<Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> as a Probiotic Potential from Kouzeh Cheese (Traditional Iranian Cheese) and Its Antimicrobial Activity

The aim of this study is to isolate and identify Lactobacillus plantarum isolates from traditional cheese, Kouzeh, and evaluate their antimicrobial activity against some food pathogens. In total, 56 lactic acid bacteria were isolated by morphological and biochemical methods, 12 of which were identified as Lactobacillus plantarum by biochemical method and 11 were confirmed by molecular method. For analyzing the antimicrobial activity of these isolates properly, diffusion method was performed. The isolates were identified by 318 bp band dedicated for L. plantarum. The isolated L. plantarum represented an inhibitory activity against four of the pathogenic bacteria and showed different inhibition halos against each other. The larger halos were observed against Staphylococcus aureus and Staphylococcus epidermidis (15 ± 0.3 and 14.8 ± 0.7 mm, respectively). The inhibition halo of Escherichia coli was smaller than that of other pathogen and some L. plantarum did not show any inhibitory activity against E. coli, which were resistant to antimicrobial compounds produced by L. plantarum. The isolated L. plantarum isolates with the antimicrobial activity in this study had strong probiotic properties. These results indicated the nutritional value of Kouzeh cheese and usage of the isolated isolates as probiotic strains.     

Potential probiotic properties of lactic acid bacteria isolated from the intestinal mucosa of healthy piglets

In the present study, the probiotic properties of 52 lactic acid bacteria strains, isolated from the intestinal mucosa of 60-day-old healthy piglets, were evaluated in vitro in order to acquire probiotics of potential application. Based on acidic and bile salt resistance, 11 lactic acid bacteria strains were selected, among which 1 was identified as Pediococcus acidilactici, 3 as Enterococcus faecium, 3 as Lactobacillus rhamnosus, 2 as Lactobacillus brevis, and 2 as Lactobacillus plantarum by 16S rRNA gene sequencing. All selected strains were further investigated for transit tolerance in simulated upper gastrointestinal tract, for adhesion capacity to swine intestinal epithelial cells J2 (IPEC-J2), for cell surface characteristics including hydrophobicity, co-aggregation and auto-aggregation, and for antimicrobial activities. Moreover, hemolytic, bile salt hydrolase and biogenic amine-producing abilities were investigated for safety assessment. Two E. faecium (WEI-9 and WEI-10) and one L. plantarum (WEI-51) exhibited good simulated upper gastrointestinal tract tolerance, and showed high auto-aggregation and co-aggregation with Escherichia coli 1570. The strains WEI-9 and WEI-10 demonstrated the highest adherence capacity. The 11 selected strains mentioned above exhibited strong antimicrobial activity against E. coli CVCC1570, Staphylococcus aureus CVCC1882 and Salmonella pullorum AS1.1859. None of the 11 selected strains, except WEI-9 and WEI-33, exhibited bile salt hydrolase, hemolytic or biogenic amine-producing abilities. This work showed that the E. faecium WEI-10 and L. plantarum WEI-51were found to have the probiotic properties required for use as potential probiotics in animal feed supplements.     

Safety,probiotic and technological properties of <Emphasis Type="Italic">Lactobacilli</Emphasis> isolated from unpasteurised ovine and caprine cheeses

Eleven Lactobacillus plantarum from Slovak ovine and caprine lump and stored cheeses, and from four commercial probiotic and yogurt cultures (Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus acidophilus) identified using a Maldi-TOF MS analysis were screened in vitro for selected aspects correlated with safety (antibiotic susceptibility patterns, biochemical and haemolytic activity, presence of genes responsible for biogenic amines production), functional traits (including acid, bile tolerance and antimicrobial activity), ecological roles (ability to produce biofilms), and technological applications (acidification and milk coagulation capacity) for assurance of their quality and diversity. The antibiotic susceptibility showed two L. plantarum strains, 19l5 and 18l4, with the presence of the non-wild-type ECOFFs (epidemiological cut-off) for clindamycin and/or gentamicin. All these strains expressed a high acid tolerance at pH 2.5 after a 4 h exposure (bacteria viability varied between 60% and 91%), and bile resistance at 0.3% oxgall ranged from 60% to 99% with no haemolytic activity. Three wild L. plantarum strains, 17l1, 16l4, 18l2, had no harmful metabolic activities, and formed strong biofilms that were measured by a crystal violet assay. Simultaneously, the acid cell-free culture supernatant (ACFCS) from L. plantarum 18l2 had a marked inhibitory effect on the viability of the pathogens as evaluated by flow-cytometry, and also exhibited fast acidification and milk coagulation. As a result, we conclude that L. plantarum 18l2 can be included as part of the created lactobacilli collection that is useful as a starter, or starter adjunct, in the dairy industry, due to its desirable safety and probiotic characteristics, together with rapid acidification capacity compared with other investigated strains from commercially accessible products.     

