Characterization Of Lactic Acid Bacteria Research Articles

Probiotic Characteristics of Lactic Acid Bacteria Isolated From Sui Wu’u: A Traditional Food from Bajawa, West Flores, Indonesia

The probiotic potential of lactic acid bacteria originating from traditional food will always be a concern for researchers, along with increasing public awareness of health. One source of LAB isolates with probiotic potential is traditional food. This study aims to investigate the probiotic potential of lactic acid bacteria from Sui Wu’u, a traditional food-based pork originating from Bajawa, East Nusa Tenggara, Indonesia. Sui Wu’u was prepared based on method of the Bajawa community and was analyzed after being stored for six months. Total LAB, morphological, and phenotypic identification was carried out as well as testing the ability of isolates to ferment sugar. Probiotics potency was tested on resistance to low pH and gastric acid, resistance to pathogenic bacteria, and exposure to antibiotics. The results indicated that LAB isolated from Sui Wu’u were dominated by the coci form. The four selected isolates had resistance with a survival rate of 88.3%–96.88% when exposed to pH 2.5 and a survival rate of 98.69%–99.03% when exposed to bile salts at 0.3%. Moderate resistance was exhibited by all isolates against E. coli, S. typhimurium, and S. aureus, while no resistance was observed against B. cereus. All strains demonstrated sensitivity to tetracycline, ampicillin, and chloramphenicol but exhibited resistant to streptomycin. All four isolates were identified as Lactococcus lactis. These results show that four strains of Sui Wu’u have demonstrated their potential as probiotics.

Motility in Periweissella Species: Genomic and Phenotypic Characterization and Update on Motility in Lactobacillaceae.

The genus Weissella and the recently described genus Periweissella, to which some previously named Weissella species have been reclassified as a result of a taxogenomic assessment, includes lactic acid bacteria species with high biotechnological and probiotic potential. Only one species, namely, Periweissella (P.) beninensis, whose type strain has been shown to possess probiotic features, has so far been described to be motile. However, the availability of numerous genome sequences of Weissella and Periweissella species prompted the possibility to screen for the presence of the genetic determinants encoding motility in Weissella and Periweissellas spp. other than P. beninensis. Herein, we performed a comprehensive genomic analysis to identify motility-related proteins in all Weissella and Periweissella species described so far, and extended the analysis to the recently sequenced Lactobacillaceae spp. Furthermore, we performed motility assays and transmission electron microscopy (TEM) on Periweissella type strains to confirm the genomic prediction. The homology-based analysis revealed genes coding for motility proteins only in the type strains of P. beninensis, P. fabalis, P. fabaria and P. ghanensis genomes. However, only the P. beninensis type strain was positive in the motility assay and displayed run-and-tumble behavior. Many peritrichous and long flagella on bacterial cells were visualized via TEM, as well. As for the Lactobacillaceae, in addition to the species previously described to harbor motility proteins, the genetic determinants of motility were also found in the genomes of the type strains of Lactobacillus rogosae and Ligilactobacillus salitolerans. This study, which is one of the first to analyze the genomes of Weissella, Periweissella and the recently sequenced Lactobacillaceae spp. for the presence of genes coding for motility proteins and which assesses the associated motility phenotypes, provides novel results that expand knowledge on these genera and are useful in the further characterization of lactic acid bacteria.

Characterization of Lactic Acid Bacteria and Yeast from Grains as Starter Cultures for Gluten-Free Sourdough.

With the increasing number of people affected by gluten consumption-related diseases, adhering to a gluten-free (GF) diet is the most effective preventive measure. Herein, we aimed to isolate and characterize the functional properties of autochthonous lactic acid bacteria (LAB) and yeast from various GF sourdoughs to determine their suitability in starter cultures for sourdough preparation. Three LAB, Weissella confusa BAQ2, Lactobacillus brevis AQ2, Leuconostoc citreum YC2, and Saccharomyces cerevisiae BW1, were identified. The isolated LAB exhibited greater TTA, faster acidification rates, and higher acid tolerance than commercial LAB. W. confusa BAQ2 exhibited the highest EPS production, W. confusa BAQ2 and L. brevis AQ2 showed high maltose utilization, and S. cerevisiae BW1 exhibited the highest CO2 production rate. Accordingly, all four microbial strains were mixed for the starter culture. The sourdough prepared with starter cultures exhibited differences in gas production depending on fermentation time, which influenced the volume of GF bread dough. GF bread prepared with fermented sourdough exhibited a 16% higher specific volume and enhanced crumb firmness and elasticity than that prepared using non-fermented sourdough. Thus, autochthonous LAB strains isolated from various GF sourdoughs can be used together to improve the quality of sourdough bread, demonstrating their potential for use in starter cultures for GF sourdough production.

