Bacteriocin Production Research Articles

Purification and characterisation of a novel bacteriocin produced by Enterococcus faecalis from the indigenous North East fermented food aakhone

Aakohone, a traditional Manipuri fermented dish made from sticky fermented soybeans, possesses unique clinically beneficial properties. Since these fermented foods have been consumed for generations, bacterial cultures isolated from them are unlikely to be perceived as foreign by the human immune system when used as probiotics. In this study, a bacteriocin-producing Enterococcus faecalis strain was isolated from aakhone. The culture-free supernatant was collected, precipitated and dialyzed. The antibacterial activity of the supernatant and dialyzed sample was tested against Listeria monocytogenes, Escherichia coli and Streptococcus mutans. Various physiological properties, including growth patterns, bacteriocin production and sensitivity to different enzymes, cholesterol reduction test, acid tolerance and biofilm activity were all studied, as well as the effects of temperature, pH and salinity. Using Lowry's method, the cell wall protein was isolated from the strain and quantified. Silver staining was used to identify the low molecular weight protein bands and to analyse their molecular weight. To purify the sample, column chromatography was used. After being lyophilized, the three fractions exhibiting antibacterial activity were applied to SDS-PAGE. According to the current study, E. faecalis from aakhone is a promising strain for future probiotic research.

Lactobacillus as Anti-Biofilm Therapeutics: Formulation and Delivery Challenges in Clinical Translation

Background: Biofilm-associated infections contribute to nearly 65% of all microbial infections and are notoriously resistant to conventional antibiotics. The protective extracellular polymeric matrix and metabolic heterogeneity of biofilms make treatment particularly challenging. Lactobacillus species have emerged as promising anti-biofilm agents due to their ability to produce antimicrobial compounds, disrupt biofilm architecture, and enhance host immune responses. However, their clinical application remains limited by significant formulation and delivery barriers. The objective of the review is to critically evaluate the anti-biofilm potential of Lactobacillus, identify the key challenges hindering its clinical translation, and explore technological and regulatory strategies to overcome these limitations. Methods: This review integrates current literature on the antimicrobial mechanisms of Lactobacillus, assesses the environmental and physiological stressors impacting therapeutic viability, and analyzes recent advances in protective formulation technologies, genetic engineering, and synergistic therapies. The review also examines the regulatory landscape governing Live Biotherapeutic Products (LBPs). Results: Lactobacillus exerts multi-modal anti-biofilm effects through the production of organic acids, bacteriocins, biosurfactants, and hydrogen peroxide, alongside competitive exclusion and immunomodulation. However, survival is severely compromised by manufacturing stress, gastric acidity, bile exposure, oxidative damage, and microbiota competition. Technological innovations such as microencapsulation, enteric coatings, biofilm-based delivery platforms, and CRISPR-based strain enhancements significantly improve viability and efficacy. Combination therapies with bacteriophages and matrix-degrading enzymes offer synergistic benefits. Nonetheless, the regulatory framework for LBPs demands extensive characterization, safety assurance, and novel clinical trial designs, presenting additional hurdles. Conclusion: Lactobacillus-based therapeutics offer a promising solution for biofilm-related infections, but successful clinical translation demands integrated advances in formulation, genetic engineering, regulation, and personalized strategies—driven by interdisciplinary collaboration

A novel insight into ComE-mediated activation of gene expression in Streptococcus mutans.

