Project description:Antimicrobial peptides (AMPs) constitute a broad range of bioactive compounds in diverse organisms, including fish. They are effector molecules for the innate immune response, against pathogens, tissue damage and infections. Still, AMPs from African Catfish, Clarias gariepinus skin mucus are largely unexplored despite their possible therapeutic role in combating antimicrobial resistance. In this study, African Catfish Antimicrobial peptides (ACAPs) were identified from the skin mucus of African Catfish, C. gariepinus. Native peptides were extracted from fish mucus scrapings in 10% acetic acid (v/v) and ultra-filtered using 5kDa molecular cut-off membrane. The extract was purified using C18 Solid Phase Extraction. The antibacterial activity was determined using the Agar Well Diffusion method and broth-dilution method utilizing Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). Thereafter, Sephadex G-25 gel filtration was further utilized in bio-guided isolation of the most active fractions prior to peptide identification using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The skin mucus extracted from African Catfish from all the three major lakes of Uganda exhibited antimicrobial activity on E. coli and S. aureus. Lake Albert’s C. gariepinus demonstrated the best activity with the lowest MIC of 2.84 µg/mL and 0.71 µg/mL on S. aureus and E. coli respectively. Sephadex G-25 peak I mass spectrometry analysis alongside in silico analysis revealed seven short peptides (11-15 amino acid residues) of high antimicrobial scores (0.561-0.905 units). In addition, these peptides had a low molecular weight (1005.57-1622.05 Da), and had percentage hydrophobicity above 54%. Up to four of these antimicrobial peptides demonstrated α-helix structure conformation, rendering them amphipathic. The findings of this study indicate that novel antimicrobial peptides can be sourced from the skin mucus of C. gariepinus. Such antimicrobial peptides are potential alternatives to the traditional antibiotics and can be of great application to food and pharmaceutical industries; however, further studies are still needed to establish their drug-likeness and safety profiles.
Project description:Antimicrobial peptides (AMPs) are garnering attention as possible alternatives to antibiotics. Here, we describe the antimicrobial properties of epinecidin-1 against multi-drug resistant clinical isolates of P. aeruginosa (P. aeruginosa (R)) and P. aeruginosa from ATCC (P. aeruginosa (19660)) in vivo. The minimum inhibitory concentrations (MICs) of epinecidin-1 against P. aeruginosa (R) and P. aeruginosa (19660) were determined, and compared with those of imipenem. Epinecidin-1 was found to be highly effective at combating peritonitis infection caused by P. aeruginosa (R) or P. aeruginosa (19660) in mouse models, without inducing adverse behavioral effects, or liver or kidney toxicity. Taken together, our results indicate that epinecidin-1 enhances the survival rate of mice infected with the bacterial pathogen P. aeruginosa through both antimicrobial and immunomodulatory effects. RNA from mice treated with epinecidin-1 were individually compared to RNA from PBS control mice.
Project description:Campylobacter spp. cause food-borne illnesses worldwide due to contaminated food and cross-contamination. This is at least partly the result of Campylobacter resistance in the food production chain, as modern food production facilitates the emergence and spread of resistance through intensive use of antimicrobials and international trade in raw materials and food products. The biofilm 'lifestyle' of Campylobacter contributes to this spread as it enables them to withstand stress in the environment both outside and inside the host. Campylobacter adhesion and biofilm formation has major implications for the food industry, where biofilms can be persistent sources of contamination. In our study, we described how the proteome of C. jejuni is affected by the deletion of the luxS gene on the planktonic cell type of C. jejuni, which is the first step of biofilm formation. In C. jejuni, the presence of the luxS gene has been associated with several phenotypes, including intercellular signalling, motility, biofilm formation, host colonisation, virulence, autoagglutination, cellular adherence and invasion, oxidative stress and chemotaxis. Deletion of the luxS gene is associated with a reduction or absence of the above properties compared to wild type (Elvers and Park, 2002; Guerry et al., 2006; He et al., 2008; Jeon et al., 2003; Quiñones et al., 2009; Plummer et al., 2011; Plummer, 2012; Reeser et al., 2007).
