Potential Of Lactic Acid Bacteria Research Articles

Novel Probiotic Lactic Acid Bacteria Were Identified from Healthy Infant Feces and Exhibited Anti-Inflammatory Capacities.

The current study aims to evaluate the probiotic potential of lactic acid bacteria isolated from infant feces, and select candidates to be used as potential antioxidants for the treatment of oxidative stress-related diseases; To meet the criteria for probiotic attributes, the isolates were subjected to various in vitro tests and 16S rRNA genotypic characterization. Besides, anti-inflammatory and anti-oxidative effects of selected isolates were separately assessed by real-time quantitative PCR and Western blot; The selected strains belonged to Lactobacillus gasseri, Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus. Notably, three selected strains (L. gasseri FWJL-4, L. plantarum Fjias-5 and L. rhamnosus FSJ-13) particularly L. gasseri FWJL-4 significantly down-regulated mRNA expression levels of tumor necrosis factor α (TNFα), Interleukin-6 (IL-6) and IL-1β. Most importantly, three strains-treated RAW 264.7 murine macrophages displayed enhanced activities of antioxidant enzymes and reduced H2O2 production, which were associated with the enhanced expression levels of nuclear factor-erythroid 2 related factor 2 and heme oxygenase-1; Three selected strains, particularly L. gasseri FWJL-4, are good candidates that merit additional in vivo investigation for the validation and application of their health-promoting effects.

Technological characterization and flavor-producing potential of lactic acid bacteria isolated from traditional dry fermented sausages in northeast China

Thirty-seven lactic acid bacteria (LAB) strains were isolated from traditional dry sausages collected from Northeast China, including Latilactobacillus sakei (29 strains), Lactiplantibacillus plantarum (4 strains), Latilactobacillus curvatus (2 strains), Weissella hellenica (1 strain), and Lactococcus lactis (1 strain). Some LAB strains had tolerance to high concentrations of sodium chloride (6%), sodium nitrite (150 mg/L NaNO2), and acid (pH 4.0). They showed good growth and acidification properties and antimicrobial activity. Among them, five LAB strains that exhibited the best technological properties were selected and inoculated in the sausage model to explore their roles in flavor development. The contents of total free amino acids (FAAs) decreased ranging from 109.11 mg/g to 58.06 mg/g. A total of 46 volatile compounds were identified and the contents of volatile compounds increased in the sausage model during fermentation. Partial least squares regression analysis showed that Lb. sakei HRB10, Lb. plantarum MDJ2, W. hellenica HRB6, and Lc. lactis HRB0 promoted the generation of FAAs and volatile compounds in the sausage model. These findings demonstrated that the autochthonous LAB species are promising for the production of sausage with better flavor and fermentation performance.

Probiotic Potential of Lactic Acid Bacteria on Feed Efficiency, Weight and Carcass Percentage in Ducks

The aim of the study was to determine the effect of the use of probiotic lactic acid bacteria (Lactobacillus acidophilus, Lactobacillus casei, Lactococcus lactis, and Bifidobacterium sp) on feed efficiency, carcass weight and carcass percentage in broiler ducks. Probiotics lactic acid bacteria produce bacteriocins and organic acids that inhibit the growth of pathogenic microbes in the digestive tract of poultry, so that the intestinal villi of broiler ducks are healthy. Besides that, probiotics are able to reduce cholesterol levels in meat when consumed by humans and can improve health. This study used 48 peking ducks. The probiotics of Lactic Acid Bacteria used were a concentration of 1.2 x 108 CFU/ml. In this study there were four different treatments, namely P0 (without probiotics), P1 (given 1 ml probiotics/liter drinking water), P2 (given 2 ml probiotics/liter drinking water) and P3 (given 3 ml probiotics/liter of drinking water). The results of the feed efficiency study showed that there was a significant difference (p<0.05) in the P0, P1, P2 and P3 treatments. The highest feed efficiency was at P3 (33.81%) while the lowest was P0 (30.84%). The results of the study on carcass weight indicated that the probiotics tended to be higher than those who were not given probiotics but statistically not significantly different (p>0.05). The highest carcass weight was P3 (1749.92 g) and the lowest was P0 (1709.25 g). The results of the study on the percentage of carcass weight showed a significant difference (p<0.05) in both P0, P1, P2 and P3 treatments. The highest percentage of carcass weight was at P3 (64.60%) and the lowest was P0 (60.96%). It can be concluded that the administration of probiotics lactic acid bacteria (Lactobacillus acidophilus, Lactobacillus casei, Lactococcus lactis, and Bifidobacterium sp) at a dose of 1 ml/liter of drinking water, 2 ml/liter of drinking water and 3 ml/liter of drinking water can affect feed efficiency and the percentage of duck carcasses. but has no effect on the carcass weight of broiler ducks.

