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1.
Gut Microbes ; 16(1): 2342583, 2024.
Article in English | MEDLINE | ID: mdl-38722061

ABSTRACT

Vancomycin and metronidazole are commonly used treatments for Clostridioides difficile infection (CDI). However, these antibiotics have been associated with high levels of relapse in patients. Fidaxomicin is a new treatment for CDI that is described as a narrow spectrum antibiotic that is minimally active on the commensal bacteria of the gut microbiome. The aim of this study was to compare the effect of fidaxomicin on the human gut microbiome with a number of narrow (thuricin CD) and broad spectrum (vancomycin and nisin) antimicrobials. The spectrum of activity of each antimicrobial was tested against 47 bacterial strains by well-diffusion assay. Minimum inhibitory concentrations (MICs) were calculated against a select number of these strains. Further, a pooled fecal slurry of 6 donors was prepared and incubated for 24 h with 100 µM of each antimicrobial in a mini-fermentation system together with a no-treatment control. Fidaxomicin, vancomycin, and nisin were active against most gram positive bacteria tested in vitro, although fidaxomicin and vancomycin produced larger zones of inhibition compared to nisin. In contrast, the antimicrobial activity of thuricin CD was specific to C. difficile and some Bacillus spp. The MICs showed similar results. Thuricin CD exhibited low MICs (<3.1 µg/mL) for C. difficile and Bacillus firmus, whereas fidaxomicin, vancomycin, and nisin demonstrated lower MICs for all other strains tested when compared to thuricin CD. The narrow spectrum of thuricin CD was also observed in the gut model system. We conclude that the spectrum of activity of fidaxomicin is comparable to that of the broad-spectrum antibiotic vancomycin in vitro and the broad spectrum bacteriocin nisin in a complex community.


Subject(s)
Anti-Bacterial Agents , Feces , Fidaxomicin , Gastrointestinal Microbiome , Microbial Sensitivity Tests , Nisin , Vancomycin , Nisin/pharmacology , Anti-Bacterial Agents/pharmacology , Humans , Fidaxomicin/pharmacology , Vancomycin/pharmacology , Gastrointestinal Microbiome/drug effects , Feces/microbiology , Bacteria/drug effects , Bacteria/classification , Clostridioides difficile/drug effects , Clostridium Infections/drug therapy , Clostridium Infections/microbiology , Bacteriocins/pharmacology
2.
Microbiologyopen ; 13(3): e1411, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38706434

ABSTRACT

Traditional bacteriocin screening methods often face limitations due to diffusion-related challenges in agar matrices, which can prevent the peptides from reaching their target organism. Turbidimetric techniques offer a solution to these issues, eliminating diffusion-related problems and providing an initial quantification of bacteriocin efficacy in producer organisms. This study involved screening the cell-free supernatant (CFS) from eight uncharacterized asymptomatic bacteriuria (ABU) isolates and Escherichia coli 83972 for antimicrobial activity against clinical uropathogenic E. coli (UPEC) strains using turbidimetric growth methods. ABU isolates exhibiting activity against five or more UPEC strains were further characterized (PUTS 37, PUTS 58, PUTS 59, S-07-4, and SK-106-1). The inhibition of the CFS by proteinase K suggested that the antimicrobial activity was proteinaceous in nature, potentially bacteriocins. The activity of E. coli PUTS 58 and SK-106-1 was enhanced in an artificial urine medium, with both inhibiting all eight UPECs. A putative microcin H47 operon was identified in E. coli SK-106-1, along with a previously identified microcin V and colicin E7 in E. coli PUTS 37 and PUTS 58, respectively. These findings indicate that ABU bacteriocin-producers could serve as viable prophylactics and therapeutics in the face of increasing antibiotic resistance among uropathogens.


Subject(s)
Bacteriuria , Escherichia coli Infections , Uropathogenic Escherichia coli , Uropathogenic Escherichia coli/drug effects , Uropathogenic Escherichia coli/genetics , Bacteriuria/microbiology , Humans , Escherichia coli Infections/microbiology , Escherichia coli Infections/drug therapy , Bacteriocins/pharmacology , Bacteriocins/genetics , Nephelometry and Turbidimetry , Biological Assay/methods , Anti-Bacterial Agents/pharmacology , Microbial Sensitivity Tests , Urinary Tract Infections/microbiology
3.
Int J Mol Sci ; 25(10)2024 May 15.
Article in English | MEDLINE | ID: mdl-38791443