Probiotic Evaluation of Antimicrobial <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> VJC38 Isolated from the Crop of Broiler Chicken

The aim of this study was to evaluate probiotic properties of antimicrobial Lactobacillus plantarum VJC38 in vitro. L. plantarum VJC38 was isolated from the crop of broiler chicken and characterized using dnaK gene sequence. The inhibitory activities of L. plantarum VJC38 against bacterial and fungal pathogens were evaluated. Antifungal compounds secreted by the strain VJC38 were identified using Gas Chromatography and Mass Spectrometry (GC-MS). The strain was evaluated for its tolerance to low pH, resistance to bile salts, auto-aggregation, co-aggregation with pathogenic Escherichia coli, cell surface hydrophobicity, cholesterol lowering activity, β-galactosidase production, adhesion ability to Caco-2 cells, mucin degradation, hemolytic activity and biogenic amine production. Phylogenetic analysis of dnaK gene of bacterial strain VJC38 showed 99% sequence similarity to Lactobacillus plantarum var. plantarum. It showed effective inhibition against food spoiling and pathogenic organisms like Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Aspergillus niger, Penicillium expansum and Eurotium species. The antifungal compound phenol- 2,4-bis(1,1-dimethylethyl) (PD) was identified in the culture filtrate of L. plantarum VJC38 and reported to have inhibition against Aspergillus species. L. plantarum VJC38 exhibited tolerance to low pH, resistance to bile salts, bile salt hydrolase activity, auto-aggregation (87.5%), co-aggregation with Escherichia coli (55.7%), cholesterol lowering activity (64%), β-galactosidase production (1206 MU), adherence to Caco-2 cells (11%), negative for mucin degradation, hemolytic activity and biogenic amine production. L. plantarum VJC38 could be a good candidate for further investigation in vivo to elucidate its health benefits and to evaluate its technological properties as a bio-protective strain.     

Screening for potential probiotic from spontaneously fermented non-dairy foods based on in vitro probiotic and safety properties

The aim of this study was to screen potential probiotic lactic acid bacteria from Chinese spontaneously fermented non-dairy foods by evaluating their probiotic and safety properties. All lactic acid bacteria (LAB) strains were identified by 16S rRNA gene sequencing. The in vitro probiotic tests included survival under low pH and bile salts, cell surface hydrophobicity, auto-aggregation, co-aggregation, antibacterial activity, and adherence ability to cells. The safety properties were evaluated based on hemolytic activity and antibiotic resistance profile. The salt tolerance, growth in litmus milk, and acidification ability were examined on selected potential probiotic LAB strains to investigate their potential use in food fermentation. A total of 122 strains were isolated and identified at the species level by 16S rRNA gene sequencing and included 62 Lactobacillus plantarum, 40 Weissella cibaria, 12 Lactobacillus brevis, 6 Weissella confusa, and 2 Lactobacillus sakei strains. One W. cibaria and nine L. plantarum isolates were selected based on their tolerance to low pH and bile salts. The hydrophobicity, auto-aggregation, co-aggregation, and antagonistic activities of these isolates varied greatly. All of the 10 selected strains showed multiple antibiotic resistance phenotypes and no hemolytic activity. The highest adhesion capacity to SW480 cells was observed with L. plantarum SK1. The isolates L. plantarum SK1, CB9, and CB10 were the most similar strains to Lactobacillus rhamnosus GG and selected for their high salt tolerance and acidifying activity. The results revealed strain-specific probiotic properties were and potential probiotics that can be used in the food industry.     