Characterization and Selection of Potential Antifungal Lactic Acid Bacteria Isolated From Turkish Spontaneous Sourdough.

The aim of this research was to investigate the antifungal potential of lactic acid bacteria (LAB) isolated from Turkish spontaneous sourdough collected in summer and winter seasons from 25 different small bakeries in Trabzon, Giresun, Ordu, and Samsun. Lactic acid bacteria (933 isolates) were screened for inhibition of three common food spoilage molds (Aspergillus flavus, Aspergillus niger, and Penicillium expansum). Eight LAB isolates identified as Weissella cibaria 908, Lactiplantibacillus plantarum subsp. plantarum 2114, Leuconostoc pseudomesenteroides 2619, L. plantarum subsp. plantarum 2702, Fructilactobacillus sanfranciscensis 2709, Levilactobacillus brevis 2216Y, L. pentosus Y118, and L. plantarum subsp. plantarum Y201 by 16 S rRNA sequencing, which were found to have high antifungal activity against all the test molds. The antifungal activity of cell free supernatants from LAB isolates was not altered after thermal treatment and proteolytic enzyme proteinase K. The cell free supernatants obtained from LAB showed a high antifungal effect against molds with inhibition zone diameter up to 20mm at pH 3.0, but no inhibitory activity was determined after pH neutralization. Moreover, all cell free suspension samples were able to maintain their efficacy up to a 1:4 dilution. The antifungal activity of supernatants was mostly related to organic acid content, especially lactic acid ranged from 4.33 to 8.41g/L. The results indicated that eight bacterial isolates obtained from spontaneous Turkish sourdough could constitute biopreservative cultures, which may be used in food industry.

Determination of probiotic and some technological properties of lactic acid bacteria isolated from cheeses sold in the Kilis region, Turkey

Aims: The purpose of this study is to evaluate technological properties and probiotics potential of lactic acid bacteria (LAB) isolated from 15 raw milk Turkish Beyaz fresh cheese made in the Kilis region, Turkey.Methods and Results: 287 colonies from 15 cheese samples were selected and 91 of them were analyzed as Gram-positive and catalase-negative. 19 strains of 91 colonies were accepted as potential probiotics since they stayed alive in pH 3.5 and 0.3% bile salt. They were identified as Lactobacillus sp. (11 strains), Leuconostoc sp. (3 strains), Streptococcus sp. (2 strains), Lactococcus sp. (2 strains), and Enterococcus sp. (1 strain) by biochemical tests and API test kit. It was determined that 19 strains with high acidification rate, 15 strains demonstrated weak proteolytic activity, 3 ones moderate, and 1 strong proteolytic activity. It was determined that 1 of the strains were resistant to chloramphenicol, 2 to tetracycline, and 6 to vancomycin. No strains resistant to penicillin and erythromycin could be detected. In the artificial gastric juice resistance test, although no viability was detected at pH 2.0. But it was determined that the viability values varied between 89.49-111.79% at pH 3.0. Also, these strains showed growth at bile salt. According to plasmid profiles of strains, 13 of 19 potential probiotic strains were determined to have plasmid DNA in the range of 1-5, while other strains were determined to not have plasmid DNA. The molecular sizes of the plasmid DNA of the isolated strains ranged from 2-16 kb.Conclusions: In the research, it was determined that LABs isolated from Turkish white fresh cheese produced in Kilis have probiotic potential and can be used as starters in various fermented foods.Significance and Impact of the Study: According to the results obtained, it was concluded that some strains can be used as probiotic starter culture in cheese production and others can be used for ripening of cheese.

