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Journal of Bacteriology Dec 1990Batch cultures of Pseudomonas mendocina, grown in rich medium with glucose excess, showed metabolic differences dependent upon whether the growth conditions were aerobic...
Batch cultures of Pseudomonas mendocina, grown in rich medium with glucose excess, showed metabolic differences dependent upon whether the growth conditions were aerobic or anaerobic, with or without added electron acceptor. Under anaerobic conditions in the absence of nitrate, P. mendocina reached the stationary phase of growth after 2 or 3 days, followed by a stationary phase of 4 to 5 days. Under these conditions, a mixed-type fermentative metabolism (formic, lactic, and acetic acids) appeared. A fivefold-higher specific rate of glucose consumption and eightfold-higher production of organic acids, compared with aerobic cultures, were shown by this microorganism growing anaerobically in the absence of exogenous electron acceptors. The gradients of organic acid produced by P. mendocina under these conditions reached a maximum (lactate, 180 mV; formate, 150 mV; acetate, 215 mV) between days 2 and 3 of culture. The proton motive force (delta p) decreased during growth from -254 to -71 mV. The intracellular pH remained alkaline during the culture, reaching a steady-state value of 7.9. The gradients of organic acids apparently contributed to the generation of a delta p, which, according to the Energy Recycling Model (P. A. M. Michels, J. P. J. Michels, J. Boonstra, and W. N. Konings, FEMS Microbiol. Lett. 5:357-364, 1979), would produce an average energy gain of 1 or 1.5 mol of ATP equivalents per mol of glucose consumed with H+/ATP stoichiometry of 3 or 2, respectively. Low YATP and Yglucose values were observed, suggesting that an uncoupled metabolism exists; i.e., ATP produced by catabolic processes is not directly used for biomass synthesis. This metabolic uncoupling could be induced at least in part by organic acids and the ATP wastage could be induced by a membrane-bound ATPase involved in intracellular pH regulation.
Topics: Acids; Aerobiosis; Anaerobiosis; Electron Transport; Energy Metabolism; Fermentation; Hydrogen-Ion Concentration; Membrane Potentials; Pseudomonas; Uncoupling Agents
PubMed: 2254245
DOI: 10.1128/jb.172.12.6673-6681.1990 -
Applied and Environmental Microbiology Aug 1996Seven toluene-oxidizing bacterial strains (Pseudomonas mendocina KR1, Burkholderia cepacia G4, Pseudomonas putida F1, Pseudomonas pickettii PKO1, and Pseudomonas sp....
Seven toluene-oxidizing bacterial strains (Pseudomonas mendocina KR1, Burkholderia cepacia G4, Pseudomonas putida F1, Pseudomonas pickettii PKO1, and Pseudomonas sp. strains ENVPC5, ENVBF1, and ENV113) were tested for their ability to degrade chloroform (CF). The greatest rate of CF oxidation was achieved with strain ENVBF1 (1.9 nmol/min/mg of cell protein). CF also was oxidized by P. mendocina KR1 (0.48 nmol/min/mg of cell protein), strain ENVPC5 (0.49 nmol/min/mg of cell protein), and Escherichia coli DH510B(pRS202), which contained cloned toluene 4-monooxygenase genes from P. mendocina KR1 (0.16 nmol/min/mg of cell protein). Degradation of [14C]CF and ion analysis of culture extracts revealed that CF was mineralized to CO2 (approximately 30 to 57% of the total products), soluble metabolites (approximately 15%), a total carbon fraction irreversibly bound to particulate cellular constituents (approximately 30%), and chloride ions (approximately 75% of the expected yield). CF oxidation by each strain was inhibited in the presence of trichloroethylene, and acetylene significantly inhibited trichloroethylene oxidation by P. mendocina KR1. Differences in the abilities of the CF-oxidizing strains to degrade other halogenated compounds were also identified. CF was not degraded by B. cepacia G4, P. putida F1, P. pickettii PKO1, Pseudomonas sp. strain ENV113, or P. mendocina KRMT, which contains a tmo mutation.