In Vitro Characterization of <Emphasis Type="Italic">Lactobacillus</Emphasis> Strains Isolated from Fruit Processing By-Products as Potential Probiotics

Nine wild Lactobacillus strains, namely Lactobacillus plantarum 53, Lactobacillus fermentum 56, L. fermentum 60, Lactobacillus paracasei 106, L. fermentum 250, L. fermentum 263, L. fermentum 139, L. fermentum 141, and L. fermentum 296, isolated from fruit processing by-products were evaluated in vitro for a series of safety, physiological functionality, and technological properties that could enable their use as probiotics. Considering the safety aspects, the resistance to antibiotics varied among the examined strains, and none of the strains presented hemolytic and mucinolytic activity. Regarding the physiological functionality properties, none of the strains were able to deconjugate bile salts; all of them presented low to moderate cell hydrophobicity and were able to autoaggregate, coaggregate with Listeria monocytogenes and Escherichia coli, and antagonize pathogenic bacteria. Exposure to pH 2 sharply decreased the survival of the examined strains after 1- or 2-h exposure; variable decreases were noted after 3-h exposure to pH 3. Overall, exposure to pH 5 and to bile salts (0.15, 0.3, and 1%) did not decrease the strains’ survival. Examined strains presented better ability to survive from the exposure to simulated gastrointestinal conditions in laboratorial media and milk than in grape juice. Considering the technological properties, all the strains were positive for proteolytic activity and EPS and diacetyl production, and most of them had good tolerance to 1–4% NaCl. These results indicate that wild Lactobacillus strains isolated from fruit processing by-products could present performance compatible with probiotic properties and technological features that enable the development of probiotic foods with distinct characteristics.     

Antibacterial and Antibiofilm Activity of Lactic Acid Bacteria Isolated from Traditional Artisanal Milk Cheese from Northeast China Against Enteropathogenic Bacteria

The present study aims to investigate the probiotic properties of novel strains of lactic acid bacteria isolated from traditional artisanal milk cheese from Northeast China and to explore their antibacterial activity against enteropathogenic bacteria. Of the 321 isolates, 86 exhibited survival in low pH, resistance to pancreatin, and tolerance to bile salts; of these, 12 inhibited the growth of more than seven enteropathogenic bacteria and exhibited antibiofilm activities against Staphylococcus aureus CMCC26003 and/or Escherichia coli CVCC230. Based on 16S ribosomal RNA sequence analysis, the 12 isolates were assigned to Lactobacillus plantarum (7), Lactobacillus helveticus (3), Pediococcus acidilactici (1), and Enterococcus faecium (1) species. In addition, 5 of the 12 strains were susceptible to most of the tested antibiotics. Furthermore, four strains with sensitivity to antibiotics showed significantly high levels of hydrophobicity similar to or better than the reference strain Lactobacillus rhamnosus GG. Moreover, three strains were confirmed safe through non-hemolytic activities and bacterial translocation. Overall, the selected Lact. plantarum 27053 and 27172 and Lact. helveticus 27058 strains can be considered potential probiotic strains and candidates for further application in functional food and prevention or treatment of gastrointestinal diseases.     

Effect of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Tennozu-SU2 on <Emphasis Type="Italic">Salmonella</Emphasis> Typhimurium Infection in Human Enterocyte-Like HT-29-Luc Cells and BALB/c Mice

The probiotic properties and inhibitory effect on Salmonella Typhimurium adhesion on human enterocyte-like HT-29-Luc cells of three Lactobacillus plantarum strains isolated from fermented fish, beach sand and a coastal plant were determined. Compared with the type strain L. plantarum NBRC 15891^T, which was isolated from pickled cabbage, L. plantarum Tennozu-SU2 isolated from the acorn of a coastal tree showed high autoaggregation in de Man, Rogosa and Sharpe (MRS) broth and an antagonistic effect against S. Typhimurium in brain heart infusion (BHI) broth. Furthermore, heat-killed L. plantarum Tennozu-SU2 cells inhibited S. Typhimurium adhesion on HT-29-Luc cells. Both live and heat-killed L. plantarum Tennozu-SU2 cells showed an inhibitory effect on gut colonisation in BALB/c mice, as assessed by viable Salmonella count in faecal samples and by invasion into liver and spleen tissues. The properties shown in this study suggest that L. plantarum Tennozu-SU2 is useful as a starter and probiotic bacteria in functional food material.     

