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.     

Combination of culture-dependent and culture-independent molecular methods for the determination of lactic microbiota in sucuk

In this study, the culture-dependent and culture-independent molecular methods were used for the identification of lactic acid bacteria (LAB) in sucuk a Turkish fermented dry sausage. On the one hand, the PCR-DGGE method targetting the V1 and V3 regions of 16S DNA was applied to DNA that was directly extracted from sucuk samples. On the other hand, rep-PCR fingerprinting was performed for the primary differentiation and grouping of the isolates, and the results were confirmed by sequencing of the 16S rDNA and 16S-23S rDNA intergenic spacer region. As a result of the PCR-DGGE analysis of all the samples, total 8 different lactic acid bacteria were identified, and Lactobacillus sakei, Lactobacillus curvatus and Weissella viridescens were the dominant microbiota among these bacteria. The culture-dependent approach indicated that the majority of the strains belonged to the Lactobacillus genera including Lb. sakei, Lactobacillus plantarum, Lb. curvatus, Lactobacillus brevis, Lactobacillus farciminis and Lactobacillus alimentarius. However, Leuconostoc and Weisella were also detected as minor genera. Again, Lactococcus piscium, Weissella halotolerans, Staphylococcus succinus and the comigrated Staphylococcus piscifermentans/Staphylococcus condimenti/Staphylococcus carnosus group were detected only with the culture-independent method while Lb. plantarum, Leuconostoc mesenteroides and Leuconostoc citreum were identified only by using the culture-dependent method. In the results, it was concluded that the combination of culture-dependent and culture-independent methods was necessary for reliable and detailed investigation of LAB communities in fermented food products.     

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.     

Analysis of volatile compounds produced by different species of lactobacilli in rye sourdough using multiple headspace extraction

Profiles of volatile organic compound (VOC) produced by nine individual lactic acid bacteria (LAB) during rye sourdough fermentation were compared by automated SPME and GC/MS‐Tof. The dough samples were inoculated with individual strains, placed inside the headspace vials and incubated during next 24 h. The production or loss of VOC‐s was followed by adsorbing volatiles onto 85‐m Car/PDMS fibre in every 4 h. Volatile profiles differed among LAB species and divided LAB into two main groups – hetero‐ and homofermentative. Hetrofermentative LAB (Lactobacillus brevis; Leuconostoc citreum; Lactobacillus vaginalis, Lactobacillus panis) showed high production of acetic acid, CO₂, ethanol, ethylacetate, producing also hexyl acetate, ethyl hexanoate and isopentyl acetate. Whereas homofermentative LAB species (Lactobacillus helveticus; Lactobacillus casei; Lactobacillus sakei; Lactobacillus curvatus) produced a considerable amount of 2,3‐butanedione. Production of l ‐leucine methyl ester was unique for Lb. sakei, Lb. casei and Lb. curvatus strains. Lb. helveticus was the only LAB that produced benzaldehyde.     

Description of the microflora of sourdoughs by culture-dependent and culture-independent methods

Four types of sourdoughs (L, C, B, Q) from artisanal bakeries in Northern Italy were studied using culture-dependent and culture-independent methods. In all samples, the yeast numbers ranged from 160 to 10⁷ cfu/g, and the numbers of lactic acid bacteria (LAB) ranged from 10³ to 10⁹ cfu/g. The isolated LAB were sequenced, and a similarity was noted between two samples (C, Q), both in terms of the species that were present and in terms of the percentage of isolates. In these two samples, Lactobacillus plantarum accounted for 73% and 89% of the bacteria, and Lactobacillus brevis represented 27% and 11%. In the third sample (B), however, the dominant LAB isolate was Lb. brevis (73%), while Lb. plantarum accounted for only 27%. The fourth sourdough (L) was completely different from the others. In this sample, the most prominent isolate was Weisella cibaria (56%), followed by Lb. plantarum (36%) and Pediococcus pentosaceus (8%). In three out of four samples (L, C and Q), all of the yeasts isolated were identified as Saccharomyces cerevisiae, yet only Candida humilis (90%) and Candida milleri (10%) were isolated in the fourth sample (B). The microbial ecology of the sourdoughs was also examined with direct methods. The results obtained by culture-independent methods and DGGE analysis underline a partial correspondence between the DNA and RNA analysis. These results demonstrate the importance of using a combined analytical approach to explore the microbial communities of sourdoughs.     