Molecular Characterization of Lactic Acid Bacteria in Bakery and Pastry Starter Ferments.

Bread is the oldest and most essential food consumed by humans, with its consumption exceeding nutritional needs and becoming part of cultural habits. Fermentation is an important step in the bread-making process, giving it its rheological, organoleptic, aromatic, and nutritional properties. Lactic acid bacteria and yeasts are both responsible for the fermentation step and part of the natural flour microbiota. In this study, we aimed to characterize LAB in three types of flour, namely, wheat, oat, and rice flour, using conventional phenotypic and biochemical assays and to carry out molecular-biology-based characterization via studying the rrn Operon using RFLP of the ITS region and via PCR using species-specific primers. Additionally, the effect of LAB diversity among the three types of flour and their influence on dough characteristics were assessed. Also, we evaluated the antagonistic effects of LAB on two bacterial (E. coli and S. aureus) and two fungal (Botrytis and Fusarium) pathogens. This study showed that LAB are not the predominant species in rice flour, while they were predominant in wheat and oat flour. Additionally, Lactobacillus sanfranciscencis was found to be the predominant species in wheat flour, while its presence in oat flour was minor. Finally, through their production of soluble substances, LAB exerted antagonistic effects on the four types of pathogenic microorganisms.

Bioactive compound and chemical characterization of lactic acid bacteria from fermented food as bio-preservative agents to control food-borne pathogens

Context: Lactic acid bacteria (LAB), which are found in many fermented foods, are known to produce antimicrobial compounds that play a vital role in food bio-preservation. Aims: To screen, identify, characterize, and determine the secondary metabolites of LAB isolated from Thai fermented foods that are beneficial against Escherichia coli and Staphylococcus aureus. Methods: The antimicrobial activity of cell free supernatant (CFS) was evaluated by agar well diffusion assay, and determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC). Bacterial strains were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and chemical compound was conducted by gas chromatography and mass spectrometry (GC-MS). Additionally, microbial dynamic and bile salt tolerance were assessed. Results: Seven of the 90 lactic acid isolates from Thai fermented foods, showed antibacterial activity against E. coli and S. aureus in the 12.00–16.00 mm inhibitory zone. It was identified that the bacteria were Lactobacillus pentosus, Lactobacillus farciminis, Lactobacillus brevis, and Lactobacillus plantarum. The best antibacterial activity was represented by LBST1861 strain, which also provided bile salt resistance at 0.3% for 24 hours and had MIC and MBC values of 12.5 mg/mL and 50.0 mg/mL against S. aureus and E. coli, respectively. Furthermore, the GC-MS discovered a total of 16 chemical compounds that may be used to limit microbial growth and has a potential to be employed as a bio-preservative. Conclusions: The most potent strain of LBST1861 strain against S. aureus and E. coli as L. plantarum, isolated from fermented foods in Thailand, generated significant bioactive chemicals that can be applied to promote food products.

Isolation, biochemical and molecular characterization of lactic acid bacteria from whey of a Nigerian traditionally fermented yoghurt drink

Lactic Acid Bacteria (LAB) have been identified as an essentialgroup of microorganisms due to the health-promoting effects theyexert on human and animal hosts. This research was conducted to,isolate LAB from whey obtained from kindirmo a locally fermentedcow milk product in Nigeria, characterize the strains based onphysiological and biochemical properties and identify them using16SrRNA sequencing. A total of 32 samples were collectedaseptically and the whey cultured on an MRS and M17 media.Physiological and biochemical results showed that the isolatedorganisms, which were mostly rod and cocci shaped, includedgram positive and catalase negative species. The organisms didnot only vary in their abilities to tolerate and grow at differentconcentrations of pH, temperature and NaCl, but were able toferment twelve different sugars distinctively. The ten most desirablestrains obtained were subsequently screened by moleculartechniques using PCR and sequence analysis. The PCR resultsrevealed that 98% of the identified organisms were Lactobacillusbulgaricus, Lactobacillus casei, Lactobacillus acidophilus,Streptococcus thermophilus, Lactobacillus gasseri andLactobacillus plantarum. These findings showed that kindirmocould be an excellent and potential source of probiotic bacteria,which are often the main sources of probiotics. Further screeningand identification processes were recommended to ascertain thefunctional, technological and probiotic properties of the strains.

