Characterization and purification of a bacteriocin produced by a potential probiotic culture, Lactobacillus acidophilus 30SC

Combined Action of Antibiotics and Bacteriocins against Vancomycin-Resistant Enterococci

Antibiotics have been one of the most important discoveries in the area of applied medical microbiology; however, as a result of various factors, we are currently facing a dramatic and relatively dangerous increase in the number of cases of antibiotic resistance, and the need for new types of antimicrobials continues to grow. New approaches are needed to combat antibiotic-resistant pathogens. Bacteriocins, as part of the group of antimicrobial peptides, can be considered as alternatives and/or complements to known antibiotics. Their narrow spectra of activity can be explored for the control of various pathogens, such as vancomycin-resistant enterococci (VRE), as single therapies or in combination with known antibiotics. In the present study, we isolated bacteriocins from different lactic acid bacteria (LAB) strains, including Enterococcus and Pediococcus, and explored the possible synergistic inhibition of growth by bacteriocins and vancomycin. It was observed in the growth dynamics with previously selected VRE strains that the bacteriocins had a high specificity and a promising inhibitory effect against the VRE strains, and these results were validated by a propidium iodide viability test using flow cytometry. The data obtained indicate that the selected bacteriocins can be used to control VRE in the food industry or even as an alternative treatment to combat infections with antibiotic-resistant bacteria.

Overview of the angiogenic effect of probiotics (Lactobacillus acidophilus and Lactobacillus rhamnosus) at human umbilical vein endothelial cells

Introduction: Angiogenesis (neovascularization), which means new vessel construction, is normal and physiologically, wound healing, embryogenesis, a necessary menstrual cycle it's a mechanism. When taken in appropriate amounts together with or separately with nutrients, mucosal and by regulating systemic immunity, ensuring nutritional and microbial balance in the intestines living nonpatogenic microorganisms that positively affect the health of the host it is called "probiotics". Lactic acid bacteria, the most probiotic microorganisms it constitutes its important group. Where probiotics have an effect on angiogenesis, and it is thought to help heal wounds through the road. With this research indicated that roles of Lactobacillus acidophilus and Lactobacillus rhamnosus on angiogenesis if present to demonstrate in vitro methods and the gene expression responsible for the formation of these effects it is intended to reveal. Material and Method: This study is an experimental study conducted in vitro human umbilical cord vein endothelial cell (HUVEC) MTT test in cell culture with (3-[4,5-Dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide; Thiazolyl blue) evaluation of viability and proliferation wound healing model, tube formation method and gene expression with real rime-polymer chain reaction (RT-PCR) methods of appointment were used. Results: HUVEC cells L. acidophilus 10⁹ CFU\ml after extract application statistical of mRNA expression of VEGF and FGF genes by control group 24 per hour it was found to increase significantly. L. rhamnosus 10 6 CFU\ml and 109 CFU\ml after application of extracts VEGF gene mRNA by control group 24 per hour its expression was found to be statistically significantly increased. Also L. rhamnosus extracts cell proliferation and migration of in vitro wound model it was found to increase statistically significantly. Conclusion: In this study, in vitro L. acidophilus 10⁹ CFU\ml extract and 10⁶ CFU\ml and 10⁹ CFU\ml extract of L. rhamnosus, VEGF gene mRNA revealed to be effective on angiogenesis in HUVEC cells by increasing expression it is.

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.

The Use of Probiotics to Fight Biofilms in Medical Devices: A Systematic Review and Meta-Analysis

Medical device-associated infections (MDAI) are a critical problem due to the increasing usage of medical devices in the aging population. The inhibition of biofilm formation through the use of probiotics has received attention from the medical field in the last years. However, this sparse knowledge has not been properly reviewed, so that successful strategies for biofilm management can be developed. This study aims to summarize the relevant literature about the effect of probiotics and their metabolites on biofilm formation in medical devices using a PRISMA-oriented (Preferred Reporting Items for Systematic reviews and Meta-Analyses) systematic search and meta-analysis. This approach revealed that the use of probiotics and their products is a promising strategy to hinder biofilm growth by a broad spectrum of pathogenic microorganisms. The meta-analysis showed a pooled effect estimate for the proportion of biofilm reduction of 70% for biosurfactants, 76% for cell-free supernatants (CFS), 77% for probiotic cells and 88% for exopolysaccharides (EPS). This review also highlights the need to properly analyze and report data, as well as the importance of standardizing the in vitro culture conditions to facilitate the comparison between studies. This is essential to increase the predictive value of the studies and translate their findings into clinical applications.