Bacteria use two-component signal transduction systems (TCSs) to sense and respond to environmental changes. TCSs comprise a histidine kinase that senses environmental signals and a response regulator that regulates cognate promoters. Most response regulators are incapable of regulating their promoters in the absence of the cognate histidine kinases. Here, we demonstrated that constitutive expression of the well-studied response regulator ComE of Streptococcus mutans (a dental pathogen) activates the nlmA promoter (PnlmA) for bacteriocin production without the involvement of its cognate histidine kinase ComD. To confirm the phosphorylation-independent role of ComE, we generated a phospho-mimicking (D60E) and a phospho-inactivating (D60A) variant and examined their ability to activate PnlmA in a ΔcomD knockout strain. We found that the phospho-mimicking D60E variant was able to induce the PnlmA expression. However, we also found that the phospho-inactivating variant also activates PnlmA. Furthermore, an in vitro binding assay suggested that both the phospho-mimicking and the phospho-inactivating variants were able to bind to PnlmA. Using a Phos-Tag gel analysis, we confirmed that the D60 of ComE is responsible for phosphorylation. Overall, this study demonstrated the autonomous role of the response regulator ComE by modulating the expression of its cognate promoters. We believe that other streptococcal ComE homologs might activate their target genes in a phosphorylation-independent manner similar to S. mutans ComE.IMPORTANCEBacteria utilize two-component signal transduction systems to detect and respond to environmental changes, typically involving a histidine kinase and a response regulator. While most response regulators need their cognate histidine kinases to modulate gene expression, our study shows that the response regulator ComE in Streptococcus mutans, a dental pathogen, can activate bacteriocin production without its cognate histidine kinase ComD. This study indicates that ComE can autonomously modulate promoter expression, suggesting similar mechanisms in other streptococcal ComE homologs.

Probiotic potential and safety assessment of bacteriocinogenic Enterococcus faecalis CAUM157

IntroductionOver the past few years, the genus Enterococcus has been implicated as both probiotic and pathogenic bacteria, making it challenging to introduce enterococcal probiotic candidates. Based on rigid case-by-case analysis, some enterococcal strains have been developed as probiotics, exhibiting various beneficial activities that promote the health of the host. In this study, the probiotic potential of Enterococcus faecalis CAUM157 (KACC81148BP), isolated from raw cow’s milk, was examined, leveraging its bacteriocin production for potential control of pathogenic and spoilage-associated bacteria.MethodsThe probiotic properties of Enterococcus faecalis CAUM157 were evaluated using a combination of genomic analyses and in vitro assays. In addition, various in silico analyses were performed to assess the safety of the strain and correlate its genotype with the observed phenotypic characteristics.Results and discussionGenomic analyses revealed virulence factors associated with adhesion, biofilm formation, and anti-phagocytosis. Various enzymes and antimicrobial resistance genes that confer resistance to aminoglycosides, lincosamides, macrolides, streptogramins A and B, and tetracyclines were also identified. Although generally regarded as detrimental, virulence factors are crucial to colonization, niche establishment, and subsequent manifestation of the beneficial effects of the strain, as evident in other probiotic lactic acid bacteria. Notably, CAUM157 was sensitive to clinically important antibiotics like ampicillin (MIC, 4.0 µg/mL) and vancomycin (MIC, 1.0 µg/mL), congruent with its ST21 MLST typing. CAUM157 survived in acidic conditions (pH 3.0 and pH 2.0) with 100.72 ± 0.20% and 97.28 ± 2.19% survival rates, respectively, and showed high survival rates when exposed to 0.3% (104.16 ± 3.42%) and 0.5% (90.65 ± 1.22%) bile extract, attributed to the enzymatic activity of bile salt hydrolase. CAUM157 also exhibited robust auto-aggregation and co-aggregation when interacting with Listeria monocytogenes. Finally, the ability to produce a broad-spectrum bacteriocin in conjunction with other factors indicates a potentially efficient mechanism for mitigating the pathogenicity of detrimental bacteria, including Staphylococcus aureus, Clostridium perfringens, and Streptococcus mutans.ConclusionEnterococcus faecalis CAUM157 survived exposure to artificial gastric conditions and exhibited robust auto- and co-aggregation capacity with Listeria. Additionally, the ST21 MLST typing of the strain, along with the identified niche factors and the lack of resistance to vancomycin and ampicillin, highlights its apparent safety. The results of this study suggest that strain CAUM157 may be a potential probiotic candidate in the food and feed industries.