ABSTRACT

Broad-spectrum antibiotics are frequently used to treat bacteria-induced infections, but the overuse of antibiotics may induce the gut microbiota dysbiosis and disrupt gastrointestinal tract function. Probiotics can be applied to restore disturbed gut microbiota and repair abnormal intestinal metabolism. In the present study, two strains of Enterococcus faecium (named DC-K7 and DC-K9) were isolated and characterized from the fecal samples of infant dogs. The genomic features of E. faecium DC-K7 and DC-K9 were analyzed, the carbohydrate-active enzyme (CAZyme)-encoding genes were predicted, and their abilities to produce short-chain fatty acids (SCFAs) were investigated. The bacteriocin-encoding genes in the genome sequences of E. faecium DC-K7 and DC-K9 were analyzed, and the gene cluster of Enterolysin-A, which encoded a 401-amino-acid peptide, was predicted. Moreover, the modulating effects of E. faecium DC-K7 and DC-K9 on the gut microbiota dysbiosis induced by antibiotics were analyzed. The current results demonstrated that oral administrations of E. faecium DC-K7 and DC-K9 could enhance the relative abundances of beneficial microbes and decrease the relative abundances of harmful microbes. Therefore, the isolated E. faecium DC-K7 and DC-K9 were proven to be able to alter the gut microbiota dysbiosis induced by antibiotic treatment.


Subject(s)
Anti-Bacterial Agents , Dysbiosis , Enterococcus faecium , Gastrointestinal Microbiome , Animals , Dysbiosis/microbiology , Gastrointestinal Microbiome/drug effects , Anti-Bacterial Agents/pharmacology , Mice , Feces/microbiology , Fatty Acids, Volatile/metabolism , Probiotics/pharmacology , Dogs , Bacteriocins/pharmacology
4.
Arch Microbiol ; 206(6): 269, 2024 May 20.
Article in English | MEDLINE | ID: mdl-38767708

ABSTRACT

Bacteriocins are ribosomally synthesized bacterial peptides endowed with antibacterial, antiprotozoal, anticancer and antiviral activities. In the present study, we evaluated the antiviral activities of two bacteriocins, enterocin DD14 (EntDD14) and lacticaseicin 30, against herpes simplex virus type 1 (HSV-1), human coronavirus 229E (HCoV-229E) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Vero, Huh7 and Vero E6 cells, respectively. In addition, the interactions of these bacteriocins with the envelope glycoprotein D of HSV-1 and the receptor binding domains of HCoV-229E and SARS-CoV-2 have been computationally evaluated using protein-protein docking and molecular dynamics simulations. HSV-1 replication in Vero cells was inhibited by EntDD14 and, to a lesser extent, by lacticaseicin 30 added to cells after virus inoculation. EntDD14 and lacticaseicin 30 had no apparent antiviral activity against HCoV-229E; however, EntDD14 was able to inhibit SARS-CoV-2 in Vero E6 cells. Further studies are needed to elucidate the antiviral mechanism of these bacteriocins.


Subject(s)
Antiviral Agents , Bacteriocins , SARS-CoV-2 , Bacteriocins/pharmacology , Chlorocebus aethiops , Animals , Antiviral Agents/pharmacology , Vero Cells , Humans , SARS-CoV-2/drug effects , Virus Replication/drug effects , Herpesvirus 1, Human/drug effects , Herpesvirus 1, Human/physiology , Molecular Docking Simulation , Molecular Dynamics Simulation , Bridged-Ring Compounds
5.
Vet Res ; 55(1): 66, 2024 May 22.
Article in English | MEDLINE | ID: mdl-38778424

ABSTRACT

The lasso peptide microcin Y (MccY) effectively inhibits various serotypes of Salmonella in vitro, but the antibacterial effect against S. Pullorum in poultry is still unclear. This study was the first to evaluate the safety and anti-S. Pullorum infection of MccY in specific pathogen-free (SPF) chicks. The safety test showed that the body weight, IgA and IgM levels of serum, and cecal microbiota structure of 3 groups of chicks orally administrated with different doses of MccY (5 mg/kg, 10 mg/kg, 20 mg/kg) for 14 days were not significantly different from those of the control group. Then, the chicks were randomized into 3 groups for the experiment of anti-S. Pullorum infection: (I) negative control group (NC), (II) S. Pullorum-challenged group (SP, 5 × 108 CFU/bird), (III) MccY-treated group (MccY, 20 mg/kg). The results indicated that compared to the SP group, treatment of MccY increased body weight and average daily gain (P < 0.05), reduced S. Pullorum burden in feces, liver, and cecum (P < 0.05), enhanced the thymus, and decreased the spleen and liver index (P < 0.05). Additionally, MccY increased the jejunal villus height, lowered the jejunal and ileal crypt depth (P < 0.05), and upregulated the expression of IL-4, IL-10, ZO-1 in the jejunum and ileum, as well as CLDN-1 in the jejunum (P < 0.05) compared to the SP group. Furthermore, MccY increased probiotic flora (Barnesiella, etc.), while decreasing (P < 0.05) the relative abundance of pathogenic flora (Escherichia and Salmonella, etc.) compared to the SP group.


