High γ-aminobutyric acid production from lactic acid bacteria: Emphasis on Lactobacillus brevis as a functional dairy starter

γ-Aminobutyric acid (GABA) and GABA-rich foods have shown anti-hypertensive and anti-depressant activities as the major functions in humans and animals. Hence, high GABA-producing lactic acid bacteria (LAB) could be used as functional starters for manufacturing novel fermented dairy foods. Glutamic acid decarboxylases (GADs) from LAB are highly conserved at the species level based on the phylogenetic tree of GADs from LAB. Moreover, two functionally distinct GADs and one intact gad operon were observed in all the completely sequenced Lactobacillus brevis strains suggesting its common capability to synthesize GABA. Difficulties and strategies for the manufacture of GABA-rich fermented dairy foods have been discussed and proposed, respectively. In addition, a genetic survey on the sequenced LAB strains demonstrated the absence of cell envelope proteinases in the majority of LAB including Lb. brevis, which diminishes their cell viabilities in milk environments due to their non-proteolytic nature. Thus, several strategies have been proposed to overcome the non-proteolytic nature of Lb. brevis in order to produce GABA-rich dairy foods.     

Probiotic properties of lactic acid bacteria isolated from Mukeunji, a long-term ripened kimchi

Lactic acid bacteria (LAB) isolated from mukeunji was screened for characterization of beneficial properties required as probiotics. Among the isolates from mukeunji, 5 LAB strains were selected due to their high levels of tolerance to simulated gastric fluid. These strains were identified by using SDS-PAGE of whole cell protein pattern and 16S rDNA sequencing. Subsequently, it was found that 2 isolates, Lactobacillus brevis C1 and Lactobacillus plantarum G4 among the 5 isolates were highly resistant to bile cytotoxicity in terms of survival rate, 162.2 and 114.3%, respectively. According to the results of in vitro adhesion assay, Lb. brevis C1, Lb. plantarum G4, and Lactobacillus sakei N1 had higher numbers of adhesion to Caco-2 epithelium cells than that of Lactobacillus rhamnosus GG, a well known probiotic. None of the isolates produced a carcinogenic enzyme, β-glucuronidase. In addition, Lb. brevis C1 and Lb. plantarum G4 exhibited high levels of DPPH scavenging capacity. These results suggest that 2 isolates from mukeunji, Lb. brevis C1 and Lb. plantarum G4 may have potential for food products as probiotics because they showed high levels of bile acid tolerance and probiotic properties.     

Biodiversity of lactic acid bacteria isolated from fermented milk products in Xinjiang,China

Fermented dairy products have been produced and consumed for thousands of years in Xinjiang, China. In this study, traditional culture-dependent methods and 16S rRNA gene analyses were performed to analyze the composition of lactic acid bacteria (LAB) from 86 samples of traditional fermented dairy products collected from four regions of Xinjiang. Quantitative polymerase chain reaction (qPCR) was used to quantify Bifidobacterium and Lactobacillus species. The LAB isolates (N = 705) were identified as belonging to seven genera and 26 species or subspecies. The predominant species of all isolates were Lactobacillus (Lb.) delbrueckii subsp. bulgaricus, Lb. fermentum, and Lb. helveticus. The LAB counts of these samples ranged from 5.35 to 10.06 Log CFU/mL. The bacterial counts of seven lactobacilli species and Bifidobacterium ranged from 0.98 ± 0.14 Log CFU/mL (for Lb. sakei from fermented mare milk) to 9.91 ± 0.17 Log CFU/mL (for Lb. helveticus from fermented mare milk). While the microbiota was significantly different between yak and cow milk, there was no significant difference between the Tex and Zhaosu counties. In conclusion, LAB communities in traditional fermented dairy products are complex and differ among local regions within Xinjiang.     

