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One Health (Amsterdam, Netherlands) Dec 2021In this study, a phylogenic analysis was performed on pathogens previously identified in Hong Kong wet markets' cutting boards. Phylogenetic comparisons were made...
In this study, a phylogenic analysis was performed on pathogens previously identified in Hong Kong wet markets' cutting boards. Phylogenetic comparisons were made between phylotypes obtained in this study and environmental and clinical phylotypes for establishing the possible origin of selected bacterial species isolated from wet market cutting board ecosystems. The results reveal a strong relationship between wet market bacterial assemblages and environmental and clinically relevant phylotypes. However, our poor knowledge of potential cross-contamination sources within these wet markets is further exacerbated by failing to determine the exact or presumed origin of its identified pathogens. In this study, several clinically relevant bacterial pathogens such as , and were linked to cutting boards associated with pork; , , , and in those associated with poultry; and , , , and in those associated with seafood. Identifying non-foodborne clinically relevant pathogens in wet market cutting boards in this study confirms the need for safety approaches for wet market meat, including cold storage. The presented study justifies the need for future systematic epidemiological studies to determine identified microbial pathogens. Such studies should bring about significant improvements in the management of hygienic practices in Hong Kong's wet markets and work towards a One Health goal by recognizing the importance of wet markets as areas interconnecting food processing with animal and clinical environments.
PubMed: 34409148
DOI: 10.1016/j.onehlt.2021.100300 -
ChemCatChem May 2021Pyridoxal 5'-phosphate (PLP)-dependent enzymes are a versatile class of biocatalysts and feature a variety of industrial applications. However, PLP is light sensitive...
Pyridoxal 5'-phosphate (PLP)-dependent enzymes are a versatile class of biocatalysts and feature a variety of industrial applications. However, PLP is light sensitive and can cause inactivation of enzymes in certain light conditions. As most of the PLP-dependent enzymes are usually not handled in dark conditions, we evaluated the effect of visible light on the activity of PLP-dependent enzymes during production as well as transformation. We tested four amine transaminases, from , , and a variant from as well as two lysine decarboxylases, from and the LDCc from . It appeared that five of these six enzymes suffered from a significant decrease in activity by up to 90 % when handled in laboratory light conditions. Surprisingly, only the amine transaminase variant from appeared to be unaffected by light exposure and even showed an activation to 150 % relative activity over the course of 6 h regardless of the light conditions.
PubMed: 34249169
DOI: 10.1002/cctc.202100163 -
Bioorganic & Medicinal Chemistry Aug 2021Apremilast is an important active pharmaceutical ingredient that relies on a resolution to produce the key chiral amine intermediate. To provide a new catalytic and...
Apremilast is an important active pharmaceutical ingredient that relies on a resolution to produce the key chiral amine intermediate. To provide a new catalytic and enzymatic process for Apremilast, we performed the directed evolution of the amine transaminase fromVibriofluvialis. Six rounds of evolution resulted in the VF-8M-E variant with > 400-fold increase specific activity over the wildtype enzyme. A homology model of VF-8M-E was built and a molecular docking study was performed to explain the increase in activity. The purified VF-8M-E was successfully applied to produce the key chiral amine intermediate in enantiopure form and 49% conversion via a kinetic resolution, representing a new enzymatic access towards Apremilast.
Topics: Amines; Biocatalysis; Kinetics; Molecular Structure; Thalidomide; Transaminases; Vibrio
PubMed: 34171757
DOI: 10.1016/j.bmc.2021.116271 -
Frontiers in Microbiology 2021Water resources contaminated with pathogenic species are usually a source of devastating infection outbreaks that have been a public health concern in both developed...
Water resources contaminated with pathogenic species are usually a source of devastating infection outbreaks that have been a public health concern in both developed and developing countries over the decades. The present study assessed the prevalence of six medically significant species in some water resources in Eastern Cape Province, South Africa for 12 months. We detected vibrios in all the 194 water samples analyzed using polymerase chain reaction (PCR). The prevalence of , , , , , and in freshwater samples was 34, 19, 9, 2, 3, and 2%, and that in brackish water samples was 44, 28, 10, 7, 46, and 51%, respectively. The population of the presumptive spp. isolated from freshwater (628) and brackish water (342) samples that were confirmed by PCR was 79% (497/628) and 85% (291/342), respectively. Twenty-two percent of the PCR-confirmed isolates from freshwater ( = 497) samples and 41% of the PCR-confirmed isolates from brackish water samples ( = 291) fall among the species of interest. The incidences of , , , , , and amidst these spp. of interest that were recovered from freshwater samples were 75, 14, 4, 6, 1, and 1%, whereas those from brackish water samples were 24, 7, 3, 3, 47, and 18%, respectively. Our observation during the study suggests pollution as the reason for the unusual isolation of medically important vibrios in winter. Correlation analysis revealed that temperature drives the frequency of isolation, whereas salinity drives the composition of the targeted species at our sampling sites. The finding of the study is of public health importance going by the usefulness of the water resources investigated. Although controlling and preventing most of the factors that contribute to the prevalence of medically important bacteria, such as species, at the sampling points might be difficult, regular monitoring for creating health risk awareness will go a long way to prevent possible -related infection outbreaks at the sampling sites and their immediate environment.