Topics: Acetylene; Base Sequence; Chlorides; Chloroform; Methane; Molecular Sequence Data; Oxidation-Reduction; Pseudomonas; Toluene
PubMed: 8702263
DOI: 10.1128/aem.62.8.2716-2722.1996 -
Journal of Bacteriology Dec 2002The tmoABCDEF genes encode the toluene-4-monooxygenase from Pseudomonas mendocina KR1. Upstream from the tmoA gene an open reading frame, tmoX, encoding a protein 83%...
The tmoABCDEF genes encode the toluene-4-monooxygenase from Pseudomonas mendocina KR1. Upstream from the tmoA gene an open reading frame, tmoX, encoding a protein 83% identical to TodX (todX being the initial gene in the todXFC1C2BADEGIH operon from Pseudomonas putida DOT-T1E) was found. The tmoX gene is also the initial gene in the tmoXABCDEF gene cluster. The transcription initiation point from the tmoX promoter was mapped, and the sequence upstream revealed striking identity with the promoter of the tod operon of P. putida. The tod operon is regulated by a two-component signal transduction system encoded by the todST genes. Two novel genes from P. mendocina KR1, tmoST, were rescued by complementation of a P. putida DOT-T1E todST knockout mutant, whose gene products shared about 85% identity with TodS-TodT. We show that transcription from P(tmoX) and P(todX) can be mediated by TmoS-TmoT or TodS-TodT, in the presence of toluene, revealing cross-regulation between these two catabolic pathways.
Topics: Bacterial Proteins; Multigene Family; Promoter Regions, Genetic; Protein Kinases; Pseudomonas; Pseudomonas putida; Signal Transduction; Toluene; Trans-Activators; Transcription, Genetic
PubMed: 12446657
DOI: 10.1128/JB.184.24.7062-7067.2002 -
Journal of Bacteriology May 1991The route of toluene degradation by Pseudomonas mendocina KR1 was studied by separating or purifying from toluene-grown cells the catabolic enzymes responsible for...
The route of toluene degradation by Pseudomonas mendocina KR1 was studied by separating or purifying from toluene-grown cells the catabolic enzymes responsible for oxidation of p-cresol through the ring cleavage step. Enzymatic transformations corresponding to each of the metabolic steps in the proposed degradative pathway were conducted with cell-free preparations. p-Cresol was metabolized by the enzyme p-cresol methylhydroxylase to p-hydroxybenzaldehyde. p-Hydroxybenzaldehyde was further oxidized by partially purified enzyme preparations to p-hydroxybenzoate and subsequently hydroxylated to form protocatechuate. Protocatechuate was then oxidized by ortho ring cleavage.
Topics: Alcohol Oxidoreductases; Aldehyde Oxidoreductases; Cresols; Electrophoresis, Polyacrylamide Gel; Mixed Function Oxygenases; Pseudomonas; Spectrum Analysis; Toluene
PubMed: 2019564
DOI: 10.1128/jb.173.9.3017-3020.1991 -
Environmental Health Insights 2022Antimicrobial resistance (AMR) is one of the top 10 public health threats. One approach to tackling the AMR menace could involve expanding the range of AMR surveillance...
BACKGROUND
Antimicrobial resistance (AMR) is one of the top 10 public health threats. One approach to tackling the AMR menace could involve expanding the range of AMR surveillance domains to include hospital wastewater (HWW), a domain that has largely been overlooked by researchers.
AIM
To evaluate the occurrence of multidrug-resistant bacteria in hospital wastewater of the Korle Bu Teaching Hospital (KBTH).
METHODOLOGY
This was a longitudinal study involving 288 HWW samples consecutively collected across 12 weeks from the pool of wastewater emanating from 2 critical care units of KBTH-The Child Health Unit and the Maternity Unit-on Mondays and Thursdays, each week. The samples were cultured for bacteria, which were identified using the Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) technique and subjected to antimicrobial susceptibility testing via the Kirby-Bauer method.
RESULTS
In total, 294 bacteria of 23 different types, all being Gram-negative, were isolated from the 288 samples. The predominant ones were (30.6%, n = 90), (11.2%, n = 33), (10.9%, n = 32), (5.8%, n = 17), and (5.4%, n = 16). The prevalence of multidrug resistance among the isolates was 55.4% (n = 163). Moreover, the prevalence of extended-spectrum beta-lactamase (ESBL) producers was 15.6% (n = 46). accounted for the most ESBL-producing organisms (28.9%, n = 26).
