Characterization of bacteriocins produced by strains of Pediococcus pentosaceus isolated from Minas cheese

Isolation, identification, and in vitro probiotic characterization of forty novel Bifidobacterium strains from neonatal feces in Erzurum province, Türkiye

BACKGROUND

Neonatal feces are one of the most important sources for probiotic isolation. The purpose of this study was the isolation and identification of Bifidobacterium spp. from neonatal feces and the evaluation of in vitro probiotic properties of strains including safety tests.

RESULTS

A total of 40 isolates were obtained from 14 healthy newborns' feces in Erzurum province, Türkiye. By their rep-PCR patterns and 16S rRNA gene sequences, isolates were identified as 26 Bifidobacterium breve and 14 Bifidobacterium longum. Fifteen of the isolates tolerated bile salts and showed high resistance to simulated gastric juice. Isolates exhibited varying rates of auto-aggregation and hydrophobicity. In addition, most of the isolates displayed antibacterial activity against Escherichia coli O157:H7, Staphylococcus aureus ATCC 29213, Salmonella Typhimurium RSHMB 95091, and Pseudomonas aeruginosa ATCC 9027. However, only one strain showed bile salt hydrolase activity and two strains showed the ability to produce H2O2. Bifidobacterium strains were generally sensitive to the tested antibiotics and lacked kanamycin, gentamicin, and streptomycin resistance genes, and hemolytic and DNAse activities. On the other hand, it was determined that five strains had various virulence genes including gelE, esp, efaAfs, hyl, and ace.

CONCLUSION

Results of the present study suggested that B. longum BH28, B. breve BH4 and B. breve BH5 strains have the potential as probiotic candidates for further studies. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Draft genome sequencing of Pediococcus pentosaceus strains isolated from cow milk

We sequenced the genomes of Pediococcus pentosaceus strains MBBL4 and MBBL6, isolated from raw milk samples of healthy cows. The draft genomes of the MBBL4 and MBBL6 were 1,896,831 bp and 1,849,397 bp, respectively, and were fragmented into 58 and 42 contigs, with coverages of 118.2× and 128.7×, respectively.

Halophilic lactic acid bacteria - Play a vital role in the fermented food industry

Halophilic lactic acid bacteria have been widely found in various high-salt fermented foods. The distribution of these species in salt-fermented foods contributes significantly to the development of the product's flavor. Besides, these bacteria also have the ability to biosynthesize bioactive components which potentially apply to different areas. In this review, insights into the metabolic properties, salt stress responses, and potential applications of these bacteria have been have been elucidated. The purpose of this review highlights the important role of halophilic lactic acid bacteria in improving the quality and safety of salt-fermented products and explores the potential application of these bacteria.

Plasmid-Associated Bacteriocin Produced by Pediococcus pentosaceus Isolated from Smoked Salmon: Partial Characterization and Some Aspects of his Mode of Action

Strain ST3Ha, isolated from commercially available smoked salmon, was identified as Pediococcus pentosaceus based on biochemical and physiological tests and 16S rRNA sequencing. Strain ST3Ha produces a class IIa bacteriocin active against lactic acid bacteria, Listeria monocytogenes and Enterococcus faecalis. The antimicrobial peptide was inactivated by proteolytic enzymes, confirming his proteinaceous nature, but was not affected when treated with α-amylase, SDS, Tween 20, Tween 80, urea, and EDTA. No change in activity was recorded after 2 h at pH values between 2.0 and 9.0 and after treatment at 100 °C for 120 min or 121 °C for 15 min. The mode of action against Listeria ivanovii subsp. ivanovii ATCC 19119 and E. faecalis ATCC 19443 was bactericidal, resulting in cell lyses and enzyme leakage. The highest level of activity (1.6 × 106 AU/mL) was recorded when cells were grown at 37 °C or 30 °C in MRS broth (pH 6.5). Antimicrobial peptide ST3Ha adsorbs at high levels to the sensitive test organisms on strain-specific manner and depending on incubation temperature, environmental pH, and presence of supplemented chemicals. Based on PCR analysis, P. pentosaceus ST3Ha harbor a 1044-bp plasmid-associated fragment corresponding in size to that recorded for pediocin PA-1. Sequencing of the fragment revealed a gene identical to pedB, reported for pediocin PA-1. The combined application of the low levels (below MIC) of ciprofloxacin and bacteriocin ST3Ha results in the synergetic effect in the inhibition of L. ivanovii subsp. ivanovii ATCC 19119. Expressed by P. pentosaceus ST3Ha, bacteriocin was characterized as low cytotoxic, a characteristic relevant for its application in food industry and/or in human and veterinary medical practices.