Evaluation of the antagonistic effect of some species of lactic acid bacteria isolated from fermented food against toxigenic Aspergillus flavus

The presence of mycotoxigenic molds in food potentially poses hazards to healthy living and needs to be controlled. There is a greater risk that the resistance phenomenon will increase in the future due to the frequent use of antibiotics and preservatives, unlike biopreservation. Lactic acid bacteria are capable of producing secondary metabolites with antimicrobial properties. This study was conducted to evaluate the antagonistic effect of lactic acid bacteria isolates against toxigenic mold, Aspergillus flavus. Lactic acid bacteria were isolated from palm wine, ogi, and yogurt samples, and their antagonistic activity against toxigenic mold was investigated using the agar overlay method. Streptomyces spp. had the highest counts of 15.1×104 cfu/ml, while the least count of 2.0×104 cfu/ml from Lactobacillus plantarum was obtained. Pediococcus damnosus and Lactobacillus plantarum were present in both yogurt and palm wine samples. Similarly, Streptococcus spp. was identified in both yogurt and pap (ogi) samples. Aspergillus flavus was susceptible to half of the lactic acid bacterial isolates with varying degrees of inhibition. Total inhibition of toxigenic mold was observed on the control plate and plates inoculated with L. lactis, S. thermophilus, Leuconostoc mesenteriodes, P. damnosus, and L. bulgaricus. The antifungal activity of lactic acid bacteria suggests their biocontrol efficacy against A. flavus. Also, the antimicrobial properties of lactic acid bacteria can make them a suitable candidate in food preservation. Furthermore, this study can stand as a preliminary step in multistep research to investigate the anti-fungal and anti-aflatoxigenic potential of lactic acid bacteria from fermented foods against toxigenic A. flavus.

Probiotic potential of lactic acid bacteria isolated from Vietnamese sour-fermented fish product

Probiotic potential of lactic acid bacteria isolated from Vietnamese sour-fermented fish product

Probiotic Potential of Lactic Acid Bacteria Isolated from Broiler Chickens in Côte d’Ivoire

Probiotic Potential of Lactic Acid Bacteria Isolated from Broiler Chickens in Côte d’Ivoire

Evaluation of the Probiotic Potential of Lactobacillus delbrueckii ssp. indicus WDS-7 Isolated from Chinese Traditional Fermented Buffalo Milk In Vitro.

The present study aimed to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from Chinese traditional fermented buffalo milk. Out of 22 isolates, 11 were putatively identified as LAB preliminarily. A total of six LAB strains displayed strong adhesion to HT-29 cells and all these strains showed preferable tolerance to artificially simulated gastrointestinal juices. WDS-4, WDS-7, and WDS-18 exhibited excellent antioxidant capacities, including DPPH radical, ABTS+ radical, and superoxide anion scavenging activities. Compared with the other two LAB strains, WDS-7 had a stronger inhibition effect on four pathogens. Based on the 16S rRNA gene sequencing and phylogenetic analysis, WDS-7 was identified as Lactobacillus delbrueckii ssp. indicus and selected to assess the potential and safety of probiotics further. The results revealed that WDS-7 strain had a strong capacity for acid production and good thermal stability. WDS-7 strain also possessed bile salt hydrolase (BSH) activity. Compared to LGG, WDS-7 was a greater biofilm producer on the plastic surface and exhibited a better EPS production ability (1.94 mg/ml as a glucose equivalent). WDS-7 was proved to be sensitive in the majority of tested antibiotics and absence of hemolytic activity. Moreover, no production of biogenic amines and β-glucuronidase was observed in WDS-7. The findings of this work indicated that L. delbrueckii ssp. indicus WDS-7 fulfilled the probiotic criteria in vitro and could be exploited for further evaluation in vivo.

