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BMC Infectious Diseases Feb 2024Pseudomonas nitroreducens is a non-fermenting, gram-negative, rod-shaped bacterium commonly inhabiting soil, particularly soil contaminated with oil brine. To our...
BACKGROUND
Pseudomonas nitroreducens is a non-fermenting, gram-negative, rod-shaped bacterium commonly inhabiting soil, particularly soil contaminated with oil brine. To our knowledge, no cases of human infection with P. nitroreducens have been previously reported. Here, we present the first documented case of cholangitis caused by P. nitroreducens in a patient with bacteremia.
CASE PRESENTATION
A 46-year-old Japanese man with an advanced pancreatic neuroendocrine tumor was hospitalized with fever and chills. Four days before admission, the patient developed right upper abdominal pain. Two days later, he also experienced fever and chills. Endoscopic retrograde cholangiopancreatography was performed on the day of admission, and the patient was diagnosed as having cholangitis associated with stent dysfunction. Gram-negative rods were isolated from blood cultures, but attempts to identify the bacteria using VITEK2 and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with VITEK MS ver. 4.7.1 (bioMérieux Japan Co. Ltd., Tokyo, Japan) were unsuccessful. Finally, the organism was identified as P. nitroreducens using MALDI-TOF MS with a MALDI Biotyper (Bruker Daltonics Co., Ltd., Billerica, MA, USA) and 16 S ribosomal RNA sequencing. Despite thorough interviews with the patient, he denied any exposure to contaminated soil. The patient was treated with intravenous cefepime and oral ciprofloxacin for 16 days based on susceptibility results, achieving a good therapeutic outcome. At the outpatient follow-up on day 28, the patient was in good general condition.
CONCLUSIONS
This is the first reported human case of cholangitis with bloodstream infection caused by P. nitroreducens. This report provides clinicians with novel insights into the clinical manifestations and diagnostic methods necessary for the accurate diagnosis of P. nitroreducens, along with guidance on treatment.
Topics: Male; Humans; Middle Aged; Neuroendocrine Tumors; Bacteremia; Bacteria; Pseudomonas; Bacteria, Aerobic; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Cholangitis; Soil; Pancreatic Neoplasms
PubMed: 38336644
DOI: 10.1186/s12879-024-09092-8 -
ISME Communications Sep 2023Food safety of leafy greens is an emerging public health issue as they can harbor opportunistic human pathogens (OHPs) and expose OHPs to consumers. Protists are an...
Food safety of leafy greens is an emerging public health issue as they can harbor opportunistic human pathogens (OHPs) and expose OHPs to consumers. Protists are an integral part of phyllosphere microbial ecosystems. However, our understanding of protist-pathogen associations in the phyllosphere and their consequences on public health remains poor. Here, we examined phyllosphere protists, human pathogen marker genes (HPMGs), and protist endosymbionts from four species of leafy greens from major supermarkets in Xiamen, China. Our results showed that Staphylococcus aureus and Klebsiella pneumoniae were the dominant human pathogens in the vegetable phyllosphere. The distribution of HPMGs and protistan communities differed between vegetable species, of which Chinese chive possessed the most diverse protists and highest abundance of HPMGs. HPMGs abundance positively correlated with the diversity and relative abundance of phagotrophic protists. Whole genome sequencing further uncovered that most isolated phyllosphere protists harbored multiple OHPs which carried antibiotic resistance genes, virulence factors, and metal resistance genes and had the potential to HGT. Colpoda were identified as key phagotrophic protists which positively linked to OHPs and carried diverse resistance and virulence potential endosymbiont OHPs including Pseudomonas nitroreducens, Achromobacter xylosoxidans, and Stenotrophomonas maltophilia. We highlight that phyllosphere protists contribute to the transmission of resistant OHPs through internalization and thus pose risks to the food safety of leafy greens and human health. Our study provides insights into the protist-OHP interactions in the phyllosphere, which will help in food safety surveillance and human health.
PubMed: 37660098
DOI: 10.1038/s43705-023-00302-z -
Heliyon Jun 2023Polystyrene is a plastic that leads to environmental pollution. In particular, expanded polystyrene is very light and takes up much space, causing additional...