Subject(s)
Bacteriocins , Chickens , Gastrointestinal Microbiome , Poultry Diseases , Salmonella Infections, Animal , Animals , Gastrointestinal Microbiome/drug effects , Poultry Diseases/microbiology , Salmonella Infections, Animal/microbiology , Bacteriocins/administration & dosage , Bacteriocins/pharmacology , Administration, Oral , Salmonella/drug effects , Salmonella/physiology , Specific Pathogen-Free Organisms , Animal Feed/analysis , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/administration & dosage , Random Allocation , Intestinal Barrier Function
6.
Food Microbiol ; 121: 104491, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38637093

ABSTRACT

The effect of lactocin AL705, bacteriocin produced by Latilactobacillus (Lat.) curvatus CRL1579 against Listeria biofilms on stainless steel (SS) and polytetrafluoroethylene (PTFE) coupons at 10 °C was investigated. L. monocytogenes FBUNT showed the greatest adhesion on both surfaces associated to the hydrophobicity of cell surface. Partially purified bacteriocin (800 UA/mL) effectively inhibited L. monocytogenes preformed biofilm through displacement strategy, reducing the pathogen by 5.54 ± 0.26 and 4.74 ± 0.05 log cycles at 3 and 6 days, respectively. The bacteriocin-producer decreased the pathogen biofilm by ∼2.84 log cycles. Control and Bac- treated samples reached cell counts of 7.05 ± 0.18 and 6.79 ± 0.06 log CFU/cm2 after 6 days of incubation. Confocal scanning laser microscopy (CLSM) allowed visualizing the inhibitory effect of lactocin AL705 on L. monocytogenes preformed biofilms under static and hydrodynamic flow conditions. A greater effect of the bacteriocin was found at 3 days independently of the surface matrix and pathogen growth conditions at 10 °C. As a more realistic approach, biofilm displacement strategy under continuous flow conditions showed a significant loss of biomass, mean thickness and substratum coverage of pathogen biofilm. These findings highlight the anti-biofilm capacity of lactocin AL705 and their potential application in food industries.


Subject(s)
Bacteriocins , Listeria monocytogenes , Listeria , Biofilms , Bacteriocins/pharmacology , Lactobacillus , Stainless Steel/analysis , Food Microbiology
7.
Food Funct ; 15(9): 5026-5040, 2024 May 07.
Article in English | MEDLINE | ID: mdl-38650522

ABSTRACT

This study utilized high-throughput sequencing and SEM observation to elucidate the microbial composition of a Tibetan herder's homemade kefir grain named TKG-Y. Subsequently, S. warneri KYS-164 was isolated from TKG-Y, which can produce mixed protein substances with antibacterial activity, namely bacteriocin-like inhibitory substances (BLIS). BLIS can significantly reduce the growth rate of Escherichia coli 366-a, Staphylococcus aureus CICC 10384 and mixed strains at low concentrations (1 × MIC). The presence of the warnericin-centered gene cluster in KYS-164 may explain the antibacterial properties of the BLIS. Pepsin and an acidic environment can reduce the number of colonies of KYS-164 by 2.5 Log10 CFU mL-1 within 1 h, and reduce the antibacterial activity of BLIS by 21.48%. S. warneri KYS-164 showed no antibiotic resistance and biological toxicity after 80 subcultures, while BLIS produced by 40 generations of the strain retained their inhibitory efficacy against pathogenic bacteria. After 48-hour fermentation of milk with KYS-164, volatile compounds such as aldehydes, phenols, esters, and alcohols, giving it a floral, fruity, milky, oily, and nutty aroma, were released, enriching the sensory characteristics of dairy products. This study not only revealed the bacterial colony composition information of home-made kefir grain TKG-Y but also discovered and proved that S. warneri KYS-164 has the potential to inhibit bacteria and ferment dairy products. This will provide a basis for subsequent applied research on KYS-164.