Identification and Characterization of Lactic Acid Bacteria Isolated from Effluents Generated During Cassava Fermentation as Potential Candidates for Probiotics

ABSTRACT Fermented cassava is obtained through fermentation process where the main role is played by various lactic acid bacteria (LAB), while the by-products (effluents) are discarded. The objective of this study was to isolate, identify and analyze potential probiotics in fermented cassava by-products/effluents using molecular techniques. We quantified the LAB’s metabolites and tested their antimicrobial properties. We isolated 13 LAB strains which are all Gram-positive, and catalase, oxidase, indole and coagulase negative. Only 6 out of 13 selected isolates survived the low pH of 1.5 and 0.3% bile salt. These 6 isolates showed different levels of antimicrobial activity against the tested pathogens with zones of inhibition ranging from 5.10 mm to 22.80 mm. The isolated LAB were identified as Lactiplantibacillus plantarum and Limosilactobacillus fermentum. The results indicated that the selected LAB strains have potential as probiotics due to their ability to survive in acidic and bile-rich environments as well as their antimicrobial properties.

Isolation and characterization of lactic acid bacteria with probiotic potential from traditional fermented special Kurdish cheese (Zhazhi) in Kurdistan Region, Iraq.

Zhazhi cheese is a unique farmhouse traditional fermented dairy of the Kurdistan Region in Iraq for its desired aroma and flavor. Undoubtedly, the lactic acid bacteria (LAB) are the critical factors in developing the aroma, flavor, and texture of Zhazhi cheese but it has not been studied or characterised. LAB has many important nutritional benefits, including increasing the nutritional value of food. Therefore, this research was performed to isolate and identify the potential probiotic LAB from traditional homemade Kurdish cheese. Then, the identified strains were tested to determine their probiotics traits, which include acid resistance, bile-salt tolerance, haemolytic, DNase, hydrophobic, autoaggregation, antimicrobial and antibiotic activities. The isolated five LAB strains comprised Lactobacillus casei, Lactobacillus rhamnosus, Enterococcus faecium, Pediococcus pentocaseus and Lactobacillus helvaticum were recognized as promising and the most potential probiotics for further applications. This is the first report on the direct selection of potentially probiotic LAB from Kurdish special cheese (Zhazhi).

Exploration of probiotic attributes in lactic acid bacteria isolated from fermented Theobroma cacao L. fruit using in vitro techniques.

Probiotics are known for their health-promoting properties and are recognized as beneficial microorganisms. The current investigation delves into the isolation and comprehensive in vitro characterization of lactic acid bacteria (LAB) obtained from the Indian-origin Theobroma cacao L. Forastero variety to assess their potential as probiotic candidates. Eleven LAB isolates were obtained, and among them, five exhibited classical LAB traits. These five isolates underwent rigorous in vitro characterization to evaluate their suitability as probiotics. The assessments included resilience against acid and bile salts, which are crucial for probiotic viability. Additionally, the isolates were subjected to simulated gastric and pancreatic fluids and lysozyme exposure to assess their survival rates. Auto- aggregation, co-aggregation, hydrophobicity, and exopolysaccharide production were also examined. The inhibitory potential of α-glucosidase, an enzyme related to glucose metabolism, was measured, and antioxidant activity was evaluated using DPPH and ABTS assays. A safety assessment was conducted to confirm the non-pathogenic nature of the isolates. Among the five isolates, CR2 emerged as a standout candidate with maximal bile salt hydrolase activity, phenol resistance, and lysozyme resistance. CR2 and CYF3 exhibited notable survival rates under simulated conditions. The isolates displayed variable degrees of auto-aggregation, co-aggregation, and hydrophobicity. CR2 exhibited the highest exopolysaccharide production (0.66 mg/mL), suggesting diverse applications in the food industry. CR2 also demonstrated the highest inhibition rate against α-glucosidase (56.55%) and substantial antioxidant activity (79.62% DPPH, 83.45% ABTS). Safety assessment confirmed the non- pathogenic nature of the isolates. Molecular characterization identified CR2 as Lactococcus lactis subsp. lactis and CYF3 as Limnosilactobacillus fermentum. Both strains exhibited commendable probiotic and technological attributes, positioning them as promising candidates for functional foods and beyond. This study provides valuable insights into the in vitro characterization of LAB isolated from Indian Theobroma cacao L., highlighting their potential as probiotic candidates with advantageous traits, including survival in hostile conditions, beneficial enzymatic activities, bioactivity, and other essential attributes.