Isolation and identification of new species Leuconostoc carnosum from cauliflower and broccoli

A study was conducted on cauliflower and broccoli which were fermented to isolate and characterize lactic acid bacteria that are consumed in these fermented foods by people. One –hundred eighty isolates belong to the lactic acid bacteria were obtained from 120 samples of different parts of cauliflower and broccoli were taken from different markets of Baghdad city. Only 20 isolates were bacteriocin producers thus showed antibacterial activity against indicator bacterial isolates (S. aureus, S. agalactiae, E. coli and P. aeruginosa). The lactic acid bacteria (LabBr no. 28) isolate had the highest activity against indicator bacteria with inhibition zones of (22 mm) against S. aureus, (16.5 mm) against S. agalactiae ,(18mm) against P. aeruginosa and (19mm) against E.coli. This isolate was identified by using conventional methods then by VITEK®2 System .The identification was confirmed by16sRNA sequencing to characterize and describe the new species Leuconostoc carnosum . The aim of this study: Recognition of lactic acid bacteria species that found in cauliflower and broccoli, which have ability to produce the bacteriocin by detection their ability to inhibit growth of pathogenic bacteria.

In Silico Detection of Genetic Determinants for the Acquired Antibiotic Resistance and Biologically Active Compounds of Lactic Acid Bacteria from the Human Oral Microbiome

The whole-genome sequencing of lactic acid bacteria provides a valuable resource for identifying the genetic determinants underlying molecular mechanisms related to their probiotic properties. Analysis of draft genome sequences relies on bioinformatics tools for genetic data processing and in silico analytical methods to pinpoint the genetic determinants encoding biologically active compounds. The aim of this study was to perform the phenotypic determination of the antibiotic sensitivity and bioinformatics analyses on whole-genome assemblies from LAB from the human oral microbiome, and determine the presence of acquired antibiotic resistance genes, peptidases, adhesion proteins, and bacteriocins. Bioinformatics processing was performed in order to establish the molecular mechanisms responsible for the previously observed probiotic properties. The tested LAB strains exhibited a broad spectrum of antibiotic multiresistance, but did not possess acquired antibiotic resistance genes. The detected genes for peptidase activity were from the Pep family of hydrolase enzymes. Genetic determinants for adhesion proteins contained LPxTG, YSIRK, KxYKxGKxW, and SEC 10/PgrA domains, as well as MucBP domains. Lectins were found for five of the strains with the presence of WxL domains from the CscC protein family and L-type lectin domains. The in silico analyses show that some of the tested strains possessed mechanisms for bacteriocin production.

Isolation and Identification of Bacteriocin Producers from Bayburt Local Fermented Dairy and Characterization of Bacteriocins

Lactic acid bacteria (LAB) have antimicrobial activity due to their bacteriocin production. Using bacteriocins in the production of foods has considerable contributions to improving food safety and extending shelf life. One of the essential characteristics of bacteriocins is that they have structural variations according to the variety of producers and, accordingly, they have different antimicrobial activity spectrums. Therefore, new bacteriocins still need to be investigated and characterized. In this study, bacteriocin-producing LAB were isolated from local fermented dairy of Bayburt and these bacteria were identified. The antimicrobial spectrum of bacteriocin-producing strains was then determined and their sensitivity to different temperatures and enzymes was characterized. Bacteriocin producing LAB were identified as Lactobacillus plantarum, Pediococcus pentosaceus and Enterococuus faecium, respectively. Theese strains were found to be antibacterial against 7, 6 and 4 different pathogens, respectively. It was determined that bacteriocins produced by all LAB lost their activity upon treatment with proteolytic enzymes and had a protein nature. Bacteriocins were found to be stable after 100 C for 10 minutes, 80 C for 10 minutes and 80 C for 15 minutes heat treatment, respectively.

The diverse virulence potential of atypical enteropathogenic Escherichia coli isolated from diarrhea: the emergence of a hybrid pathotype?