Potential of lactic acid bacteria to produce functional fermented whey beverage with putative health promoting attributes

A functional fermented whey (FW) beverage was produced by lactic acid bacteria (LAB), Pediococcus pentosaceus ENM104 and Lactiplantibacillus plantarum SPS109. Both strains grew well in MRS medium under aerobic and anaerobic conditions, were susceptible to antibiotics, and showed antibacterial activity via metabolites i.e. organic acids and produced biofilm. A co-culture of the LAB in phosphate-buffered saline reduced heterocyclic aromatic amines, nitrosamines, and biogenic amines, including 2-phenethylamine, putrescine, cadaverine, histamine and tyramine. The cholesterol content of whey fermented for 72 h with the co-culture was 37.60 ± 18.28% lower than the initial content, while γ-aminobutyric acid production increased by 3.91 ± 0.10 μg·mL−1. Angiotensin-converting enzyme (ACE) inhibitory activity increased by 36.07 ± 3.94%. Oxygen radical absorbance capacity (ORAC) increased to 362.06 ± 8.63 nmol TE·mL−1. Putrescine and cadaverine were reduced by 11.84 ± 2.20% and 53.82 ± 2.91%, respectively. This FW inhibited Bacillus cereus TISTR 687, Listeria monocytogenes DMST 17303, and Streptococcus mutans ATCC 25175 with minimum inhibitory concentration (MIC) from 30 to 40% and biofilm inhibitory concentration (BIC) from 35 to 40%. The most sensitive strain was S. mutans, which exhibited 98.52 ± 0.99% biofilm inhibition. Both LAB in a mixed starter showed great potential to produce functional FW through their joint beneficial activities.

​Potential of Lactic Acid Bacteria in Plant Growth Promotion

Background: Lactic acid bacteria are regarded the most important bacteria concerning food fermentation, pharmaceutical and special dietary applications. Strains have been isolated from environments rich in available carbohydrate substrates, such as food and feed, but also in human and animal cavities and in sewage and plant material. Besides lactic acid, other side products include acetate, ethanol, CO2, formate and succinate. The most important advantage of Lactic acid bacteria making them suitable for the use in food biotechnology, is that they are generally recognized as safe (GRAS). Studies on Lactic acid bacteria isolated from aerial parts of plants are scarce. Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria. Several substances produced by antagonistic rhizobacteria have been related to pathogen control and indirect promotion of growth in many plants. The present work explores the potential use of Lactic acid bacteria in promotion of plant growth. Methods: Three isolates were obtained from aerial parts of pomegranate plant and confirmed by 16S rRNA sequencing to belong to Leuconostoc sp. The isolates were checked for plant growth promoting traits viz. antifungal activity, production of plant growth hormones, enzymes and 1-amino cyclopropane carboxylate deaminase activity. Result: As LAB showed plant growth promoting traits, they can be suitably used for plant growth promotion.

Yoghurt Production Potential of Lactic Acid Bacteria Isolated from Leguminous Seeds and Effects of Encapsulated Lactic Acid Bacteria on Bacterial Viability and Physicochemical and Sensory Properties of Yoghurt

