Bacteriocin-producing Lactic Acid Bacteria Research Articles

Improving the Functionality of Yogurt after Fortification with a Synbiotic Combination of a Potential Probiotic and Bacteriocin-Producing Bacteria and Hydnora abyssinica Phytosomes

Functional dairy products are attracting consumers’ attention, as they simultaneously have nutritional and health benefits. Hence, we aimed in this study to fortify a dairy product (yogurt) with phytosomes of extract from Hydnora abyssinica (a holoparasitic plant that has ethnobotanical value) and a potential bacteriocin-producing probiotic lactic acid bacterium (LAB). Goat cheese was screened for LAB with promising antimicrobial activity, and the safety and probiotic potential of the selected isolate were studied. As a result, strain GA5 was selected due to its wide antimicrobial activity that was suggested to be caused by bacteriocin production. Moreover, this strain showed promising stress tolerance, in vitro antioxidant activity (95 ± 2.8%), and hydrophobic potential (87.18 ± 3.43%). Strain GA5 was molecularly identified as Lactiplantibacillus plantarum GA5. On the other hand, a hydromethanolic extract was prepared from H. abyssinica flowers, and its prebiotic potential and polyphenol content were evaluated. This extract was also encapsulated in phytosomes. Then, the physical and morphological characteristics of prepared phytosomes were studied. Yogurt fortified with these ingredients (L. plantarum GA5 together with free H. abyssinica extract or its extract encapsulated in phytosomes) showed higher antioxidant content, viscosity, texture profile, and sensory properties than the control. Furthermore, the yogurt remained unspoiled for over 21 days, indicating that the added ingredients prolonged its shelf life. As far as we know, this is the first study describing the fortification of yogurt with H. abyssinica phytosomes and a potential bacteriocin-producing probiotic LAB.

BACTERIOCIN PRODUCED BY LACTIC ACID BACTERIA: A PROBIOTIC

Chemical preservatives, usually used during the long period, to protect the food materials by controlling undesirable bacteria and harmful spoiler, have been proved as toxic to human health. Conscious consumers have serious awareness to purchase safe foods without chemical additives. In the recent years, bio-preservation is gained increasing attention to harmonize consumer demands along with standard food quality. Various attempts are growing on the use of micro-organisms or their antimicrobial metabolites for the protection of food products. The bacteriocins produced by lactic acid bacteria (LAB) have a relatively broad antimicrobial spectrum against variety of food-borne pathogenic and spoilage bacteria. Bacteriocin-producing lactic acid bacteria or bacteriocins can be used in foods as bio-preservatives. The review is focused on bacteriocin produced by lactic acid bacteria.

Complete genome sequence of Ligilactobacillus agilis LDTM47, bacteriocin-producing lactic acid bacteria isolated from broiler gastrointestinal tract

Complete genome sequence of Ligilactobacillus agilis LDTM47, bacteriocin-producing lactic acid bacteria isolated from broiler gastrointestinal tract

Bacteriocin producing lactic acid bacteria from camel milk and its fermented products: A review

Bacteriocin producing lactic acid bacteria from camel milk and its fermented products: A review

Essential Oils and Their Combination with Lactic Acid Bacteria and Bacteriocins to Improve the Safety and Shelf Life of Foods: A Review.

The use of plant extracts (e.g., essential oils and their active compounds) represents an interesting alternative to chemical additives and preservatives applied to delay the alteration and oxidation of foods during their storage. Essential oils (EO) are nowadays considered valuable sources of food preservatives as they provide a healthier alternative to synthetic chemicals while serving the same purpose without affecting food quality parameters. The natural antimicrobial molecules found in medicinal plants represent a possible solution against drug-resistant bacteria, which represent a global health problem, especially for foodborne infections. Several solutions related to their application on food have been described, such as incorporation in active packaging or edible film and direct encapsulation. However, the use of bioactive concentrations of plant derivatives may negatively impact the sensorial characteristics of the final product, and to solve this problem, their application has been proposed in combination with other hurdles, including biocontrol agents. Biocontrol agents are microbial cultures capable of producing natural antimicrobials, including bacteriocins, organic acids, volatile organic compounds, and hydrolytic enzymes. The major effect of bacteriocins or bacteriocin-producing LAB (lactic acid bacteria) on food is obtained when their use is combined with other preservation methods. The combined use of EOs and biocontrol agents in fruit and vegetables, meat, and dairy products is becoming more and more important due to growing concerns about potentially dangerous and toxic synthetic additives. The combination of these two hurdles can improve the safety and shelf life (inactivation of spoilage or pathogenic microorganisms) of the final products while maintaining or stabilizing their sensory and nutritional quality. This review critically describes and collects the most updated works regarding the application of EOs in different food sectors and their combination with biocontrol agents and bacteriocins.