Subject(s)
Anti-Bacterial Agents , Fermentation , Kefir , Milk , Kefir/microbiology , Milk/microbiology , Anti-Bacterial Agents/pharmacology , Animals , Tibet , Staphylococcus aureus/drug effects , Escherichia coli/drug effects , Bacteriocins/pharmacology
8.
Arch Microbiol ; 206(5): 233, 2024 Apr 25.
Article in English | MEDLINE | ID: mdl-38662051

ABSTRACT

Bacteriocins are highly diverse, abundant, and heterogeneous antimicrobial peptides that are ribosomally synthesized by bacteria and archaea. Since their discovery about a century ago, there has been a growing interest in bacteriocin research and applications. This is mainly due to their high antimicrobial properties, narrow or broad spectrum of activity, specificity, low cytotoxicity, and stability. Though initially used to improve food quality and safety, bacteriocins are now globally exploited for innovative applications in human, animal, and food systems as sustainable alternatives to antibiotics. Bacteriocins have the potential to beneficially modulate microbiota, providing viable microbiome-based solutions for the treatment, management, and non-invasive bio-diagnosis of infectious and non-infectious diseases. The use of bacteriocins holds great promise in the modulation of food microbiomes, antimicrobial food packaging, bio-sanitizers and antibiofilm, pre/post-harvest biocontrol, functional food, growth promotion, and sustainable aquaculture. This can undoubtedly improve food security, safety, and quality globally. This review highlights the current trends in bacteriocin research, especially the increasing research outputs and funding, which we believe may proportionate the soaring global interest in bacteriocins. The use of cutting-edge technologies, such as bioengineering, can further enhance the exploitation of bacteriocins for innovative applications in human, animal, and food systems.


Subject(s)
Anti-Bacterial Agents , Bacteriocins , Bacteriocins/metabolism , Bacteriocins/pharmacology , Humans , Animals , Anti-Bacterial Agents/pharmacology , Bacteria/metabolism , Bacteria/drug effects , Bacteria/genetics , Food Microbiology , Microbiota , Food Packaging , Food Safety
9.
Food Chem ; 451: 139344, 2024 Sep 01.
Article in English | MEDLINE | ID: mdl-38663238

ABSTRACT

A novel bacteriocin, plantaricin ZFM9, was purified from Lactiplantibacillus plantarum ZFM9 using a combination of ammonium sulfate precipitation, XAD-2 macroporous resin, Sephadex G-50, Sephadex LH-20, and reversed-phase high performance liquid chromatography. The molecular mass of plantaricin ZFM9 was 1151.606 Da, and the purity was 98.3%. Plantaricin ZFM9 has thermal stability (95.6% retention at 120 °C for 30 min), pH stability (pH ≤ 5), and sensitivity to the pepsin, trypsin, papain, and proteinase K. Plantaricin ZFM9 exhibited broad-spectrum antimicrobial activity and notably inhibit methicillin-resistant Staphylococcus aureus D48 (MRSA). According to the results of electron microscopy and fluorescence leakage assay, it was found that plantaricin ZFM9 caused damage to the cells membrane and leakage of the contents of S. aureus D48. In addition, Lipid II was not the anti-MRSA target of plantaricin ZFM9. This study underscores the potential of plantaricin ZFM9 for applications in the food field and biopharmaceuticals against MRSA infection.


Subject(s)
Anti-Bacterial Agents , Bacteriocins , Methicillin-Resistant Staphylococcus aureus , Methicillin-Resistant Staphylococcus aureus/drug effects , Bacteriocins/pharmacology , Bacteriocins/chemistry , Bacteriocins/isolation & purification , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Microbial Sensitivity Tests , Molecular Weight , Lactobacillus plantarum/chemistry , Lactobacillus plantarum/isolation & purification
10.
Food Chem ; 447: 138962, 2024 Jul 30.
Article in English | MEDLINE | ID: mdl-38518614

ABSTRACT

A bacteriocin paracin wx3 was investigated as a candidate of natural preservative to control green pepper soft rot. Firstly, paracin wx3 was heterologously expressed in Pichia pastoris X33 with an improved yield of 0.537 g/L. Its size and amino acid sequence were confirmed by Tricine-SDS-PAGE and LC-MS/MS. Then, result of antibacterial activity showed that its MIC value against Pectobacterium carotovorum was 16 µg/mL. In vitro, paracin wx3 completely killed the pathogen at high concentrations ≥8 × MIC. In vivo, disease incidence of green pepper soft rot was decreased from 90% (control) to <2% (8 × MIC). Subsequently, results of action mode showed that paracin wx3 inhibited the growth of pathogen by pore-formation on cell membrane. Last, paracin wx3 treatment reduced losses of weight, firmness, total soluble solid, Vc of green pepper during storage. It also inhibited the production of soft rot volatile p-xylene, 1-butanol, 2-methyl-2-propanol, 3-hydroxybutan-2-one-D, 2-pentyl furan, butanal, etc.