Identification of lactic acid bacteria involved in the spoilage of pasteurized “foie gras” products

The spoiling microflora of a re-packaged French “foie gras” product was studied. A total of 54 isolates, originating from two different factories, were identified using phenotypical and molecular methods (partial 16S rDNA sequencing). Weissella viridescens was the main species detected in the products from factory 1 (64% of the isolates). These products had a low lactic acid concentration and were considered as non-spoiled. The microflora of factory 2 was dominated mainly by the genus Lactobacillus (95% of the isolates), and the high lactic acid concentration of these products was linked with a strong spoilage. Among the 30 Lactobacillus strains, three species were predominant: Lactobacillus sakei (nine isolates), Lactobacillus coryniformis (eight isolates) and Lactobacillus paraplantarum (five isolates). Challenge tests were performed to confirm the involvement of the Lactobacillus strains in the spoilage of the product. Sterile “foie gras” samples were inoculated with 14 LAB strains from the collection. The most acidifying strains belonged to the species L. sakei, Lactobacillus plantarum and L. paraplantarum. This confirmed the role of the strains from the Lactobacillus genus as the main spoilers of “foie gras” products and will be useful to design new quality protocols and extend the shelf-life of these products.     

Characterization of Proteolytic Effect of Lactic Acid Bacteria Starter Cultures on Thai Fermented Sausages

The objective of this study was to investigate the effect of starter culture addition on proteolysis of Thai fermented sausages. Sausages inoculated with six different external starter cultures—Pediococcus pentosaceous, Pediococcus acidilactici, Weissella cibaria, Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus sakei—were compared with naturally fermented sausages. The results of microbiological analysis indicated that the dominance of lactic acid bacteria (LAB) could inhibit the growth of pathogens and spoilage. Proteolysis was observed during fermentation by the reduction of myofibrillar and sarcoplasmic proteins and the increase in nonprotein nitrogen (NPN) and total free amino acids. The highest increase in concentration of NPN and free amino acids was obtained from sausages inoculated with LAB. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed a similar pattern of proteolysis of sarcoplasmic proteins in all sausages, while that of the inoculated sausages with L. plantarum, L. pentsus, and L. sakei exhibited increased degradation of myofibrillar protein bands at 200 and 45 kDa.     

Bacteriocin-producing lactobacilli in Spanish-style fermented sausages: characterization of bacteriocins

Three bacteriocins were studied. Sakacin K, a bacteriocin from Lactobacillus sake CTC494 was purified to homogeneity by a four-step system involving ammonium sulphate precipitation, binding to a cation exchanger, hydrophobic interaction and reverse phase chromatography in FPLC (fast performance liquid chromatography) system. The peptide sequence was determined by Edman degradation. The first 30 amino acid residues from the N-terminus of sakacin K were identical to those of curvacin A from Lactobacillus curvatus LTH1174 and sakacin A from Lactobacillus sakei Lb706. The structural gene of sakacin K in Lb. sake CTC494 was located on a 60 Kbp plasmid (as has been previously reported) by curvacin A in Lb. curvatus LTH1174 and sakacin A in Lb. sakei Lb706. Plantaricin D, a bacteriocin-like compound isolated from Lb. plantarum CTC305 was purified and sequenced using the same procedure as described for sakacin K. The first 15 amino acid residues of plantaricin D were identical to those obtained from the bacteriocin inducer peptide (termed plantaricin A) of the bacteriocinogenic system in Lb. plantarum C11. The structural gene of the plantaricin D peptide was located on a similar EcoRl chromosomal fragment when compared to plantaricin A in Lb. plantarum C11. These two isolated bacteriocin-like peptides (sakacin K and plantaricin D) were purified from two new different strains obtained from fermented meat, confirming the ecological importance of these substances. Lactobacillus sakei CTC372, the third bacteriocinogenic strain selected in this study from fermented sausages, produced a bacteriocin named sakacin T. The bacteriocin is not found free in the supernatant of the cells. It is active against Listeria monocytogenes and Staphylococcus aureus. The genetic determinant of this bacteriocin was localized in a 84·4 Kbp plasmid by conjugative transfer and curing assays.     

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.     