Probiotic Potential of Lactic Acid Starter Cultures Isolated from a Traditional Fermented Sorghum-Millet Beverage

The purpose of this study was to establish the probiotic potential of lactic acid bacteria (LAB) starter cultures, Lb. plantarum MNC 21, L. lactis MNC 24, and W. confusa MNC 20, isolated from a traditionally fermented sorghum-millet beverage from Uganda. The cultures were examined for tolerance to acid and bile salts, bile salt hydrolase (BSH) activity, antibiotic susceptibility, biogenic amine production, mucin degradation, hydrophobicity, auto-aggregation, adherence to the ileum, coaggregation, and antimicrobial properties against selected pathogenic species. Lb. rhamnosus yoba 2012, a known probiotic, was the reference. The isolates were tolerant to acid (pH = 3) and bile (1%). W. confusa MNC 20 and Lb. plantarum MNC 21 exhibited medium BSH activity (11-15 mm diameter of hydrolysis zone) while L. lactis and Lb. rhamnosus yoba 2012 exhibited low BSH activity (<10 mm diameter of hydrolysis zone). All isolates lacked mucolytic activity. Lb. plantarum MNC 21 and W. confusa MNC 20 produced agmatine. The candidate and reference microorganisms were resistant to 10 of 21 and 5 of 21 antibiotics, respectively. The isolates exhibited hydrophobic, auto-aggregation and coaggregation properties. These three properties were exhibited more (p < 0.05) by the reference than the potential probiotics. The ability of the potential probiotics to attach onto the goat ileum (7.3-8.0 log cfu/cm²) was comparable to that of Lb. rhamnosus yoba 2012 (7.6 log cfu/cm²). The four LAB inhibited E. coli, S. aureus, and S. enterica to the same extent (p < 0.05). The findings indicated potential probiotic activity of the starter cultures. However, further in vivo examination of these isolates is required to confirm their probiotic capabilities.

The secondary metabolites produced by Lactobacillus plantarum downregulate BCL-2 and BUFFY genes on breast cancer cell line and model organism Drosophila melanogaster: molecular docking approach

PURPOSE

The current study was designed to evaluate the toxicity of the secondary metabolites of Lactobacillus plantarum against the human breast cancer cell line (MCF-7) and the Drosophila melanogaster.

METHODS

In this study, toxicity analyses of secondary metabolites of Lactobacillus plantarum were analyzed on breast cancer cells, and the Drosophila melanogaster. After application, in the MCF-7 cell line, expression levels of RRAS-2, TP53, BCL-2, APAF-1, CASP-3, FADD, CASP-7, BOK genes; in D. melanogaster; expression levels of RAS64B P53, BUFFY, DARK, DECAY, FADD, DRICE, and DEBCL genes were determined by RT-PCR. In addition, analysis of L. plantarum secondary metabolite was performed by GC-MS method and molecular binding poses of secondary metabolites and human enzymes were investigated in silico.

RESULTS

Drosophila melanogaster being used as a model organism where some of the human genes were preserved. The IC50 value of the secondary metabolite in the MCF-7 cell line was determined to be 0.0011 mg/ml. Lethal concentration 50 (LC₅₀) and 99 (LC₉₉) values of secondary metabolites against fruit fly adults were 0.24 mg/ml and 0.54 mg/ml, respectively. The expression levels of BCL-2 and BUFFY genes which are anti-apoptotic in human and fruit flies have been reduced, and at the same time, increased expression of DECAY, FADD, RAS64B apoptotic genes in D. melanogaster.

