Distribution of bacteriocin genes in the lineages of Lactiplantibacillus plantarum

Lactiplantibacillus plantarum, previously named “Lactobacillus plantarum,” is found in a wide variety of environments exhibiting a high level of intraspecies genetic diversity. To investigate the strain diversity, we performed comparative genomic analyses of the 54 complete genome sequences. The results revealed that L. plantarum subsp. plantarum was split into three lineages, A, B and C. Of the genes beneficial for probiotic activity, only those associated with the biosynthesis of plantaricin (Pln), an L. plantarum-specific bacteriocin, were found to be significantly different among the lineages. The genes related to the biosynthesis of plnE/F were conserved throughout the three lineages, whereas the outgroups did not possess any Pln-producing genes. In lineage C, the deepest and ancestral type branch, plnE/F genes, were well conserved. In lineage B, loss of gene function was observed due to mobile elements in the pln loci. In lineage A, most strains were predicted to produce more than one type of Pln by possessing diverse Pln-encoding genes. These results showed the presence of functional diversity arising from the trifurcating evolution in L. plantarum subsp. plantarum and demonstrated that Pln is an indicator for differentiating the three lineages.

Exploring clinically isolated Staphylococcus sp. bacteriocins revealed the production of amonabactin, micrococcin, and α-circulocin

Background and Objectives: Bacteriocins are considered alternative non-conventional antimicrobials produced by certain bacteria with activity against closely related species. The present study focuses on screening, characterization, and partial purification of bacteriocins produced by Staphylococcus sp. isolated from different clinical sources such as pus and blood. Materials and Methods: A total of 100 Staphylococcus isolates were screened for bacteriocin production using spot on lawn assay and agar diffusion method against five indicator bacteria. Bacteriocins from five selected highly active isolates were subjected to proteinase-K enzyme, different pH, and heating at different temperatures, and investigated the stabilities of their antimicrobials. Two selected isolates, MK65 and MK88, were molecularly identified by 16S rRNA gene sequencing, explored for the presence of 18 bacteriocin genes, and liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HRESIMS) was used to identify their different metabolites. Results: Twenty isolates exhibited inhibitory effect against at least one indicator bacteria. Micrococcus luteus ATCC 4698 showed the highest sensitivity to such bacteriocins. Proteinase K, acidic pH, and heating at 100°C triggered marked activity inhibition. However, amylase enzyme, alkaline pH, and heating at 80°C caused trivial effects. Four out of eighteen bacteriocin genes were detected using PCR. Fermentation, partial purification, and LC-HRESIMS of total protein extracts of two selected isolates, MK65 and MK88, revealed the production of different antimicrobial peptides. Conclusion: To the best of our knowledge, this is the first study to report the production of micrococcin and α-circulocin from Staphylococcus aureus MK65 and the production of amonabactin from Staphylococcus epidermidis MK88.

Isolation and Screening of Lactic Acid Bacteria Strains With Antibacterial Properties From The Vagina of Healthy Cows

Background Lactic acid bacteria with probiotic and antibacterial properties were isolated from the vagina of healthy cows. The purpose of the study is to isolation and screening of lactic acid bacteria strains with antibacterial properties from the vagina of healthy cows, which could be used to treat cow vaginal inflammation. Results Isolation and identification of eight dominant lactic acid bacteria strains from 55 isolates was performed using classic microbiology methods and fermentation engineering. Eight strains were selected that had no spores and capsules, exhibited strong acid production capacity (pH <4.5) and had a rapid acid production (time ≤12 h) at the lowest pH. These strains were screened using fermentation engineering, pharmacology, cell biology and molecular biology methods. Lactobacillus johnsonii (SQ0048) had the lowest pH (4.32) and shortest acid-producing time (8 h). L. johnsonii (SQ0048) could produce hydrogen peroxide, inhibit the growth of Staphylococcus aureus and Escherichia coli and adhere to the vaginal epithelial cells of cows. The average number adhering to each cell was 304±2.67. Bacteriocin genes were detected in L. johnsonii (SQ0048), and the bacteriocin gene of a positive clone of this strain was 100% similar to that of Lactobacillus johnsonii NCC 533 (NC_005362.1). Expression of the bacteriocin genes had inhibitory activity against S. aureus and E. coli. Conclusions These advantages indicate that SQ0048 is a promising candidate for use in antimicrobial preparations.

Antibacterial Activity of Bacteriocinogenic Commensal Escherichia coli against Zoonotic Strains Resistant and Sensitive to Antibiotics

Antibiotic resistance concerns various areas with high consumption of antibiotics, including husbandry. Resistant strains are transmitted to humans from livestock and agricultural products via the food chain and may pose a health risk. The commensal microbiota protects against the invasion of environmental strains by secretion of bacteriocins, among other mechanisms. The present study aims to characterize the bactericidal potential of bacteriocinogenic Escherichia coli from healthy humans against multidrug-resistant and antibiotic-sensitive strains from pigs and cattle. Bacteriocin production was tested by the double-layer plate method, and bacteriocin genes were identified by the PCR method. At least one bacteriocinogenic E. coli was detected in the fecal samples of 55% of tested individuals, adults and children. Among all isolates (n = 210), 37.1% were bacteriocinogenic and contained genes of colicin (Col) Ib, ColE1, microcin (Mcc) H47, ColIa, ColM, MccV, ColK, ColB, and single ColE2 and ColE7. Twenty-five E. coli carrying various sets of bacteriocin genes were further characterized and tested for their activity against zoonotic strains (n = 60). Strains with ColE7 (88%), ColE1-ColIa-ColK-MccH47 (85%), MccH47-MccV (85%), ColE1-ColIa-ColM (82%), ColE1 (75%), ColM (67%), and ColK (65%) were most active against zoonotic strains. Statistically significant differences in activity toward antibiotic-resistant strains were shown by commensal E. coli carrying MccV, ColK-MccV, and ColIb-ColK. The study demonstrates that bacteriocinogenic commensal E. coli exerts antagonistic activity against zoonotic strains and may constitute a defense line against multidrug-resistant strains.