Functional Characterization of Potential Probiotic Lactic Acid Bacteria Isolated from <Emphasis Type="Italic">Kalarei</Emphasis> and Development of Probiotic Fermented Oat Flour

Considerable variations among probiotics with respect to their health benefitting attributes fuel the research on bioprospecting of proficient probiotic strains from various ecological niches especially the poorly unexplored ones. In the current study, kalarei, an indigenous cheese-like fermented milk product, and other dairy-based sources like curd and raw milk were used for isolation of lactic acid bacteria (LAB). Among 34 LAB isolates, 7 that could withstand simulated gastrointestinal (GI) conditions were characterized for functional probiotic attributes, viz. adhesion ability, aggregation and coaggregation, extracellular enzyme producing capability, antibacterial activity against pathogens and antibiotic resistance. The isolate M-13 (from kalarei) which exhibited most of the desirable probiotic functional properties was identified as Lactobacillus plantarum based on 16S ribosomal DNA sequence analysis and designated as L. plantarum M-13. The sequence was submitted to GenBank (accession number KT592509). The study presents the first ever report of isolation of potential probiotic LAB, i.e. L. plantarum M-13 from indigenous food kalarei, and its application for development of potential probiotic fermented oat flour (PFOF). PFOF was analysed for parameters like viability of L. plantarum M-13, acidity and pH. Results show that PFOF serves as a good matrix for potential probiotic L. plantarum M-13 as it supported adequate growth of the organism (14.4 log cfu/ml after 72 h of fermentation). In addition, appreciable acid production by L. plantarum M-13 and consequential pH reduction indicates the vigorous and active metabolic status of the potential probiotic organism in the food matrix. Thus, study shows that fermented oat flour may possibly be developed as a potential probiotic carrier especially in view of the problems associated with dairy products as probiotic vehicles.     

New perspectives of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> as a probiotic: The gut-heart-brain axis

Lactobacillus plantarum is a non-gas-producing lactic acid bacterium that is generally regarded as safe (GRAS) with Qualified Presumption of Safety (QPS) status. Although traditionally used for dairy, meat and vegetable fermentation, L. plantarum is gaining increasing significance as a probiotic. With the newly acclaimed gut-heart-brain axis, strains of L. plantarum have proven to be a valuable species for the development of probiotics, with various beneficial effects on gut health, metabolic disorders and brain health. In this review, the classification and taxonomy, and the relation of these with safety aspects are introduced. Characteristics of L. plantarum to fulfill the criteria as a probiotic are discussed. Emphasis are also given to the beneficial functions of L. plantarum in gut disorders such as inflammatory bowel diseases, metabolic syndromes, dyslipidemia, hypercholesteromia, obesity, and diabetes, and brain health aspects involving psychological disorders.     

Selection and evaluation of functional characteristics of autochthonous lactic acid bacteria isolated from traditional fermented stinky bean (<Emphasis Type="Italic">Sataw-Dong</Emphasis>)

The aim of this study was to evaluate the technological and functional potential of lactic acid bacteria (LAB) isolated from fermented stinky bean (Sataw-Dong). Of the 114 LAB colonies isolated from spontaneously fermented stinky bean which showed inhibitory activity against two food-borne pathogens (Staphylococcus aureus DMST 4480 and Escherichia coli DMST 4212), the five isolates (KJ03, KJ15, KJ17, KJ22, KJ23) exhibiting excellent antagonistic activity were subjected to further study. These five strains showed titratable acidity as lactic acid in the range of 1.47–1.55 %, with strains KJ03 and KJ23 additionally exhibiting a high NaCl tolerance of >7 % (w/v). Using 16S rRNA gene sequence analysis, strains KJ03 and KJ23 were identified as Lactobacillus plantarum and L. fermentum, respectively, and further investigated for their functional properties in vitro. Both strains survived well in a simulated gastrointestinal tract environment with <1 log cell decrease over 8 h (>8 log CFU/ml). Lactobacillus plantarum KJ03 showed the best performance with respect to cholesterol removal (53 %), while L. fermentum KJ23 showed the highest cell-surface hydrophobicity (39.5 %). Neither of the two strains showed any hemolysis activity. Both strains hydrolyzed glycodeoxycholic and taurodeoxycholic acids. In terms of antibiotic susceptibility, L. fermentum KJ23 was not sensitive to tetracycline. Taking all of the results into account, L. plantarum KJ03 possessed desirable in vitro functional properties. This strain is therefore a good candidate for further investigation for use in Sataw-Dong fermentation to assess its technological performance as a potential probiotic starter.     