PubMed: 34149632
DOI: 10.3389/fmicb.2021.617703 -
Biochemical and Biophysical Research... Jun 2021V. cholerae, the causative agent of cholera epidemic, and V. fluvialis, the emerging foodborne pathogen, share highly homologous T6SS consisting of one large cluster...
V. cholerae, the causative agent of cholera epidemic, and V. fluvialis, the emerging foodborne pathogen, share highly homologous T6SS consisting of one large cluster and two small orphan or auxiliary clusters, and each of which was generally recognized as one operon. Here, we showed that the genes in each of the small clusters are organized into two transcriptional units. Specifically, the inner tube coding gene hcp/tssD is highly transcribed as one monocistron, while the tip component vgrG/tssI and its downstream effector and immunity genes are in one polycistron with very low transcriptional level. This conclusion is supported by qPCR analysis of mRNA abundance, reporter fusion analysis and transcriptional unit definition with RT-PCR analysis. Taking tssI2_a of V. fluvialis as an example, we further demonstrated that quorum sensing (QS) regulator HapR and global regulator IHF activate vgrG/tssI transcription by directly binding to its promoter region. Taken together, current studies deepen our understanding of T6SS system, highlighting its regulatory complexity during functional execution process.
Topics: Bacterial Proteins; Gene Expression Regulation, Bacterial; Humans; Quorum Sensing; Transcriptional Activation; Type VI Secretion Systems; Vibrio; Vibrio Infections; Vibrio cholerae
PubMed: 33932896
DOI: 10.1016/j.bbrc.2021.04.092 -
Frontiers in Microbiology 2021Bacterial pathogens are a major cause of infectious diseases in aquatic animals. The abuse of antibiotics in the aquatic industry has led to the proliferation of...
Bacterial pathogens are a major cause of infectious diseases in aquatic animals. The abuse of antibiotics in the aquatic industry has led to the proliferation of antibiotic resistance. It is therefore essential to develop more effective and safer strategies to increase the efficacy and extend the life span of the antibiotics used in aquaculture. In this study, we show that six aquaculture bacterial pathogens (i.e., , , , , , and ) in the stationary phase can be rapidly killed after immersion in gentamicin- or neomycin-containing, ion-free solutions for a few minutes. Such hypoionic shock treatment enhances the bacterial uptake of gentamicin in an ATP-dependent manner. Importantly, we demonstrate, as a proof of concept, that gentamicin under hypoionic shock conditions can effectively kill in a skin infection model of zebrafish (), completely curing the infected fish. Given that pathogenic bacteria generally adhere to the skin surface and gills of aquatic animals, our strategy is of potential significance for bacterial infection control, especially for small-scale economic fish farming and ornamental fish farming. Further, the combined treatment can be completed within 5 min with a relatively small volume of solution, thus minimizing the amount of residual antibiotics in both animals and the environment.
PubMed: 33889141
DOI: 10.3389/fmicb.2021.641846 -
Archives of Microbiology Aug 2021Vibrio fluvialis is a halophilic bacterium frequently found in estuarine and coastal waters environments. The strain 362.3 was isolated from Mussismilia braziliensis...
Vibrio fluvialis is a halophilic bacterium frequently found in estuarine and coastal waters environments. The strain 362.3 was isolated from Mussismilia braziliensis coral of Abrolhos Bank. In this study, to gain insights into the marine adaptation in V. fluvialis, we sequenced the genome of 362.3 strain, which comprised 4,607,294 bp with a G + C content of 50.2%. In silico analysis showed that V. fluvialis 362.2 encodes genes related to chitin catabolic pathway, iron metabolism, osmotic stress and membrane transport.
Topics: Adaptation, Physiological; Animals; Anthozoa; Base Sequence; Genome, Bacterial; Phylogeny; Vibrio; Water Microbiology
PubMed: 33829291
DOI: 10.1007/s00203-021-02279-6 -
Journal of Applied Microbiology Oct 2021This study aimed to evaluate the in vitro cytotoxicity and efficacy of synthetic host defence peptides (HDPs), alone or in combination with florfenicol (FFC),...
AIMS
This study aimed to evaluate the in vitro cytotoxicity and efficacy of synthetic host defence peptides (HDPs), alone or in combination with florfenicol (FFC), oxytetracycline (OTC) or thiamphenicol (TAP), against different pathogenic bacteria isolated from diseased fish.