Antimicrobial Peptides (Bacteriocins) Produced by Lactococcus lactis and Pediococcus pentosaceus Strains with Activity Against Clinical and Food-Borne Pathogens

Bacteriocins are ribosomal-synthesized peptides with antimicrobial activity, produced by different groups of bacteria, including lactic acid bacteria (LAB). Most of the produced by LAB bacteriocins can be described with rather broad spectra of inhibition and they offer suggested applications in food preservation and pharmaceutical sector. Different LAB were isolated from fermented food products and fruits, obtained from the region of Pohang, Korea, and identified based on physiological, biochemical, and molecular methods. The promising isolates, Pediococcus pentosaceus 732, Lactococcus lactis 808, and Lactococcus lactis subsp. lactis 431, were identified based on biochemical, physiological, and biomolecular approaches, including 16S rRNA partial sequencing, and were evaluated for production of bacteriocin, including stability in presence of enzymes, chemicals, pH, and temperatures. Adherence properties for the expressed bacteriocins by P. pentosaceus 732, Lc. lactis 808, and Lc. lactis subsp. lactis 431 were evaluated at presence of selected chemicals, pH, and temperatures. The presence of bacteriocin genes in the strains was investigated and analyzed. The bacterial effect of bacteriocin produced by studied strains on Listeria spp. and Staphylococcus spp. has been shown for actively growing and stationary cells. Similar growth and bacteriocin production were observed when studied strains were cultured in MRS at 30 °C or 37 °C. The presence of nisin operon with some point mutations on the genomic DNA was recorded based on the performed PCR reactions targeting different genes associated with nisin expression for both lactococcal strains. Pediocin PA-1 operon was evaluated in a similar manner for P. pentosaceus 732.

The potential of postbiotics as a novel approach in food packaging and biopreservation: a systematic review of the latest developments

Metabolic by-products are part of the so-called postbiotics of probiotics and other beneficial microorganisms, particularly lactic acid bacteria, which have gained popularity as a feasible alternative to improving food quality and safety. Postbiotics in dry and liquid forms can be easily integrated into food formulations and packaging materials, exhibiting antimicrobial and antioxidant effects owing to the presence of multiple antimicrobials, such as organic acids, bacteriocins, exopolysaccharides and bioactive peptides. Postbiotics can thus control the growth of pathogens and spoilage microorganisms, thereby extending the shelf life of food products. Because of their ability to be easily manufactured without requiring extensive processing, postbiotics are regarded as a safer and more sustainable alternative to synthetic preservatives, which can have negative environmental consequences. Additionally, food manufacturers can readily adopt postbiotics in food formulations without significant modifications. This systematic review provides an in-depth analysis of studies on the use of postbiotics in the biopreservation and packaging of a wide range of food products. The review evaluates and discusses the types of microorganisms, postbiotics preparation and modification techniques, methods of usage in dairy products, meat, poultry, seafood, fruits, vegetables, bread, and egg, and their effects on food quality and safety.

Bacteriocin and Antioxidant Production, a Beneficial Properties of Lactic Acid Bacteria Isolated from Fermented Vegetables of Northwest Bulgaria

Lactiplantibacillus plantarum ST01BG, ST07BG, ST10BG, and ST15BG; Latilactobacillus curvatus ST02BG; Lacticaseibacillus paracasei ST04BG; Pediococcus pentosaceus ST05BG; Leuconostoc mesenteroides ST06BG; and Enterococcus faecium ST11BG were isolated from home-made fermented vegetables from Northwest Bulgaria and identified by biochemical, physiological, and biomolecular analyses, including partial 16S rRNA sequencing. The strains were designated as bacteriocin producers and the expressed antimicrobials partially characterized with a focus on their proteinaceous nature, stability to different pH and temperatures. The bacteriocins were effective in inhibiting different strains of Listeria spp., Enterococcus spp. (including vancomycin resistant enterococci) and Staphylococcus spp. These strains can be considered safe, based on the evaluation of hemolytic activity, production of biogenic amines, mucin degradation, antibiotic susceptibility/resistance, and gelatinase enzyme production. Moreover, the strains can be considered potentially beneficial based on their stability and survival under simulated gastrointestinal tract conditions (stomach and duodenum), the production of diacetyl, and specific levels of hydrophobicity. Special attention was given to antioxidant properties (DPPH radical, hydroxyl radical, superoxide anion radical scavenging activity, Fe+2 ion chelating activity, and anti-lipid peroxidation) of the strains. Antioxidant properties were found to be strain specific. The beneficial attributes (antimicrobial and antioxidant) of these cultures to fermented food products may enable the reduction of chemical additives in line with consumers' demand for more natural and chemical-free food commodities.