Subject(s)
Bacteriocins , Capsicum , Bacteriocins/genetics , Bacteriocins/pharmacology , Bacteriocins/metabolism , Capsicum/metabolism , Chromatography, Liquid , Tandem Mass Spectrometry , Anti-Bacterial Agents/chemistry , Plant Diseases/microbiology
11.
World J Microbiol Biotechnol ; 40(4): 117, 2024 Mar 02.
Article in English | MEDLINE | ID: mdl-38429597

ABSTRACT

Biofilm, a microbial community formed by especially pathogenic and spoilage bacterial species, is a critical problem in the food industries. It is an important cause of continued contamination by foodborne pathogenic bacteria. Therefore, removing biofilm is the key to solving the high pollution caused by foodborne pathogenic bacteria in the food industry. Lactobacillus, a commonly recognized probiotic that is healthy for consumer, have been proven useful for isolating the potential biofilm inhibitors. However, the addition of surface components and metabolites of Lactobacillus is not a current widely adopted biofilm control strategy at present. This review focuses on the effects and preliminary mechanism of action on biofilm inhibition of Lactobacillus-derived components including lipoteichoic acid, exopolysaccharides, bacteriocins, secreted protein, organic acids and some new identified molecules. Further, the review discusses several modern biofilm identification techniques and particularly interesting new technology of biofilm inhibition molecules. These molecules exhibit stronger inhibition of biofilm formation, playing a pivotal role in food preservation and storage. Overall, this review article discusses the application of biofilm inhibitors produced by Lactobacillus, which would greatly aid efforts to eradicate undesirable bacteria from environment in the food industries.


Subject(s)
Bacteriocins , Lactobacillus , Lactobacillus/metabolism , Food Industry , Food-Processing Industry , Bacteriocins/pharmacology , Bacteriocins/metabolism , Biofilms
12.
ISME J ; 18(1)2024 Jan 08.
Article in English | MEDLINE | ID: mdl-38470311

ABSTRACT

Many bacteria produce antimicrobial compounds such as lantibiotics to gain advantage in the competitive natural environments of microbiomes. Epilancins constitute an until now underexplored family of lantibiotics with an unknown ecological role and unresolved mode of action. We discovered production of an epilancin in the nasal isolate Staphylococcus epidermidis A37. Using bioinformatic tools, we found that epilancins are frequently encoded within staphylococcal genomes, highlighting their ecological relevance. We demonstrate that production of epilancin A37 contributes to Staphylococcus epidermidis competition specifically against natural corynebacterial competitors. Combining microbiological approaches with quantitative in vivo and in vitro fluorescence microscopy and cryo-electron tomography, we show that A37 enters the corynebacterial cytoplasm through a partially transmembrane-potential-driven uptake without impairing the cell membrane function. Upon intracellular aggregation, A37 induces the formation of intracellular membrane vesicles, which are heavily loaded with the compound and are essential for the antibacterial activity of the epilancin. Our work sheds light on the ecological role of epilancins for staphylococci mediated by a mode of action previously unknown for lantibiotics.


Subject(s)
Bacteriocins , Microbiota , Bacteriocins/pharmacology , Staphylococcus epidermidis/metabolism , Staphylococcus , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/metabolism
13.
J Appl Microbiol ; 135(3)2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38439668

ABSTRACT

AIMS: Enterocins K1 and EJ97 have specific antimicrobial activity against Enterococcus faecium and Enterococcus faecalis, respectively. The aim of this study was to investigate the utility of these enterocins for in vivo treatment of systemic enterococcal infections. METHODS AND RESULTS: The antimicrobial effect in blood was analysed and compared against the effect in saline. Colony forming unit counts revealed that the enterocins killed all the bacteria within 1 hour. Additionally, the bactericidal effect against E. faecalis was more rapid in blood, indicating a possible synergy between EntEJ97 and blood. Importantly, no enterocin resistant mutants emerged in these experiments. Injecting the enterocins intraperitoneally in an in vivo mouse model and using fluorescence and minimum inhibitory concentration determination to estimate concentrations of the peptides in plasma, indicate that the enterocins exist in circulation in therapeutic concentrations. Alanine aminotransferase detection, and haemolysis analysis indicates that there is no detectable liver damage or haemolytic effect after injection. CONCLUSIONS: The study revealed that EntK1 and EntEJ97 are able to kill all bacteria ex vivo in the presence of blood. In vivo experiments determine that the enterocins exist in circulation in therapeutic concentrations without causing liver damage or haemolysis. Future experiments should test these peptides for treatment of infection in a relevant in vivo model.