OBJECTIVES
Polystyrene is a plastic that leads to environmental pollution. In particular, expanded polystyrene is very light and takes up much space, causing additional environmental problems. The aim of this study was to isolate new symbiotic bacteria which degraded polystyrene from mealworms.
METHODS
The population of polystyrene degrading bacteria was increased by enrichment culture of intestinal bacteria from mealworms with polystyrene as a sole carbon source. The degradation activity of isolated bacteria was evaluated by morphological change of micro-polystyrene particles and the surface change of polystyrene films.
RESULTS
Eight isolated species (, , , , , , , and ) were identified that degrade polystyrene.
CONCLUSION
Bacterial identification shows that a broad spectrum of bacteria decomposing polystyrene coexists in the intestinal tract of mealworms.
PubMed: 37426801
DOI: 10.1016/j.heliyon.2023.e17352 -
Frontiers in Microbiology 2023The root-knot nematodes (RKN), especially spp., are globally emerging harmful animals for many agricultural crops.
INTRODUCTION
The root-knot nematodes (RKN), especially spp., are globally emerging harmful animals for many agricultural crops.
METHODS
To explore microbial agents for biological control of these nematodes, the microbial communities of the rhizosphere soils and roots of sponge gourd () infected and non-infected by nematodes, were investigated using culture-dependent and -independent methods.
RESULTS
Thirty-two culturable bacterial and eight fungal species, along with 10,561 bacterial and 2,427 fungal operational taxonomic units (OTUs), were identified. Nine culturable bacterial species, 955 bacterial and 701 fungal OTUs were shared in both four groups. More culturable bacterial and fungal isolates were detected from the uninfected soils and roots than from the infected soils and roots (except no fungi detected from the uninfected roots), and among all samples, nine bacterial species ( sp., sp., , Enterobacteriaceae sp., , sp., Micrococcaceae sp., Rhizobiaceae sp., and sp.) were shared, with sp. and sp. being dominant. was exclusively present in the infested soils, while , , and sp., together with , sp., , and sp. were found only in the uninfected soils. , sp., , and sp. were only in the uninfected roots while sp. only in infected roots. After infestation, 319 bacterial OTUs (such as ) and 171 fungal OTUs (such as ) were increased in rhizosphere soils, while 181 bacterial OTUs (such as ) and 166 fungal OTUs (such as ) rose their abundance in plant roots. Meanwhile, much more decreased bacterial or fungal OTUs were identified from rhizosphere soils rather than from plant roots, exhibiting the protective effects of host plant on endophytes. Among the detected bacterial isolates, sp. TR27 was discovered to exhibit nematocidal activity, and , sp. P35, and to show repellent potentials for the second stage juveniles, which can be used to develop RKN bio-control agents.
DISCUSSION
These findings provided insights into the interactions among root-knot nematodes, host plants, and microorganisms, which will inspire explorations of novel nematicides.
PubMed: 37303801
DOI: 10.3389/fmicb.2023.1168179 -
RdmA Is a Key Regulator in Autoinduction of DSF Quorum Quenching in Pseudomonas nitroreducens HS-18.MBio Feb 2023Diffusible signal factor (DSF) represents a family of widely conserved quorum-sensing (QS) signals which regulate virulence factor production and pathogenicity in...