In vitro screening and characterization of lactic acid bacteria from Lithuanian fermented food with potential probiotic properties.

The present work aimed to identify probiotic candidates from Lithuanian homemade fermented food samples. A total of 23 lactic acid bacteria were isolated from different fermented food samples. Among these, only 12 showed resistance to low pH, tolerance to pepsin, bile salts, and pancreatin. The 12 strains also exhibited antimicrobial activity against Staphylococcus aureus ATCC 29213, Salmonella Typhimurium ATCC 14028, Streptococcus pyogenes ATCC 12384, Streptococcus pyogenes ATCC 19615, and Klebsiella pneumoniae ATCC 13883. Cell-free supernatants of isolate 3A and 55w showed the strongest antioxidant activity of 26.37 μg/mL and 26.06 μg/mL, respectively. Isolate 11w exhibited the strongest auto-aggregation ability of 79.96% as well as the strongest adhesion to HCT116 colon cells (25.671 ± 0.43%). The selected strains were tested for their synbiotic relation in the presence of a prebiotic. The selected candidates showed high proliferation in the presence of 4% as compared to 2% galactooligosaccharides. Among the strains tested for tryptophan production ability, isolate 11w produced the highest L-tryptophan levels of 16.63 ± 2.25 μm, exhibiting psychobiotic ability in the presence of a prebiotic. The safety of these strains was studied by ascertaining their antibiotic susceptibility, mucin degradation, gelatin hydrolysis, and hemolytic activity. In all, isolates 40C and 11w demonstrated the most desirable probiotic potentials and were identified by 16S RNA and later confirmed by whole genome sequencing as Lacticaseibacillus paracasei 11w, and Lactiplantibacillus plantarum 40C: following with the harboring plasmid investigation. Out of all the 23 selected strains, only Lacticaseibacillus paracasei 11w showed the potential and desirable probiotic properties.

Identification of Lactic Acid Bacteria From Pandan Civet Feces (P. hermaphroditus) in West Kalimantan Based on Phenotypic Similarity

Lactic acid bacteria are included in the gram positive bacteria that are widely distributed in the digestive tract of living things, such as in the feces of the Pandan Luwak (P. hermaphroditus) and important role in improving the microbial balance in the body. The purpose of this study was to obtain phenotypic characters, types of bacteria and similarity relationship between lactic acid bacteria from feces of Pandan Civet (P. hermaphroditus) in West Kalimantan and lactic acid bacteria in the identification book Bergey's manual of determinative bacteriology. This research was conducted by the method of isolation and screening bacteria using MRSA media supplemented with CaCO3 1%. Characterization of lactic acid bacteria based on morphological, biochemical, and physiological characters in Bergey's Manual of Determination Bacteriology. The results of the analysis using the MVSP (Multivariant Statistic Package) program with SSM coefficients and the UPGMA method obtained 44 bacterial isolates thought to belong to two genera, namely the genus Lactobacillus and Bifidobacterium with three species, namely L. casei, L. brevis and B. bifidum. The results of the analysis showed that 12 bacterial isolates had a similarity index of 87,6% to L. casei, 17 bacterial isolates had a similarity index of 92,2% to B. bifidum and 15 bacterial isolates had a similarity index of 84,5% to L. brevis.