CONCLUSION

The substance detected in the secondary metabolite content and encoded as L13 (3-phenyl-1, 2, 4-benzotriazine) has been observed to have high binding affinity in the studied genes.

Probiotic potential and biochemical and technological properties of Lactococcus lactis ssp. lactis strains isolated from raw milk and kefir grains

Lactococcus lactis ssp. lactis is one of the most important starter bacteria used in dairy technology and it is of great economic importance because of its use in the production of dairy products, including cheese, butter, cream, and fermented milks. Numerous studies have evaluated the biochemical and probiotic properties of lactococci; however, limited studies on the probiotic characteristics of lactococci were conducted using strains originating from raw milk and dairy products. Characterizing the probiotic properties of strains isolated from raw milk and fermented milk products is important in terms of selecting starter culture strains for the production of functional dairy products. In this study, biochemical properties (including antibiotic sensitivity, lipolytic activity, amino acid decarboxylation, antioxidant activity) and probiotic properties (including antimicrobial activity, growth in the presence of bile salts, bile salts deconjugation, and hydrophobicity) of 14 Lactococcus lactis strains isolated from raw milk and kefir grains were investigated. Strains originating from kefir grains had better characteristics in terms of antimicrobial activity and bile salt deconjugation, whereas strains from raw milk had better hydrophobicity and antioxidant activity characteristics. None of the strains were able to grow in the presence of bile salt and did not show amino acid decarboxylation or lipolytic activities. Biochemical and probiotic properties of L. lactis strains varied depending on the strain and some of these strains could be used as functional cultures depending on their properties. However, these strains did not possess all of the properties required to meet the definition of a probiotic.

Influences of quorum-quenching probiotic bacteria on the gut microbial community and immune function in weaning pigs

The aim of this study is to investigate the dynamic gut microbial diversity in weaning swine after administering feed supplemented with probiotic bacteria that specifically inhibit the activity of quorum molecules. Initially, the universal quorum molecule autoinducer-2 (AI-2) bioassay results indicated that AI-2 activity was profoundly inhibited in enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the presence of Lactobacillus acidophilus strain 30SC cell extract, although the growth of EHEC was not affected. Based on plate counting results, bacterial community analysis revealed a specific reduction in coliforms compared to the control, whereas the population of lactobacilli increased in weaning swine in in vivo trials. Supplementation with L. acidophilus strain 30SC did not affect the counts of other communities, such as total aerobes and yeast/mold. In addition, PCR-denaturing gradient gel electrophoresis analysis showed a significant difference in the 16S rRNA gene products after administering L. acidophilus strain 30SC. Selected bands were sequenced, and most of them were identified as uncultured bacterium clones or a Lactobacillus- and Bifidobacterium-specific community. Therefore, our results indicate that quorum-quenching probiotic bacteria can significantly modulate the gut microbiota of swine and these beneficial effects can contribute to the improvement of performance and health in the gastrointestinal tract of weaning pigs.

The use of Lactobacillus as an alternative of antibiotic growth promoters in pigs: A review

Antibiotics, often supplemented in feed, used as a growth promoter, may cause their residual effect in animal produce and also trigger antibiotic resistance in bacteria, which is of serious concern among swine farming entrepreneurs. As an alternative, supplementing probiotics gained interest in recent years. Lactobacillus being the most commonly used probiotic agent improves growth performance, feed conversion efficiency, nutrient utilization, intestinal microbiota, gut health and regulates immune system in pigs. The characteristics of Lactobacillus spp. and their probiotic effects in swine production are reviewed here under.

Use of probiotics in prevention and treatment of patients with Clostridium difficile infection

Clostridium difficile is an anaerobic, gram positive, sporulating, toxin-producing bacillus which causes a spectrum of clinical disease ranging from an asymptomatic carrier state to toxic megacolon and fulminant disease. Infection with C. difficile is an expensive and pervasive health care burden. The current theory regarding the development of C. difficile infection (CDI) suggests that disruption of the structure and/or function of an individual's normal intestinal microbiota enables colonization by C. difficile, and in the absence of an effective immune response, the bacteria causes illness. In this article we discuss the role of the colonic microbiota in the development of CDI and the potential role of probiotics in preventing and treating CDI. We review the evidence from in vitro laboratory and pre-clinical studies, as well as evidence from clinical studies and discuss the current recommendations for the use of probiotics for CDI in clinical practice.