Despite being in the era of advanced technology, the world still suffers from old infectious diseases, both intestinal and extraintestinal, where Escherichia coli plays a major role as the etiological agent. Atypical enteropathogenic E. coli (aEPEC) is one of six intestinal pathogenic E. coli pathotypes and one of the major agents causing diarrhea in low- and middle-income countries like Brazil. In this work, we have investigated to what extent a collection of aEPEC isolated from the intestinal tract of children has incorporated virulence traits involved in the development of extraintestinal infections. The phylogenetic origin and the presence of extraintestinal pathogenic E. coli (ExPEC) -related Pathogenicity Islands (PAIs) were evaluated by PCR for a collection of 111 aEPEC isolated from stool. Additionally, they were screened by PCR for the presence of specific ExPEC virulence factors. Phenotypically evaluated for bacteriocin and hemolysin production and assessed for serum resistance. Finally, four strains were sequenced and had their genome characterized. Most of the strains originated from phylogroup B1 (48.6%) and A (36.3%), followed by groups B2 (13.5%) and E (8.1%). About half of the aEPEC strains presented markers for pathogenicity islands originally described in uropathogenic E. coli (UPEC), PAI IV536 being the most prevalent. Many aEPEC strains presented the virulence genetic markers that are the hallmark of ExPEC. Besides, many strains produced bacteriocins and hemolysins and survived in human serum. Five strains fulfilled the molecular criteria to be classified as ExPEC and one as UPEC, highlighting the existence of hybrid genotypes among aEPEC strains. Three non-phylogenetic-related hybrid strains were chosen for further experiments. These strains were lethal in the Galleria mellonella model for ExPEC virulence, and the comparative analysis of their genomes revealed they belong to different EPEC/ EHEC global clonal groups. Overall, this study reports the presence of many attributes of virulence of ExPEC in a comprehensive collection of aEPEC strains. The data presented here indicate the existence of genotypic hybrid aEPEC/ExPEC and aEPEC/UPEC pathogens, suggesting that they can express both intestinal and extraintestinal virulence determinants in humans. Therefore, the consequences of their colonization and infection are more concerning and potentially life-threatening.

Lactic Acid Bacteria (LAB) and Their Bacteriocins for Applications in Food Safety Against Listeria monocytogenes.

Listeria monocytogenes is a major foodborne pathogen responsible for listeriosis, a serious illness with high morbidity and mortality, particularly in vulnerable populations. Its persistence in food processing environments and resistance to conventional preservation methods pose significant food safety challenges. Lactic acid bacteria (LAB) offer a promising natural alternative due to their antimicrobial properties, especially through the production of bacteriocins. This study investigates the competitive interactions between Lactococcus lactis and L. monocytogenes under co-culture conditions, with a focus on changes in their secretomes to better understand how LAB-derived bacteriocins can help mitigate the Listeria burden. Proteomic approaches, including Tricine-SDS-PAGE, two-dimensional electrophoresis, and shotgun proteomics, were employed to analyze the molecular adaptations of both species in response to bacterial competition. Our results reveal a significant increase in the secretion of enolase by L. monocytogenes when in competition with L. lactis, suggesting its role as a stress-responsive moonlighting protein involved in adhesion, immune evasion, and biofilm formation. Concurrently, L. lactis exhibited a shift in the production of its bacteriocin, nisin, favoring the expression of Nisin Z-a variant with improved solubility and diffusion properties. This differential regulation indicates that bacteriocin production is modulated by bacterial competition, likely as a defensive response to the presence of pathogens. These findings highlight the dynamic interplay between LAB and L. monocytogenes, underscoring the potential of LAB-derived bacteriocins as natural biopreservatives. Understanding the molecular mechanisms underlying microbial competition could enhance food safety strategies, particularly in dairy products, by reducing reliance on chemical preservatives and mitigating the risk of L. monocytogenes contamination.