Genomic, metabolomic, and functional characterisation of beneficial properties of Pediococcus pentosaceus ST58, isolated from human oral cavity

Bacteriocins produced by lactic acid bacteria are proteinaceous antibacterial metabolites that normally exhibit bactericidal or bacteriostatic activity against genetically closely related bacteria. In this work, the bacteriocinogenic potential of Pediococcus pentosaceus strain ST58, isolated from oral cavity of a healthy volunteer was evaluated. To better understand the biological role of this strain, its technological and safety traits were deeply investigated through a combined approach considering physiological, metabolomic and genomic properties. Three out of 14 colonies generating inhibition zones were confirmed to be bacteriocin producers and, according to repPCR and RAPD-PCR, differentiation assays, and 16S rRNA sequencing it was confirmed to be replicates of the same strain, identified as P. pentosaceus, named ST58. Based on multiple isolation of the same strain (P. pentosaceus ST58) over the 26 weeks in screening process for the potential bacteriocinogenic strains from the oral cavity of the same volunteer, strain ST58 can be considered a persistent component of oral cavity microbiota. Genomic analysis of P. pentosaceus ST58 revealed the presence of operons encoding for bacteriocins pediocin PA-1 and penocin A. The produced bacteriocin(s) inhibited the growth of Listeria monocytogenes, Enterococcus spp. and some Lactobacillus spp. used to determine the activity spectrum. The highest levels of production (6400 AU/ml) were recorded against L. monocytogenes strains after 24 h of incubation and the antimicrobial activity was inhibited after treatment of the cell-free supernatants with proteolytic enzymes. Noteworthy, P. pentosaceus ST58 also presented antifungal activity and key metabolites potentially involved in these properties were identified. Overall, this strain can be of great biotechnological interest towards the development of effective bio-preservation cultures as well as potential health promoting microbes.

Beneficial features of pediococcus: from starter cultures and inhibitory activities to probiotic benefits

Pediococci are lactic acid bacteria (LAB) which have been used for centuries in the production of traditional fermented foods. There fermentative abilities were explored by the modern food processing industry in use of pediococci as starter cultures, enabling the production of fermented foods with distinct characteristics. Furthermore, some pediococci strains can produce bacteriocins and other antimicrobial metabolites (AMM), such as pediocins, which are increasingly being explored as bio-preservatives in various food matrices. Due to their versatility and inhibitory spectrum, pediococci bacteriocins and AMM are being extensively researched not only in the food industry, but also in veterinary and human medicine. Some of the pediococci were evaluated as potential probiotics with different beneficial areas of application associated with human and other animals' health. The main taxonomic characteristics of pediococci species are presented here, as well as and their potential roles and applications as starter cultures, as bio-preservatives and as probiotic candidates.

Isolation, Characterization, and Effect on Biofilm Formation of Bacteriocin Produced by Lactococcus lactis F01 Isolated from Cyprinus carpio and Application for Biopreservation of Fish Sausage

The aim of this work was the screening of bacteriocin-producing LABs isolated from fish, the selection of promising/prominent strain(s), the characterization of the bacteriocin produced, and the evaluation of its potential to be used as biopreservative(s). Amplification and sequencing of the 16S rRNA gene of the bacteriocin-producing strain was performed. Then a partial purification of the produced bacteriocin, using a combination of ammonium sulfate and chloroform-methanol precipitation, was done. Its molecular weight was determined by SDS-PAGE. In addition, the action spectrum, the hemolysis test, and its ability to inhibit biofilm formation were analyzed. A total of 88 isolates of lactic acid bacteria (LAB) including one bacteriocin producer, which was identified as Lactococcus lactis F01, were collected. The bacteriocin was partially purified with an estimated yield of 40%. Regarding the SDS-PAGE profile, the secreted bacteriocin has molecular weight of about 3.5 kDa and was identified as class I bacteriocin. The antimicrobial test showed that the bacteriocin inhibits pathogenic and/or spoilage bacteria, 10 Gram-positive and 16 Gram-negative bacterial species. Moreover, it can inhibit biofilm formation from 1.3% (Escherichia coli) to 63.92% (Pseudomonas aeruginosa ATCC15692) depending on the strain. The hemolytic activity of novel bacteriocin was observed at the concentration of 10 μg/ml of bacteriocin crude extract, which was $0.7\pm 0.0029\%$ . In addition, it exhibited good thermal and pH stability with retained antibacterial activity of 85.25% after treatment at 121°C for 20 min, as well as at a pH range between 2.0 and 10.0. Moreover, this bacteriocin showed the ability to inhibit the growth of bacterial culture load in fish sausage stored at 8°C for 28 days. Considering the results obtained, bacteriocin could be potentially exploited as an alternative to chemical preservatives or as a substitute for antibiotics.