Antibacterial Activity of Probiotic Lactobacillus plantarum HK01: Effect of Divalent Metal Cations and Food Additives on Production Efficiency of Antibacterial Compounds

One hundred and sixty lactic acid bacteria, isolated from Iranian traditional dairy products, were screened for antibacterial potential. Among them, an isolate showing remarkable antibacterial activity against both Staphylococcus aureus (PTCC 1112) and Escherichia coli (PTCC 1338) was selected based on minimum inhibitory concentration (AU/mL). The morphological and biochemical characteristics of the isolate matched the literature description about genus Lactobacillus. Partial sequencing of 16S rRNA gene and its alignment with other Lactobacillus strains revealed that the isolate was closely related to the Lactobacillus plantarum. The isolate also exhibited the highest similarity (>99 %) to L. plantarum. We thus tentatively classified the bacterial isolate as L. plantarum HK01. The antibacterial active compound from HK01 strain remained stable for 45 min at 121 °C, and it reached a maximum activity at the end of log phase and the early part of stationary phase. The antibacterial activity of the test isolate, its probiotic properties and production efficacy through addition of some divalent metal cations and food additives were studied as well. The study of bile salt hydrolase (BSH) activity as a function of growth revealed that HK01 strain hydrolysing up to 5 % of sodium salt of glycodeoxycholic acid, correlated with the presence of bsh gene in the isolate. HK01 strain showed high resistance to lysozyme, good adaptation to simulated gastric juice and a moderate bile tolerance. Results obtained from simulated gastric juice conditions showed no significant difference occured during the 70 min. HK01 strain was classified as a strain with low hydrophobicity (34.2 %). Addition of trisodium citrate dehydrates as a food-grade chelator of divalent cations restored antibacterial compound production in MRS broth. Antibacterial compounds of L. plantarum HK01 endured treatment with 10 g/L of SDS, Tween 20, Tween 80 and urea. Concerning food additives, the results demonstrated that antibacterial compound production by L. plantarum HK01 was influenced by the presence of surfactants, EDTA, KCl and sodium citrate.

A study on characterization of new bacteriocin produced from a novel strain of Lactobacillus spicheri G2 isolated from Gundruk- a fermented vegetable product of North East India: A novel bacteriocin production from Lactobacillus spicheri G2

Bacteriocin producing Lactobacillus spicheri G2, isolated from Gundruk - a traditional fermented vegetable product of North East India. L. spicheri G2 identified by morphological, biochemical techniques followed by 16S rRNA gene technique. The 16Sr RNA sequence of bacteriocin producer is registered in NCBI under accession no. JX481912. The bacteriocin producing potential of L. spicheri is being reported for the first time in the present investigation. Bacteriocin of L. spicheri G2 showed strong antagonism against food spoiling and pathogenic bacteria viz. Listeria monocytogenes, Staphlococcus aureus, Clostridium perfringens, Streptococcus mutans, Lactobacillus plantarum, Leuconostoc mesenteroides and Bacillus cereus. Bacteriocin production of L. spicheri G2 was enhanced by optimization of production time, pH of medium and incubation temperature by following one variable at a time method. Maximum bacteriocin activity (2000 AU/ml) was recorded in MRS broth at 34 h with an initial pH of 4.0 after incubating at 35 °C. The bacteriocin was purified by single step gel exclusion chromatography. Molecular weight of this novel bacteriocin was determined by SDS PAGE which was found to be 43 kDa. Purified bacteriocin was found resistant to high temperature and varied pH range but sensitive to proteolytic enzymes like trypsin and proteinase k, the characters desirable for food preservation.