Selection of Potential Probiotic <Emphasis Type="Italic">Lactobacillus</Emphasis> with Inhibitory Activity Against <Emphasis Type="Italic">Salmonella</Emphasis> and Fecal Coliform Bacteria

Three hundred and sixty presumptive lactic acid bacteria (LAB) isolated from pregnant sows, newborn, suckling, and weaned piglets were preliminarily screened for anti-Salmonella activity. Fifty-eight isolates consisting of Lactobacillus reuteri (n = 32), Lactobacillus salivarius (n = 10), Lactobacillus mucosae (n = 8), Lactobacillus johnsonii (n = 5), and Lactobacillus crispatus (n = 3) were selected and further characterized for probiotic properties including production of antimicrobial substances, acid and bile tolerance, and cell adherence to Caco-2 cells. Eight isolates including Lact. johnsonii LJ202 and Lact. reuteri LR108 were identified as potential probiotics. LJ202 was selected for further use in co-culture studies of two-bacterial and multiple-bacterial species to examine its inhibitory activity against Salmonella enterica serovar Enteritidis DMST7106 (SE7106). Co-culture of LJ202 and SE7106 showed that LJ202 could completely inhibit the growth of SE7106 in 10 h of co-culture. In co-culture of multiple-bacterial species, culturable fecal bacteria from pig feces were used as representative of multiple-bacterial species. The study was performed to examine whether interactions among multiple-bacterial species would influence antagonistic activity of LJ202 against SE7106 and fecal coliform bacteria. Co-culture of SE7106 with different combinations of fecal bacteria and probiotic (LJ202 and LR108) or non-probiotic (Lact. mucosae LM303) strains revealed that the growth of SE7106 was completely inhibited either in the presence or in the absence of probiotic strains. Intriguingly, LJ202 exhibited notable inhibitory activity against fecal coliform bacteria while LR108 did not. Taken together, the results of co-culture studies suggested that LJ202 is a good probiotic candidate for further study its inhibitory effects against pathogen infections in pigs.     

Isolation of <Emphasis Type="Italic">Lactobacillus</Emphasis> strains from shellfish for their potential use as probiotics

Microorganisms intended for use as probiotics in aquaculture should exert antimicrobial activity and be regarded as safe not only for their aquatic hosts but also for their surrounding environments and humans. The objective of this work was to investigate antimicrobial activity against various pathogens, bile salt tolerance, and acid tolerance of 65 presumptive Lactobacillus spp. isolated from shellfish samples. Four strains (HL1, HL12, HL20, and JL28) were selected after qualitatively identifying high levels of antimicrobial activity against bacteria including Staphylococcus aureus, Salmonella typhimurium, Salmonella enteritidis, Escherichia coli O157:H7, Vibrio ichthyoenteri, Edwardsiella tarda, Streptococcus iniae, and V. parahaemolyticus. The sequence analysis of their 16S rRNA genes revealed that the four strains belong to the Lactobacillus plantarum species. In addition, their survivability was tested in bile salt and acidic conditions to show their potential use as probiotics in the gastrointestinal tract.     

<Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> and Its Probiotic and Food Potentialities

The number of studies claiming probiotic health effects of Lactobacillus plantarum is escalating. Lb. plantarum is a lactic acid bacterium found in diverse ecological niches, highlighting its particular capabilities of adaptation and genome plasticity. Another function that needs to be underlined is the capabilities of Lb. plantarum to produce diverse and potent bacteriocins, which are antimicrobial peptides with possible applications as food preservative or antibiotic complementary agents. Taken together, all these characteristics design Lb. plantarum as a genuine model for academic research and viable biological agent with promising applications. The present review aims at shedding light on the safety of Lb. plantarum and run through the main studies underpinning its beneficial claims. The mechanisms explaining probiotic-related features are discussed.     