Isolation and Characterization of Lactic Acid Bacteria from Cocoa Mucilage and Meat: Exploring Their Potential as Biopreservatives for Beef

The aim of this study was to characterize lactic acid bacteria (LAB) isolated from cocoa mucilage and beef and evaluate their inhibitory effect in vitro against pathogenic bacteria, as well as determine their effect on beef quality. For the antagonist assay, 11 strains of LAB were selected and tested against pathogenic strains of Escherichia coli and Salmonella sp. The pathogenic bacteria were cultured in a medium, and a previously reactivated LAB bacterial pellet was added. After incubation, halos were observed around the bacterial colonies of the pathogenic strains, indicating inhibition by the LAB. It was identified that the LAB strains used belonged to the genus Lactobacillus, and the CCN-5 strain showed high percentages of inhibition against Salmonella sp. (58.33%) and E. coli (59%). The effectiveness of LAB application methods (immersion, injection, and spraying) did not present statistical differences. Furthermore, no significant changes in the physicochemical characteristics of beef were observed after the application of LAB. The results obtained demonstrate the potential of cocoa mucilage, as a biological control agent through LAB application, for beef biopreservation due to its ability to inhibit the growth of pathogenic bacteria.

Technological and genotypic characteristics of lactic acid bacteria isolated from Algerian artisanal dairy products

Twenty two strains collected from different artisanal dairy products and various areas in Algeria were identified at species level and characterised at genetic level using PCR and 16S RNA sequencing. The growth kinetics of the strains was studied, and the strains were evaluated for several technological activities. After 16S RNA sequencing, the strains were assigned to Enterococcus faecium (50.0%), Limosilactobacillus fermentum (36.4%), Lactiplantibacillus pentosus (9.1%), and Lactiplantibacillus plantarum (4.5%). Most of the strains exhibited good acidification, proteolytic, autolytic, and antimicrobial activities alongside weak lipolytic, flavouring, texturising, and thickening activities. Of the 22 strains studied, 3 exhibited a coagulation time of 8–10 h and a syneresis rate of no more than 2.30 ± 0.42, 4 strains demonstrated a good lipolytic activity and 6 strains had aromatic, texturising, and thickening activities.

Potential probiotic characterization of lactic acid bacteria isolated from Duimaj, an Iranian traditional snack food, using biochemical, molecular and computational approaches

The aim of this study was isolation and identification of lactic acid bacteria from Duimaj (an Iranian traditional snack food) and in vitro characterization of probiotic features. In total, thirty presumptive LAB colonies were surveyed, of which 22 exhibited high rates of survival in artificial gastrointestinal fluids, which were found to belong to Lactobacillus, Enterococcus, and Pediococcus genera based on 16 S-rRNA gene sequence. The selected strains had strong antagonistic effects, with auto-aggregation abilities ranging from 26.52 to 81.50% and co-aggregation capacity up to 88.33 and 80.14% with E. coli and S. aureus, respectively. Moreover, the cell surface hydrophobicity of strains ranged from 31.06 to 85.62%. Results indicated that nine isolated LAB harbored the cholesterol assimilation rates greater than 30%. Moreover, none of the selected strains showed hemolytic activity. Among the isolates, five strains were negative for all nine tested virulent genes, and exhibited favorable adhesion percentage to human intestinal epithelial cells ranging from 31.76 to 52.37. Hence, naturally occurring Lactiplantibacillus plantarum and Lactiplantibacillus pentosus isolated from Duimaj were proposed as suitable probiotic candidates for use in functional foods.

Isolation and some basic characteristics of lactic acid bacteria from beetroot (Beta vulgaris L.) —A preliminary study