Short communication: Development of a direct in vivo screening model to identify potential probiotic bacteria using Caenorhabditis elegans

Caenorhabditis elegans is an accepted model host to study host-bacteria interactions in the gut, in addition to being a simple model with which to study conserved aspects of biological signaling pathways in intestinal environments, because these nematode worms have similar intestinal cells to those of humans. Here, we used C. elegans to develop a new in vivo screening system for potential probiotic lactic acid bacteria (LAB). Initially, critical colonization ability of LAB strains isolated from Korean infant feces was screened in the worm intestinal tract over a period of 5 d. Furthermore, we investigated host health-promoting activities, including longevity-extending effects and immune-enhancing activities against foodborne pathogen infection. We identified 4 LAB strains that were highly persistent in the nematode gut and that significantly prolonged the longevity of C. elegans and improved the survival of C. elegans in response to infection by Staphylococcus aureus. The 4 LAB strains we identified showed resistance to acid and bile conditions, assimilated cholesterol, and were able to attach to a mucus layer. The 4 LAB isolates were identified as Lactobacillus plantarum using 16S rRNA sequencing analysis. Taken together, we developed a direct in vivo screening system using C. elegans to study host health-promoting LAB. Our system is simple, rapid, cost-effective, and reliable, and we anticipate that this system will result in the discovery of many more potential probiotic bacteria for dairy foods.

Characterization of a noncytotoxic bacteriocin from probiotic Lactobacillus plantarum DM5 with potential as a food preservative

The aim of this work was to purify and characterize the bacteriocin produced by probiotic Lactobacillus plantarum DM5 in order to evaluate its potential as nutraceuticals. Lb. plantarum DM5 exhibited in vitro probiotic properties such as high resistance to gastric juice and bile salt, adherence to human adenocarcinoma (HT-29) cells, bile salt hydrolase and cholesterol assimilation activity. Moreover, Lb. plantarum DM5 showed bacteriocin activity against several major food borne pathogens. Zymogram analysis of purified bacteriocin (plantaricin DM5) showed a molecular size of ∼15.2 kDa. Plantaricin DM5 was sensitive to proteolytic enzymes but stable in the pH range of 2.0-10.0, and it was heat resistant (121 °C for 15 min) and remained active upon treatment with surfactants and detergents. Cytotoxicity analysis of plantaricin DM5 on human embryonic kidney 293 (HEK 293) and human cervical cancer (HeLa) cell lines revealed its nontoxic and biocompatible nature. To the best of our knowledge, this is the first study on the isolated strain expressing probiotic properties and broad antimicrobial activity without any cytotoxic effect on mammalian cells from indigenous fermented beverage Marcha from India, and thus contributes to the food industry as a novel bio-preservant.

Some probiotic and antibacterial properties of Lactobacillus acidophilus cultured from dahi a native milk product

In this study, different strains of Lactobacillus acidophilus from dahi were analyzed for certain probiotic and antibacterial properties. Initially, these strains were confirmed by the amplification of 16S rRNA regions and then screened for antibacterial activities against food borne pathogens. The phenotypic relationship between apparent antibacterial activity and cell wall proteins were established by cluster analysis. It was observed that those strains, which have prominent bands having size 22-25 kDa possess antibacterial activity. On the basis of wide spectrum of killing pattern, a strain LA06FT was further characterized that showed no change in its behavior when subjected to the antibiotic protected environment and grow well in acid-bile conditions. The bacteriocin produced by this strain has specific antibacterial activity of 5369.13 AU mg(-1). It remained stable at 60-90 °C and pH range of 4.5-6.5 while proteolytic enzymes inactivate the bacteriocin that confirm its proteinic nature having molecular weight of ≤8.5 kDa.