Subject(s)
Bacterial Infections , Bacteriocins , Enterococcus faecium , Vancomycin-Resistant Enterococci , Animals , Mice , Bacteriocins/pharmacology , Hemolysis , Feasibility Studies , Anti-Bacterial Agents/pharmacology , Peptides/pharmacology , Microbial Sensitivity Tests
14.
Arch Microbiol ; 206(4): 143, 2024 Mar 05.
Article in English | MEDLINE | ID: mdl-38443732

ABSTRACT

The probiotic strain Bacillus licheniformis MCC2514 has been shown to produce a strong antibacterial peptide and the whole genome sequence of this strain is also reported in our previous study. The present study is focused on the genome level investigation of this peptide antibiotic and its characterization. Genome mining of the culture revealed the presence of three putative bacteriocin clusters, viz. lichenicidin, sonorensin and lasso peptide. Hence, the mode of action of the peptide was investigated by reporter assay, scanning electron microscopy, and Fourier Transform Infrared spectroscopy. Additionally, the peptide treated groups of Kocuria rhizophila showed a reduction in the fold expression for transcription-related genes. The gene expression studies, quantitative ß-galactosidase induction assay using the RNA stress reporter strain, yvgS along with the homology studies concluded that lasso peptide is responsible for the antibacterial activity of the peptide which acts as an inhibitor of RNA biosynthesis. Gene expression analysis showed a considerable increase in fold expression of lasso peptide genes at various fermentation hours. Also, the peptide was isolated, and its time-kill kinetics and minimum inhibitory concentration against the indicator pathogen K. rhizophila were examined. The peptide was also purified and the molecular weight was determined to be ~ 2 kDa. Our study suggests that this bacteriocin can function as an effective antibacterial agent in food products as well as in therapeutics as it contains lasso peptide, which inhibits the RNA biosynthesis.


Subject(s)
Bacillus licheniformis , Bacteriocins , Bacillus licheniformis/genetics , Multigene Family , Anti-Bacterial Agents/pharmacology , Bacteriocins/genetics , Bacteriocins/pharmacology , Peptides , RNA
15.
Arch Microbiol ; 206(4): 191, 2024 Mar 23.
Article in English | MEDLINE | ID: mdl-38520490

ABSTRACT

Escherichia coli are generally resistant to the lantibiotic's action (nisin and warnerin), but we have shown increased sensitivity of E. coli to lantibiotics in the presence of subinhibitory concentrations of polymyxins. Synergistic lantibiotic-polymyxin combinations were found for polymyxins B and M. The killing of cells at the planktonic and biofilm levels was observed for two collection and four clinical multidrug-resistant E. coli strains after treatment with lantibiotic-polymyxin B combinations. Thus, 24-h treatment of E. coli mature biofilms with warnerin-polymyxin B or nisin-polymyxin B leads to five to tenfold decrease in the number of viable cells, depending on the strain. AFM revealed that the warnerin and polymyxin B combination caused the loss of the structural integrity of biofilm and the destruction of cells within the biofilm. It has been shown that pretreatment of cells with polymyxin B leads to an increase of Ca2+ and Mg2+ ions in the culture medium, as detected by atomic absorption spectroscopy. The subsequent exposure to warnerin caused cell death with the loss of K+ ions and cell destruction with DNA and protein release. Thus, polymyxins display synergy with lantibiotics against planktonic and biofilm cells of E. coli, and can be used to overcome the resistance of Gram-negative bacteria to lantibiotics.


Subject(s)
Bacteriocins , Nisin , Polymyxins/pharmacology , Polymyxin B/pharmacology , Anti-Bacterial Agents/pharmacology , Nisin/pharmacology , Escherichia coli/genetics , Plankton , Bacteriocins/pharmacology , Biofilms , Ions , Microbial Sensitivity Tests
16.
Microb Ecol ; 87(1): 41, 2024 Feb 14.
Article in English | MEDLINE | ID: mdl-38351266

ABSTRACT

Bacteriocins are gene-encoded antimicrobial peptides produced by bacteria. These peptides are heterogeneous in terms of structure, antimicrobial activities, biosynthetic clusters, and regulatory mechanisms. Bacteriocins are widespread in nature and may contribute to microbial diversity due to their capacity to target specific bacteria. Primarily studied as food preservatives and therapeutic agents, their function in natural settings is however less known. This review emphasizes the ecological significance of bacteriocins as multifunctional peptides by exploring bacteriocin distribution, mobility, and their impact on bacterial population dynamics and biofilms.


