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BioRxiv : the Preprint Server For... Oct 2023Previously, we discovered that a small RNA from a clinical isolate of PA14, induces learned avoidance and its transgenerational inheritance in . is an important human...
Previously, we discovered that a small RNA from a clinical isolate of PA14, induces learned avoidance and its transgenerational inheritance in . is an important human pathogen, and there are other in natural habitat, but it is unclear whether ever encounters PA14-like bacteria in the wild. Thus, it is not known if small RNAs from bacteria found in natural habitat can also regulate host behavior and produce heritable behavioral effects. Here we found that a pathogenic strain isolated from the microbiota, GRb0427, like PA14, regulates worm behavior: worms learn to avoid this pathogenic bacterium following exposure to GRb0427, and this learned avoidance is inherited for four generations. The learned response is entirely mediated by bacterially-produced small RNAs, which induce avoidance and transgenerational inheritance, providing further support that such mechanisms of learning and inheritance exist in the wild. Using bacterial small RNA sequencing, we identified Pv1, a small RNA from GRb0427, that matches the sequence of . We find that Pv1 is both necessary and sufficient to induce learned avoidance of Grb0427. However, Pv1 also results in avoidance of a beneficial microbiome strain, ; this potentially maladaptive response may favor reversal of the transgenerational memory after a few generations. Our findings suggest that bacterial small RNA-mediated regulation of host behavior and its transgenerational inheritance are functional in natural environment, and that different bacterial small RNA-mediated regulation systems evolved independently but define shared molecular features of bacterial small RNAs that produce transgenerationally-inherited effects.
PubMed: 37503135
DOI: 10.1101/2023.07.20.549962 -
Environmental Research Aug 2023Nitrogen (N) and phosphorous (P) removal by a single bacterium could improve the biological reaction efficiency and reduce the operating cost and complexity in...
Nitrogen (N) and phosphorous (P) removal by a single bacterium could improve the biological reaction efficiency and reduce the operating cost and complexity in wastewater treatment plants (WWTPs). Here, an isolated strain was identified as Pseudomonas mendocina SCZ-2 and showed high performance of heterotrophic nitrification (HN) and aerobic denitrification (AD) without intermediate accumulation. During the AD process, the nitrate removal efficiency and rate reached a maximum of 100% and 47.70 mg/L/h, respectively, under optimal conditions of sodium citrate as carbon source, a carbon-to-nitrogen ratio of 10, a temperature of 35 °C, and shaking a speed of 200 rpm. Most importantly, the strain SCZ-2 could rapidly and simultaneously eliminate N and P with maximum NH-N, NO-N, NO-N, and PO-P removal rates of 14.38, 17.77, 20.13 mg N/L/h, and 2.93 mg P/L/h, respectively. Both the N and P degradation curves matched well with the modified Gompertz model. Moreover, the amplification results of functional genes, whole genome sequencing, and enzyme activity tests provided theoretical support for simultaneous N and P removal pathways. This study deepens our understanding of the role of HN-AD bacteria and provides more options for simultaneous N and P removal from actual sewage.
Topics: Denitrification; Pseudomonas mendocina; Nitrogen; Aerobiosis; Nitrification; Phosphorus; Carbon; Nitrites
PubMed: 37149028
DOI: 10.1016/j.envres.2023.116062 -
Microbiology Spectrum Jun 2023Several variants of the plasmid-carried tigecycline resistance gene cluster, , have been identified. This study characterized another novel variant, , located on the...