Diversity and probiotic potentials of lactic acid bacteria isolated from gilaburu,a traditional Turkish fermented European cranberrybush (Viburnum opulus L.) fruit drink

The aim of the present study was to characterize lactic acid bacteria (LAB) strains isolated from traditional fermented gilaburu fruit juice and their probiotic potential. The LAB counts of the fermented gilaburu fruit juice were in the range of 3.92–8.30 log cfu/g. Total of 332 isolates belonging to Lactobacillus and Leuconostoc species were characterized from traditional fermented gilaburu juice by genotypic methods. It was also determined that the major LAB strains belong to Lactobacillus plantarum (173 isolates), Lactobacillus casei (52 isolates) and Lactobacillus brevis (24 isolates), while Lactobacillus buchneri, Lactobacillus parabuchneri, Lactobacillus pantheris, Leuconostoc pseudomesenteroides and Lactobacillus harbinensis were the least in isolated LAB strains. In terms of the probiotic potentials, Lb. plantarum strains were able to grow at pH 2.5, but 3 of Lb. casei strains, one of each Lb. brevis and Lb. buchneri strains could not grow at the same pH. All selected LAB stains were resistant to bile salt at ≤ 0.3% concentration. While all the LAB species grew at 15 °C, two Lactobacillus hordei strains could also grow at 45 °C. The highest cell hydrophobicity degrees were for Lb. casei (G20a) and Lb. plantarum (G19e) as 87.5 and 86.0%, respectively. Listeria monocytogenes and Bacillus cereus were the most sensitive bacteria against the selected LAB strains, while Escherichia coli and Staphylococcus aureus were the most resistant. Again all the isolated LAB species were resistant to three antibiotics; kanamycin, streptomycin and vancomycin. Characterization and probiotic potentials of the LAB isolated from fermented gilaburu (Viburnum opulus) juice were studied first time, and further research needs to be done on their behaviors in similar food formulations as a probiotic.     

Diversity and screening of lactic acid bacteria in la-baicai made by Korean-Chinese in northeastern China

This study investigated the lactic acid bacteria (LAB) population in la-baicai (spicy cabbage), a traditional fermented food made by the Korean-Chinese community in northeastern China and screened for functional LAB. LAB diversity was analyzed using denaturing gradient gel electrophoresis (DGGE), and 81 LAB strains were isolated and identified based on 16S rDNA sequencing analysis. Polymerase chain reaction DGGE detected 21 LAB species, belonging to the genera Lactobacillus (Lb.), Leuconostoc (Leu.), Pediococcus and Weissella, in 45 la-baicai samples. Lb. plantarum and Lb. sakei were considered to be dominant in the bacterial community. Among 81 LAB isolated by traditional pure culture methods were Lb. plantarum (25 strains), Lb. brevis (two strains), Lb. casei, (four strains), Lb. pentosus (three strains), Enterococcus faecium (45 strains), and E. durans (two strains). The tolerances of these LAB were investigated. Six LAB with high salt (NaCl)-tolerance were screened from the isolates, and 16% (w/v) was the highest salt-tolerance reached. Among the isolates, strain N1, identified as Lb. pentosus, survived well in a simulated digestive environment. Traditional fermented la-baicai from northeastern China is a rich LAB resource. Further study is needed and would be worthwhile to advance the benefits of these LAB.     

Organic whey as a source of Lactobacillus strains with selected technological and antimicrobial properties