This study aims to determine the yoghurt production potential of lactic acid bacteria isolated from legumes seeds (lentils, beans, cowpea, and broad beans) and examine the effects of alginate capsules of selected starter cultures with high yoghurt production potential on the physicochemical properties, sensory properties of yoghurt, and bacterial viability during storage time at 4°C. The exopolysaccharide (EPS), proteolytic activity, and acidification properties of eight different isolates were determined, and sixteen different yoghurt combinations prepared. The samples showed similar physicochemical (pH, titratable acidity, dry matter, and whey separation), bacterial count, and sensory results in comparison with the commercial yoghurt used as a control sample. The acidity and pH of the yoghurt samples were significantly affected by the storage time. Total solids of yoghurt samples generally tend to decrease and syneresis of yoghurt samples also differed for each starter culture combination during the storage time. The total count of lactic acid bacteria during the storage time was higher than 107 CFU/g. The sensory analysis results of bacterial combinations are significantly different ( p < 0.05 ). Results indicated that isolated starter cultures have potential as commercial starters to improve the quality of yoghurt. Selected starter cultures with yoghurt production potential were encapsulated. Lactic acid bacteria with encapsulation efficiency of 86,3 ± 0,2 and 82,26 ± 0,79 were selected for yoghurt production. The physicochemical properties of the yoghurt with free and encapsulated starter culture were significantly different during the storage time. The reduction (∼0,5 log cfu/g) in the numbers of free and encapsulated starter cultures is over during the storage time ( p < 0.05 ). The acceptability of yoghurt containing encapsulated bacteria was lower than the yoghurt containing free bacteria by the panelists. Consequently, it was determined that alginate capsules increased bacterial viability, but the sensory properties of yoghurt were affected adversely. The LAB isolated form legumes can be introduced to the national microbial collection.

Probiotic potential of lactic acid bacteria isolated from different sources of food and milk products

Probiotic potential of lactic acid bacteria isolated from different sources of food and milk products

Probiotic characterisation of Enterococcus faecalis strain isolated from a household dahi sample of Wayanad district, Kerala

Household dahi sample with good organoleptic properties from Wayanad district of Kerala was screened for lactic acid bacteria. Gram positive cocci exhibiting potential to ferment lactose was further characterised biochemically and later identified by 16srRNA sequencing as Enterococcus faecalis. The isolate was evaluated for its physiological and probiotic properties like temperature tolerance, salt tolerance and proteolytic activity. Probiotic properties like acid tolerance, bile tolerance, adhesion potential and antimicrobial activity against clinical isolate of E. coli were evaluated. Virulence based on haemolysis in blood agar was also done. The isolate was able to survive both 4o C and 45o C as well as salt concentration of 2 to 8 per cent. This remarkably proteolytic isolate was able to survive at pH 2 and 3 for 3 h and could tolerate bile concentration of 0.3 per cent for 3 h and 0.6 per cent for 1 h. Cell surface hydrophobicity was found to be 19.6 per cent and auto aggregation 80.39 per cent. The isolate could inhibit the growth of pathogenic E.coli by producing a zone of clearance of 19mm. Antibiogram revealed resistance to Ceftriaxone, Cefotaxime, Cefazolin and Vancomycin. The isolate produced alpha haemolysis in blood agar. Study revealed that detail biochemical and molecular level characterization is required for assessing probiotic potential of lactic acid bacteria from naturally fermented products.

Selection of Potential Lactic Acid Bacteria as a Candidate Probiotic on Cheese Making by Product Whey

Selection of Potential Lactic Acid Bacteria as a Candidate Probiotic on Cheese Making by Product Whey

Biochemical characterization and antibacterial potential of lactic acid bacteria from <em>Idli</em> batter and their influences on properties of batter