Dual Role of Probiotic Lactic Acid Bacteria Cultures for Fermentation and Control Pathogenic Bacteria in Fruit-Enriched Fermented Milk.

The food industry has been developing new products with health benefits, extended shelf life, and without chemical preservation. Bacteriocin-producing lactic acid bacteria (LAB) strains have been evaluated for food fermentation to prevent contamination and increase shelf life. In this study, potentially probiotic LAB strains, Lactiplantibacillus (Lb.) plantarum ST8Sh, Lacticaseibacillus (Lb.) casei SJRP38, and commercial starter Streptococcus (St.) thermophilus ST080, were evaluated for their production of antimicrobial compounds, lactic acid and enzyme production, carbohydrate assimilation, and susceptibility to antibiotics. The characterization of antimicrobial compounds, the proteolytic activity, and its inhibitory property against Listeria (List.) monocytogenes and Staphylococcus (Staph.) spp. was evaluated in buriti and passion fruit-supplemented fermented milk formulations (FMF) produced with LAB strains. Lb. plantarum ST8Sh was found to inhibit List. monocytogenes through bacteriocin production and produced both L(+) and D(-) lactic acid isomers, while Lb. casei SJRP38 mainly produced L(+) lactic acid. The carbohydrate assimilation profiles were compatible with those usually found in LAB. The potentially probiotic strains were susceptible to streptomycin and tobramycin, while Lb. plantarum ST8Sh was also susceptible to ciprofloxacin. All FMF produced high amounts of L(+) lactic acid and the viability of total lactobacilli remained higher than 8.5 log CFU/mL during monitored storage period. Staph. aureus ATCC 43300 in fermented milk with passion fruit pulp (FMFP) and fermented milk with buritipulp (FMB), and Staph. epidermidis KACC 13234 in all formulations were completely inhibited after 14days of storage. The combination of Lb. plantarum ST8Sh and Lb. casei SJRP38 and fruit pulps can provide increased safety and shelf-life for fermented products, and natural food preservation meets the trends of the food market.

Identification of lactic acid bacteria with anti-listeria activity. Characterization and application of a bacteriocinogenic strain in the control of Listeria monocytogenes in cheese.

The purpose of the research paper was firstly to identify bacteriocin-producing lactic acid bacteria characterizing strains with anti-listeria activity and, secondly, to characterize bacteriocin evaluating its in vitro efficiency as a natural preservative and, thirdly, to evaluate the anti-listeria effect of the bacteriocinogenic strain of Lactiplantibacillus plantarum in cheeses and produce an edible film with anti-listerial effect. Of 355 lactic acid bacteria strains tested, two were able to produce bacteriocin against Listeria monocytogenes and were identified as Lactiplantibacillus plantarum and Lactiplantibacillus pentosus. A bactericidal effect of strain QS494 (Lactiplantibacillus plantarum) was observed in the first 8 h, with a reduction of 1.7 log, using cell-free supernatant with Listeria monocytogenes, where viable cells were counted on listeria selective agar. Both strains showed good technological characteristics and were without production of virulence factors. Changes in the pH of the cell-free supernatant obtained from Lactiplantibacillus plantarum did not affect its antimicrobial activity, which remained stable after heat treatments for up to 15 min at 121°C. Inhibitory activity was also observed after 12 weeks of storage at -20°C. In the evaluation of the anti-listeria effect in cheeses, a 3 log reduction in the Listeria monocytogenes count was observed in 120 h in cheeses produced with bacteriocinogenic lactic acid bacteria, while in cheeses produced with non-bacteriocinogenic culture, we observed a 2 log increase in the count. Edible films produced with the addition of precipitate from the cell free supernatant showed an antimicrobial effect against Listeria monocytogenes. Thus, the two strains studied have technological and biosafety potential.

Bacteriocin production and technological properties of Enterococcus mundtii and Enterococcus faecium strains isolated from sheep and goat colostrum.