Characterization of bacteriocin related genes discovered in a novel probiotic isolate Enterococcus faecium W1

Aims: To isolate and characterize the bacteriocin activity identified by the genomic analysis of a novel enterococcal isolate, Enterococcus faecium W1 Methods and Results: Culture fermentates of a novel E. faecium isolate, W1 showed high levels of antimicrobial activity against Listeria monocytogenesisand a variety of other Gram+ve and Gram-ve bacteria. Ammonium sulphate precipitation of the fermentates followed by hydrophobic interaction chromatography showed bactericidal activity correlated with fractions containing only low molecular weight proteins. The same fractions had activity on human cancer cell line HT-29 measured by cytotoxicity assay (MTT) and apoptosis induction. Whole-genome sequencing of E. faecium W1 revealed five bacteriocin related gene clusters, a lack of virulence factors and lack of antibiotic resistance genes. To confirm that antimicrobial activity was correlated with the bacteriocin genes identified, selected bacteriocin genes were cloned and expressed as His-tagged proteins in E. coli. Bactericidal activity against L. monocytogenes was associated with protein purified by metal affinity chromatography. A structure-function analysis to investigate the role of key residues in activity is ongoing. Conclusion: E. faecium W1 is a promising candidate for use as a probiotic supplement or in food preservation. The bacteriocin related genes are functional and could be improved for future use as antimicrobial and cancer cell therapeutics. Significance and Impact of the Study: There is a need for new approaches to the growing problem of antibiotic resistance. Expression of bacteriocins identified in E. faecium W1 could contribute to this endeavour in addition to its use as a probiotic organism.

Gene Identification for Bacteriocin Production by Lactic Acid Bacteria Isolated from Selected Fermented Foods

Bacteriocin genes are biosynthetic genes which encodes proteins involved in bacteriocin regulation, self-immunity, transport and modification. This research was aimed at identifying the gene for the synthesis of bacteriocin. Four strains of lactic acid bacteria previously isolated from fermented foods (Nono (N2), Ogi (O3), Dawadawa (D1 and D3) and Wara (W3) were identified using molecular technique and used to produce bacteriocin. The bacteriocin activity was assayed against some test bacteria (Staphylococcus aureus, Escherichia coli, Klebsiella sp and methicillin resistant Staphylococcus aureus) using agar well diffusion method and the bacteriocin genes were identified using BAGEL3. The LAB identified were Lactobacillus fermentum O3, Leuconostoc mesenteroides N2, Weissella cibaria D1 and 2 strains of Lactobacillus plantarum D3 and W3. The entire identified LAB was able to produce bacteriocin. The antimicrobial activity showed varied inhibitory effects of the bacteriocins on the test bacteria. Bacteriocin from isolate O3 showed the highest inhibition zone 16mm on S. aureus. The identified gene for these bacteriocins were plnJK gene for Lactobacillus plantarum str WCFS1 and strain LZ95 (W3 and D3), entA gene for Lactobacillus fermentum str 3872 (O3) and ppnC7 gene for Leuconostoc mesenteroides str SRA3 (N2) with the interaction of other peptides were responsible for bacteriocin production.

Draft Genome Sequences of 12 Leuconostoc carnosum Strains Isolated from Cooked Ham Packaged in a Modified Atmosphere and from Fresh Sausages

Leuconostoc carnosum is a lactic acid bacterium that preferentially colonizes meat. In this work, we present the draft genome sequences of 12 Leuconostoc carnosum strains isolated from modified-atmosphere-packaged cooked ham and fresh sausages. Three strains harbor bacteriocin genes.

Lactobacillus acidophilus JCM 1132 Strain and Its Mutant with Different Bacteriocin-Producing Behaviour Have Various In Situ Effects on the Gut Microbiota of Healthy Mice

The production of bacteriocin is considered to be a probiotic trait of lactic acid bacteria (LAB). However, not all strains of LAB harbour bacteriocin genes, even within the same species. Moreover, the effects of bacteriocins on the host gut microbiota and on host physiological indicators are rarely studied. This study evaluated the effects of the bacteriocin-producing Lactobacillus acidophilus strain JCM1132 and its non-producing spontaneous mutant, L. acidophilus CCFM720, on the physiological statuses and gut microbiota of healthy mice. Mice that received the bacteriocin-producing strain JCM1132 exhibited reduced water and food intake. Furthermore, the administration of these strains induced significant changes in the compositional abundance of faecal microbiota at the phylum and genus levels, and some of these changes were more pronounced after one week of withdrawal. The effects of CCFM720 treatment on the gut microbiota seemed to favour the prevention of metabolic diseases to some extent. However, individuals that received JCM1132 treatment exhibited weaker inflammatory responses than those that received CCFM720 treatment. Our results indicate that treatment with bacteriocin-producing or non-producing strains can have different effects on the host. Accordingly, this trait should be considered in the applications of LAB.