Diffusible signal factor (DSF) represents a family of widely conserved quorum-sensing (QS) signals which regulate virulence factor production and pathogenicity in numerous Gram-negative bacterial pathogens. We recently reported the identification of a highly potent DSF-quenching bacterial isolate, Pseudomonas nitroreducens HS-18, which contains an operon with four DSF-inducible genes, , or , that are responsible for degradation of DSF signals. However, the regulatory mechanisms that govern the response to DSF induction have not yet been characterized. In this study, we identified a novel transcriptional regulator we designated RdmA (regulator of DSF metabolism) which negatively regulates the expression of and represses DSF degradation. In addition, we found that a gene cluster located adjacent to was also negatively regulated by RdmA and played a key role in DSF degradation; this cluster was hence named (DSF metabolism genes). An electrophoretic mobility shift assay and genetic analysis showed that RdmA represses the transcriptional expression of the genes in a direct manner. Further studies demonstrated that DSF acts as an antagonist and binds to RdmA, which abrogates RdmA binding to the target promoter and its suppression on transcriptional expression of the genes. Taken together, the results from this study have unveiled a central regulator and a gene cluster associated with the autoinduction of DSF degradation in HS-18, and this will aid in the understanding of the genetic basis and regulatory mechanisms that govern the quorum-quenching activity of this potent biocontrol agent. DSF family quorum-sensing (QS) signals play important roles in regulation of bacterial physiology and virulence in a wide range of plant and human bacterial pathogens. Quorum quenching (QQ), which acts by either degrading QS signals or blocking QS communication, has proven to be a potent disease control strategy, but QQ mechanisms that target DSF family signals and associated regulatory mechanisms remain largely unknown. Recently, we identified four autoinduced DSF degradation genes () in HS-18. By using a combination of transcriptome and genetic analysis, we identified a central regulator that plays a key role in autoinduction of expression, as well as a new gene cluster () involved in DSF degradation. The significance of our study is in unveiling the autoinduction mechanism that governs DSF signal quorum quenching for the first time, to our knowledge, and in identification of new genes and enzymes responsible for DSF degradation. The findings from this study shed new light on our understanding of the DSF metabolism pathway and the regulatory mechanisms that modulate DSF quorum quenching and will provide useful clues for design and development of a new generation of highly potent QQ biocontrol agents against DSF-mediated bacterial infections.
Topics: Humans; Quorum Sensing; Pseudomonas; Virulence; Virulence Factors; Bacterial Proteins
PubMed: 36537811
DOI: 10.1128/mbio.03010-22 -
International Journal of Molecular... Nov 2022The B12-producing strains DSM 1650 and sp. CCUG 2519 (both formerly ), with the most distributed pathway among bacteria for exogenous choline/betaine utilization, are...
The B12-producing strains DSM 1650 and sp. CCUG 2519 (both formerly ), with the most distributed pathway among bacteria for exogenous choline/betaine utilization, are promising recombinant hosts for the endogenous production of B12 precursor betaine by direct methylation of bioavailable glycine or non-proteinogenic -alanine. Two plasmid-based de novo betaine pathways, distinguished by their enzymes, have provided an expression of the genes encoding for -methyltransferases of the halotolerant cyanobacterium or plant to synthesize the internal glycine betaine or -alanine betaine, respectively. These betaines equally allowed the recombinant pseudomonads to grow effectively and to synthesize a high level of cobalamin, as well as to increase their protective properties against abiotic stresses to a degree comparable with the supplementation of an exogenous betaine. Both de novo betaine pathways significantly enforced the protection of bacterial cells against lowering temperature to 15 °C and increasing salinity to 400 mM of NaCl. However, the expression of the single plant-derived gene for the -alanine-specific -methyltransferase additionally increased the effectiveness of exogenous glycine betaine almost twofold on cobalamin biosynthesis, probably due to the ' ability to use two independent pathways, their own choline/betaine pathway and the plant -alanine betaine biosynthetic pathway.
Topics: Betaine; Choline; Pseudomonas; Stress, Physiological; Methyltransferases; beta-Alanine; Vitamin B 12
PubMed: 36430408
DOI: 10.3390/ijms232213934 -
Frontiers in Microbiology 2022Electrified biotrickling filters represent sustainable microbial electrochemical technology for treating organic carbon-deficient ammonium-contaminated waters. However,...
Electrified biotrickling filters represent sustainable microbial electrochemical technology for treating organic carbon-deficient ammonium-contaminated waters. However, information on the microbiome of the conductive granule bed cathode remains inexistent. For uncovering this black box and for identifying key process parameters, minimally invasive sampling units were introduced, allowing for the extraction of granules from different reactor layers during reactor operation. Sampled granules were analyzed using cyclic voltammetry and molecular biological tools. Two main redox sites [-288 ± 18 mV and -206 ± 21 mV vs. standard hydrogen electrode (SHE)] related to bioelectrochemical denitrification were identified, exhibiting high activity in a broad pH range (pH 6-10). A genome-centric analysis revealed a complex nitrogen food web and the presence of typical denitrifiers like and with none of these species being identified as electroactive microorganism so far. These are the first results to provide insights into microbial structure-function relationships within electrified biotrickling filters and underline the robustness and application potential of bioelectrochemical denitrification for environmental remediation.