Enterococci are lactic acid bacteria (LAB) that play a role in the aroma formation, maturation, and sensory development of fermented foods such as meat and dairy products. They also contribute to the improvement of the extended shelf life of fermented foods by producing bacteriocin. The aim of this study was to isolate bacteriocin-producing LAB from sheep and goat colostrum, to characterize the bacteriocin-producing strains, and determine the technological properties of the strains. A total of 13 bacteriocin-producing LAB was isolated and identified as 11 Enterococcus mundtii and two Enterococcus faecium. The strains were found to be genetically different from each other by phylogenetic analysis of 16S rRNA gene sequences and random amplified polymorphic-DNA (RAPD-PCR). It has been determined that bacteriocins show activity in a wide pH range and are resistant to heat, lose their activity with proteolytic enzymes and α-amylase, but are resistant to detergents. While the presence of the munKS gene was detected in all of the strains, it was determined that E. faecium HC121.4, HC161.1, E. mundtii HC147.1, HC166.5, and HC166.8 strains contained multiple enterocin genes. Trisin-SDS-PAGE analysis revealed two active protein bands of approximately 5.1 and 5.5kDa in E. faecium HC121.4 and one active protein band with a weight of approximately 4.96kDa in other strains. E. mundtii strains and E. faecium HC161.1 were identified as mundticin KS producers, and E. faecium HC121.4 was defined as an enterocin A and B producer. Except for E. mundtii HC166.8, acid production of strains was found to be slow at 6h and moderate at 24h. None of them showed extracellular proteolytic and lipolytic activities. It was found that the strains had esterase, esterase lipase, leucine arylamidase, acid phosphatase, and naphthol-AS-Bl-phosphohydrolase activities, while protease activities were low and peptidase activities were high. In conclusion, bacteriocin producer 13 Enterococcus strains isolated from sheep and goat colostrum were found to have the potential to be included in starter culture combinations.

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 ± 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.

Inhibition of Listeria monocytogenes in Fresh Cheese Using a Bacteriocin-Producing Lactococcus lactis CAU2013 Strain.

In recent years, biocontrol of foodborne pathogens has become a concern in the food industry, owing to safety issues. Listeria monocytogenes is one of the foodborne pathogens that causes listeriosis. The major concern in the control of L. monocytogenes is its viability as it can survive in a wide range of environments. The purpose of this study was to isolate lactic acid bacteria with antimicrobial activity, evaluate their applicability as a cheese starter, and evaluate their inhibitory effects on L. monocytogenes. Lactococcus lactis strain with antibacterial activity was isolated from raw milk. The isolated strain was a low acidifier, making it a suitable candidate as an adjunct starter culture. The commercial starter culture TCC-3 was used as a primary starter in this study. Fresh cheese was produced using TCC-3 and L. lactis CAU2013 at a laboratory scale. Growth of L. monocytogenes (5 Log CFU/g) in the cheese inoculated with it was monitored during the storage at 4°C and 10°C for 5 days. The count of L. monocytogenes was 1 Log unit lower in the cheese produced using the lactic acid bacteria strain compared to that in the cheese produced using the commercial starter. The use of bacteriocin-producing lactic acid bacteria as a starter culture efficiently inhibited the growth of L. monocytogenes. Therefore, L. lactis can be used as a protective adjunct starter culture for cheese production and can improve the safety of the product leading to an increase in its shelf-life.

Efficacy of Bacteriocin Producing Lactic Acid Bacteria Isolated from Ugba and Okpiye Against some Selected Bacterial Food Spoilage Agents

Numerous food products owe their production and characteristics to the fermentative activities of microorganisms. Bacteriocins are antimicrobial proteins produced by bacteria that kill or inhibit the growth of other related species. Lactic acid producing bacteria were isolated from Ugba and Okpiye using standard methods. The test organisms used were Staphylococcus aureus, Pseudomonas aeruginosa (VRFPA04) and Escherichia coli (ST2747) Fifty (50) samples of Ugba and Okpiye were collected and evaluated for the presence of bacteriocin lactic acid producers using a selective medium; De Mann Rogosa Sharpe (MRS) agar. A total of 288 isolates was isolated from the two traditional food condiments; 148 from ugba and 140 from Okpiye. It was observed that the total lactic acid bacterial count in Ugba ranges from 5.80 x 104 to 1.7 x 107 cfu/ml on MRS medium; while that of Okpiye ranges from 5.0 x 104 to 2.0 x 107 cfu/ml on MRS medium. Lactic acid bacterial count was higher in Ugba than in Okpiyeconsidering the mode of storage in the market. The highest inhibitory activity was demonstrated against E. coli in Ugba sample while the least activity was demonstrated against P. aeuroginosa, also a significant high level of inhibition was shown against S. aureus while P. aeuroginosa and E. coli had little or no inhibitory activities recorded for Okpiye samples. The bacteriocin producers isolated from Ugba and Okpiye (U5, U6, OK1, OK2, OK3 and OK4) were identified as Lactobacillus sp and Lactococcus sp based on their morphological and biochemical characteristics. The antibacterial activity of the bacteriocins produced by the lactic acid bacteria has potential for use in biopreservation of condiments against food spoilage agents.