Diversity and Probiotic Potential of Lactic Acid Bacteria Isolated from Horreh,a Traditional Iranian Fermented Food

The aim of this study was to evaluate the probiotic potential of lactic acid bacteria (LAB) strains isolated from Horreh. Some probiotic properties, e.g., resistance to acid, bile tolerance, antibacterial activity, and antibiotic susceptibility, were investigated. A total of 140 Gram-positive and catalase-negative isolates from Horreh were subjected to identification and grouping by cultural methods and the 16S rRNA sequencing. The new isolates were identified to be Lactobacillus (fermentum, plantarum, and brevis) Weissella cibaria, Enterococcus (faecium and faecalis), Leuconostoc (citreum and mesenteroides subsp. mesenteroides) and Pediococcus pentosaceus. Probiotic potential study of LAB isolates showed that Lb. plantarum and Leu. mesenteroides subsp. mesenteroides isolates were able to grow at pH 2.5 and 3.5. Lactobacillus plantarum (isolate A44) showed the highest cell hydrophobicity (84.5%). According to antibacterial activity tests, Listeria innocua and Staphylococcus aureus were the most sensitive indicators against the selected LAB strains, while Escherichia coli and Bacillus cereus were the most resistant. In addition, all the isolated LAB species were resistant to vancomycin. The results of the present study suggested that the Lactobacillus fermentum and plantarum isolated from Horreh, characterized in this study, have potential use for industrial purposes as probiotics.     

Comparison of L-lactate dehydrogenases of different origins produced in the cells of yeast <Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis>

The expression of L-lactate dehydrogenase genes ldh1 (Bos taurus), ldhA (Homo sapiens), ldhA (Rhizopus oryzae), ldh1 (Lactobacillus plantarum), and ldh1 (Lactobacillus pentosus) in the cells of yeast Schizosaccharomyces pombe VKPM U-3106 has been investigated. The catalytic characteristics of the enzymes encoded by these genes have been compared, and the intensity of lactic acid synthesis by the recombinant strains obtained has been evaluated. The enzymatic activity of L-lactate dehydrogenases from L. plantarum and L. pentosus was the highest (approximately 2 to 2.5 times higher than that of the mammalian enzymes), and these enzymes therefore appear to have the highest potential for the development of lactic-acid producing strains of yeast S. pombe.     

Viability and Stress Response of Putative Probiotic <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Strains in Honey Environment

Due to problem of preservation of dairy products which serve as a matrix for probiotics, it is challenging to use these probiotics as food supplements in many developing countries. To determine the suitability of the Lactobacillus strains for exploitation as probiotics in honey, we investigated the effect of their storage on the viability, functionality, and the mechanism associated with their protective effect. Three isolates obtained from our laboratory collection were identified through amplification of the 16S rRNA gene. The viability of the strains in honey at different storage conditions was studied. Three genes (hdc, gtf, and clpL) responsible for the resistance of bacteria in acidic environments were screened. SDS-PAGE analysis of total protein was performed to observe protein profile changes of the strains after exposure to honey. All the three isolates, namely, GGU, GLA51, and GLP56, were identified as Lactobacillus plantarum strains. After 28 days of storage in honey at 4 °C, viable cell concentrations of the three strains were higher than 2.04?×?10⁶ CFU/ml. During the same period at room temperature, only the Lactobacillus plantarum GLP56 strain remained viable with a cell concentration of 1.86?×?10⁴ CFU/ml. The clpL gene coding for ATPase was detected in all the three strains. The protein of molecular weight ~?50 kDa was absent in the protein profile of Lactobacillus plantarum GGU after 60 days of storage in honey at 4 °C. The Lactobacillus plantarum GLP56, Lactobacillus plantarum GLA51, and Lactobacillus plantarum GGU strains exposed to honey can withstand acidic environmental stress but their viability declines over time.     