CONCLUSION
The wastewater generated by the Maternity and Child Health Units of KBTH harbored a wide range of multidrug resistant bacteria, with a good proportion of these being ESBL producers, and the predominant one being . The study thus identifies the wastewater of KBTH as an important source of multidrug resistant organisms, and underscores the significance of appropriate treatment of wastewater of the hospital and other clinical, and related settings prior to its discharge.
PubMed: 36311334
DOI: 10.1177/11786302221130613 -
Antimicrobial Agents and Chemotherapy May 1992Strains of Pseudomonas aeruginosa, including imipenem- or ofloxacin-resistant clinical isolates, and some other species in the genus Pseudomonas were inhibited by novel...
Strains of Pseudomonas aeruginosa, including imipenem- or ofloxacin-resistant clinical isolates, and some other species in the genus Pseudomonas were inhibited by novel antibiotics of the mureidomycin (MRD) group. On the other hand, almost all other gram-positive and gram-negative bacteria were resistant to MRDs, though the antibiotics potently inhibited the in vitro peptidoglycan synthesis of Escherichia coli and P. aeruginosa. All of the strains in the genus Pseudomonas that were inhibited by less than or equal to 200 micrograms of MRDs per ml were classified into the rRNA groups I and III, and none of the tested strains of rRNA group I were resistant to MRDs, suggesting that these two groups are closely related to each other evolutionary. Among group I strains, P. aeruginosa, P. mendocina, P. stutzeri, and P. alcaligenes were more susceptible than the others, suggesting a closer relationship among these species.
Topics: Anti-Bacterial Agents; Escherichia coli; Microbial Sensitivity Tests; Nucleosides; Peptides; Peptidoglycan; Pseudomonas
PubMed: 1510388
DOI: 10.1128/AAC.36.5.1024 -
Infection and Immunity Feb 2013The importance of our inner microbial communities for proper immune responses against invading pathogens is now well accepted, but the mechanisms underlying this...
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.
Topics: Animals; Bacillus megaterium; Bacterial Infections; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Metagenome; Pseudomonas aeruginosa; Pseudomonas mendocina; Soil Microbiology; Virulence; p38 Mitogen-Activated Protein Kinases
PubMed: 23230286
DOI: 10.1128/IAI.00653-12 -
Journal of Bacteriology Jul 1985Unlike enteric bacteria, Pseudomonas spp. generally lack thymidine phosphorylase and thymidine kinase activities, thus preventing their utilization of exogenous thymine...
Unlike enteric bacteria, Pseudomonas spp. generally lack thymidine phosphorylase and thymidine kinase activities, thus preventing their utilization of exogenous thymine or thymidine and precluding specific radioactive labeling of their DNA in vivo. To overcome this limitation, a DNA fragment encoding thymidine kinase (EC 2.7.1.21) from Escherichia coli was cloned into pKT230, a small, broad-host-range plasmid derived from plasmid RSF1010. From transformed E. coli colonies, the recombinant plasmid bearing the thymidine kinase gene was conjugally transferred to Pseudomonas stutzeri, Pseudomonas aeruginosa, Pseudomonas mendocina, Pseudomonas alcaligenes, and Pseudomonas pseudoalcaligenes. Thymidine kinase activity was expressed in all of these species, and all gained the ability to incorporate exogenous [2-14C]thymidine into their DNA. Thymidine incorporation into P. stutzeri was enhanced 12-fold more in mutants lacking thymidylate synthetase activity. These mutants produced higher levels of thymidine kinase and were thymidine auxotrophs; thymineless death resulted from removal of thymidine from a growing culture.