Twenty‐five strains, isolated from raw, non‐pasteurised, organic whey samples, were identified phenotypically and genotypically. Biochemical tests were performed, and enzyme profiles, antibiotic resistance and antimicrobial properties were investigated. Sixteen strains were identified as genus Lactobacillus. Based on 16S rDNA gene sequence, the strains were identified as Lb. plantarum and Lb. fermentum. All of the strains had β‐galactosidase activity, and some of them reduced nitrate content. All strains utilised carbohydrates. The tested strains were characterised by low or average lipolytic and esterolytic activity. Moreover, the strains showed low proteolytic activity which is advantageous for their use as starter cultures for foods with low protein content. Strains Lb. fermentum S20, SM1, SM3, S2R and Lb. plantarum SM5 produced harmful N‐acetyl‐β‐glucosaminidase; moreover, the strain S20 produced also β‐glucuronidase. None of the strains produced α‐chymotrypsin. In phenotypic studies, most of the test strains were susceptible to gentamicin, ampicillin, tetracycline, chloramphenicol, penicillin and erythromycin. Strains Lb. plantarum S1 and Lb. fermentum S4, S7, S8, S10, SM1 and SM3 did not possess any transfer resistance genes. Antagonistic activity of the culture LAB strains was assessed as high or moderate in relation to the indicator strains, with the greatest zones of inhibition for E.coli and the smallest for L. monocytogenes ATCC 15313. This study reveals that the LAB strains isolated from organic whey have high potential for food application. Some strains of species Lb. fermentum (S4, S7, S8, S10) have been identified as the best candidates.     

Molecular and technological characterization of lactic acid bacteria from traditional fermented sausages of Basilicata region (Southern Italy)

Lactic acid bacteria (LAB) from traditional fermented sausages of the Basilicata region were investigated by ARDRA-PCR and RAPD-PCR for taxonomic identification at species and strain level and characterized on the basis of the growth and acidification at different temperatures, incubation times, levels of NaCl and KNO₂, hydrolysis of sarcoplasmatic and myofibrillar proteins and antimicrobial, peptide/amino acid release and nitrate reductase activities.Lactobacillus sakei was the predominant species (67%) followed by Pediococcus pentosaceus (16%), Leuconostoc carnosum (8%), Lactobacillus plantarum (4%), Lactobacillus brevis (2%) and Leuconostoc pseudomesenteroides (2%). The technological characterization revealed that most of the isolates had good acidifying and proteolytic properties. Moreover, Lb. sakei strains showed antimicrobial ability, while Leuconostoc strains the highest reduction of nitrates.This work was a preliminary study in the formulation of autochthonous starter cultures in order to standardize the production process of sausages, to preserve their typical organoleptic and sensory characteristics and to improve the quality of final product.     

γ-aminobutyric acid production in skim milk co-fermented with Lactobacillus brevis 877G and Lactobacillus sakei 795

γ-Aminobutyric acid (GABA)-producing Lactobacillus brevis 877G strain isolated from traditional Korean fermented food, kimchi, produced 18.94 mM GABA under 59.13 mM L-monosodium glutamate (MSG). Also, skim milk co-fermented with Lb. brevis 877G as a GABA producer and Lactobacillus sakei 795 as a protease producer resulted in a significant increase in GABA production (22.51 mM) with 29.57 mM MSG. The results indicate that Lb. brevis 877G itself and skim milk cofermented with Lb. brevis 877G and Lb. sakei 795 could be developed to be a useful starter for functional fermented food and dairy food product fortified in GABA.     

Effect of adzuki bean sprout fermented milk enriched in γ-aminobutyric acid on mild depression in a mouse model

This study focused on the ability of adzuki bean (Vigna angularis) sprout fermented milk, which is rich in γ-aminobutyric acid (GABA), to relieve anxiety and mild depression. A high-yield GABA-producing strain, Lactobacillus brevis J1, from a healthy cow was screened, and its physiological and probiotic properties were evaluated. The effect of adzuki bean sprout fermented milk was investigated in vivo in a chronic depression mouse model. The results showed that Lb. brevis J1 had excellent probiotic properties, grew well at low pH and 3% NaCl, and adhered to the surface of HT-29 cells. The GABA-enriched (241.30 ± 1.62 µg/mL) adzuki bean sprout fermented milk prepared with Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum, and Lb. brevis J1 can reduce and possibly prevent mild depression-like symptoms in mice (C57/B6) by increasing social interaction and enhancing the pleasure derived from movement. The research revealed that the GABA_B-cyclic AMP-protein kinase A-cAMP-response element binding protein (GABA_B-cAMP-PKA-CREB) signaling pathway was related to the depression-like symptoms and that levels of 5-hydroxytryptamine, norepinephrine, and dopamine in the hippocampus of mice increased after treatment with the adzuki bean sprout fermented milk. Our results suggest that GABA-enriched dairy products have the potential to prevent or treat mild depression-like symptoms in mice, which suggests a new approach for a dietary therapy to treat chronic social stress.     