<em>Idli </em>is one of the flour-based foods fermented by lactic acid bacteria. This study was designed to characterize the lactic acid bacteria isolated from <em>Idli </em>batter and to determine their antibacterial activity. Physicochemical changes of batter during fermentation and sensory qualities of the final product (<em>Idli</em>) also were determined. Lactic acid bacteria were isolated from <em>Idli </em>batter and characterized up to genus level. Agar well diffusion assay was used to determine the antibacterial activity of isolates against foodborne pathogens (<em>Salmonella enterica</em>, <em>Escherichia coli </em>and <em>Staphylococcus aureus)</em>. Changes of pH, lactic acid bacterial count, titratable acidity of batter during fermentation and sensory properties of the final product were measured. Ten isolates (I-1 to I-10) were isolated from <em>Idli </em>batter, of which, six were rod and other four were cocci shaped. All ten isolates were Gram positive, non-motile, non-spore formers and catalase activity negative. It was confirmed that all isolates belong to lactic acid bacteria up to genus level. Based on diameter of the inhibition zone, among ten isolates, I-6 was considered as the highest potential bacteriocinogenic isolate. Inhibition zone diameter of isolates ranged from 7.3±1.53 to 16.3±0.58 mm. The pH dropped steadily from 6.28 to 3.72, while titratable acidity increased from 0.24 to 0.92% throughout the fermentation period (0-32 h). With fermentation, the lactic acid bacterial count was increased, and highest lactic acid bacterial count of 9.88 log10cfu/g was observed after 12 h of fermentation. <em>Idli </em>prepared from <em>Idli </em>batter after 8-12 h of fermentation scored maximum for the sensory quality. From this study it is concluded that all lactic acid bacteria isolates possess antimicrobial activity and physicochemical and sensory qualities of <em>Idli </em>batter changed with duration of fermentation.

Screening and characterization of potential cyanide tolerating lactic acid bacteria from cassava pulp juice

Lactic acid bacteria are predominant microorganisms that play important roles during cassava fermentation. Most efforts to develop cyanide tolerant isolates for cassava fermented products have been unsuccessful because of cyanide toxicity in cassava tubers. The objectives of this study were identifying cyanide tolerating bacteria and study their tolerability efficiency. 119 lactic acid bacteria were isolated from fermented cassava pulp juice. Out of the total isolated bacteria, ten potential cyanide tolerating bacteria was screened. The cyanide tolerance efficiency was studied at 100, 400, 600 and 8000mg/L potassium cyanide, growth at different temperature and pH were analyzed. The maximum growth rate reading of the screened isolates ranges (0.674 to 1.116) at 600nm in maximum cyanide concentration. Isolate CD1, LA2, LA1 and CD2 showed maximum cyanide tolerance of (74.4, 72.66, 70.66 and 68.73%) respectively at 800mg/l after 48hr of incubation. The cyanide tolerability potential of individual isolates varies across different cyanide concentration. Above all 10 isolates were resistant to maximum cyanide concentration and possess potential of cyanide tolerating properties that help their selection and application in a controlled process to detoxify cassava roots for food and feed utilization. There was a general decrement in all samples over 48 h fermentation periods from 6.00 to 3.18 and the bacterial isolates showed significant growth at room temperature which were between ʺ25°Cʺ and ʺ40°Cʺ.

Isolation and probiotic potential of lactic acid bacteria from swine feces for feed additive composition

Animal microbiota is becoming an object of interest as a source of beneficial bacteria for commercial use. Moreover, the escalating problem of bacterial resistance to antibiotics is threatening animals and humans; therefore, in the last decade intensive search for alternative antimicrobials has been observed. In this study, lactic acid bacteria (LAB) were isolated from suckling and weaned pigs feces (376) and characterized to determine their functional properties and usability as pigs additives. Selection of the most promising LAB was made after each stage of research. Isolates were tested for their antimicrobial activity (376) and susceptibility to antibiotics (71). Selected LAB isolates (41) were tested for the production of organic acids, enzymatic activity, cell surface hydrophobicity and survival in gastrointestinal tract. Isolates selected for feed additive (5) were identified by MALDI-TOF mass spectrometry and partial sequence analysis of 16S rRNA gene, represented by Lentilactobacillus, Lacticaseibacillus (both previously classified as Lactobacillus) and Pediococcus genus. Feed additive prototype demonstrated high viability after lyophilization and during storage at 4 °C and − 20 °C for 30 days. Finally, feed additive was tested for survival in simulated alimentary tract of pigs, showing viability at the sufficient level to colonize the host. Studies are focused on obtaining beneficial strains of LAB with probiotic properties for pigs feed additive.