Subject(s)
Bacteriocins , Bacteriocins/pharmacology , Biofilms , Bacteria , Peptides , Anti-Bacterial Agents/pharmacology
17.
Sci Rep ; 14(1): 3319, 2024 02 09.
Article in English | MEDLINE | ID: mdl-38336830

ABSTRACT

The PsdRSAB and ApsRSAB detoxification modules, together with the antimicrobial peptides (AMPs)-resistance determinants Dlt system and MprF protein, play major roles in the response to AMPs in Lacticaseibacillus paracasei BL23. Sensitivity assays with a collection of mutants showed that the PsdAB ABC transporter and the Dlt system are the main subtilin resistance determinants. Quantification of the transcriptional response to subtilin indicate that this response is exclusively regulated by the two paralogous systems PsdRSAB and ApsRSAB. Remarkably, a cross-regulation of the derAB, mprF and dlt-operon genes-usually under control of ApsR-by PsdR in response to subtilin was unveiled. The high similarity of the predicted structures of both response regulators (RR), and of the RR-binding sites support this possibility, which we experimentally verified by protein-DNA binding studies. ApsR-P shows a preferential binding in the order PderA > Pdlt > PmprF > PpsdA. However, PsdR-P bound with similar apparent affinity constants to the four promoters. This supports the cross-regulation of derAB, mprF and the dlt-operon by PsdR. The possibility of cross-regulation at the level of RR-promoter interaction allows some regulatory overlap with two RRs controlling the expression of systems involved in maintenance of critical cell membrane functions in response to lantibiotics.


Subject(s)
Bacteriocins , Lacticaseibacillus paracasei , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacteriocins/genetics , Bacteriocins/pharmacology , Bacteriocins/metabolism , Promoter Regions, Genetic , Operon , Gene Expression Regulation, Bacterial
18.
Int J Mol Sci ; 25(4)2024 Feb 07.
Article in English | MEDLINE | ID: mdl-38396696

ABSTRACT

The rise of antimicrobial resistance poses a significant global health threat, necessitating urgent efforts to identify novel antimicrobial agents. In this study, we undertook a thorough screening of soil-derived bacterial isolates to identify candidates showing antimicrobial activity against Gram-positive bacteria. A highly active antagonistic isolate was initially identified as Bacillus altitudinis ECC22, being further subjected to whole genome sequencing. A bioinformatic analysis of the B. altitudinis ECC22 genome revealed the presence of two gene clusters responsible for synthesizing two circular bacteriocins: pumilarin and a novel circular bacteriocin named altitudin A, alongside a closticin 574-like bacteriocin (CLB) structural gene. The synthesis and antimicrobial activity of the bacteriocins, pumilarin and altitudin A, were evaluated and validated using an in vitro cell-free protein synthesis (IV-CFPS) protocol coupled to a split-intein-mediated ligation procedure, as well as through their in vivo production by recombinant E. coli cells. However, the IV-CFPS of CLB showed no antimicrobial activity against the bacterial indicators tested. The purification of the bacteriocins produced by B. altitudinis ECC22, and their evaluation by MALDI-TOF MS analysis and LC-MS/MS-derived targeted proteomics identification combined with massive peptide analysis, confirmed the production and circular conformation of pumilarin and altitudin A. Both bacteriocins exhibited a spectrum of activity primarily directed against other Bacillus spp. strains. Structural three-dimensional predictions revealed that pumilarin and altitudin A may adopt a circular conformation with five- and four-α-helices, respectively.