O-082 Discrepancies between vaginal and endometrial microbiomes in IVF patients: implications for reproductive success

Abstract Study question Can vaginal microbiome analysis predict endometrial microbiome status in IVF patients? Summary answer Only 38% of paired vaginal and endometrial samples showed correlation, indicating that vaginal microbiome analysis cannot accurately predict endometrial microbiome status. What is known already A healthy vaginal microbiome is predominantly composed by Lactobacillus species and low presence of other bacteria, since Lactobacillus has specific properties (production of lactic acid and bacteriocins) that allow to create a protective environment and prevent colonization by pathogens or the overgrowth of opportunistic bacteria. In recent years, specific endometrial microbiome has also been described. As in vagina, it should be predominantly composed by Lactobacillus to ensure a balanced environment (eubiosis). Certain studies have correlated predominance of Lactobacillus species and the absence of pathogens, to higher rates of reproductive success including increased pregnancy rates and reduced implantation failure and miscarriage. Study design, size, duration This retrospective study analyzed 58 paired endometrial and vaginal sample from 58 patients (average age: 38.8 ± 5.1 years) with a clinical history of implantation failure and/or miscarriage. Microbiome analysis was conducted from March 2022 to November 2024. Participants/materials, setting, methods Each patient underwent endometrial biopsy and vaginal swab procedures on the same day. DNA was extracted from both samples, and bacterial and fungal species were identified using Real-Time qPCR. The ratio of Lactobacillus species, opportunistic bacteria and pathogens (strict and facultative), was calculated. Main results and the role of chance In endometrial samples, 38% were eubiotic (>90% Lactobacillus), compared to 53% in vaginal samples. Comparing paired samples, 67% showed concordance in eubiosis or dysbiosis profiles, while 33% did not. No Pathogens were detected in eubiotic endometrial samples, whereas 22% of dysbiotic samples were pathogenic. In vaginal samples, pathogens were detected in 31% of eubiotic and 34% of dysbiotic samples. Pathogen presence was significantly higher in vaginal than endometrial samples (65% vs 22%, p < 0.0001). Concordance for pathogen presence between vaginal and endometrial samples s was 50% with 45% of the samples showing pathogens in the vagina but not in the endometrium). Among the samples where pathogens were present at both sites, 7 out of 11 showed concordance (at least one matching pathogen). Overall, considering Lactobacillus dominance and pathogen presence, vaginal and endometrial microbiomes correlated in only 38% (22/58) of samples. Limitations, reasons for caution The limited sample size requires, further studies to confirm these findings. Wider implications of the findings This study shows that although there is some concordance in the results of endometrial and vaginal analysis, it is limited. Analyzing both samples could offer a more comprehensive understanding of the overall condition of the reproductive tract, facilitating personalized treatments and potentially enhancing IVF outcomes for patients experiencing implantation failure. Trial registration number No

Enhanced bacteriocin production by lactic acid bacteria by co-culture of Lactiplantibacillus plantarum and Limosilactobacillus fermentum

Enhanced bacteriocin production by lactic acid bacteria by co-culture of Lactiplantibacillus plantarum and Limosilactobacillus fermentum

The potential mechanism and key genes of bacteriocin production in Lactiplantibacillus plantarum ZY-1 induced by co-cultivation with Limosilactobacillus fermentum RC4

The potential mechanism and key genes of bacteriocin production in Lactiplantibacillus plantarum ZY-1 induced by co-cultivation with Limosilactobacillus fermentum RC4

Protection induced in pigs previously infected by the non-virulent strain 1330 of Streptococcus suis serotype 2 is not due to the secretion of the bacteriocin suicin

Streptococcus suis is a systemic pathogen of swine and imposes a significant economic burden on the swine industry. Disease with S. suis is controlled with antibiotic treatment and vaccination with inactivated vaccines, which can be derived from the strains circulating on the farm. Inactivated vaccines have shown mixed results with minimal data supporting reductions in morbidity and mortality following their use. With increasing restrictions on antibiotic use and increasing concerns surrounding antimicrobial resistance, alternatives to antibiotics or novel, highly effective vaccines are needed for treating or preventing disease with S. suis. Bacteriocins are a potential alternative to antibiotics, as bacteriocins are antimicrobial peptides produced by bacteria. However, the use of bacteriocins to limit pathogenic S. suis remains relatively under-examined. Live vaccines are a potential novel and effective method of preventing disease, as they provide competition for pathogenic strains and would limit pathogenic strain colonization while stimulating a protective immune response. This study investigated the use of an avirulent, bacteriocin producing isolate of S. suis (90–1330) as an intranasal vaccine and evaluated the role of the bacteriocin by comparing protection to animals inoculated with a mutant lacking bacteriocin production (90–1330Δsuicin). Animals were protected from systemic disease when challenged with a virulent isolate 21 days after inoculation with either 90–1330 or 90–1330Δsuicin but were not protected when challenged 3 days after inoculation. Evaluation of antibody titers showed increased titers 21 days post-inoculation, and the humoral response was likely providing systemic protection. Although 90–1330 was unable to protect animals challenged 3 days post-inoculation, the strain should be considered a good candidate for vaccine development. S. suis 90–1330 was able to induce a protective immune response with a single intranasal inoculation and bacteriocin production may be able to contribute to protection when animals have a lower exposure dose, as in a production setting.