Novel pathways in bacteriocin synthesis by lactic acid bacteria with special reference to ethnic fermented foods

Ethnic fermented foods are known for their unique aroma, flavour, taste, texture and other sensory properties preferred by every ethnic community in this world culturally as parts of their eatables. Some beneficial microorganisms associated with fermented foods have several functional properties and health-promoting benefits. Bacteriocins are the secondary metabolites produced by the microorganisms mostly lactic acid bacteria present in the fermented foods which can act as lantibiotics against the pathogen bacteria. Several studies have been conducted regarding the isolation and characterization of potent strains as well as their association with different types of bacteriocins. Collective information regarding the gene organizations responsible for the potent effect of bacteriocins as lantibiotics, mode of action on pathogen bacterial cells is not yet available. This review focuses on the gene organizations, pathways include for bacteriocin and their mode of action for various classes of bacteriocins produced by lactic acid bacteria in some ethnic fermented foods.

Bacteriocins Produced by LAB Isolated from Cheeses within the Period 2009-2021: a Review

A survey is presented concerning original research articles published in well-reputed scientific journals on the isolation of lactic acid bacteria (LAB) from cheeses worldwide, where researchers evaluated the bacteriocin production by such isolates in searching for novel functional peptides that can exhibit potential for biotechnological applications. Seventy-one articles were published in the period of study, with contributions being American (45%), Asiatic (28%), and European (21%), being Brazil-USA-Mexico, Turkey-China, and France-Italy the countries that contributed the most for each said continent, respectively. Most of the isolated LAB belong to the genera Enterococcus (35%), Lactobacillus (30%), Lactococcus (14%), and Pediococcus (10%), coming from soft (64%), hard (27%), and semi-hard (9%) cheeses, predominantly. Also, scholars focused mainly on the food biopreservation (81%) and pharmaceutical field (18%) potential applications.

Bacteriocinogenic Potential of Bacillus amyloliquefaciens Isolated from Kimchi, a Traditional Korean Fermented Cabbage

Bacteriocin production is considered a favorable property for various beneficial cultures. In addition to their potential as biopreservatives, bacteriocins are also promising alternatives for the control of multidrug-resistant pathogens and the inhibition of some viruses and cancer cells. The objective of this study was to screen and characterize a bacteriocin-producing strain with the aim of its future application for control of Listeria monocytogenes, an important food-borne pathogen. A total of 22 potentially bacteriocinogenic strains active against L. monocytogenes ATCC15313 were isolated from locally produced kimchi through a three-level approach. Pure cultures were obtained according to good microbiological practices and differentiated through RAPD-PCR using the primers OPL01, OPL09, and OPL11. Altogether, 5 strains were selected for further study. Specific focus was given to strain ST05DL based on its specific inhibitory activity against L. monocytogenes ATCC15313, while not affecting different strains belonging to the genera Lactobacillus, Pediococcus, Leuconostoc, and Weissella, most of which are beneficial microorganisms. The strain ST05DL was identified as Bacillus amyloliquefaciens based on its sugar fermentation profile obtained through API50CHB analysis and 16S rRNA partial sequencing. The antimicrobial compound produced by B. amyloliquefaciens ST05DL was found to be sensitive to pepsin and α-chymotrypsin, evidence of its proteinaceous nature. The presence of skim milk, NaCl, Tween 80, glycerol, and SDS did not affect the antimicrobial activity. The addition of 20% cell-free supernatant (CFS) obtained from a 24-h culture of B. amyloliquefaciens ST05DL to an exponentially growing culture of L. monocytogenes ATCC15313 successfully inhibited the test microorganisms during the monitored 10-h incubation. Optimal bacteriocin production by B. amyloliquefaciens ST05DL was observed during the stationary phase at 12 h (800 AU/mL) and remained stable for the next 15 h. The ratio between live and dead cells during this period was 74.37% and 25.66%, respectively, as determined by flow cytometry. The presence of the virulence genes hblA, hblB, hblC, nheA, nheB, and nheC was not detected in the total DNA of B. amyloliquefaciens ST05DL, and the strain was resistant only to ampicillin out of 10 tested antibiotics. Future evaluation of expressed bacteriocin/s by B. amyloliquefaciens ST05DL (amino acid sequence, molecular mass, cytotoxicity, detailed mode of action, etc.), will be the next step in the characterization and its potential application as biopreservative and/or pharmaceutical product.