Biosynthesis and Production of Class II Bacteriocins of Food-Associated Lactic Acid Bacteria

Bacteriocins are ribosomally synthesized peptides made by bacteria that inhibit the growth of similar or closely related bacterial strains. Class II bacteriocins are a class of bacteriocins that are heat-resistant and do not undergo extensive posttranslational modification. In lactic acid bacteria (LAB), class II bacteriocins are widely distributed, and some of them have been successfully applied as food preservatives or antibiotic alternatives. Class II bacteriocins can be further divided into four subcategories. In the same subcategory, variations were observed in terms of amino acid identity, peptide length, pI, etc. The production of class II bacteriocin is controlled by a dedicated gene cluster located in the plasmid or chromosome. Besides the pre-bacteriocin encoding gene, the gene cluster generally includes various combinations of immunity, transportation, and regulatory genes. Among class II bacteriocin-producing LAB, some strains/species showed low yield. A multitude of fermentation factors including medium composition, temperature, and pH have a strong influence on bacteriocin production which is usually strain-specific. Consequently, scientists are motivated to develop high-yielding strains through the genetic engineering approach. Thus, this review aims to present and discuss the distribution, sequence characteristics, as well as biosynthesis of class II bacteriocins of LAB. Moreover, the integration of modern biotechnology and genetics with conventional fermentation technology to improve bacteriocin production will also be discussed in this review.

Complete genome sequences of Lactococcus lactis JNU 534, a potential food and feed preservative.

A new bacteriocin-producing lactic acid bacteria isolated from kimchi was identified as Lactococcus lactis JNU 534, presenting preservative properties for foods of animal origin. In this study, we present the complete genome sequence of the bacterial strain JNU 534. The final complete genome assembly consists of one circular chromosome (2,443,687 bp [base pair]) with an overall GC (guanine-cytosine) content of 35.2%, one circular plasmid sequence (46,387 bp) with a GC content of 34.5%, and one circular contig sequence (7,666 bp) with a GC content of 36.2%.

Bacteriocin-Producing Lactic Acid Bacteria Strains with Antimicrobial Activity Screened from Bamei Pig Feces.

Lactic acid bacteria (LAB), which are characterized by producing various functional metabolites, including antioxidants, organic acids, and antimicrobial compounds, are widely used in the food industry to improve gut health and prevent the growth of spoilage microorganisms. With the continual incidence of foodborne disease and advocacy of consumers for gut health, LAB have been designated as vital biopreservative agents in recent years. Therefore, LAB with excellent antimicrobial properties and environmental tolerance should be explored further. In this study, we focus on screening the LAB strains from a specialty pig (Bamei pig) feces of the Tibetan plateau region and determine their antimicrobial properties and environmental tolerance to evaluate their potential probiotic values. A total of 116 LAB strains were isolated, from which the LAB strain Qinghai (QP)28-1 was identified as Lactiplantibacillus (L.) plantarum subsp. plantarum using 16S rDNA sequencing and recA amplification, showing the best growth capacity, acid production capacities, environmental tolerance, hydrophobicity, antibiotic susceptibility, and bacteriocin production capacity. Furthermore, this strain inhibited the growth of multiple pathogens by producing organic acids and bacteriocin. These bacteriocin-encoding genes were identified using PCR amplification, including plnS, plnN, and plnW. In conclusion, bacteriocin-producing L. plantarum subsp. plantarum QP28-1 stands out among these 116 LAB strains, and was considered to be a promising strain used for LAB-related food fermentation. Moreover, this study provides a convenient, comprehensive, and shareable profile for screening of superior functional and bacteriocin-producing LAB strains, which can be used in the food industry.

Combating biofilms of foodborne pathogens with bacteriocins by lactic acid bacteria in the food industry.