BLIS Fingerprinting as a Tool to Investigate the Distribution and Significance of Bacteriocin Production and Immunity in Streptococcus pyogenes and Streptococcus salivarius

The study of bacteriocins has significantly enhanced our understanding of microbial interactions, notably within the genus Streptococcus. Among the most functionally diverse and clinically relevant bacteriocins are those belonging to the lantibiotic class, which exhibit potent antimicrobial properties and are central to the competitive dynamics of streptococcal species. This review focuses on the discovery and characterization of bacteriocins produced by Streptococcus pyogenes and Streptococcus salivarius, emphasizing their biological significance within their exclusive human host. A cornerstone of these studies has been the development and application of the pioneer agar culture-based bacteriocin detection methodology, known as streptococcal bacteriocin fingerprinting. This approach has proven invaluable for the initial detection and differentiation of a wide array of bacteriocin-like inhibitory substances (BLIS) in streptococcal populations. A central theme of this review is the diverse biological roles of lantibiotics in S. pyogenes and S. salivarius, particularly in relation to microbial competition, colonization dynamics, and host interactions. The expression of lantibiotic determinants provides distinct advantages to the producing strain, including enhanced niche establishment and the ability to suppress competing microbes. Furthermore, the presence of specific lantibiotic immunity mechanisms safeguards the producer from self-inhibition and potential antagonism from closely related competitors. In S. pyogenes, lantibiotic production has been implicated in virulence modulation, raising important questions about its role in pathogenicity and host immune evasion. Conversely, S. salivarius, a prominent commensal and probiotic candidate species, utilizes its lantibiotic arsenal to confer colonization benefits and mediate beneficial interactions, especially within the oral and upper respiratory tract microbiomes. The implications of in situ lantibiotic expression extend beyond microbial ecology, presenting opportunities for innovative probiotic and therapeutic applications. The potential for harnessing bacteriocin-producing streptococci in antimicrobial interventions, particularly in combating antibiotic-resistant pathogens, underscores the translational relevance of these findings. This review integrates historical and contemporary perspectives on streptococcal bacteriocin research, providing insights into future avenues for leveraging these bioactive peptides in clinical and biotechnological contexts.

Molecular and functional analysis of a putative pyocin S9, with endonuclease activity from P. chlororaphis subsp aurantiaca PB-St2.