The carbohydrate content of fruit and vegetable juices has made them a suitable environment for the growth of lactic acid bacteria. Various studies have shown that beetroot can be a good substrate for the production of probiotic drinks for consumers. Therefore, this study was performed to isolate and identify lactic acid bacteria from beetroot juice. Beetroot juice was prepared from two kilograms of washed beetroot with a cold press. Sterile samples of beetroot juice were first enriched in MRS broth and then cultured on MRS agar. Gram and catalase tests were used for the initial detection of lactic acid bacteria. Then, to identify the species of lactic acid bacteria, biochemical confirmation tests such as the melting of gelatin, and the growth of bacteria has been studied in the ideal condition that is 15-45° C, sugars fermentation, gas production from glucose, and growth in at different concentrations of salt were performed. The final verification of species was done using polymerase chain reaction-amplified 16S rRNA-specific DNA. All isolates formed creamy white round colonies on MRS agar medium, were gram-positive, were able to grow in anaerobic conditions, and were also rod-shaped and catalase-negative. Based on biochemical tests, four types of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus helveticus, Lactobacillus salivarius, and Lactobacillus acidophilus) were identified. The findings of this study indicated the presence and diversity of lactic acid bacteria in beet juice, which can be a potential platform for the production of probiotic beetroot juice as a non-dairy product.

Isolation and Characterization of Lactic Acid Bacteria With Probiotic Attributes From Different Parts of the Gastrointestinal Tract of Free-living Wild Boars in Hungary.

Lactic acid bacteria (LAB) in the microbiota play an important role in human and animal health and, when used as probiotics, can contribute to an increased growth performance in livestock management. Animals living in their native habitat can serve as natural sources of microorganisms, so isolation of LAB strains from wild boars could provide the opportunity to develop effective probiotics to improve production in swine industry.In this study, the probiotic potential of 56 LAB isolates, originated from the ileum, colon, caecum and faeces of 5 wild boars, were assessed in vitro in details. Their taxonomic identity at species level and their antibacterial activity against four representative strains of potentially pathogenic bacteria were determined. The ability to tolerate low pH and bile salt, antibiotic susceptibility, bile salt hydrolase activity and lack of hemolysis were tested.Draft genome sequences of ten Limosilactobacillus mucosae and three Leuconostoc suionicum strains were determined. Bioinformatic analysis excluded the presence of any known acquired antibiotic resistance genes. Three genes, encoding mesentericin B105 and two different bacteriocin-IIc class proteins, as well as two genes with possible involvement in mesentericin secretion (mesE) and transport (mesD) were identified in two L. suionicum strains. Lam29 protein, a component of an ABC transporter with proved function as mucin- and epithelial cell-adhesion factor, and a bile salt hydrolase gene were found in all ten L. mucosae genomes. Comprehensive reconsideration of all data helps to select candidate strains to assess their probiotic potential further in animal experiments.

Quality Improvement of Zao Pepper by Inoculation with Lactobacillus plantarum 5-1: Probiotic Ability and Fermentation Characteristics of Lactic Acid Bacteria

Zao pepper is a fermented type with a distinct flavor, and Zao pepper-based dishes are popular. However, in spontaneous fermentation (SF), the adverse microorganisms of Zao pepper are uncontrollable and alter the product quality. Lactic acid bacteria (LAB) inhibit the growth of harmful bacteria and endow a sour taste in SF. Therefore, the purpose of this study was to isolate autochthonic LAB from SF and through inoculated fermentation (IF) to improve Zao pepper quality. Four LAB strains were selected for probiotic experiments by sensory evaluation based on the flavor of Zao pepper in vitro. Intriguingly, Lactobacillus plantarum 5-1 showed superior safety and probiotics, with the fastest growth and acid-production rate. Moreover, the nitrite reductase viability of L. plantarum 5-1 reached 4.73 μmol/mL·h. The use of IF via L. plantarum 5-1 increased the total acid content 2-fold and reduced the nitrite content by 0.36-fold compared to SF in Zao pepper. In addition, IF improved the color and texture of Zao pepper. These results indicate that the autochthonic L. plantarum 5-1 improved the quality of Zao pepper, providing a new strategy for enhancing the stability of fermented pepper.