Inhibition of Cronobacter sakazakii by heat labile bacteriocins produced by probiotic LAB isolated from healthy infants

Cronobacter sakazakii is an opportunistic pathogen that can cause bacteremia, meningitis, and necrotizing enterocolitis, most often in neonates with case-fatality rates that may reach 80%. The antimicrobial activity of lactic acid bacteria against a wide range of foodborne pathogens is well-established in different types of food products. The objective of the current study was to investigate the antibacterial activity of Lactobacillus acidophilus and L. casei isolated from feces of healthy infants against different strains of C. sakazakii in agar and a rehydrated infant milk formula (RIMF) model. The inhibition zones of C. sakazakii around L. acidophilus or L. casei ranged from 22 to 32 mm on eMan Rogosa Sharpe (MRS) agar under aerobic conditions, while a slight reduction in antibacterial activity was noted on modified MRS (0.2% glucose) under anaerobic conditions. It was observed that pH-neutralized cell-free supernatant (CFS) of L. acidophilus or L. casei was inhibitory against tested C. sakazakii strains. The inhibition zones of neutralized CFS were lower than the antibacterial activities of live cultures. The antibacterial activity of CFS was abolished when CFS from L. acidophilus or L. casei was heated at 60 or 80 °C for either 10 min or 2 h, or treated with trypsin or pepsin. This was considered strong evidence that the inhibition was due to the production of bacteriocins by L. casei and L. acidophilus. Both the CFS and active growing cells of L. casei and L. acidophilus were able to reduce the viability of C. sakazakii in the RIMF model. The results may extend the use of natural antimicrobials instead of conventional preservation methods to improve the safety of RIMF.

Probiotic features of two oral Lactobacillus isolates

In this study, we checked lactobacilli strains of human origin for their potential as probiotic. Samples were collected from oral mucosa of 16 healthy individuals, out of which twenty isolates were obtained and two of them were selected and identified as Lactobacillus plantarum (G1) and L. casei (G3). Both isolates exhibited antagonistic action towards pathogenic microorganisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella abony, and Clostridium sporogenes, but not on the growth of Candida albicans. The bacteriocin activity against Staphylococcus aureus ATCC 6358-P was shown only by L. plantarum G1. Moreover, the isolates G1 and G3 showed good viability in the acid gastric environment and in the gut environment containing bovine bile salts. The viability of G1 and G3 isolates in the gastrointestinal tract, and the adhesion to the intestinal mucosa were also confirmed in vivo. The biochemical tests of blood samples revealed lower levels of serum triglycerides and cholesterol, as well as reduced activity of alkaline phosphatase in all lactobacilli-treated Wistar rats, compared to control ones. No toxicity for NMRI Ham mice was observed. According to our experimental results, these findings imply that L. plantarum G1 and L. casei G3 could be characterized as potential probiotics.

Evaluation of Leuconostoc mesenteroides YML003 as a probiotic against low-pathogenic avian influenza (H9N2) virus in chickens

AIM

  The aims of the study were to isolate anti-H9N2 bacteria from Korean Kimchi isolates and to evaluate its performance in cell line, egg and in specific pathogen-free (SPF) chickens.

METHODS AND RESULTS

  Using Madin-Darby canine kidney (MDCK) cell line, 220 bacterial isolates were screened and the isolate YML003 was selected having pronounced antiviral activity against H9N2 virus. This isolate was identified as Leuconostoc mesenteroides by 16S rRNA gene sequencing. Anti-H9N2 activity of the strain was also evaluated by hemagglutination assay. Leuconostoc mesenteroides YML003 was assessed for its survival in gastric juice and 5% bile acid and the antibiotic susceptibility. Both live and heat-killed cells were selected for in vivo chicken feeding experiment. Body weight, immune index, serobiochemical parameters and splenic IFN-γ production were assessed during selected intervals. Viral population in the trachea and cloacae were calculated by quantitative real-time reverse transcriptase PCR (qRT-PCR).

CONCLUSIONS

  Leuconostoc mesenteroides YML003 exhibited anti-H9N2 activity both in in vitro cell line as well as in vivo SPF chickens.

SIGNIFICANCE AND IMPACT OF THE STUDY

  This is a primary report on the anti-H9N2 activity by a Leuconostoc strain. Amid the increasing reports of avian influenza virus occurrence resulting in severe losses to the poultry industry, prophylactic administration of such probiotic strains are highly significant.