METHODS AND RESULTS
Solid-phase synthesis, purification and characterization of several HDPs were performed manually, using the fluorenylmethyloxycarbonyl protecting group in different resins and via high-performance liquid chromatography-mass spectrometry, respectively. The in vitro cytotoxicity and antimicrobial activity of HDPs, FFC, OTC and TAP against Nile tilapia red blood cells (RBCs) and relevant fish pathogenic bacteria (Aeromonas, Citrobacter, Edwardsiella, Streptococcus, Lactococcus and Vibrio) was determined using the haemolysis assay and broth microdilution method, respectively. The checkerboard assay was used to evaluate the synergy between the most active HDPs and other antimicrobials against the tested strains. MUC 7 12-mer, FFC, OTC and TAP were not cytotoxic to Nile tilapia RBCs, in all tested concentrations. LL-37, (p-BthTX-I) and Hylin-a1 were not cytotoxic at concentrations up to 78·13, 19·53 and 9·77 μg ml , respectively. HDPs demonstrated potent antimicrobial activity (minimum inhibitory concentration ≤31·25 µg ml ) against Aeromonas jandaei (KR-12-a5), Citrobacter freundii (Kr-12-a5; (p-BthTX-I) ; LL-37; and Hylin a1), Streptococcus agalactiae (Hylin a1; (p-BthTX-I) and LL-37), Lactococcus garviae (Hylin a1), and Vibrio fluvialis (KR-12-a5). The combinations of (p-BthTX-I) with TAP and LL-37 with FFC showed synergistic activity against C. freundii (fractional inhibitory concentration index of 0·25 and 0·50, respectively).
CONCLUSIONS
Synthetic HDPs have the potential as a good treatment option for bacterial diseases in aquaculture.
SIGNIFICANCE AND IMPACT OF THE STUDY
The in vivo effectiveness of synthetic HDPs such as KR-12-a5; LL-37; (p-BthTX-I) and Hylin a1 can be tested alone or in combination with conventional antimicrobials as a treatment option to reduce the use of antimicrobials in aquaculture.
Topics: Aeromonas; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antimicrobial Cationic Peptides; Cichlids; Fish Diseases; Lactococcus; Microbial Sensitivity Tests; Vibrio
PubMed: 33742508
DOI: 10.1111/jam.15080 -
Emerging Microbes & Infections Dec 2021is an emerging enteric pathogen of increasing public health threat. Two quorum sensing (QS) systems, VfqI-VfqR and CqsA/LuxS-HapR, and two type VI secretion systems...
is an emerging enteric pathogen of increasing public health threat. Two quorum sensing (QS) systems, VfqI-VfqR and CqsA/LuxS-HapR, and two type VI secretion systems (T6SSs), VflT6SS1 and VflT6SS2, have been identified in . Whether there exists any correlation between the two systems is unclear. In this study, we found that CqsA/LuxS-HapR circuit regulator LuxO represses while HapR activates VflT6SS2. The effect of LuxO is more pronounced at low cell density and is HapR-dependent. Deletion of abolished Hcp expression and alleviated antibacterial virulence. However, these effects were rescued by HapR-expressing plasmid. Reporter fusion analyses showed that HapR is required for the promoter activities of VflT6SS2. Sequence inspection of the major cluster promoter revealed two potential Motif 1 HapR binding sites, and their bindings to HapR were confirmed by both electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay. Meanwhile, two single Motif 2 sites were identified in 2_a (A) and 2_b (B) promoter regions of the orphan cluster which are less conserved and displayed lower affinities to HapR. Together, our study demonstrated that CqsA/LuxS-HapR QS manipulate VflT6SS2 in , and this finding will enhance our understanding of possible crosstalk between T6SS and QS in microbes.
Topics: Amino Acid Motifs; Bacterial Proteins; Binding Sites; DNA-Binding Proteins; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Mutation; Promoter Regions, Genetic; Quorum Sensing; RNA, Bacterial; Repressor Proteins; Trans-Activators; Type VI Secretion Systems; Vibrio; Virulence
PubMed: 33689580
DOI: 10.1080/22221751.2021.1902244 -
Probiotics and Antimicrobial Proteins Aug 2021Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides of approximately 100 amino acid residues with a broad spectrum of antimicrobial activity. It is an...
Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides of approximately 100 amino acid residues with a broad spectrum of antimicrobial activity. It is an amphipathic peptide with an N-terminal hydrophobic region and a lipopolysaccharide binding domain (LBD). In the present study, we report an isoform of the anti-lipopolysaccharide factor (Mm-ALF) from the speckled shrimp, Metapenaeus monoceros. A 359 bp cDNA encoded 119 amino acids, and the sequence showed 99.16% similarity to ALF from the shrimp Fenneropenaeus indicus. The mature peptide of 94 amino acids has a net charge of +8, molecular weight 10.62 kDa, and pI 10.11. The mature peptide Mm-ALF was recombinantly expressed in E. coli Rosetta-gami cells, and the peptide was isolated and purified. The rMm-ALF exhibited notable antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Escherichia coli, Edwardsiella tarda, Aeromonas hydrophila, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio proteolyticus, Vibrio cholerae and Vibrio fluvialis) bacteria.
Topics: Amino Acids; Animals; Antimicrobial Peptides; Gram-Negative Bacteria; Gram-Positive Bacteria; Lipopolysaccharides; Penaeidae
PubMed: 33569748
DOI: 10.1007/s12602-021-09741-3