Pyocins are bacteriocins which are explicitly associated with pseudomonads. In this study, the genome mining and in-depth sequence analysis identified three similar S9-like (a, b, and c), an S3-like (d) and one R-type pyocin systems from P. chlororaphis subsp aurantiaca PB-St2. The phenotypic screening of bacteriocin production by PB-St2 indicated narrow-spectrum bactericidal activity against closely related Pseudomonas species i.e., Pseudomonas aeruginosa PAi, PAc1, PAc3, PAc4; Pseudomonas fluorescens Psi-RS1 and Pseudomonas kilonensis OSRS3. Herein, the proposed pyocin S9c was further selected for molecular and functional characterization. The presumptive N-terminal receptor binding domain of candidate system lacks significant similarity with any characterized HNH-type pyocin S DNases from P. aeruginosa. In contrast, the cytotoxic domain showed 53% sequence similarity with pyocin S8 and 70% to pyocin S9. Thus, pyocin S9c was suggested as an isoform under the Class I DNase (H-N-H) family in pyocin S9 cluster, commonly found in P. chlororaphis subsp. aurantiaca and P. chlororaphis subsp aureofaciens strains. Molecular screening of the pyocin S9c system revealed its presence in 6 out of 7 tested strains of P. chlororaphis subsp. aurantiaca GS1, GS3, GS4, GS6, ARS38, FS2 and one P. chlororaphis RP4 relative strains, isolated from diverse plant hosts. The 1.59kb fragment consisting of two structural genes of pyocin-immunity operon (S9c) in P. aurantiaca PB-St2 were cloned in pET28a(+) and expressed in Escherichia coli BL21 DE3 (pLysS) strain as a fusion protein with histidine tag. The recombinant cytotoxic protein of pyocin S9c operon was purified with N-term His-tag with a molecular weight of ≈ 50kDa. The identity of target protein was affirmed by tandem mass spectrometry analysis. The purified cytotoxic protein was active against P. chlororaphis subsp. aurantiaca GS7, with a minimum inhibitory concentration of 12.5µg/ml. The mechanism of cytotoxicity was affirmed as a metal-dependent endonuclease by evidence of non-specific hydrolysis of pTZ57R plasmid isoforms. These results indicate that pyocin S9c can contribute to the rhizo-competence of this strain in plant-associated natural habitats, occupied by related Pseudomonas strains.

Effect of cheese-making and ripening processes on the anti-Clostridium activity of Lactococcus strains.

Effect of cheese-making and ripening processes on the anti-Clostridium activity of Lactococcus strains.

Genomic insights into the taxonomic status and bioactive gene cluster profiling of Bacillus velezensis RVMD2 isolated from desert rock varnish in Ma'an, Jordan.

Extreme environments like arid and semi-arid deserts harbor unique microbial diversity, offering rich sources of specialized microbial metabolites. This study explores Bacillus velezensis RVMD2, a strain isolated from rock varnish in the Ma'an Desert, Jordan. The genome was sequenced using the Illumina NextSeq 2000 platform, resulting in a 4,212,579 bp assembly with a GC content of 45.94%. The assembled genome comprises 112 contigs and encodes 4,250 proteins, 77 tRNA genes, and 4 rRNA genes. Phylogenetic analysis of the 16S rRNA gene indicated a 99.84% similarity to previously identified B. velezensis strains. Whole-genome phylogeny using EzBiome, MiGA, and TYGS confirmed its classification as B. velezensis. Functional annotation identified genes involved in carbohydrate metabolism, including 324 carbohydrate-active enzyme (CAZyme) genes, stress response, and secondary metabolite biosynthesis. The genome also contains 50 genes associated with heavy metal resistance and plant growth promotion. Analysis using AntiSMASH identified 12 biosynthetic gene clusters involved in the production of secondary metabolites, including fengycin, surfactin, polyketides, terpenes, and bacteriocins. Notably, several clusters did not match any known sequences, suggesting the presence of potentially novel antimicrobial compounds. The genomic features of RVMD2 highlight its adaptability to extreme environments and its potential for biotechnological applications, including bioremediation and the discovery of novel bioactive metabolites.

Bacteriocin Production by Lactiplantibacillus plantarum LD1 in Solid-State Fermentation Using Lignocellulosic Substrates

