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Frontiers in Microbiology 2020Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections. It interferes with QS by the inhibition...
Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections. It interferes with QS by the inhibition of signal synthesis, the detection of enzyme-catalyzed degradation, and the modification of signals. -Acyl homoserine lactones (AHLs) represent a family of widely conserved QS signals involved in the regulation of virulence factor production in many Gram-negative bacterial pathogens. In this study, AHL-degrading bacterial strains were isolated, and the most efficient one was evaluated for its potential against QS-mediated pathogens. Results showed that an AHL-degrading bacteria D-2 effectively attenuated maceration produced by the pathogen subsp. (Pcc) on radish and potato slices. Strain D-2 exhibited a superior AHL degradation activity and efficiently degraded various AHLs, including -hexanoyl-L-homoserine lactone (C6HSL), -(3-oxohexanoyl)-L-homoserine lactone (3OC6HSL), -(3-oxooctanoyl)-L-homoserine lactone (3OC8HSL), and -(3-oxododecanoyl)-L-homoserine lactone (3OC12HSL). Analysis of the degradation products of AHL by gas chromatography-mass spectrometry led to the identification of -cyclohexyl-propanamide and propanamide as the main intermediate products, suggesting that AHL was degraded by hydrolysis. Annotation and analysis of the whole genome sequence of strain D-2 revealed the presence of an AHL-lactonase, termed AidF. Moreover, the application of strain D-2 was able to substantially reduce the disease severity caused by Pcc on host plants. These results reveal the biochemical basis of a highly efficient AHL-degrading bacterial isolate and present the potential to attenuate Pcc virulence through QQ.
PubMed: 32457732
DOI: 10.3389/fmicb.2020.00898 -
Journal of Hazardous Materials Aug 2014In real environmental applications, such as heavy metal bioremediation, microorganisms are generally not kept at their optimum growth conditions; therefore, it is...
In real environmental applications, such as heavy metal bioremediation, microorganisms are generally not kept at their optimum growth conditions; therefore, it is imperative to investigate their heavy metal removal performance under diverse environmental conditions. The present study aims to investigate the effects of pH, temperature and growth phases on the removal of Cu(2+) and Cr(6+) by two environmental isolates identified as Ochrobactrum intermedium LBr and Cupriavidus metallidurans CH34. Results showed that cells in logarithmic phase presented better biosorption capacity than cells in stationary phase for both isolates. The Cr(6+) metal was removed more efficiently by live O. intermedium LBr than dead cells; while dead C. metallidurans CH34 biosorbed better than live ones. It was also found that the pH and temperature affected the biosorption capacity. The optimum temperatures were determined to be 37°C and 27°C, and the optimum pH values were 6 and 7 for O. intermedium LBr and C. metallidurans CH34, respectively. Additionally, both microorganisms preferentially adsorbed Cu(2+) in Cu(2+)/Cr(6+) mixtures. The main mechanism of adsorption was determined to be through carboxylic, hydroxyl, and amino functional groups.
Topics: Biodegradation, Environmental; Biomass; Chromium Compounds; Copper; Cupriavidus; Hydrogen-Ion Concentration; Metals, Heavy; Microbial Sensitivity Tests; Ochrobactrum; Temperature; Thermodynamics
PubMed: 25064261
DOI: 10.1016/j.jhazmat.2014.07.016 -
Journal of Hazardous Materials Jul 2019Plant-bacterial mutualism has tremendous potential for remediation of herbicide contaminated soils. Generally, bacterial inoculation helps plants to grow well in the...
Plant-bacterial mutualism has tremendous potential for remediation of herbicide contaminated soils. Generally, bacterial inoculation helps plants to grow well in the contaminated environment. Here, we investigated the impact of bispyribac sodium (BS) degrading bacterial consortium (BDAM) on BS remediation, plant growth promotion and BS accumulation in plant parts. Wheat (Triticum aestivum) was planted in BS spiked soil and inoculated with BDAM. Inoculation showed a beneficial effect on plant biomass production and degradation of BS in the rhizosphere and the rhizosheath. After 40 and 60 days of inoculation, the degradation of BS was more than 96% and approximately 100% respectively in the planted and inoculated soil spiked with 2 and 5 mg kg BS. However, in planted and un-inoculated soil, the degradation of BS was 72% after 60 days of sowing. Furthermore, inoculated bacterial strains colonized both in rhizo- and endosphere of the inoculated plants. In comparison with the un-inoculated soil, significantly less accumulation of BS was found in the roots and shoots of the plants growing in inoculated soil. We report the efficiency of plant-bacterial partnership for enhanced biodegradation of BS and to eliminate the BS residual toxicity to non-target plants.