Bacteriocin production by Leuconostoc citreum ST110LD isolated from organic farm soil, a promising biopreservative

AIMS

The objective of this study was to isolate a bacteriocin-producing strain and to characterize the expressed bacteriocin for the control of Listeria monocytogenes with aim of biopreservation application.

METHODS AND RESULTS

Soil samples from a Korean organic farm were subjected to microbiological analysis for isolation of potential bacteriocinogenic LAB, based on a three-level approach, using L. monocytogenes ATCC 15313 as an indicator test micro-organism. From a total of 17 isolates with inhibitory potential, seven were confirmed to be bacteriocin producers. The selected isolates were differentiated based on their morphology, catalase reaction, sugar fermentation profile obtained by API50CHL and by RAPD-PCR generating two unique profiles. One of the isolates, ST110LD, a specific strong producer of anti-Listeria bacteriocins (12 800 AU ml^-1 ) was identified as Leuconostoc citreum. The proteinaceous nature of the inhibitory compound produced by Leuc. citreum ST110LD was confirmed through treatment with pepsin and α-chymotrypsin. Bacteriocin activity was observed to be not affected by the presence of milk, NaCl, SDS, Tween 80 or glycerol. Bacteriocin ST110LD effectively inhibited the growth of exponentially growing L. monocytogenes ATCC 15313 during a 10-h incubation period in BHI at 37°C. In addition, this bacteriocin showed specific inhibition of only Listeria spp., but did not inhibit the growth of beneficial cultures included in the microbial test panel for assessment of the spectrum of activity.

CONCLUSIONS

Leuconostoc citreum ST110LD was evaluated as safe bacterium strain, producing bacteriocin with high specificity against listerial and enterococcal species. Specificity of producer strain and expressed bacteriocin can be explored in biopreservation of different fermented food products or applied in biotherapy of antibiotic resistant listerial or enterococcal infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the best of our knowledge, this is the first report of bacteriocin produced by Leuc. citreum strain with highly specific antimicrobial activity against Listeria sp. and Enterococcus sp.

Evaluation of Pediococcus pentosaceus SP2 as Starter Culture on Sourdough Bread Making

In the present study, a novel Pediococcus pentosaceus SP2 strain, recently isolated from kefir grains, was evaluated as a starter culture in sourdough bread making. The novel starter was applied in fresh, freeze-dried, and freeze-dried immobilized (on wheat bran) form. The type of culture (fresh, freeze-dried, immobilized cells) influenced the bread characteristics. Specifically, the application of freeze-dried immobilized cells led to higher total titratable acidity (TTA) values (9.81 mL NaOH N/10), and the produced bread presented higher resistance to mold and rope spoilage. Moreover, the produced sourdough breads were significantly better in terms of pH, TTA, organic acids content, and resistance to mold and rope spoilage, compared to breads made with a commercial, wild microbiota, sourdough. The organic acids content was also significantly higher than the commercial sourdough sample (2.93 g/kg lactic acid; 1.01 g/kg acetic acid). Determination of volatile compounds through solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) analysis and sensorial assessments indicated no significant differences between the tested sourdough breads.

Enhanced Bacteriocin Production by Pediococcus pentosaceus 147 in Co-culture With Lactobacillus plantarum LE27 on Cheese Whey Broth

The production of bacteriocins by lactic acid bacteria (LAB) has been of wide interest in the food industry due to their potential application in biopreservation. The production of bacteriocins is usually low in single strain fermentation, but can improve when the bacteriocinogenic strain is cultured in association with another bacteria. The present work aims to evaluate the growth and production of bacteriocins by Pediococcus pentosaceus 147 (bacteriocinogenic strain) in co-culture with Lactobacillus plantarum LE27 (inducer strain) using a culture medium based on cheese whey (CW). Strains were inoculated in co-culture in a CW broth at 7.24 Log CFU/mL of initial concentration of P. pentosaceus 147 and incubated at 37°C. Bacteriocin production was measured after 24 h by the critical dilution method, biomass was measured by plating on MRS agar (1% aniline blue), and a mono-culture was used as a control. The titers of bacteriocins produced by P. pentosaceus 147 in mono-culture were 19,200 AU/mL lower than those obtained in co-culture with Lb. plantarum LE27 at 51,200 AU/mL. The effect of adding the inducer strain at different times of incubation (3, 6, 9, and 12 h) was evaluated, with the addition of the induction factor at the beginning of the incubation of P. pentosaceus 147 generating the highest bacteriocin activity. This study shows the potential of inducing bacteriocinogenesis using co-cultures of strains of the genera Pediococcus and Lactobacillus and using alternative substrates such as cheese whey.