Radical scavenging capacities of saba-narezushi,Japanese fermented chub mackerel,and its lactic acid bacteria

Narezushi (salted and fermented fish with rice) is a traditional Japanese food prepared using lactic acid-fermentation. In the current study, the antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH^?)) and superoxide anion radical (O₂^?) scavenging capacities of four saba-narezushi (fermented chub mackerel with rice) products were determined. Lactose utilizing, bile resistant, acidophilic and antioxidative lactic acid bacteria (LAB) were also screened from 182 isolates derived from narezushi samples for use as starters of fermented foods as well probiotics. Radical scavenging capacities varied by product, with viable cell counts ranging from 7.9 to 9.4 log CFU/g and lactic acid content ranging from 0.27 to 1.2 mmol/g. Of the LAB isolates examined, five (four Lactobacillus plantarum and one Leuconostoc mesenteroides) were identified that were able to ferment lactose, grow in MRS containing 3 g/L bile, grow in broth adjusted to pH 3.6, and scavenge DPPH^? and/or O₂^? radicals. Two strains, Lb. plantarum 7FM10 and Ln. mesenteroides 1RM3, were able to grow and ferment in soybean milk and vegetable juice. These LAB also exhibited synergistic effects in milk fermentation, where samples containing both LAB showed a significant increase in O₂^? radical scavenging capacity.     

Effect of selected autochthonous starter cultures on processing and quality characteristics of Greek fermented sausages

Selected autochthonous starter (SAS) cultures (i.e. Lactobacillus sakei 8416, Lactobacillus sakei 4413, and L. sakei 8426, L. plantarum 7423 and L. curvatus 8427) were used as starter cultures in addition to a control treatment in the production of fermented sausages. The SAS cultures had a rapid growth and dominated the fortuitous population of LAB during the whole fermentation and ripening process improving the sensory attributes in comparison to control. Apart from the treatment produced with L. sakei 8416, all other SAS cultures prevented the lipid oxidation to values lower than 1 mg malonaldehyde/kg. The Micrococcaceae count and the redness of the sausages was not affected by the smoking and the acidification during the fermentation in the treatments produced with L. sakei 8416 and L. sakei 4413. The treatment of L. sakei 4413 had the lowest (*P < 0.05) content of all biogenic amines. In comparison to the control, the reduction of tyramine was 13%, tryptamine 55%, cadaverine 60% and putrescine 72%. Sausages produced with SAS cultures L. sakei 4413 and L. sakei 8416 had the highest scores for all sensory attributes. The results indicated that the SAS culture of L. sakei 4413 is the best autochthonous starter culture for fermented sausages.     

Changes in the bacterial communities of vacuum-packaged pork during chilled storage analyzed by PCR–DGGE

In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial communities of vacuum-packaged pork during chilled storage. Eight kinds of lactic acid bacteria (LAB) were identified from the strains isolated from MRS plates by PCR–DGGE of the V3 region, and Lactobacillus sakei was the representative isolate at the end of the monitoring. By means of the direct meat analysis of PCR–DGGE, LAB increased gradually and Carnobacterium sp./Car. divergens, Lactobacillus sakei and Lactococcus sp./Lc. piscium, became the predominant bacteria at the end of the storage. The results of Lactobacillus-specific PCR and DGGE showed that different Lactobacillus populations were present at different storage periods and Lb. sakei became the predominant bacteria in the end. In conclusion, the PCR–DGGE technique as a culture-independent method is applicable to monitoring bacterial population dynamics in vacuum-packaged pork.     

Phenotypic and genotypic identification of lactic acid bacteria isolated from a small-scale facility producing traditional dry sausages

Aims: A survey on lactic acid bacteria isolated from a small-scale facility producing traditional dry sausage. A first report on LAB in raw material, products and processing equipment.Methods and Results: A total of 88 isolates were identified phenotypically and genotypically. Phenotypic characterization at the species level indicated that 36 (40.9%) were Lactobacillus sakei, 27 (30.68%) were Enterococcus faecium, 14 (15.90%) were “Enterococcus seriolicida”, 10 (11.36%) were Enterococcus faecalis and 1 (1.13%) was Leuconostoc mesenteroides subsp. mesenteroides/dextranicum 2. In general, genotypic identification correlated well with phenotypic classification since it indicated 36 Lb. sakei, 22 Ec. faecium, 16 Lactococcus garvieae (senior synonym of Ec. seriolicida), 11 Vagococcus carniphilus and 1 Ln. mesenteroides subsp. mesenteroides. Two isolates were assigned as Enterococcus spp.Conclusions: While Ec. faecium, Vc. carniphilus and Lc. garvieae were the predominant species isolated from processing equipment and raw material, Lb. sakei species became the predominant species during fermentation of the product.Significance and Impact of the Study: This study constitutes the first step in the designing process of LAB starter cultures endogenous to the small-scale facility in order to protect the typical organoleptic characteristics of its traditional dry sausage. Otherwise, the presence of undesirable micro-organisms in the processing equipment emphasizes the necessity of improving the general hygienic conditions of sausage production in this facility.     

