was linked to impaired egg laying, corresponding to a known trade-off between fecundity and resistance, the mechanism underlying protection conferred by P. mendocina depended on weak induction of immune genes regulated by the p38 MAPK pathway. Disruption of the p38 ortholog, pmk-1, abolished protection. P. mendocina enhanced resistance to P. aeruginosa but not to the Gram-positive pathogen Enterococcus faecalis. Furthermore, protection from P. aeruginosa was similarly induced by a P. aeruginosa gacA mutant with attenuated virulence but not by a different C. elegans-associated Pseudomonas sp. isolate. Our results support a pivotal role for the conserved p38 pathway in microbiota-initiated immune protection and suggest that similarity between microbiota members and pathogens may play a role in such protection.

[Screening, denitrification characteristics, and anaerobic ammonium oxidation ability of denitrifying bacterium aHD7].

A highly efficient denitrifying bacterium aHD7 was screened from activated sludge. After static culture at 30 degrees C for 3 days, the denitrification rate of the aHD7 reached 91.7%, and during denitrification, nitrite had lower accumulation, with its concentration basically maintained at 1.8 mg x L(-1). The microscopy observation demonstrated that the aHD7 was a gram-negative bacillus, with an average size of 0.5 microm x (1.5-2.5) microm. Based on its biochemical/morphological characteristics and homologic analysis of 16S rDNA sequence, the aHD7 was identified as Pseudomonas mendocina. The investigation on the factors affecting the denitrification capacity of aHD7 showed that at the initial concentration of nitrate nitrogen being less than 276.95 mg x L(-1), the denitrification rate was almost 100%, and when the initial concentration of nitrate nitrogen was as high as 553.59 mg x L(-1), the denitrification rate could reach 66.8%, with little nitrite accumulated. Ethanol was the most suitable carbon source. C/N ratio 6-8 and pH value 6-9 benefited the denitrification. The aHD7 had a good ability of anaerobic ammonium oxidation, and its average ammonium utilization rate reached 4.56 mg x L(-1) x d(-1).

[Isolation, identification and soil remediation of fomesafen-degrading strain FB8].

OBJECTIVE: In order to find new strains to degrade fomesafen in contaminated soil, we isolated and identified a high-efficiency degrading bacterium from polluted soil. The degrading characteristics and remediation ability of the strain were also studied. METHODS: Characteristics of morphological, physiological, biochemical and 16S rRNA sequence were applied to identify the strain. The optimum growth conditions were obtained by studying the effect of environmental factors such as fomesafen concentration, primary pH and temperature on the strain. The strain's remediation ability to fomesafen-polluted soil was verified by sensitive crop and target weeds bioassay in pot soil. RESULTS: A high-efficiency degrading strain FB8 that used fomesafen as sole carbon source was isolated from soybean field suffering fomesafen in Heilongjiang province. It was initially identified as a member of the genus Pseudomonas. The strain could degrade 86.75% of 500 mg/L fomesafen within 96 h. Its optimal growth conditions were determined as follows: 500 mg/L fomesafen, primary pH between 6.0 and 8.0, and at 35 to 37 degrees C. The strain could remedy the sensitive crop maize and sorghum biomass after treating for 30 d for soil contaminated with 5 mg/kg of fomesafen. CONCLUSION: A fomesafen-degrading strain FB8 was selected from fomesafen-contaminated soil in Heilongjiang Province. The strain was closely related to Pseudomonas mendocina. The strain was a suitable candidate for bioremediation of fomesafen-contaminated soil.

Complete genome of Pseudomonas mendocina NK-01, which synthesizes medium-chain-length polyhydroxyalkanoates and alginate oligosaccharides.

Pseudomonas mendocina NK-01 can synthesize medium-chain-length polyhydroxyalkanoate (PHA(MCL)) and alginate oligosaccharides (AO) simultaneously from glucose under conditions of limited nitrogen. Here, we report the complete sequence of the 5.4-Mbp genome of Pseudomonas mendocina NK-01, which was isolated from farmland soil in Tianjin, China.

Pseudo-outbreak of Pseudomonas mendocina in stem cell cultures.

Pseudomonas mendocina was first isolated in the 1970s from soil and water samples collected in the province of Mendoza, Argentina. Its recovery from human clinical specimens other than urine and leg ulcers was not documented until 1992, when a case report of an endocarditis caused by P. mendocina was published. We report the detection of P. mendocina in diagnostic stem cell cultures in the haematology unit, which initiated an outbreak investigation after identification of P. mendocina from three diagnostic stem cell cultures. Culture of a reagent used for the preparation of the diagnostic stem cell cultures revealed P. mendocina. Further outbreak investigation at the manufacturing site confirmed contamination of the product. This is the first report of an outbreak caused by P. mendocina from a commercial 'sterile' product. We conclude that this environmental pathogen has the potential to cause contamination of reagents used in clinical settings. Detection of P. mendocina should alert hospital personnel to possible product contamination.

First description of bla IMP-8 in a Pseudomonas mendocina isolated at the Hospital Infante D. Pedro, Aveiro, Portugal.

Pseudomonas mendocina carrying a novel class 1 integron containing an IMP-8 gene was isolated from an inanimate surface in a female ward sanitary facility of the Hospital Infante D. Pedro, Aveiro, Portugal. Hybridization with the integrase gene (intI1) and 16S rDNA revealed that the integron is chromosomally located. Here we report for the first time the presence of an IMP-8 metallo-beta-lactamase gene in the Pseudomonas genus.

Detection and identification of bacteria in an isolated system with near-infrared spectroscopy and multivariate analysis.

Near-infrared (NIR) transflectance spectra of Listeria innocua FH, Lactococcus lactis, Pseudomonas fluorescens, Pseudomonas mendocina, and Pseudomonas putida suspensions were collected and investigated for their potential use in the identification and classification of bacteria. Unmodified spectral data were transformed (first and second derivative) using the Savitzsky-Golay algorithm. Principal component analysis (PCA), partial least-squares discriminant analysis (PLS2-DA), and soft independent modeling of class analogy (SIMCA) were used in the analysis. Using either full cross-validation or separate calibration and prediction data sets, PLS2 regression classified the five bacterial suspensions with 100% accuracy at species level. At Pseudomonas genus level, PLS2 regression classified the three Pseudomonas species with 100% accuracy. In the case of SIMCA, prediction of an unknown sample set produced correct classification rates of 100% except for L. innocua FH (77%). At genus level, SIMCA produced correct classification rates of 96.7, 100, and 100% for P. fluorescens, P. mendocina, and P. putida, respectively. This successful investigation suggests that NIR spectroscopy can become a useful, rapid, and noninvasive tool for bacterial identification.

Native valve endocarditis due to Pseudomonas mendocina in a patient with mental retardation and a review of literature.

Pseudomonas mendocina, a Gram-negative non-fermentative rod, occurs in water and soil but is rarely recovered as a human pathogen. We report a native valve endocarditis due to Pseudomonas mendocina in a patient with mental retardation.