Topics: DNA Replication; Escherichia coli; Gene Expression Regulation; Genes; Genes, Bacterial; Plasmids; Pseudomonas; Pseudomonas aeruginosa; Thymidine; Thymidine Kinase
PubMed: 3924894
DOI: 10.1128/jb.163.1.291-295.1985 -
Applied and Environmental Microbiology Mar 1996The degradation of trichloroethylene (TCE) by toluene-oxidizing bacteria has been extensively studied, and yet the influence of environmental conditions and... (Comparative Study)
Comparative Study
The degradation of trichloroethylene (TCE) by toluene-oxidizing bacteria has been extensively studied, and yet the influence of environmental conditions and physiological characteristics of individual strains has received little attention. To consider these effects, the levels of TCE degradation by strains distinguishable on the basis of toluene and nitrate metabolism were compared under aerobic or hypoxic conditions in the presence and absence of nitrate and an exogenous electron donor, lactate. Under aerobic conditions with toluene-induced cells, strains expressing toluene dioxygenases (Pseudomonas putida F1, Pseudomonas sp. strain JS150, Pseudomonas fluorescens CFS215, and Pseudomonas sp. strain W31) degraded TCE at low rates, with less than 12% of the TCE removed in 18 h. In contrast, strains expressing toluene monooxygenases (Burkholderia cepacia G4, Burkholderia pickettii PKO1, and Pseudomonas mendocina KR1) degraded 36 to 67% of the TCE over the same period. Under hypoxic conditions (1.7 mg of dissolved oxygen per liter) or when lactate was added as an electron donor, the extent of TCE degradation by toluene-induced cells was generally lower. In the presence of lactate, degradation of TCE by denitrifying strain PKO1 was enhanced by nitrate under conditions in which dissimilatory nitrate reduction was observed. The results of experiments performed with strains F1, G4, PKO1, and KR1 suggested that TCE or an oxidation product induces toluene degradation and that TCE induces its own degradation in the monooxygenase strains. The role of TCE as an inducer of toluene oxygenase activity in PKO1 was confirmed by performing a promoter probe analysis, in which we found that TCE activates transcription from the PKO1 3-monooxygenase operon promoter.
Topics: Biodegradation, Environmental; Burkholderia; Environmental Pollutants; Enzyme Induction; Oxidation-Reduction; Oxygenases; Pseudomonas; Toluene; Trichloroethylene
PubMed: 8975612
DOI: 10.1128/aem.62.3.825-833.1996 -
Frontiers in Microbiology 2014When iron-starved, the Mn(II)-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1), siderophores that both influence...
When iron-starved, the Mn(II)-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1), siderophores that both influence iron uptake and inhibit manganese(II) oxidation by these strains. To explore the properties and genetics of a PVD that can affect manganese oxidation, LC-MS/MS, and various siderotyping techniques were used to identify the peptides of PVDGB-1 and PVDMnB1 as being (for both PVDs): chromophore-Asp-Lys-OHAsp-Ser-Gly-aThr-Lys-cOHOrn, resembling a structure previously reported for P. putida CFML 90-51, which does not oxidize Mn. All three strains also produced an azotobactin and a sulfonated PVD, each with the peptide sequence above, but with unknown regulatory or metabolic effects. Bioinformatic analysis of the sequenced genome of P. putida GB-1 suggested that a particular non-ribosomal peptide synthetase (NRPS), coded by the operon PputGB1_4083-4086, could produce the peptide backbone of PVDGB-1. To verify this prediction, plasmid integration disruption of PputGB1_4083 was performed and the resulting mutant failed to produce detectable PVD. In silico analysis of the modules in PputGB1_4083-4086 predicted a peptide sequence of Asp-Lys-Asp-Ser-Ala-Thr-Lsy-Orn, which closely matches the peptide determined by MS/MS. To extend these studies to other organisms, various Mn(II)-oxidizing and non-oxidizing isolates of P. putida, P. fluorescens, P. marincola, P. fluorescens-syringae group, P. mendocina-resinovorans group, and P. stutzerii group were screened for PVD synthesis. The PVD producers (12 out of 16 tested strains) were siderotyped and placed into four sets of differing PVD structures, some corresponding to previously characterized PVDs and some to novel PVDs. These results combined with previous studies suggested that the presence of OHAsp or the flexibility of the pyoverdine polypeptide may enable efficient binding of Mn(III).
PubMed: 24847318
DOI: 10.3389/fmicb.2014.00202