PubMed: 35711746
DOI: 10.3389/fmicb.2022.869474 -
3 Biotech May 2022A novel glufosinate-tolerant sp. LA21, was isolated from soil samples of an oil palm plantation with a long history of glufosinate application. The genome of sp. LA21...
UNLABELLED
A novel glufosinate-tolerant sp. LA21, was isolated from soil samples of an oil palm plantation with a long history of glufosinate application. The genome of sp. LA21 was sequenced with 150 bp paired-end conducted using Illumina sequencing technology. De novo genome assembly was performed using SPAdes, ABySS, and Velvet assemblers. Phylogenetic analysis using 16S rRNA gene sequence showed that sp. LA21 was closely related to ATCC 33634. Multilocus sequence analysis (MLSA) based on four bacterial housekeeping genes (16S rRNA, , , and ) was conducted together with 138 reference genomes of species. The phylogenetic tree derived from MLSA analysis using concatenated 16S rRNA- sequences grouped sp. LA21 under group and subgroup. Detailed phylogenomic analysis using average nucleotide identity (ANI) and genome-to-genome distance calculator (GGDC) approaches showed that sp. LA21 could be classified as a novel species.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s13205-022-03185-4.
PubMed: 35547011
DOI: 10.1007/s13205-022-03185-4 -
Molecular Plant-microbe Interactions :... Apr 2022
Topics: Acyl-Butyrolactones; Pseudomonas; Quorum Sensing
PubMed: 35285671
DOI: 10.1094/MPMI-12-21-0310-A -
Chinese Medicine Nov 2021Codonopsis pilosula, an important medicinal plant, can accumulate certain metabolites under moderate drought stress. Endophytes are involved in the metabolite...
BACKGROUND
Codonopsis pilosula, an important medicinal plant, can accumulate certain metabolites under moderate drought stress. Endophytes are involved in the metabolite accumulations within medicinal plants. It is still unknown that the endophytes of C. pilosula are associated with the accumulations of metabolites. This study aims to investigate the promoting effect of endophytes on the accumulations of active substances in C. pilosula under drought stress.
METHODS
High-performance liquid chromatography and high-throughput sequencing technology were performed to investigate changes in the contents of secondary metabolite and endophyte abundances of C. pilosula under drought stress, respectively. Spearman's correlation analysis was further conducted to identify the endophytic biomarkers related to accumulations of pharmacodynamic compounds. Culture-dependent experiments were performed to confirm the functions of endophytes in metabolite accumulations.
RESULTS
The distribution of pharmacological components and diversity and composition of endophytes showed tissue specificity within C. pilosula. The contents of lobetyolin, syringin, and atractylolide III in C. pilosula under drought stress were increased by 8.47%‒86.47%, 28.78%‒230.98%, and 32.17%‒177.86%, respectively, in comparison with those in untreated groups. The Chao 1 and Shannon indices in different parts of drought-stressed C. pilosula increased compared with those in untreated parts. The composition of endophytic communities in drought treatment parts of C. pilosula was different from that in control parts. A total of 226 microbial taxa were identified as potential biomarkers, of which the abundances of 42 taxa were significantly and positively correlated to the pharmacodynamic contents. Culture-dependent experiments confirmed that the contents of lobetyolin and atractylolide III were increased by the application of Epicoccum thailandicum, Filobasidium magnum, and Paraphoma rhaphiolepidis at the rates of 11.12%‒46.02%, and that the content of syringin was increased by Pseudomonas nitroreducens at the rates of 118.61%‒119.36%.
CONCLUSIONS
Certain endophytes participated in the accumulations of bioactive metabolites, which provided a scientific evidence for the development and application of microorganisms to improve the quality of traditional Chinese medicine.
PubMed: 34809641
DOI: 10.1186/s13020-021-00533-z