Complete genome sequencing of Lactobacillus acidophilus 30SC, isolated from swine intestine

Lactobacillus acidophilus 30SC has been isolated from swine intestines and considered a probiotic strain for dairy products because of its ability to assimilate cholesterol and produce bacteriocins. Here, we report the complete genome sequence of Lactobacillus acidophilus 30SC (2,078,001 bp) exhibiting strong acid resistance and enhanced bile tolerance.

Partial characterization of bacteriocins produced by two Lactobacilus strains with probiotic properties

The probiotic characteristics of Lactobacillus brevis BG18 and Lb. plantarum BG33, isolated from traditional Turkish Tulum cheese were assessed. These two bacteriocinproducer strains exhibited good probiotic characteristics such as resistance in media containing 0.3% bile salt, pepsin (3 mg mL⁻¹), and pancreatine (1 mg mL⁻¹) as well as acid resistance at pH 2. They were also adhered to Caco-2 epithelial cells in a manner comparable to Escherichia coli LMG3083 (ETEC) and Salmonella Typhimurium SL1344. The strains produced a heat-stable antimicrobial compound that was shown to be proteinaceous in nature, and therefore, referred to as bacteriocins. The bacteriocins were able to inhibit growth of a number grampositive bacteria such as Listeria monocytogenes, Clostridium botulinum, Staphylococcus aureus and Bacillus cereus. Tricine-SDS-PAGE of the active fraction resulted in single bands with estimated molecular masses of 2.5 kDA and 2.7 kDA for Lb. brevis BG18 and Lb. plantarum BG33 bacteriocins, respectively.

Characterization and antimicrobial activity of vaginal lactobacillus isolate

The aim of this study was to investigate the probiotic potential of bacteriocin-producing lactobacilli strain Lactobacillus plantarum G2 isolated from the vaginal mucus of healthy women. The antimicrobial effect of G2 was confirmed in the mixed culture with pathogenic Escherichia coli, Staphylococcus aureus, Salmonella abony and Pseudomonas aeruginosa, while bacteriocine activity was detected against S. aureus and S. abony only. The strain showed an excellent survival rate in low pH and in the presence of bile salts. The percentage of adhered cells of L. plantarum G2 to hexadecane was 63.85?2.0 indicating the intermediate hydrophobicity.

Characterization of the properties of Pediococcus parvulus for probiotic or protective culture use

Pediococcus parvulus 2.6 (previously Pediococcus damnosus 2.6, here confirmed as P. parvulus by 16S DNA sequencing) displayed antibacterial activity toward several bacterial species, including isolates found as contaminants in oats, herein genetically identified as Bacillus cereus. No inhibition of Listeria monocytogenes was found under the conditions used. Antibacterial activity was retrieved after ammonium sulfate or acetone precipitation showed it to be peptide mediated. P. parvulus 2.6 has previously shown good technological properties in oat-based products. This, together with the currently found inhibition of food spoilage microorganisms like B. cereus, makes it suitable as a food protective culture. Survival trials of P. parvulus 2.6 at conditions mimicking the gastrointestinal tract were prompted by previously found cholesterol-lowering effects in humans after consumption of oat products cofermented by using P. parvulus 2.6 and Bifidobacterium spp. Viability was measured with in vitro, gutlike simulations at 37 degrees C. High survival was shown under two of three conditions (gastric juice, bile, and small intestine juice), defined as main obstacles of the gastrointestinal tract. The critical step was bile exposure. At a concentration of 20%, viability was low, but 0.3% bile (mean concentration in the intestine) did not have a major influence on growth. Viability of P. parvulus 2.6 was significantly decreased in gastric juice at pH 1.5 (with pepsin), but it was not significantly affected at pH 2.5, and was also improved at a lower pH in 20% oat milk. Viability was judged sufficient for colonization at gutlike conditions, qualifying the strain for further probiotic studies.