Topics: Achromobacter; Achromobacter denitrificans; Bacteria; Benzoates; Biodegradation, Environmental; Biomass; Herbicides; Microbial Consortia; Ochrobactrum; Plant Roots; Pyrimidines; Rhizosphere; Soil; Soil Microbiology; Soil Pollutants; Triticum
PubMed: 30978631
DOI: 10.1016/j.jhazmat.2019.03.130 -
Microbiological Research Apr 2015The aim of this work was to clarify the mechanism related to plant growth promoting of a bacterial strain (L115) isolated from Arachis hypogaea rhizospheres and the...
The aim of this work was to clarify the mechanism related to plant growth promoting of a bacterial strain (L115) isolated from Arachis hypogaea rhizospheres and the effects of high growth temperature and salinity on phospholipids and fatty acids composition. L115 was isolated from peanut rhizospheres and identified according to the sequence analysis of the 16S rRNA gene. Phenotypic, metabolic and plant growth promoting rhizobacteria (PGPR) characteristics of L115 were tested. Inoculation test in plant growth chamber was performed. In addition, L115 was exposed to a 37 °C and 300 mM NaCl and phospholipids and fatty acid composition were evaluated. L115 strain was identified as Ochrobactrum intermedium and was able to increase the peanut shoot and root length as well as dry weight, indicating a PGPR role by being able to produce indole acetic acid and siderophores and present ACC deaminase activity. In addition, L115 showed tolerance to both high growth temperature and 300 mM NaCl. The most striking change was a decreased percentage of 18:1 fatty acid and an increase in 16:0 and 18:0 fatty acids, under high growth temperature or a combination of increased temperature and salinity. The most important change in phospholipid levels was an increase in phosphatidylcholine biosynthesis in all growth conditions. L115 can promote the growth of peanut and can tolerate high growth temperature and salinity modifying the fatty acid unsaturation degree and increasing phosphatidylcholine levels. This work is the first to report the importance of the genus Ochrobactrum as PGPR on peanut growth as well as on the metabolic behaviour against abiotic stresses that occur in soil. This knowledge will be useful for developing strategies to improve the growth of this bacterium under stress and to enhance its bioprocess for the production of inoculants.
Topics: Arachis; Argentina; Indoleacetic Acids; Lipid Metabolism; Lipids; Molecular Sequence Data; Ochrobactrum; Phylogeny; Rhizosphere; Salinity; Sodium Chloride; Soil; Soil Microbiology; Temperature
PubMed: 25801965
DOI: 10.1016/j.micres.2014.12.012 -
Veterinary Immunology and... Jan 2015Current serological tests for swine brucellosis detect antibodies to the Brucella O-polysaccharide (O/PS). However, when infections by bacteria carrying cross-reacting...
Current serological tests for swine brucellosis detect antibodies to the Brucella O-polysaccharide (O/PS). However, when infections by bacteria carrying cross-reacting O/PS occur, these tests suffer from false positive serological reactions (FPSR), and the skin test with Brucella soluble protein extracts is the best diagnostic alternative to differentiate true Brucella suis infections from FPSR in pigs. Since this test has been seldom used in B. suis infected swine, the clinical and histological features involved have not been described properly. Here, we describe the clinical and histological events in B. suis biovar 2 infected pigs skin tested with a cytosoluble O/PS free protein extract from rough Brucella abortus Tn5::per mutant. A similar extract from rough Ochrobactrum intermedium was also used for comparative purposes. No relevant differences were evidenced between the homologous and heterologous allergens, and the main clinical feature was an elevated area of the skin showing different induration degrees. Moreover, an important vascular reaction with hyperemia and haemorrhage was produced in most infected sows 24-48 h after inoculation, thus facilitating the clinical interpretation of positive reactions. Histologically, combined immediate (type III) and delayed (type IV) hypersensitivity reactions were identified as the most relevant feature of the inflammatory responses produced.
Topics: Animals; Antigens, Bacterial; Brucella abortus; Brucella suis; Brucellosis; Cross Reactions; False Positive Reactions; Female; Gram-Negative Bacterial Infections; Ochrobactrum; Skin; Skin Tests; Swine; Swine Diseases
PubMed: 25480681
DOI: 10.1016/j.vetimm.2014.11.009 -
The Science of the Total Environment Apr 2017The presence of bacteria and heavy metals in atmospheric deposition were investigated in Kandy, Sri Lanka, which is a typical city in the developing world with...
