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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 -
Access Microbiology 2022spp. are Gram-negative bacteria found in marine ecosystems. Non-cholera spp. can cause gastrointestinal infections and can also lead to wound infections through...
spp. are Gram-negative bacteria found in marine ecosystems. Non-cholera spp. can cause gastrointestinal infections and can also lead to wound infections through exposure to contaminated seawater. infections are increasingly documented from the Baltic Sea due to extended warm weather periods. We describe the first isolation of from a wound infection acquired by an impalement injury in the shallow waters of the Baltic Sea. The severe infection required amputation of the third toe. Whole genome sequencing of the isolate was performed and revealed a genome consisting of two circular chromosomes with a size of 1.57 and 3.24 Mb.
PubMed: 35252751
DOI: 10.1099/acmi.0.000312 -
Journal of Global Antimicrobial... Dec 2023
Topics: Genomic Islands; Salmonella; beta-Lactamases
PubMed: 37748579
DOI: 10.1016/j.jgar.2023.09.014 -
Journal of Dairy Science Jan 2023Composting is a common practice used for treating animal manures before they are used as organic fertilizers for crop production. Whether composting can effectively...
Composting is a common practice used for treating animal manures before they are used as organic fertilizers for crop production. Whether composting can effectively reduce microbial pathogens and antibiotic resistance genes remain poorly understood. In this study, we compared 3 different dairy manure composting methods-anaerobic fermentation (AF), static compost (SC), and organic fertilizer production (OFP)-for their effects on antibiotic-resistant bacteria, antibiotic resistance genes, and microbial community diversity in the treated manures. The 3 composting methods produced variable and distinct effects on antibiotic-resistant bacteria, zoonotic bacteria, and resistance genes, some of which were decreased and others of which showed no significant changes during composting. Particularly, SC and OFP reduced chloramphenicol resistance gene fexA and opportunistic pathogen Vibrio fluvialis, whereas AF significantly reduced tetracycline resistance gene tetB and opportunistic pathogens Enterococcus faecium and Escherichia fergusonii. The compositions of microbial communities varied significantly during the composting processes, and there were significant differences between the 3 composting methods. In all 3 composts, the dominant phyla were Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria. Interestingly, Firmicutes, Proteobacteria, and Bacteroidetes remained stable in the entire AF process, whereas they were dominated at the beginning, decreased at the early stage of composting, and rebounded at the later stage during SC and OFP. In general, SC and OFP produced a more profound effect than AF on microbial community diversities, pathogens, and dominant species. Additionally, Enterococcus aquimarinus was isolated from AF for the first time. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States function prediction analysis indicated that the genes related to membrane transport and amino acid metabolism were abundant in the 3 composts. The metabolism of amino acids, lipids, and carbohydrates increased as composting progressed. The biosynthesis of antibiotics was enhanced after fermentation in the 3 composting methods, and the increase in the SC was the most obvious. These results reveal dynamic changes in antibiotic-resistant bacteria, antibiotic resistance genes, microbial community composition, and function succession in different dairy manure composts and provide useful information for further optimization of composting practices.
Topics: Cattle; Animals; Composting; Manure; Anti-Bacterial Agents; Phylogeny; Soil Microbiology; Drug Resistance, Microbial; Bacteria; Genes, Bacterial; Soil
PubMed: 36333143
DOI: 10.3168/jds.2022-22193 -
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 -
Biochemistry Feb 2024Globin-coupled sensors constitute an important family of heme-based gas sensors, an emerging class of heme proteins. In this study, we have identified and characterized...
Globin-coupled sensors constitute an important family of heme-based gas sensors, an emerging class of heme proteins. In this study, we have identified and characterized a globin-coupled sensor phosphodiesterase containing an HD-GYP domain (GCS-HD-GYP) from the human pathogen , which is an emerging foodborne pathogen of increasing public health concern. The amino acid sequence encoded by the gene from indicated the presence of an N-terminal globin domain and a C-terminal HD-GYP domain, with HD-GYP domains shown previously to display phosphodiesterase activity toward bis(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP), a bacterial second messenger that regulates numerous important physiological functions in bacteria, including in bacterial pathogens. Optical absorption spectral properties of GCS-HD-GYP were found to be similar to those of myoglobin and hemoglobin and of other bacterial globin-coupled sensors. The binding of O to the Fe(II) heme iron complex of GCS-HD-GYP promoted the catalysis of the hydrolysis of c-di-GMP to its linearized product, 5'-phosphoguanylyl-(3',5')-guanosine (pGpG), whereas CO and NO binding did not enhance the catalysis, indicating a strict discrimination of these gaseous ligands. These results shed new light on the molecular mechanism of gas-selective catalytic regulation by globin-coupled sensors, with these advances apt to lead to a better understanding of the family of globin-coupled sensors, a still growing family of heme-based gas sensors. In addition, given the importance of c-di-GMP in infection and virulence, our results suggested that GCS-HD-GYP could play an important role in the ability of to sense O and NO in the context of host-pathogen interactions.