Characterization of lactic acid bacteria isolated from street pickles of Dhaka, Bangladesh

Traditionally fermented pickles are a popular street food in Bangladesh famous for their unique flavors and health benefits. Pickles are often prepared by fermentation using lactic acid bacteria (LAB) that can act as probiotics. The study was aimed to isolate and characterize lactic acid bacteria from pickle samples collected from streets of Dhaka city, as well as assess the microbial quality of pickles for food safety.A total of 30 pickle samples of different kinds were collected from streets of Dhaka city. Isolation and identification were conducted using conventional cultural and biochemical tests, followed by molecular confirmation of identity. Antibiotic susceptibility of isolates was investigated against 7 antibiotics of different groups. Antimicrobial activity of LAB isolates was analyzed by well-diffusion assay and phenotypic enterocin activity assay. Physiological characterizations of LAB were performed to determine their tolerance to temperature, salt, pH, bile, carbohydrate fermentation pattern, proteolytic activity and biofilm formation.Fifty isolates were obtained from pickle samples, of which 18% was identified as LAB, including Enterococcus faecalis (6) and Enterococcus faecium (3). The rest included S. aureus (18), E. coli (11), Klebsiella spp. (5), Salmonella (3), Shigella (3) and Pseudomonas aeruginosa (1). Antibiotic resistance pattern revealed higher occurrence of resistance against azithromycin among the non-LAB isolates, but none of the LAB isolates were found to resist any of the antibiotics used. Antimicrobial activity of LAB isolates was not observed against the foodborne isolates. All LAB isolates fermented a wide range of carbohydrates and showed adequate tolerance to salt, pH, temperature and bile. Out of 9 isolates, 5 displayed proteolytic activity, and 6 were found as strong biofilm producer.These results suggest that although the LAB isolates from street pickles collected from Dhaka does not have antimicrobial activities, they still have potential to be used as probiotics. It also shows high occurrence of antibiotic resistant foodborne pathogens in pickles, indicating that consumption of such street food can be serious health hazard.

Characterization of Lactic Acid Bacteria and Pathogens Isolated from Traditionally Fermented Foods, In Relation to Food Safety and Antimicrobial Resistance in Tribal Hill Areas of Northeast India

Traditional fermented food products are often connected to various indigenous tribes and thus vary due to ethnicity, geography, and natural resource availability. The indigenous tribes from India greatly rely on fermentation processes for food preservation, flavor, and nutrition. Fermented foods can provide health benefits but also pose risks from harmful microbes and contaminants that grow in the food due to poor hygiene. In this study, we identified lactic acid bacteria (LAB) in fermented food collected from Northeast India, assessed their beneficial properties, and highlighted the risk from food pathogens that have antimicrobial resistance traits. A total of 113 different samples of fermented food products were collected from the local markets of five Northeastern Indian states (Nagaland, Manipur, Meghalaya, Arunachal Pradesh, and Sikkim). Standard laboratory methods were used to isolate LAB and determine their probiotic properties, conduct coliform counts, and isolate presumptive staphylococci from the fermented food samples. Antimicrobial susceptibility was determined by using the BD-Phoenix 100 automated system. We isolated 30 LAB with probiotic potential. The average aerobic colony count in different fermented food was 4.4–7.7 log·cfu/g, while coliforms were present in 43% (49/113, 95% (CI 34–53)) of the food samples, indicating low-hygiene levels. Additionally, some food samples contained staphylococci with phenotypic antibiotic-resistance markers (MRS, HLMUP, BLACT, and STAMLS). This study indicates that probiotic bacteria could be present in traditional fermented food products of Northeast India, but contamination with staphylococci and other bacterial pathogens with antibiotic resistance traits could put the health of consumers at risk.

Application and Research Progress of Recombinant Lactic Acid Bacteria by Genetic Engineering

Lactic acid bacteria, as a kind of food-grade microorganism, is widely used in food industry, medical care and other fields. The special function of lactic acid bacteria has been increasingly valued and needed, and the traditional strain screening method is complex, long cycle and low cost, which hinders the development and progress of lactic acid industry. At this time, the rapid development of modern genetic engineering has brought new opportunities for the medical application of LAB. By developing new functional strains of LAB, genes with specific functions can be introduced into the genome of LAB, so that LAB can meet the requirements of designers and users. First of all, this article summarizes the characteristics of lactic acid bacteria and discusses the dominant types of lactic acid bacteria in transgenic bacteria. Then, six medical applications of LAB in vaccine delivery vector, virus prevention and control, allergy treatment, cervical cancer, inflammation, lactose intolerance after genetic engineering were reviewed. Finally, the genetically motified LAB is used in the diagnosis and treatment of diseases, such as immune tolerance, vector development, immune mechanism and other issues were reviewed, and the future application of LAB in the field of genetic engineering and cancer treatment was discussed.