In vitro assessment of safety and probiotic potential characteristics of <Emphasis Type="Italic">Lactobacillus</Emphasis> strains isolated from water buffalo mozzarella cheese

The aim of this study was to evaluate the safety and probiotic potential characteristics of ten Lactobacillus spp. strains (Lactobacillus fermentum SJRP30, Lactobacillus casei SJRP37, SJRP66, SJRP141, SJRP145, SJRP146, and SJRP169, and Lactobacillus delbrueckii subsp. bulgaricus SJRP50, SJRP76, and SJRP149) that had previously been isolated from water buffalo mozzarella cheese. The safety of the strains was analyzed based on mucin degradation, hemolytic activity, resistance to antibiotics and the presence of genes encoding virulence factors. The in vitro tests concerning probiotic potential included survival under simulated gastrointestinal (GI) tract conditions, intestinal epithelial cell adhesion, the presence of genes encoding adhesion, aggregation and colonization factors, antimicrobial activity, and the production of the β-galactosidase enzyme. Although all strains presented resistance to several antibiotics, the resistance was limited to antibiotics to which the strains had intrinsic resistance. Furthermore, the strains presented a limited spread of genes encoding virulence factors and resistance to antibiotics, and none of the strains presented hemolytic or mucin degradation activity. The L. delbrueckii subsp. bulgaricus strains showed the lowest survival rate after exposure to simulated GI tract conditions, whereas all of the L. casei and L. fermentum strains showed good survivability. None of the tested lactobacilli strains presented bile salt hydrolase (BSH) activity, and only L. casei SJRP145 did not produce the β-galactosidase enzyme. The strains showed varied levels of adhesion to Caco-2 cells. None of the cell-free supernatants inhibited the growth of pathogenic target microorganisms. Overall, L. fermentum SJRP30 and L. casei SJRP145 and SJRP146 were revealed to be safe and to possess similar or superior probiotic characteristics compared to the reference strain L. rhamnosus GG (ATCC 53103).     

Probiotic potential of novel <Emphasis Type="Italic">Lactobacillus</Emphasis> strains isolated from salted-fermented shrimp as antagonists for <Emphasis Type="Italic">Vibrio parahaemolyticus</Emphasis>

Lactobacillus strains have been considered good candidates as biological control agents for prevention or treatment of plant and animal infections. One L. plantarum strain FB003 and three strains (FB011, FB081, and FB110) which closed to L. sakei were isolated from fermented and salted shrimp and their abilities in inhibiting growth of Vibrio parahaemolyticus were characterized. These strains were selected as potential probiotics based on their oro-gastro-intestinal resistance, gut colonization, adhesion to Caco-2 cells, antimicrobial activities, antibiotic resistance, and safety aspects. Results of this study revealed that these isolates possessed high aggregation activities against pathogens in host intestines. Strain FB011 strain showed higher coaggregation and immunomodulatory activity in the gastro-intestinal tract than L. plantarum. These difference effects of Lactobacillus strains provide valuable information about using them to prevent Vibrio infections in the aquaculture industry.     

A physiological comparative study of acid tolerance of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> ZDY 2013 and <Emphasis Type="Italic">L. plantarum</Emphasis> ATCC 8014 at membrane and cytoplasm levels

This study aimed to disclose the acid tolerance mechanism of Lactobacillus plantarum by comparing L. plantarum ZDY 2013 with the type strain L. plantarum ATCC 8014 in terms of cell membrane, energy metabolism, and amino acid metabolism. L. plantarum ZDY 2013 had a superior growth performance under acidic condition with 100-fold higher survival rate than that of L. plantarum ATCC 8014 at pH 2.5. To determine the acid tolerance physiological mechanism, cell integrity was investigated through scanning electron microscopy. The study revealed that L. plantarum ZDY 2013 maintained cell morphology and integrity, which is much better than L. plantarum ATCC 8014 under acid stress. Analysis of energy metabolism showed that, at pH 5.0, L. plantarum ZDY 2013 enhanced the activity of Na⁺/K⁺-ATPase and decreased the ratio of NAD⁺/NADH in comparison with L. plantarum ATCC 8014. Similarly, amino acid metabolism of intracellular arginine, glutamate, and alanine was improved in L. plantarum ZDY 2013. Correspondingly, the activity of arginine deiminase and glutamate decarboxylase of L. plantarum ZDY 2013 increased by 1.2-fold and 1.3-fold compared with L. plantarum ATCC 8014 in acid stress. In summary, it is demonstrated that the special physiological behaviors (integrity of cell membrane, enhanced energy metabolism, increased amino acid and enzyme level) of L. plantarum ZDY 2013 can protect the cells from acid stress.