Several variants of the plasmid-carried tigecycline resistance gene cluster, , have been identified. This study characterized another novel variant, , located on the chromosome of environmental-origin Pseudomonas mendocina. TMexC6D6-TOprJ1 mediates resistance to multiple drugs, including tigecycline. The promoter activity of and negative transcriptional repression by the upstream regulator tnfxB6 are crucial for the expression of . was found in the plasmids or chromosomes of different Pseudomonas species from six countries. Two genetic backgrounds, class 1 integrons and -carrying integrase units, were found adjacent to the gene cluster and might mediate the transfer of this novel efflux pump gene cluster in Pseudomonas. Further phylogenetic analysis revealed Pseudomonas as the major reservoir of variants, warranting closer monitoring in the future. Tigecycline is one of the treatment options for serious infections caused by multidrug-resistant bacteria, and tigecycline resistance has gained extensive attention. The emergence of a transferable tigecycline resistance efflux pump gene cluster, , severely challenged the efficiency of tigecycline. In this study, we identified another novel variant, , which could confer resistance to multiple classes of antibiotics, including tigecycline. Although was found only in Pseudomonas species, might spread to hosts via mobile genetic elements resembling those of other variants, compromising the therapeutic strategies. Meanwhile, novel transferable variants are constantly emerging and mostly exist in Pseudomonas spp., indicating Pseudomonas as the important hidden reservoir and origin of variants. Continuous monitoring and investigations of are urgent to control its spread.
Topics: Tigecycline; Pseudomonas; Phylogeny; Anti-Bacterial Agents; Plasmids; Microbial Sensitivity Tests
PubMed: 37067462
DOI: 10.1128/spectrum.00767-23 -
Bioresource Technology Jul 2023A highly efficient aerobic denitrifying microbe was isolated from sewage sludge by using a denitrifier enrichment strategy based on decreasing carbon content. The...
A highly efficient aerobic denitrifying microbe was isolated from sewage sludge by using a denitrifier enrichment strategy based on decreasing carbon content. The microbe was identified as Pseudomonas mendocina HITSZ-D1 (hereafter, D1). Investigation of the conditions under which D1 grew and denitrified revealed that it performed good growth and nitrate removal performance under a wide range of conditions. In particular, D1 rapidly removed all types of inorganic nitrogen without accumulation of the intermediate products nitrite and nitrous oxide. Overall, D1 showed a total nitrogen removal efficiency >96% at a C/N ratio of 8. The biotransformation modes and fates of three typical types of inorganic nitrogen were also assessed. Moreover, D1 had significantly higher denitrification efficiency and enzyme activities than other aerobic denitrifying microbes (Paracoccus denitrificans, Pseudomonas aeruginosa, and Pseudomonas putida). These results suggest that D1 has great potential for treating wastewater containing high concentrations of nitrogen.
Topics: Nitrites; Pseudomonas mendocina; Sewage; Denitrification; Nitrates; Nitrogen; Nitrification; Aerobiosis
PubMed: 37037332
DOI: 10.1016/j.biortech.2023.129039 -
Foods (Basel, Switzerland) Mar 2023Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk...
Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk for bacterial contamination. In the present study, the outer surface of imported freshwater fish were swabbed, cultured, confirmatory tests performed and antimicrobial patterns investigated. Channidae fish (Sp. A/n = 66) were contaminated with zoonotic sp./ (n = 1/66) and other bacteria implicated in cases of opportunistic human infection, these being sp. (including . and (n = 34/66)); sp. (n = 32/66); (n = 27/66) and (n = 3/66). Pangasiidae fish (Species B/n = 47) were contaminated with zoonotic (n = 10/47); sp. (n = 6/47) and environmental bacteria sp. (n = 3/47). One sample was resistant to all antimicrobials tested and is considered to be Methicillin Resistant . Mud, natural diet, or vegetation identified in Sp. A fish/or packaging were significantly associated with the presence of spp. The study also showed that visibly clean fish (Sp. B) may harbour zoonotic bacteria and that certain types of bacteria are common to fish groups, preparations, and contaminants. Further investigations are required to support the development of appropriate food safety recommendations in Australia.
PubMed: 36981215
DOI: 10.3390/foods12061288 -
Journal of Hazardous Materials May 2023Mass transfer limitation usually causes the poor performance of biotrickling filters (BTFs) for the treatment of hydrophobic volatile organic compounds (VOCs) during...