The Cek1 MAPK is a short-lived protein regulated by quorum sensing in the fungal pathogen Candida albicans

Mitogen activated protein kinase (MAPK) cascades are signal transduction mechanisms present in eukaryotic cells that allow adaptation to environmental changes. MAPK activity is mainly regulated by dual phosphorylation in a TXY motif present in the kinase subdomain VIII as well as dephosphorylation by specific phosphatases. The Cek1 MAPK is involved in filamentous growth in Candida albicans and is an important determinant of virulence in this microorganism; its activation is controlled by the Sho1 adaptor protein. Here we show that Cek1 phosphorylation is regulated by quorum sensing (QS). Cek1 phosphorylation is prevented by farnesol, a compound that also regulates the dimorphic transition in this fungus. Farnesol also induced the activation of Mkc1, the MAPK of the cell integrity pathway. The role of farnesol in Cek1 phosphorylation is independent of the Chk1 histidine kinase, a putative QS sensor, as revealed by genetic analysis. In addition, Cek1, not Hog1, is degraded by proteasome, as revealed by the use of a conditional lethal protein degradation mutant. Our data therefore describe two different mechanisms (QS and protein degradation) that control a MAPK pathway that regulates virulence in a fungal pathogen.

New functional probiotic Lactobacillus sakei probio 65 alleviates atopic symptoms in the mouse

The purpose of this study was to investigate the improvement of allergic dermatitis in chemical allergen-induced mice by Lactobacillus sakei probio 65. L. sakei probio-65 was isolated from kimchi, a traditional Korean fermented food. This strain was resistant to gastric acidity, bile, and several antibiotics and possessed antimicrobial activity against several pathogenic microorganisms. To investigate whether the probiotic activity of L. sakei probio 65 was effective for treating allergic dermatitis, the organism was supplied to mice triggered by allergen (1-chloro-2,4-dinitrobenzene). Mice that received L. sakei probio 65 showed a more rapid recovery compared to control mice, as assessed by visual evaluation of the severity of allergic dermatitis and levels of immunoglobulin (Ig) E and interleukin (IL)-4. L. sakei probio 65 exhibited good probiotic properties in vitro and in mice and was effective in reducing allergen-induced skin inflammation through the regulation of both elevated IgE and IL-4 in sensitized mice.

Probiotics: a critical review of their potential role as antihypertensives, immune modulators, hypocholesterolemics, and perimenopausal treatments

The conventional use of probiotics to modulate gastrointestinal health, such as in improving lactose intolerance, increasing natural resistance to infectious diseases in the gastrointestinal tract, suppressing traveler's diarrhea, and reducing bloating, has been well investigated and documented. Most of the mechanisms reported to date are mainly caused by the suppression of pathogenic bacteria. Currently, the potential applications of probiotics are being expanded beyond alleviating gastrointestinal disorders to include benefits involving antihypertension, immunomodulation, improving serum lipid profiles, and the alleviation of postmenopausal disorders. Although they seem promising, most of these postulated benefits are based on in vitro evaluations, and the lack of in vivo evidence and/or incompatible outcomes between in vitro experiments and in vivo trials has led to inconclusive claims. This present review highlights some of the previous roles of probiotics on gut health and addresses several potential roles currently being investigated.

Effect of bacteriocin produced by Lactococcus sp. HY 449 on skin-inflammatory bacteria

This study was carried out to evaluate the effect of bacteriocin produced by Lactococcus sp. HY 449 against skin-inflammatory bacteria such as Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus ATCC 65389, Streptococcus pyogenes ATCC 21059, and Propionibacterium acnes ATCC 6919. The spot-on-the-lawn method was used to determine the antimicrobial activity of bacteriocin against indicator strains on the human skin. The bacteriocin produced by Lactococcus sp. HY 449 inhibited the growth of S. epidermidis ATCC 12228, S. aureus ATCC 65389, Strep. pyogenes ATCC 21059, and P. acnes ATCC 6919. The treatment of crude bacteriocin caused a rapid inactivation of P. acnes ATCC 6919. The LC50 of bacteriocin on human fibroblast was ca. 50mg/ml at which the inhibition of cell proliferation was not observed. Neither any irritations nor allergic reactions by the bacteriocin were evident in a human patch test. The bacteriocin produced by Lactococcus sp. HY 449 may be a useful antimicrobial substance to control the growth of P. acnes and to prevent skin inflammation and acne.