Molecular characterization of Lactobacillus species isolated from naturally fermented sausages produced in Greece,Hungary and Italy

The ecology of the lactic acid bacteria (LAB) in naturally fermented sausages produced in three European countries was investigated with the purpose of defining the geographic distribution of specific populations responsible for the fermentation and maturation of the sausages. Three-hundred and fifty eight strains belonging to the LAB group were isolated and identified by PCR-DGGE and sequencing. Three species were common to all three countries studied and were the most numerous. Lactobacillus curvatus, L. plantarum and L. sakei strains were subjected to RAPD-PCR followed by cluster analysis to obtain a genetic characterization. The distributions reflected in almost all cases the provenience of the strains, thereby distinguishing Italian, Greek and Hungarian LAB populations. The application of molecular methods for the identification and characterization of bacterial populations isolated from naturally fermented products allows a better understanding of the ecology. As a consequence measures can be taken to protect the biodiversity characterizing a specific system.     

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.     

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.     

Isolation and characterisation of lactic acid bacteria from yan-jiang (fermented ginger), a traditional fermented food in Taiwan

BACKGROUND: Yan‐jiang (fermented ginger) is a popular traditional fermented food in Taiwan. The lactic acid bacteria (LAB) microflora in yan‐jiang has not been studied in detail. In this study, LAB from yan‐jiang were isolated, characterised and identified. RESULTS: A total of 176 LAB were isolated; 160 cultures were isolated from yan‐jiang samples and 16 cultures were isolated from raw ginger. These isolates were characterised phenotypically and then divided into nine groups (A to I) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Lactobacillus sakei and Lactococcus lactis subsp. lactis were the major LAB found in the initial 2 days of fermentation without pickled plums; these species were mostly replaced by Weissella cibaria and L. plantarum after 3 days of fermentation. In the fermentation bucket with added pickled plums, W. cibaria was the most abundant LAB found during fermentation. The antibacterial activities of the isolates were determined. Twenty‐four Lc. lactis subsp. lactis and 19 W. cibaria strains showed inhibitory activity against the indicator strain L. sakei JCM 1157^T. CONCLUSION: Results demonstrate that various LAB species were more numerous when fermentation was carried out without pickled plums. LAB also had effects on the aroma and flavour of yan‐jiang. Copyright © 2011 Society of Chemical Industry     

Bacterial community dynamics,lactic acid bacteria species diversity and metabolite kinetics of traditional Romanian vegetable fermentations

BACKGROUND: Artisanal vegetable fermentations are very popular in Eastern European countries. Fresh vegetables undergo a spontaneous fermentation in the presence of salt, which is mainly carried out by lactic acid bacteria (LAB). RESULTS: Culture‐dependent and culture‐independent analyses of end‐samples of various spontaneous vegetable fermentations carried out in houses of the Chiodju region (central Romania) revealed Lactobacillus plantarum and Lactobacillus brevis as the most frequently isolated LAB species. Leuconostoc mesenteroides and Leuconostoc citreum were also found. Furthermore, the community dynamics of spontaneous cauliflower and mixed‐vegetable (green tomatoes, carrots and cauliflower) fermentations revealed three steps: an initial phase characterised by the presence of Enterobacteriaceae and a wide LAB species diversity, encompassing Weissella species; a second phase from day 3 onwards wherein L. citreum and Lb. brevis occurred; and a final phase characterised by the prevalence of Lb. brevis and Lb. plantarum. Metabolite target analysis revealed that glucose and fructose were mostly depleted at the end of fermentation. The main products of carbohydrate metabolism were lactic acid, acetic acid, ethanol and small amounts of mannitol, indicating heterolactate fermentation. CONCLUSION: Given their prevalence at the end of vegetable fermentations, Lb. brevis and Lb. plantarum appear to be good candidate starter cultures for controlled vegetable fermentation processes. © 2012 Society of Chemical Industry     

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.