Effect of lactobacillus fermented beetroot juice on composition and activity of cecal microflora of rats

This study aimed at determination of the effect caused by ingestion of beetroot juice fermented by Lactobacillus casei 0920 and Lactobacillus brevis 0944 strains on the state of cecal ecosystem of experimental rats. The intake of fermented beetroot juice containing 3.5–4.0 × 10⁹ CFU/mL live Lactobacillus sp. cells positively modulated the cecal microflora of the rats and its metabolic activity. The counts of Lactobacillus sp., Bifidobacterium sp., Bacteriodes sp., and Enterococcus sp. were maintained at the level of 8.2–8.6, 6.2–7.5, 8.0–8.3, and 7.3–7.7 log units, respectively, while the number of Clostridium sp. cells was increased by 1.1–1.6 log units and Enterobacteriaceae bacteria were reduced by 0.8–2.1 log units. In this study, the selected cecal enzymes such as β-glucosidase, β-glucuronidase, and β-galactosidase as well as the profile and concentration of short chain fatty acids (SCFA) were the biochemical markers of metabolic activity of the intestinal ecosystem. The considerable decrease in activities of β-glucosidase and β-glucuronidase was observed in all three experimental groups fed with the fermented beetroot juice. Total concentration of SCFA was the highest (78.1 μmol/100 g BW vs. 59.2 μmol/100 g BW in control group) in intestines of rats fed with 6 mL of fermented beetroot juice daily. These results prove that the fermented beetroot juice benefits cecal microbial activity.     

Identification of potential probiotic starter cultures for Scandinavian-type fermented sausages

Potential probiotic cultures suitable as starter cultures for the Scandinavian-type fermented sausages were identified among strains well-adapted to fermented meats as well as strains originating from a culture collection. From 15 different fermented meat products, 22 strains were isolated as dominant non-starter lactic acid bacteria (NSLAB). The isolates were identified by RAPD, API and sequence analysis of 16S rRNA and showed to be five strains of Lactobacillus sakei, five strains of Lactobacillus farciminis, five strains belonging to the group of Lactobacillus plantarum/pentosus, four strains of Lactobacillus alimentarius, two strains of Lactobacillus brevis and one strain of Lactobacillus versmoldensis. Heterofermentative strains as well as strains not growing at 37 degrees C and not lowering pH below 5.1 in a meat model were excluded leaving 9 strains for further studies. These strains together with 19 strains from a culture collection were evaluated by in vitro methods including survival upon exposure to pH 2.5 or 0.3% oxgall and adhesion to the human colon adenocarcinoma cell line Caco-2 as well as antimicrobial activity against potential pathogens. Strains that fulfilled all the probiotic criteria and showed to be fast acid producers in a meat model included three strains belonging to the group of Lb. plantarum/pentosus (MF1291, MF1298, MF1300) which originated from the dominant NSLAB of fermented meat products. MF1291 and MF 1298 were further identified as Lb. plantarum and MF1300 as Lb. pentosus. The three strains were all successfully applied as starter cultures for the production of fermented sausage. The viable count at the end of the processing period reached high cell numbers (4.7x10(7)-2.9x10(8) cfu/g) and pH of the sausages decreased to pH 4.8-4.9 without any flavour deviation compared to sausage fermented by a commercial meat starter culture.     