Project description:Enterohemorrhagic Escherichia coli (EHEC), including serotype O157:H7, cause severe food-borne illness. On route to the human colon, they encounter and resist, numerous anti-microbial ingestion stresses. We hypothesize that these stresses cue EHEC to alter virulence properties. This study investigated the impact of bile salts on virulence properties and examined the genetic basis of the phenotypes. Established assays were used to examine adhesion to human epithelial cells, motility, verotoxin (VT) production and antimicrobial resistance with/without bile salt stress. Bacteria treated for 90 minute in DMEM plus 0.15% (w/v) bile salt mix demonstrated significantly enhanced adhesion to epithelial cells and resistance to several antibiotics but did not increase motility or VT production. To determine the genetic basis of these phenotypes a microarray experiment was conducted. EHEC strain 86-24, in mid-log phase of growth, were grown in DMEM pH 7.4 (control), or DMEM plus bile salt mix (0.15% w/v), for 90 minutes, statically at 37˚C, 5% CO2 prior to harvesting RNA for the microarray study. Four biological replicates were produced for each treatment. Microarray and gene expression analysis (semi-quantitative RT-PCR and beta-galactosidase reporter assays) of bile salt-treated EHEC revealed significant up-regulation of genes for lipid A modification, fimbriae, an efflux pump, and a two-component regulatory system relative to the bacteria grown in DMEM alone. This work points to several mechanisms that EHEC employs to resist the stresses of the human small intestine, notably efflux, antimicrobial resistance, and outer membrane alterations. Bile salts enhanced the virulence-related properties of increased adhesion and resistance to antimicrobials but not VT production or motility. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms this pathogen uses to successfully colonize and infect the human host. Bacteria were grown in LB broth overnight with shaking, then subcultured into DMEM and grown statically at 37˚C, 5%CO2 to mid-log phase. Bacteria were then subjected to one of two 90 minute treatments: 1) Control: DMEM pH 7.4, or 2) Bile Salt Stress: DMEM pH 7.4 plus 0.15%, grown statically at 37˚C, 5%CO2.
Project description:The balance between tolerogenic and inflammatory responses determines immune homeostasis in the gut. Dysbiosis and a defective host defense against invading intestinal bacteria can shift this balance via bacterial-derived metabolites and trigger chronic inflammation. We show that the short chain fatty acid butyrate modulates monocyte to macrophage differentiation by promoting antimicrobial effector functions. The presence of butyrate modulates antimicrobial activity via a shift in macrophage metabolism and reduction in mTOR activity. This mechanism is furthermore dependent on the inhibitory function of butyrate on histone deacetylase 3 (HDAC3) driving transcription of a set of antimicrobial peptides including calprotectin. The increased antimicrobial activity against several bacterial species is not associated with increased production of conventional cytokines. Butyrate imprints antimicrobial activity of intestinal macrophages in vivo. Our data suggest that commensal bacteria derived butyrate stabilize gut homeostasis by promoting antimicrobial host defense pathways in monocytes that differentiate into intestinal macrophages.
Project description:Campylobacter jejuni is a widespread pathogen responsible for most of the food-borne gastrointestinal diseases in Europe. For pathogen control in the food industry, the use of natural antimicrobial molecules is a promising strategy to avoid antibiotic treatments. Isothiocyanates are natural antimicrobial compounds which also display anti-cancer activity. Several studies described the chemoprotective effect of isothiocyanates on eukaryotic cells, but the antimicrobial mechanism is still poorly understood. We investigated the early cellular response of C. jejuni to benzylisothiocyanate (BITC) by both transcriptomic and physiological (respirometry, ATP content measurements and isolations of aggregated proteins).
Project description:Enterohemorrhagic Escherichia coli (EHEC), including serotype O157:H7, cause severe food-borne illness. On route to the human colon, they encounter and resist, numerous anti-microbial ingestion stresses. We hypothesize that these stresses cue EHEC to alter virulence properties. This study investigated the impact of bile salts on virulence properties and examined the genetic basis of the phenotypes. Established assays were used to examine adhesion to human epithelial cells, motility, verotoxin (VT) production and antimicrobial resistance with/without bile salt stress. Bacteria treated for 90 minute in DMEM plus 0.15% (w/v) bile salt mix demonstrated significantly enhanced adhesion to epithelial cells and resistance to several antibiotics but did not increase motility or VT production. To determine the genetic basis of these phenotypes a microarray experiment was conducted. EHEC strain 86-24, in mid-log phase of growth, were grown in DMEM pH 7.4 (control), or DMEM plus bile salt mix (0.15% w/v), for 90 minutes, statically at 37˚C, 5% CO2 prior to harvesting RNA for the microarray study. Four biological replicates were produced for each treatment. Microarray and gene expression analysis (semi-quantitative RT-PCR and beta-galactosidase reporter assays) of bile salt-treated EHEC revealed significant up-regulation of genes for lipid A modification, fimbriae, an efflux pump, and a two-component regulatory system relative to the bacteria grown in DMEM alone. This work points to several mechanisms that EHEC employs to resist the stresses of the human small intestine, notably efflux, antimicrobial resistance, and outer membrane alterations. Bile salts enhanced the virulence-related properties of increased adhesion and resistance to antimicrobials but not VT production or motility. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms this pathogen uses to successfully colonize and infect the human host.