In this study, solid-state fermentation for growth and bacteriocin production by Lactiplantibacillus plantarum LD1 was carried out using wheat bran, a lignocellulosic substrate. This is the first report showing bacteriocin production using L. plantarum LD1 in solid-state fermentation. Wheat bran supported higher production of bacteriocin (391.69 ± 12.58 AU/mL) than other substrates. Appropriate conditions were achieved using statistical designs. Significant factors identified by Plackett–Burman Design and their interactions were studied using response surface methodology. Enhanced production of bacteriocin (582.86 ± 0.87 AU/mL) and optimal growth (log10 CFU/mL 8.56 ± 0.42) were attained in wheat bran medium supplemented with peptone (1.13%), yeast extract (1.13%), glucose (1.56%), and tri-ammonium citrate (0.50%). Growth in non-optimized medium (MRS) was almost similar (log10 CFU/mL 8.15 ± 0.20), but the bacteriocin production level was lower (391.69 ± 0.58 AU/mL). Bacteriocin production was sustainable using varied quantities of wheat bran, showing the suitability of the optimized bioprocess for large-scale production. The cost for bacteriocin production in the optimized medium was found to be 444,583.60 AU/USD, which is about 4 times more economical than the cost of the commercial MRS medium, 121,497.18 AU/USD). Thus, an almost 1.5-fold improvement in bacteriocin production was achieved using wheat bran as the substrate. The cost of the production medium was reduced by approximately 25%, making the bioprocess economical.

EFFECT OF DIFFERENT CULTURE MEDIA, INITIAL pH, INCUBATION TEMPERATURE, AND CARBON SOURCES ON GROWTH AND BACTERIOCIN PRODUCTION OF ENTEROCOCCUS MUNDTII YB6.30

This study investigated the effects of various factors on the production of mundticin-KS in the Enterococcus mundtii YB6.30 strain, previously isolated from Sucuk, a dry-fermented sausage. The examined factors included the culture medium (de Man, Rogosa, and Sharpe broth; Brain Heart Infusion broth; M17 broth; Luria-Bertani broth; and Trypticase Soy Broth), initial medium pH (4.5, 5.5, 6.2, 7.4, and 8.5), incubation temperature (25°C, 30°C, 37°C, and 40°C), carbon source (glucose, fructose, lactose, or sucrose), and sucrose concentration (1%, 2%, 3%, 4%, 5%, 7.5%, and 10%). A one-factor-at-a-time (OFAT) approach was employed to determine the factors influencing bacteriocin production. Statistical analysis revealed that optimal mundticin-KS production by E. mundtii YB6.30 was achieved after 6 and 8 hours of incubation at 30°C in modified MRS broth medium, adjusted to an initial pH of 6.2 with the addition of 1% (w/v) sucrose. The bacteriocin activity under these conditions was measured at 1495.62±29.93 AU/mL at the 6th hour and 1567.21±26.27 AU/mL at the 8th hour (P>0.05).

Characterization of Lactiplantibacillus plantarum strains isolated from Algerian fruits for probiotic and biotechnological applications.

Twenty-one lactic acid bacteria (LAB) strains were isolated from Algerian fruits such as white mulberry (Morus alba L.), prickly pear (Opuntia ficus-indica), date (Phoenix dactylifera L.), grape (Vitis vinifera) and fig (Ficus carica). The initial screening showed that ten out of twenty-one strains were tolerant to acid pH and bile salts and were further identified as Lactiplantibacillus (L.) plantarum strains by MALDI-TOF mass spectrometry and 16S rDNA sequencing. The identified strains were then characterized for their surface properties such as self-aggregation, hydrophobicity and biofilm formation. The resulting data were then statistically processed using Principal Component Analysis (PCA), after which only 5 strains were selected for further analysis. These five strains, designated L. plantarum F8, F13, FB23, D21 and M1, were found to be safe and able to adhere to human epithelial colorectal adenocarcinoma Caco-2 cells. In particular, all these strains were active against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 through the production of lactic acid (up to 12g.l-1) or bacteriocins, namely plantaricins, or their combination. In addition, these strains showed high antioxidant activity against the synthetic free radicals 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis: 3-ethyl-benzothiazoline-6-sulphonic acid (ABTS +) radical. These results demonstrate the importance of these L. plantarum strains for the development of new functional foods and probiotics and as biopreservatives. This study deepens and enriches the knowledge of lactobacilli from plant raw materials by focusing on the functional properties of new strains of L. plantarum isolated from Algerian fruits. In fact, with the growing interest in natural preservatives and probiotics, the results of this study could contribute to the development of new biotechnological products aimed at improving gut health, reducing food-borne illnesses and extending the shelf life of food by preventing spoilage.