Mass transfer limitation usually causes the poor performance of biotrickling filters (BTFs) for the treatment of hydrophobic volatile organic compounds (VOCs) during long-term operation. In this study, two identical lab-scale BTFs were established to remove a mixture of n-hexane and dichloromethane (DCM) gases using non-ionic surfactant Tween 20 by Pseudomonas mendocina NX-1 and Methylobacterium rhodesianum H13. A low pressure drop (≤110 Pa) and a rapid biomass accumulation (17.1 mg g) were observed in the presence of Tween 20 during the startup period (30 d). The removal efficiency (RE) of n-hexane was enhanced by 15.0%- 20.5% while DCM was completely removed with the inlet concentration (IC) of 300 mg·m at different empty bed residence times in the Tween 20 added BTF. The viable cells and the relative hydrophobicity of the biofilm were increased under the action of Tween 20, which facilitated the mass transfer and enhanced the metabolic utilization of pollutants by microbes. Besides, Tween 20 addition enhanced the biofilm formation processes including the increased extracellular polymeric substance (EPS) secretion, biofilm roughness and biofilm adhesion. The kinetic model simulated the removal performance of the BTF with Tween 20 for the mixed hydrophobic VOCs, and the goodness-of-fit was above 0.9.
Topics: Bioreactors; Polysorbates; Volatile Organic Compounds; Kinetics; Extracellular Polymeric Substance Matrix; Air Pollutants; Filtration; Biofilms; Hydrophobic and Hydrophilic Interactions; Biodegradation, Environmental
PubMed: 36867905
DOI: 10.1016/j.jhazmat.2023.131063 -
Cornea Mar 2023The purpose of this study was to study the incidence, demographic features, clinical course, profiling, and management of uncommon species of Pseudomonas keratitis...
PURPOSE
The purpose of this study was to study the incidence, demographic features, clinical course, profiling, and management of uncommon species of Pseudomonas keratitis (other than Pseudomonas aeruginosa ) at a tertiary eye care center.
METHODS
Thirty cases of culture-proven uncommon species of Pseudomonas keratitis between January 2017 and December 2021 were retrospectively studied. The incidence, demographic and clinical profile, predisposing factors, microbial results, treatment, and visual outcomes were analyzed. We evaluated the risk factors for poor treatment outcomes.
RESULTS
Among bacterial keratitis cases, uncommon species of Pseudomonas keratitis occurred at a rate of 2.2%. The mean age at presentation was 51.37 years, and the most common predisposing factor was corneal trauma (36.7%). The mean best corrected visual acuity (BCVA) [in log of minimum angle of resolution (logMAR)] at presentation was 1.99, and the mean ulcer size was 5.75 mm. On culture, 56.7% of the cases were identified as Pseudomonas putida , 26.7% as Pseudomonas stutzeri , 10% as Pseudomonas mendocina, and 3.3% each of Pseudomonas oryzihabitans and Pseudomonas alcaligenes . We recorded good treatment responses in 66.7% of cases with the medical therapy of a combination of broad-spectrum antibiotics, whereas 33.3% of cases required surgical intervention. The risk factors for poor clinical outcome were older age, ocular trauma, previous ocular surgeries, poor BCVA at presentation, large ulcer size, delayed treatment, hypopyon, and early complications such as perforation, limbal involvement, and total ulcer.
CONCLUSIONS
Uncommon species of pseudomonas keratitis was more closely related to predisposing factors such as corneal trauma and other factors such as previous ocular surgeries, older age, large ulcers, longer duration of treatment, early surgical intervention in complicated cases, and poor visual outcome.
Topics: Humans; Retrospective Studies; Ulcer; Incidence; Keratitis; Anti-Bacterial Agents; Eye Infections, Bacterial; Risk Factors; Pseudomonas aeruginosa; Corneal Injuries; Corneal Ulcer
PubMed: 36729653
DOI: 10.1097/ICO.0000000000003194 -
Chemosphere Mar 2023The high hydrophobicity of n-hexane is the main reason why it is difficult to be removed biologically. In this study, the effects of bamboo-charcoal modified by...