Most foodborne pathogens have biofilm-forming capacity and prefer to grow in the form of biofilms. Presence of biofilms on food contact surfaces can lead to persistence of pathogens and the recurrent cross-contamination of food products, resulting in serious problems associated with food safety and economic losses. Resistance of biofilm cells to conventional sanitizers urges the development of natural alternatives to effectively inhibit biofilm formation and eradicate preformed biofilms. Lactic acid bacteria (LAB) produce bacteriocins which are ribosomally synthesized antimicrobial peptides, providing a great source of nature antimicrobials with the advantages of green and safe properties. Studies on biofilm control by newly identified bacteriocins are increasing, targeting primarily onListeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli. This review systematically complies and assesses the antibiofilm property of LAB bacteriocins in controlling foodborne bacterial-biofilms on food contact surfaces. The bacteriocin-producing LAB genera/species, test method (inhibition and eradication), activity spectrum and surfaces are discussed, and the antibiofilm mechanisms are also argued. The findings indicate that bacteriocins can effectively inhibit biofilm formation in a dose-dependent manner, but are difficult to disrupt preformed biofilms. Synergistic combination with other antimicrobials, incorporation in nanoconjugates and implementation of bioengineering can help to strengthen their antibiofilm activity. This review provides an overview of the potential and application of LAB bacteriocins in combating bacterial biofilms in food processing environments, assisting in the development and widespread use of bacteriocin as a promising antibiofilm-agent in food industries.

Lactobacillus plantarumprotective cultures to improve safety and quality of wheyless Domiati‐like cheese

This study aimed to isolate some lactic acid bacteria (LAB) with potential antimicrobial activity against Staphylococcus aureus (S. aureus) to be used as a protective culture for the manufacture of Domiati-like cheese. Eight isolates with anti-staphylococcal activity were identified as Lactobacillus plantarum (L. plantarum FFNL739 and FFNL1810) and one as Enterococcus faecium (E. farcium). Strains FFNL739 and FFNL1810 and their mixture were used as protective cultures to control S. aureus in Domiati like-cheese. The impact of both strains and their mixture on some ripening indices and sensory attributes of cheese was assessed during 8 weeks of refrigerated storage at 6±1°C. The inclusion of L. plantarum could suppress the growth of S. aureus and improve the overall acceptability, proteolysis, and lipolysis. Thus, it could be recommended to use the mixed culture of strains FFNL739 and FFNL1810 to improve the safety and quality of Domiati cheese. Practical applications There is a growing demand among consumers for chemical-free products especially those used as preservatives. Lactic acid bacteria can produce a wide variety of antimicrobial molecules, particularly bacteriocins. These natural antimicrobials are secure and could consider a good alternative to chemical preservatives. The application of bacteriocin-producing lactic acid bacteria is the main strategy of food bio-preservation. This approach is applicable, cheap, and efficient to extend the shelf-life of minimally processed and ready-to-eat products. Also, biopreservation proves to be able to improve quality, hygienic status, and improved safety of foods.

Detection of Beneficial Lactic Acid Bacteria (LAB) and Yeast In Sarawak Fermented Food

Sarawak native’s fermented food can be a catalyst for boosting the local economy in Sarawak. The Lactic Acid Bacteria (LAB) are generally regarded as safe, have a stability of usage, and originate from natural resources. Lactic acid bacteria and yeast work in synergy to provide a natural way to enhance the nutritive value and flavour of the food. The study aims to investigate the presence of potential probiotic Lactic Acid Bacteria (LAB) and yeast isolated from Sarawak fermented food. Two hundred fifty (n=250) of samples including fifty (n=50) each sample such as fermented shrimps (cencaluk), fermented mustard vegetables (kasam ensabii), fermented fish (kasam ikan), fermented dabai (Canarium odontophyllum) and fermented fish (rusip). Molecular identification of the bacteria and yeast isolates was carried out by PCR amplification of the 16S rRNA (27F and 1492-R) and ITS (ITS5-F and ITS4-R) rRNA region. The successfully amplified PCR products were sent for Sanger sequencing As a result, a total of 45.2% (113/250) Lactic Acid Bcateria (LAB) which are 96% (48/50) of W. paramesenteroides was detected in fermented dabai, 80% (40/50) S. pasteuri in fermented fish rusip samples and 50% (25/50) in P. agglomerans in cencaluk samples. Meanwhile, yeast Candida species; 90% (45/50) of C. magnoliae and 50% (25/50) of C. parapsilosis are detected in fermented dabai and ensabi respectively. Based on the findings, both yeast and bacteriocin-producing lactic acid bacteria found in the fermented food specifically in dabai. A better understanding of microbial ecology can help the food industry to improve the foods in terms of quality and safety. The good quality of the LAB and yeast in the food such as starter culture will enhance the texture and nutritional value and Sarawak fermented food product found enriched with LAB.