Topics: Humans; Phosphoric Diester Hydrolases; Globins; Bacterial Proteins; Catalysis; Cyclic GMP; Heme; Vibrio
PubMed: 38264987
DOI: 10.1021/acs.biochem.3c00484 -
Journal of Chemical Information and... Nov 2021ω-Transaminases (ω-TAs) catalyze the conversion of ketones to chiral amines, often with high enantioselectivity and specificity, which makes them attractive for...
ω-Transaminases (ω-TAs) catalyze the conversion of ketones to chiral amines, often with high enantioselectivity and specificity, which makes them attractive for industrial production of chiral amines. Tailoring ω-TAs to accept non-natural substrates is necessary because of their limited substrate range. We present a computational protocol for predicting the enantioselectivity and catalytic selectivity of an ω-TA from with different substrates and benchmark it against 62 compounds gathered from the literature. Rosetta-generated complexes containing an external aldimine intermediate of the transamination reaction are used as starting conformations for multiple short independent molecular dynamics (MD) simulations. The combination of molecular docking and MD simulations ensures sufficient and accurate sampling of the relevant conformational space. Based on the frequency of near-attack conformations observed during the MD trajectories, enantioselectivities can be quantitatively predicted. The predicted enantioselectivities are in agreement with a benchmark dataset of experimentally determined % values. The substrate-range predictions can be based on the docking score of the external aldimine intermediate. The low computational cost required to run the presented framework makes it feasible for use in enzyme design to screen thousands of enzyme variants.
Topics: Molecular Docking Simulation; Molecular Dynamics Simulation; Substrate Specificity; Transaminases; Vibrio
PubMed: 34653331
DOI: 10.1021/acs.jcim.1c00617 -
Engineering in Life Sciences Oct 2019The increasing demand for freshwater and the continued depletion of available resources has led to a deepening global water crisis. Significant water consumption...
The increasing demand for freshwater and the continued depletion of available resources has led to a deepening global water crisis. Significant water consumption required by many biotechnological processes contributes to both the environmental and economic cost of this problem. Relatively few biocatalytic processes have been developed to utilize the more abundant supply of seawater, with seawater composition and salinity limiting its use with many mesophilic enzymes. We recently reported a salt tolerant ω-transaminase enzyme, Ad2-TAm, isolated from the genome of a halophilic bacterium, sp. CSM-2, from a Triassic period salt mine. In this study we aimed to demonstrate its applicability to biocatalytic reactions carried out in a seawater-based medium. Ad2-TAm was examined for its ability to aminate the industrially relevant substrate, furfural, in both seawater and freshwater-based reaction systems. Furfural was aminated with 53.6% conversion in a buffered seawater system, displaying improved function versus freshwater. Ad2-TAm outperformed the commonly employed commercial ω-TAms from and , both of which showed decreased conversion in seawater. Given the increasingly precarious availability of global freshwater, such applications of enzymes from halophiles have the ability to reduce demand for freshwater in large-scale industrial processes, delivering considerable environmental and economic benefits.
PubMed: 32624965
DOI: 10.1002/elsc.201900053 -
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 -
Antibiotics (Basel, Switzerland) Feb 2021Cyadox has potential use as an antimicrobial agent in animals. However, its pharmacodynamic properties have not been systematically studied yet. In this study, the in...
Cyadox has potential use as an antimicrobial agent in animals. However, its pharmacodynamic properties have not been systematically studied yet. In this study, the in vitro antibacterial activities of cyadox were assayed, and the antibacterial efficacy of cyadox against facultative anaerobes was also determined under anaerobic conditions. It was shown that and (MIC = 0.25 and 1 μg/mL) from pigs, and from poultry, , spp., and from fish were highly susceptible to cyadox (MIC= 1 and 8 μg/mL). However, has no killing effect for drug tolerance. Under in vitro anaerobic conditions, the antibacterial activity of cyadox against most facultative anaerobes was considerably enhanced Under anaerobic conditions for the facultative anaerobes, susceptible bacteria were , . (including , , , , and , excluding ), , spp. (including , , and ), , , , , , and (MICs were 0.25~8 μg/mL, MBCs were 1-64 μg/mL). Intermediate bacteria were spp. (including and ), , and spp. (MICs mainly were 8~32 μg/mL, MBCs were 16~128 μg/mL). This study firstly showed that cyadox had strong antibacterial activity and had the potential to be used as a single drug in the treatment of bacterial infectious diseases.
PubMed: 33546407
DOI: 10.3390/antibiotics10020153