The high hydrophobicity of n-hexane is the main reason why it is difficult to be removed biologically. In this study, the effects of bamboo-charcoal modified by bimetallic Fe/Pd (BBC) on n-hexane biodegradation by Pseudomonas mendocina NX-1 (PM) was investigated. The n-hexane removal efficiency was increased in the presence of BC. The highest n-hexane removal efficiency at 90.0% was achieved at 0.05 g L BCE and 3 g L NH under pH 7.7 and 35 °C. Additionally, protein content (45.9 μg mL) and negative cell surface zeta potential (-26.4 mV) were increased during biodegradation process, with PM-BBC being 43.1 μg mL and 19.1 mV. Bacterial growth was improved and maximum cell surface hydrophobicity was obtained after 20 h, which was 59.4% higher than the control with PM-BBC (37.7%) or PM (16.1%), showing biodegradation products of 1-butanol and acetic acid. The results indicate that BBC improved n-hexane biodegradation efficiency by promoting bacterial growth, reducing cell zeta potential, exposing hydrophobic proteins, and increasing cell surface hydrophobicity of bacterial strain NX-1. This investigation suggests that BBC-enhanced biodegradation can be promising to treat n-hexane-containing gas.
Topics: Pseudomonas mendocina; Charcoal; Biodegradation, Environmental; Hexanes
PubMed: 36657580
DOI: 10.1016/j.chemosphere.2023.137897 -
Chemistry (Weinheim An Der Bergstrasse,... Apr 2023Monooxygenases, an important class of enzymes, have been the subject of enzyme engineering due to their high activity and versatile substrate scope. Reactions performed...
Monooxygenases, an important class of enzymes, have been the subject of enzyme engineering due to their high activity and versatile substrate scope. Reactions performed by these biocatalysts have long been monitored by a colorimetric method involving the coupling of a dye precursor to naphthalene hydroxylation products generated by the enzyme. Despite the popularity of this method, we found the dye product to be unstable, preventing quantitative readout. By incorporating an extraction step to solubilize the dye produced, we have improved this assay to the point where quantitation of enzyme activity is possible. Further, by incorporating spectral deconvolution, we have, for the first time, enabled independent quantification of the two possible regioisomeric products: 1-naphthol and 2-naphthol. Previously, such analysis was only possible with chromatographic separation, increasing the cost and complexity of analysis. The efficacy of our improved workflow was evaluated by monitoring the activity of a toluene-4-monooxygenase enzyme from Pseudomonas mendocina KR-1. Our colorimetric regioisomer quantification was found to be consistent with chromatographic analysis by HPLC. The development and validation of a quantitative colorimetric assay for monooxygenase activity that enables regioisomeric distinction and quantification represents a significant advance in analytical methods to monitor enzyme activity. By maintaining facile, low-cost, high-throughput readout while incorporating quantification, this assay represents an important alternative to more expensive chromatographic quantification techniques.
Topics: Oxygenases; Mixed Function Oxygenases
PubMed: 36593585
DOI: 10.1002/chem.202203322 -
Frontiers in Bioengineering and... 2022Metformin is used globally to treat type II diabetes, has demonstrated anti-ageing and COVID mitigation effects and is a major anthropogenic pollutant to be...
Metformin is used globally to treat type II diabetes, has demonstrated anti-ageing and COVID mitigation effects and is a major anthropogenic pollutant to be bioremediated by wastewater treatment plants (WWTPs). Metformin is not adsorbed well by activated carbon and toxic N-chloro derivatives can form in chlorinated water. Most earlier studies on metformin biodegradation have used wastewater consortia and details of the genomes, relevant genes, metabolic products, and potential for horizontal gene transfer are lacking. Here, two metformin-biodegrading bacteria from a WWTP were isolated and their biodegradation characterized. sp. MET metabolized metformin stoichiometrically to guanylurea, an intermediate known to accumulate in some environments including WWTPs. MET completely metabolized metformin and utilized all the nitrogen atoms for growth. MET also metabolized metformin breakdown products sometimes observed in WWTPs: 1-N-methylbiguanide, biguanide, guanylurea, and guanidine. The genome of each bacterium was obtained. Genes involved in the transport of guanylurea in sp. MET were expressed heterologously and shown to serve as an antiporter to expel the toxic guanidinium compound. A novel guanylurea hydrolase enzyme was identified in MET, purified, and characterized. The and each contained one plasmid of 160 kb and 90 kb, respectively. In total, these studies are significant for the bioremediation of a major pollutant in WWTPs today.
PubMed: 36588930
DOI: 10.3389/fbioe.2022.1086261