Application of an alginate-based edible coating with bacteriocin-producing Lactococcus strains in fresh cheese preservation

Edible coatings incorporated with bacteriocin-producing lactic acid bacteria (LAB) can provide an alternative natural preservation method as they can offer an additional microbiological protection to food products. The bacteriocin-producing strains Lactococcus lactis L3A21M1 and Lc. garvieae SJM17 isolated from artisanal Azorean cheeses were incorporated into an edible fresh-cheese coating composed of alginate, maltodextrin and glycerol. The immobilization of Lactococcus cells into the coating had no negative effect on their viability and antibacterial activity throughout 10 days storage at 4 °C and 10 °C. The application of coating with immobilized Lactococcus cells on cheeses reduced significantly (p < 0.05) the contamination by Listeria monocytogenes on surface and prevented the growth of mesophilic bacteria by the 6th and 8th day of storage at 4 °C. Moreover, the coating reduced moisture and weight losses of fresh cheeses during storage, without affecting the pH and titratable acidity. The coating also prevented the migration of L. monocytogenes from the surface into the cheeses. These findings indicate that alginate-maltodextrin-glycerol formulation provided an excellent matrix to support Lactococcus cells viability and bacteriocin production. This bioactive coating can act as protective antimicrobial barrier in fresh cheeses by reducing bacterial contamination after processing.

A Review of Lactic Acid Bacteria and their Bacteriocins: Classification, Biosynthesis, and Mechanism against Oral Pathogens

Lactic acid bacteria produce substances such as bacteriocins which inhibit the growth of pathogens. Their application holds promises in protecting the human body against pathogens provided that the strains used are suitable and appropriate. Oral pathogens affect the local and even the systemic health of an individual. Dental caries, gingivitis and periodontitis are the most common diseases related to these pathogens, but they are also associated with worsening systemic diseases such as diabetes, cardiovascular disease and bacterial pneumonia. Another concern is that they are developing a resistance against antibiotics. The aim of this paper is to review the characteristics and capabilities of bacteriocin-producing lactic acid bacteria isolates to control oral pathogens. A narrative approach was used to classify the biosynthesis and application of the antimicrobial producing LAB in the oral cavities. A total of 6,028 articles from Google Scholar, PubMed and Mendeley were gathered and screened based on the criteria of this paper. The final articles included were 17. Through analysis of the gathered data, this review suggests that LAB can potentially inhibit oral pathogens and therefore maintain homeostasis of the oral flora. Since LAB are now relevant for their emerging applications in the prevention of infection and amelioration, further studies on the effect against oral pathogens are needed.

Evaluation of Enterococcus strains newly isolated from Egyptian sources for bacteriocin production and probiotic potential

Screening for bacteriocin-producing lactic acid bacteria (LAB) showing probiotic properties is of high significance due to their applications in food, and health fields. Hence, the aim of the current study was to isolate, identify, and study the in vitro probiotic properties, antimicrobial and antioxidant activities of LAB isolates obtained from Egyptian sources. Out of 79 isolated bacteria, 53 isolates were selected as potential LAB and their antimicrobial activities were investigated. Seven out of them (isolates 33, 34, and 35 from feces of Nile Lechwe, and isolate 42 from feces of Grant's zebra) exhibited wide antimicrobial spectra, which were caused by a proteineous compound that were suggested to be bacteriocin. These isolates are nominated as potential probiotic strains due to their high pH tolerance and good thermal stability. Moreover, they exhibited high in vitro antioxidant activities by recording 84.47 ± 1.83, 86.84 ± 0.93, 82.37 ± 1.11, and 83.16 ± 0.84% DPPH scavenging activity, respectively. Furthermore, isolates 33, 34, and 35 showed high in vitro hydrophobic properties, which reached 93.93 ± 0.83, 87.75 ± 1.75, and 80.20 ± 1.40%, respectively. Isolates were identified using 16S rRNA sequencing as Enterococcus faecium except for isolate 10, which was classified to Enterococcus hirae. These results nominated Egyptian sources as a promising repository for potent LAB. This is the first study describing bacterial isolates from Egyptian zoo samples as potential bacteriocin producers, possible probiotic strains, and antioxidant agents,. Further studies are encouraged to evaluate the in vivo potency of these isolates for future application as antioxidant dietary supplements for feeding and treatment of human and animals.