Characterization of the Probiotic Potential of Lactic Acid Bacteria Isolated from Kimchi, Yogurt, and Baby Feces in Hong Kong and Their Performance in Soymilk Fermentation.

Background: There are several potential healthy or nutritional benefits from the use of lactic acid bacteria (LAB) in foods. This study aimed to characterize the LAB isolates from kimchi, yogurt, and baby feces in the Hong Kong area and evaluate their performance in fermented soymilk, which allowed us to assess their potential use in future experiments. Methods: General characteristics including tolerance to acid, NaCl, bile salts and phenol, antimicrobial activity to various pathogens, and adhesive ability to Caco-2 cells were evaluated using 18 LAB in this study. To further demonstrate the influence of such isolates in soymilk fermentation, we measured viability by plating and noting changes in pH, amino acid content, aglyconic isoflavones content and antioxidant capacities in vitro, such as scavenging ability, and iron chelating ability. Results: In this study, various LAB isolates belonging to Lactobacillus rhamnosus, Lactobacillus sakei, Lactiplantibacillus plantarum, and Leuconostoc mesenteroides isolated in Hong Kong were evaluated. L. plantarum isolates R7, AC12, and AC14.1, and L. rhamnosus AC1 showed higher tolerance to acid, NaCl, bile salts, and phenol as compared to the other isolates tested. L. plantarum isolates AC12, AC13 and AC14.1, and L. rhamnosus AC1 harbored strong antimicrobial activity. L. plantarum isolates R7, AC12, AC13 and AC14.1, and L. paracasei isolates R6 and R8 showed higher adhesive ability than the other tested isolates. In soymilk, the viable numbers of L. paracasei R5, L. plantarum R7, L. rhamnosus AC1, L. sakei AC2, and Leu. mesenteroides AC5 were much higher than the other tested isolates after 48 h of fermentation. The pH value measuring the lactic acid level in soymilk fermented by L. plantarum AC14.1 was the lowest in comparison to those in soymilk fermented by other isolates. In addition, the levels of free amino acids and isoflavones in the aglycone forms of L. rhamnosus AC1-fermented soymilk were the highest. L. rhamnosus AC1-fermented soymilk also showed the highest antioxidant potential, including DPPH scavenging ability and iron chelating ability. Conclusions: In general, L. plantarum isolates R7 and AC14.1 and L. rhamnosus AC1 exhibited higher tolerance to challenging conditions as compared to the other isolates. Moreover, L. rhamnosus AC1 exhibited superior performance in soymilk fermentation and potential as a starter and probiotic culture.

Isolation of Lactococcus lactis from Whole Crop Rice and Determining Its Probiotic and Antimicrobial Properties towards Gastrointestinal Associated Bacteria

Antimicrobial resistance is an emerging condition that increases the risk of spreading and prolonging infectious diseases globally. Therefore, a new alternative strategy for antibiotics is required urgently to control pathogens spreading. Probiotics are considered as an alternative for antibiotics that inhibit pathogens. In the present study, potent lactic acid bacteria (LAB) were isolated and screened for their probiotic characteristics and antagonistic activity against intestinal pathogens by agar well diffusion, Time and Dose-dependent killing assay, minimum inhibitor, and minimum bactericidal concentration (MIC/MBC), and co-culture methods. The Lactococcus lactis RWP-3 and RWP-7 fermented the different carbohydrate substrates and produced different extracellular enzymes. Both isolates showed significant tolerant capability in the gastric, duodenal, and intestinal juices. In addition, RWP-3 and RWP-7 had hydrophobicity and aggregation properties in a time-dependent manner. Furthermore, the cell-free secondary metabolites (CFS) of RWP-3 and RWP-7 showed strong antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis. A co-culture study revealed that the RWP-3 and RWP-7 strongly compete with pathogen growths. RWP-3 and RWP-7 showed strong antagonistic activities against tested pathogens with significant probiotic characteristics, suggesting that these strains obtained could be used as an alternative strategy for the antibiotic to control infectious pathogens.