Characterization of Lactobacillus isolates from infant faeces as dietary adjuncts

Lactobacillus paracasei subsp. paracasei (six strains), Lb. rhamnosus (six strains), Lb. acidophilus (two strains), Lb. gasseri (three strains) and Lb. reuteri (three strains) isolates from new-born infants were tested for their ability to grow and metabolize in milk and to resist specific conditions of the gastrointestinal tract. Many of the tested strains had desirable properties concerning their ability to withstand adverse conditions of the gastrointestinal tract, and produce carbonyl compounds. In general, strains of Lb. paracasei subsp.paracasei and Lb. rhamnosus were more resistant to low pH of the stomach than all the other strains. On the other hand, Lb. gasseri and Lb. reuteri strains did not acidify milk. Thus, Lb. paracasei subsp.paracasei , Lb. acidophilus and Lb. rhamnosus strains could be preferably used as starters to produce fermented milks with possibly interesting organoleptic properties, as well as dietary and possible therapeutic importance.     

Effect of fermented soy product on the fecal microbiota of rats fed on a beef‐based animal diet

BACKGROUND: The aim of this study was to determine whether the consumption of soy product fermented with Enterococcus faecium CRL 183, would modify the fecal microbiota of rats fed a diet containing red meat. The rats were placed in groups, distinguished by their diets. For 60 days, group I was given a standard casein‐based rodent feed and groups II–VI, the beef‐based feed. From the 30th day, groups III–VI also ingested the following products: group III, E. faecium‐fermented soy product; group IV, pure suspension of E. faecium; group V, sterilized fermented soy product; and group VI, unfermented soy product. RESULTS: Rats that ingested fermented soy product showed a slight increase in the numbers of lactobacilli (0.45 log CFU g^?1), as did the casein‐based diet group (0.47 log CFU g^?1). The fermented soy product did not cause any reduction in the number of enterobacteria or clostridia, but promoted a slight fall in the viable count of Bacteroides spp. (2.80 ± 0.20 to 2.34 ± 0.07 log CFU g^?1). CONCLUSIONS: The results indicate that the ingestion of this fermented soy product did not lead to significant changes in the fecal microbiota of the rats fed on a beef‐based diet. Copyright © 2009 Society of Chemical Industry     

Evaluation of sodium dichloroisocyanurate treatment on recovered concentrations of Salmonella enterica,Escherichia coli O157:H7, and Listeria monocytogenes from cattle hide surfaces and culture medium

A major concern of the cattle industry is cross-contamination of meat with pathogens. Cattle are exposed to fecal material, mud, and other contaminants which harbor pathogens that can be shed onto meat and meat processing equipment. Due to increased chances of meat contamination during processing, new antimicrobial formulations for carcass washing before hide removal needs to be identified and tested. Sodium dichloroisocyanurate (SDIC) has biocidal properties and belongs to the N-halamine group of compounds. Disk diffusion assays revealed, 1,000 ppm SDIC effectively reduced pathogen concentrations. SDIC was evaluated for its effects on pathogens in Tryptic Soy Broth and results revealed that 1,000 ppm SDIC had a strong correlation with time and treatment with no bacterial growth in log CFU ml⁻¹ observed at the lowest detection level. Treatment of inoculated hides with 1,000 ppm SDIC for 5 min resulted in reduction of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes at 1.97, 2.02, and 2.84 log CFU cm⁻², respectively.     

Antimicrobial resistance in Enterococcus spp. strains isolated from organic chicken, conventional chicken, and turkey meat: a comparative survey