The presence of bacteria and heavy metals in atmospheric deposition were investigated in Kandy, Sri Lanka, which is a typical city in the developing world with significant traffic congestion. Atmospheric deposition samples were analyzed for Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb which are heavy metals common to urban environments. Al and Fe were found in high concentrations due to the presence of natural sources, but may also be re-suspended by vehicular traffic. Relatively high concentrations of toxic metals such as Cr and Pb in dissolved form were also found. High Zn loads can be attributed to vehicular emissions and the wide use of Zn coated roofing materials. The metal loads in wet deposition showed higher concentrations compared to dry deposition. The metal concentrations among the different sampling sites significantly differ from each other depending on the traffic conditions. Industrial activities are not significant in Kandy City. Consequently, the traffic exerts high influence on heavy metal loadings. As part of the bacterial investigations, nine species of culturable bacteria, namely; Sphingomonas sp., Pseudomonas aeruginosa, Pseudomonas monteilii, Klebsiella pneumonia, Ochrobactrum intermedium, Leclercia adecarboxylata, Exiguobacterium sp., Bacillus pumilus and Kocuria kristinae, which are opportunistic pathogens, were identified. This is the first time Pseudomonas monteilii and Ochrobactrum intermedium has been reported from a country in Asia. The culturable fraction constituted ~0.01 to 10%. Pigmented bacteria and endospore forming bacteria were copious in the atmospheric depositions due to their capability to withstand harsh environmental conditions. The presence of pathogenic bacteria and heavy metals creates potential human and ecosystem health risk.
Topics: Air Microbiology; Air Pollutants; Bacteria; Cities; Developing Countries; Environmental Monitoring; Humans; Metals, Heavy; Sri Lanka
PubMed: 28185730
DOI: 10.1016/j.scitotenv.2017.01.121 -
PloS One 2014To provide a basis for using indigenous bacteria for bioremediation of heavy metal contaminated soil, the heavy metal resistance and plant growth-promoting activity of...
To provide a basis for using indigenous bacteria for bioremediation of heavy metal contaminated soil, the heavy metal resistance and plant growth-promoting activity of 136 isolates from V-Ti magnetite mine tailing soil were systematically analyzed. Among the 13 identified bacterial genera, the most abundant genus was Bacillus (79 isolates) out of which 32 represented B. subtilis and 14 B. pumilus, followed by Rhizobium sp. (29 isolates) and Ochrobactrum intermedium (13 isolates). Altogether 93 isolates tolerated the highest concentration (1000 mg kg(-1)) of at least one of the six tested heavy metals. Five strains were tolerant against all the tested heavy metals, 71 strains tolerated 1,000 mg kg(-1) cadmium whereas only one strain tolerated 1,000 mg kg(-1) cobalt. Altogether 67% of the bacteria produced indoleacetic acid (IAA), a plant growth-promoting phytohormone. The concentration of IAA produced by 53 isolates was higher than 20 µg ml(-1). In total 21% of the bacteria produced siderophore (5.50-167.67 µg ml(-1)) with two Bacillus sp. producing more than 100 µg ml(-1). Eighteen isolates produced both IAA and siderophore. The results suggested that the indigenous bacteria in the soil have beneficial characteristics for remediating the contaminated mine tailing soil.
Topics: Bacillus; Bacteria; Metals, Heavy; Mining; Ochrobactrum; Plant Development; Rhizobium; Siderophores; Soil Microbiology
PubMed: 25188470
DOI: 10.1371/journal.pone.0106618 -
Zoonoses and Public Health Sep 2020Increase in the number of small-scale backyard poultry flocks in the USA has substantially increased human-to-live poultry contact, leading to increased public health...
The occurrence of Salmonella, extended-spectrum β-lactamase producing Escherichia coli and carbapenem resistant non-fermenting Gram-negative bacteria in a backyard poultry flock environment.