Subject(s)
Bacillus , Bacteriocins , Bacteriocins/genetics , Bacteriocins/pharmacology , Anti-Bacterial Agents/chemistry , Chromatography, Liquid , Escherichia coli/metabolism , Tandem Mass Spectrometry , Bacillus/metabolism
19.
Toxins (Basel) ; 16(2)2024 02 07.
Article in English | MEDLINE | ID: mdl-38393172

ABSTRACT

Probiotics and their bacteriocins have increasingly attracted interest for their use as safe food preservatives. This study aimed to produce soft white cheese fortified with Lacticaseibacillus MG847589 (Lb. paracasei MG847589) and/or its bacteriocin; cheese with Lacticaseibacillus (CP), cheese with bacteriocin (CB), and cheese with both Lacticaseibacillus and bacteriocin (CPB) were compared to control cheese (CS) to evaluate their biopreservative and anti-mycotoxigenic potentials for prolonged shelf life and safe food applications. The effects of these fortifications on physiochemical, microbial, texture, microstructure, and sensory properties were studied. Fortification with Lacticaseibacillus (CP) increased acidity (0.61%) and microbial counts, which may make the microstructure porous, while CPB showed intact microstructure. The CPB showed the highest hardness value (3988.03 g), while the lowest was observed with CB (2525.73 g). Consequently, the sensory assessment reflected the panelists' preference for CPB, which gained higher scores than the control (CS). Fortification with Lb. paracasei MG847589 and bacteriocin (CPB) showed inhibition effects against S. aureus from 6.52 log10 CFU/g at time zero to 2.10 log10 CFU/g at the end of storage, A. parasiticus (from 5.06 to 3.03 log10 CFU/g), and P. chrysogenum counts (from 5.11 to 2.86 log10 CFU/g). Additionally, CPB showed an anti-mycotoxigenic effect against aflatoxins AFB1 and AFM1, causing them to be decreased (69.63 ± 0.44% and 71.38 ± 0.75%, respectively). These potentials can extend shelf life and pave the way for more suggested food applications of safe food production by fortification with both Lb. paracasei MG847589 and its bacteriocin as biopreservatives and anti-mycotoxigenic.


Subject(s)
Bacteriocins , Cheese , Lacticaseibacillus paracasei , Lactobacillus , Bacteriocins/pharmacology , Staphylococcus aureus , Food Microbiology
20.
Appl Environ Microbiol ; 90(3): e0208423, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38411065

ABSTRACT

Streptococcus mutans is a cariogenic bacterium that produces a variety of bacteriocins and retains resistance to these bacteriocins. In this study, we investigated the susceptibility of 127 S. mutans strains to nukacins produced by Staphylococcus spp., which are commensal bacteria in humans. We detected diverse susceptibilities among strains. Nineteen strains had a disrupted LctF (type I), which is responsible for nukacin susceptibility, whereas the remaining 108 strains had an intact LctF (type II) and displayed resistance to nukacins. However, the type I strains still showed resistance to nukacins to some extent. Interestingly, 18/19 (94.7%) type I strains carried a mukA-T locus, which is related to the synthesis of mutacin K8, and mukFEG, an ABC transporter. In contrast, among type II strains, only 6/108 strains (5.6%) had both the mukA-T locus and mukFEG, 19/108 strains (17.6%) carried only mukFEG, and 83/108 strains (76.9%) harbored neither mukA-T nor mukFEG. We also found that MukF had two variants: 305 amino acids (type α) and 302 amino acids (type ß). All type I strains showed a type α (MukFα), whereas most type II strains with mukFEG (22/25 strains) had a type ß (MukFß). Then, we constructed a mukFEG-deletion mutant complemented with MukFαEG or MukFßEG and found that only MukFαEG was involved in nukacin resistance. The nukacin resistance capability of type II-LctFEG was stronger than that of MukFαEG. In conclusion, we identified a novel nukacin resistance factor, MukFEG, and either LctFEG or MukFEG was active in most strains via genetic polymorphisms depending on mukA-T genes. IMPORTANCE: Streptococcus mutans is an important pathogenic bacterium not only for dental caries but also for systemic diseases. S. mutans is known to produce a variety of bacteriocins and to retain resistance these bacteriocins. In this study, two ABC transporters, LctFEG and MukFEG, were implicated in nukacin resistance and each ABC transporter has two subtypes, active and inactive. Of the two ABC transporters, only one ABC transporter was always resistant, while the other ABC transporter was inactivated by genetic mutation. Interestingly, this phenomenon was defined by the presence or absence of the mutacin K8 synthesis gene region, one of the bacteriocins of S. mutans. This suggests that the resistance acquisition is tightly controlled in each strain. This study provides important evidence that the insertion of bacteriocin synthesis genes is involved in the induction of genetic polymorphisms and suggests that bacteriocin synthesis genes may play an important role in bacterial evolution.


Subject(s)
Bacteriocins , Dental Caries , Humans , Streptococcus mutans/genetics , Streptococcus mutans/metabolism , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Bacteriocins/genetics , Bacteriocins/pharmacology , Bacteriocins/metabolism , Polymorphism, Genetic , Amino Acids/metabolism
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