The mean counts of Enterococcus spp. were determined for 30 samples each of organic chicken meat, conventional chicken meat, and turkey meat, and differences for Enterococcus contamination in meat were determined. Two enterococci strains from each sample were isolated to obtain a total of 180 strains, and resistance to ampicillin, chloramphenicol, doxycycline, ciprofloxacin, erythromycin, gentamicin, nitrofurantoin, and vancomycin was determined by a disk diffusion method. Average counts obtained showed that Enterococcus mean counts from organic chicken meat (3.18 log CFU/g) were significantly higher than those obtained from conventional chicken meat (2.06 log CFU/g) or conventional turkey meat (1.23 log CFU/g). However, the resistance data obtained showed that isolates from organic chicken meat were less resistant than enterococci isolates from conventional chicken meat to ampicillin (P = 0.0067), chloramphenicol (P = 0.0154), doxycycline (P = 0.0277), ciprofloxacin (P = 0.0024), erythromycin (P = 0.0028), and vancomycin (P = 0.0241). In addition, isolates from organic chicken were less resistant than conventional turkey meat isolates to ciprofloxacin (P = 0.001) and erythromycin (P = 0.0137). Multidrug-resistant isolates were found in every group tested, but rates of multidrug-resistant strains were significantly higher in conventional chicken and turkey than those obtained from organic chicken meat. Enterococcus faecalis was the most common species isolated from organic chicken (36.67%), whereas Enterococcus durans was the most common species isolated from conventional chicken (58.33%) and turkey (56.67%). The rates obtained for antimicrobial resistance suggest that although organic chicken meat may have higher numbers of Enterococcus, these bacteria present a lower level of antimicrobial resistance.     

Occurrence of histamine and histamine-forming bacteria in kimchi products in Taiwan

Twenty kimchi products sold in supermarkets and 17 products sold in retail markets were purchased from southern Taiwan and tested to determine the occurrence of histamine and histamine-forming bacteria. The levels of pH and salt content in all samples ranged from 3.6 to 5.1 and 1.5–16.0%, respectively. The supermarket kimchi products had 1–7.2 log CFU/g of APC and <3–600 MPN/g of total coliform (TC), and the retail market kimchi products had 4–8.03 log CFU/g of APC and <3 to >2400 MPN/g of TC. Only one of the retail market kimchi products contained 20 MPN/g Escherichia coli. Although, supermarket kimchi products had an average histamine content of 49.8 mg/100 g, 15 of them had histamine content greater than 5 mg/100 g, the allowable level set by the US Food and Drug Administration (FDA) for scombroid fish and/or product. In contrast, only eight retail market kimchi products had histamine levels greater than 5 mg/100 g. Among the supermarket samples, three contained histamine at 50.2, 273 and 535 mg/100 g, that are more than the 50 mg/100 g hazard action level. Four histamine-producing bacteria capable of producing 13.6–43.1 ppm of histamine in MRS broth supplemented with 0.25% l-histidine were identified as Lactobacillus para. paracasei (one strain), Lb. brevis (one strain), and Brevibacillus brevis (two strains). To our knowledge, this is the first report to demonstrate the occurrence of high contents of histamine and histamine-forming bacteria in kimchi products.     

Production of fermented chestnut purees by lactic acid bacteria

The objective of this study was to develop a new chestnut-based puree, in order to seasonally adjust the offer and use the surplus of undersized production, providing, at the same time, a response to the growing demand for healthy and environmentally friendly products. Broken dried chestnuts have been employed to prepare purees to be fermented with six different strains of Lactobacillus (Lb.) rhamnosus and Lactobacillus casei. The fermented purees were characterized by a technological and sensorial point of view, while the employed strains were tested for their probiotic potential. Conventional in vitro tests have indicated the six lactobacilli strains as promising probiotic candidates; moreover, being the strains able to grow and to survive in chestnut puree at a population level higher than 8 log(10) CFU/mL along 40days of storage at 4°C, the bases for the production of a new food, lactose-free and with reduced fat content, have been laid.     