Increase in the number of small-scale backyard poultry flocks in the USA has substantially increased human-to-live poultry contact, leading to increased public health risks of the transmission of multi-drug resistant (MDR) zoonotic and food-borne bacteria. The objective of this study was to detect the occurrence of Salmonella and MDR Gram-negative bacteria (GNB) in the backyard poultry flock environment. A total of 34 backyard poultry flocks in Washington State (WA) were sampled. From each flock, one composite coop sample and three drag swabs from nest floor, waterer-feeder, and a random site with visible faecal smearing, respectively, were collected. The samples were processed for isolation of Salmonella and other fermenting and non-fermenting GNB under ceftiofur selection. Each isolate was identified to species level using MALDI-TOFF and tested for resistance against 16 antibiotics belonging to eight antibiotic classes. Salmonella serovar 1,4,[5],12:i:- was isolated from one (3%) out of 34 flocks. Additionally, a total of 133 ceftiofur resistant (Cef ) GNB including Escherichia coli (53), Acinetobacter spp. (45), Pseudomonas spp. (22), Achromobacter spp. (8), Bordetella trematum (1), Hafnia alvei (1), Ochrobactrum intermedium (1), Raoultella ornithinolytica (1), and Stenotrophomonas maltophilia (1) were isolated. Of these, 110 (82%) isolates displayed MDR. Each flock was found positive for the presence of one or more Cef GNB. Several MDR E. coli (n = 15) were identified as extended-spectrum β-lactamase (ESBL) positive. Carbapenem resistance was detected in non-fermenting GNB including Acinetobacter spp. (n = 20), Pseudomonas spp. (n = 11) and Stenotrophomonas maltophila (n = 1). ESBL positive E. coli and carbapenem resistant non-fermenting GNB are widespread in the backyard poultry flock environment in WA State. These GNB are known to cause opportunistic infections, especially in immunocompromised hosts. Better understanding of the ecology and epidemiology of these GNB in the backyard poultry flock settings is needed to identify potential risks of transmission to people in proximity.
Topics: Aged; Animal Husbandry; Animals; Anti-Bacterial Agents; Carbapenems; Chickens; Child, Preschool; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Housing, Animal; Humans; Salmonella; Salmonella Infections, Animal; Surveys and Questionnaires; beta-Lactamases
PubMed: 32710700
DOI: 10.1111/zph.12756 -
Brazilian Journal of Microbiology :... 2014Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up....
Chromium pollution is produced in connection with industrial processes like in tanneries. It has been suggested that bioremediation could be a good option for clean up. The stress effect of variable chromate levels, pHs and growth temperatures on biochemical parameters of two Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 was investigated. Transmission electrone microscopy (TEM) was performed to study the intracellular distribution of Cr(VI). It was observed that initial stress of 1000 μgmL(-1) caused significant enhancement of all studied biochemical parameters at pH 7.0 and growth temperature of 37 °C showing great bioremediation potential of the strains. Transmission electron microscopy revealed that the distribution of chromium precipitates was not uniform as they were distributed in the cytoplasm as well as found associated with the periplasm and outer membrane. Fourier transform infrared spectroscopy showed the possible involvement of carboxyl, amino, sulpohonate and hydroxyl groups present on the bacterial cell surface for the binding of Cr(VI) ions. Cr(VI) stress brought about changes in the distridution of these functional groups. It can be concluded that the investigated bacterial strains adjust well to Cr(VI) stress in terms of biochemical parameters and along that exhibited alteration in morphology.
Topics: Chromium; Cytoplasm; Environmental Pollutants; Hydrogen-Ion Concentration; Microscopy, Electron, Transmission; Ochrobactrum; Oxidation-Reduction; Pseudomonas aeruginosa; Spectroscopy, Fourier Transform Infrared; Stress, Physiological; Surface Properties; Temperature
PubMed: 25242944
DOI: 10.1590/s1517-83822014000200028 -
Journal of Hazardous Materials May 2018Bispyribac sodium (BS), is a selective, systemic and post emergent herbicide used to eradicate grasses and broad leaf weeds. Extensive use of this herbicide has...
Bispyribac sodium (BS), is a selective, systemic and post emergent herbicide used to eradicate grasses and broad leaf weeds. Extensive use of this herbicide has engendered serious environmental concerns. Hence it is important to develop strategies for bioremediation of BS in a cost effective and environment friendly way. In this study a bacterial consortium named BDAM, comprising three novel isolates Achromobacter xylosoxidans (BD1), Achromobacter pulmonis (BA2), and Ochrobactrum intermedium (BM2), was developed by virtue of its potential for degradation of BS. Different culture conditions (temperature, pH and inoculum size) were optimized for degradation of BS by the consortium BDAM and the mutual interactions of these parameters were analysed using a 2 full factorial central composite design (CCD) based on Response Surface Methodology (RSM). The optimal values for temperature, pH and inoculum size were found to be 40 °C, 8 and 0.4 g/L respectively to achieve maximum degradation of BS (85.6%). Moreover, the interactive effects of these parameters were investigated using three dimensional surface plots in terms of maximum fitness function. Importantly, it was concluded that the newly developed consortium is a potential candidate for biodegradation of BS in a safe, cost-effective and environmentally friendly manner.
Topics: Achromobacter; Benzoates; Biodegradation, Environmental; Herbicides; Microbial Consortia; Ochrobactrum; Pyrimidines; RNA, Ribosomal, 16S; Soil Pollutants
PubMed: 29438823
DOI: 10.1016/j.jhazmat.2017.12.065