Diversity of lactic acid bacteria associated with traditional fermented dairy products in Mongolia

Spontaneous milk fermentation has a long history in Mongolia, and beneficial microorganisms have been handed down from one generation to the next for use in fermented dairy products. The objective of this study was to investigate the diversity of lactic acid bacteria (LAB) communities in fermented yak, mare, goat, and cow milk products by analyzing 189 samples collected from 13 different regions in Mongolia. The LAB counts in these samples varied from 3.41 to 9.03 log cfu/mL. Fermented yak and mare milks had almost identical mean numbers of LAB, which were significantly higher than those in fermented goat milk but slightly lower than those in fermented cow milk. In total, 668 isolates were obtained from these samples using de Man, Rogosa, and Sharpe agar and M17 agar. Each isolate was considered to be presumptive LAB based on gram-positive and catalase-negative properties, and was identified at the species level by 16S rRNA gene sequencing, multiplex PCR assay, and restriction fragment length polymorphism analysis. All isolates from Mongolian dairy products were accurately identified as Enterococcus faecalis (1 strain), Enterococcus durans (3 strains), Lactobacillus brevis (3 strains), Lactobacillus buchneri (2 strains), Lactobacillus casei (16 strains), Lactobacillus delbrueckii ssp. bulgaricus (142 strains), Lactobacillus diolivorans (17 strains), Lactobacillus fermentum (42 strains), Lactobacillus helveticus (183 strains), Lactobacillus kefiri (6 strains), Lactobacillus plantarum ssp. plantarum (7 strains), Lactococcus lactis ssp. lactis (7 strains), Leuconostoc lactis (22 strains), Leuconostoc mesenteroides (21 strains), Streptococcus thermophilus (195 strains), and Weissella cibaria (1 strain). The predominant LAB were Strep. thermophilus and Lb. helveticus, which were isolated from all sampling sites. The results demonstrate that traditional fermented dairy products from different regions of Mongolia have complex compositions of LAB species. Such diversity of LAB provides useful information for further studies of probiotic strain selection and starter culture design, with regard to the industrial production of traditional fermented milk.     

Evaluation of the composition and quality of watermelon and mango juices fermented by Levilactobacillus brevis,Lacticaseibacillus casei and Pediococcus pentosaceus and subsequent simulated digestion and storage

This study evaluated the composition of watermelon and mango juices fermented by Levilactobacillus (L.) brevis, Lacticaseibacillus (La.) casei and Pediococcus (P.) pentosaceus and subsequently simulated in vitro digestion and storage (4°C for 35 days). After fermentation (24 h), the microorganisms grew (~9 log CFU mL⁻¹) and fermented watermelon (FWJ) and mango juice (FMJ) became more red and yellow, respectively. DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging capacities significantly increased in L. brevis and La. casei FMJ. After in vitro digestion, all the strains except La. casei in FMJ significantly decreased (P < 0.05), and P. pentosaceus survival was 2.4 and 4.5 times higher in FWJ and FMJ, respectively, than as pure culture. After storage, cell counts remained above 7 log CFU mL⁻¹, and no changes in quality attributes, total phenolic content and antioxidant capacity were recorded in P. pentosaceus FMJ. Thus, watermelon and mango are suitable matrices for lactic acid bacteria.     

Functional properties of lactic acid bacteria isolated from ethnic fermented vegetables of the Himalayas

A total of 94 strains of Lactic acid bacteria (LAB), previously isolated from ethnic fermented vegetables and tender bamboo shoots of the Himalayas, were screened for functional properties such as acidification capacity, enzymatic activities, degradation of antinutritive factors and oligosaccharides, production of biogenic amines, hydrophobicity and adherence to mucus secreting HT29 MTX cells. Strong acidification and coagulation activities of LAB strains were recorded. Most of the LAB strains showed antimicrobial activities against the used indicator strains; however, only Lb. plantarum IB2 (BFE 948) isolated from inziangsang, a fermented leafy vegetable product, produced a bacteriocin against Staphylococcus aureus S1. LAB strains showed enzymatic activities and also degraded oligosaccharides. Almost all the strains of LAB were non-producers of biogenic amines except few strains. Some strains of Lb. plantarum showed more than 70% hydrophobicity. Adherence to the mucus secreting HT29 MTX cells was also shown by seven strains indicating their probiotic nature.