益生乳酸菌Lactobacillus casei Zhang从基础研究到产业化开发

2001年-2009年,内蒙古农业大学乳品生物技术与工程教育部重点实验室从采集自中国西部7个省市及蒙古国14个省市不同少数民族地区951份自然发酵乳制品等样品中分离鉴定出3 388株乳酸菌,建立了中国首个原创性乳酸菌菌种资源库;从菌种库中分离自传统发酵酸马奶(koumiss)的243株乳杆菌中筛选获得1株性能优良的乳酸菌—Lactobacillus casei Zhang(L.casei Zhang)。采用5种动物模型和人体试验进行了功能评价,并利用基因组学和蛋白质组学研究技术对L.casei Zhang益生分子机制进行了深入剖析。经过多年系统的基础研究,自主解决了其产业化的关键技术问题,包括其直投式发酵剂、发酵乳制品和发酵豆乳益生菌饮料的研发并实现了产业化。     

Evaluation of indigenous lactic acid bacteria of raw mare milk from pastoral areas in Xinjiang,China, for potential use in probiotic fermented dairy products

In the present study 114 lactic acid bacteria strains, isolated from raw mare milks from pastoral areas for ethnic minorities in northwest China, were screened for probiotic traits, and their characteristics were compared with those of Lactobacillus rhamnosus GG, a commercial strain. Among the 114 strains identified, the most common species was Pediococcus pentosaceus (n = 52), followed by Leuconostoc lactis (n = 35), Lactobacillus helveticus (n = 7), Lactobacillus plantarum (n = 6), Lactobacillus kefiri (n = 5), Lactobacillus curvatus (n = 4), Lactobacillus paracasei (n = 3), and Lactococcus garvieae (n = 3). Based on acid and bile salt tolerance, 15 strains were further selected. All selected strains were subjected to a series of in vitro tests to assess their technological properties, including cell surface hydrophobicity (13.6–56.2%), autoaggregation ability (9.26–38.30%), coaggregation ability, and heat and lysozyme survival rates (84.74–94.01% and 80.52–99.37%, respectively). In vitro antagonism showed that Lb. plantarum (M5–19, M8–60, M8–59) exhibited the most strong inhibitory activity against 7 tested pathogens. Moreover, antibiotic resistance and hemolytic activity were investigated for safety assessment. No strain exhibited hemolytic activity, and most of the strains were sensitive to a series of 14 antibiotics of clinical importance. Ultimately, the principal component analysis of all data obtained above showed that 2 Lb. plantarum strains (M8–59, M8–60) and Lb. paracasei M1–36 exhibited the best potential for their inclusion as adjunct functional cultures in local fermented dairy products.     

Isolation and characterisation of lactic acid bacteria strains from raw camel milk for potential use in the production of fermented Tunisian dairy products

The aim of this work was to study the suitability of camel milk for the production of dairy products by lactic acid fermentation. Sixty strains of lactic acid bacteria (LAB) were isolated from camel milk. The strains were tested for their acidification activity, ability to use citrate, exopolysaccharide production, lipolytic, proteolytic activities and resistance to antibiotics. Ten strains were investigated for their ability to metabolize carbohydrates and that resulted in the identification of 5 Lactococcus lactis, 1 Lactobacillus pentosus, 2 Lactobacillus plantarum, 1 Lactobacillus brevis and 1 Pediococcus pentosaceus strains. Two strains of Lactococcus lactis SCC133 and SLch14 were selected to produce traditional Tunisian fermented dairy products (Lben, Raib, Jben cheese and Smen). These strains were chosen based on their acid production capacity and their ability to produce a high yield of biomass.     

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.     

Investigating the bacterial microbiota of traditional fermented dairy products using propidium monoazide with single-molecule real-time sequencing

Traditional fermented dairy foods have been the major components of the Mongolian diet for millennia. In this study, we used propidium monoazide (PMA; binds to DNA of nonviable cells so that only viable cells are enumerated) and single-molecule real-time sequencing (SMRT) technology to investigate the total and viable bacterial compositions of 19 traditional fermented dairy foods, including koumiss from Inner Mongolia (KIM), koumiss from Mongolia (KM), and fermented cow milk from Mongolia (CM); sample groups treated with PMA were designated PKIM, PKM, and PCM. Full-length 16S rRNA sequencing identified 195 bacterial species in 121 genera and 13 phyla in PMA-treated and untreated samples. The PMA-treated and untreated samples differed significantly in their bacterial community composition and α-diversity values. The predominant species in KM, KIM, and CM were Lactobacillus helveticus, Streptococcus parauberis, and Lactobacillus delbrueckii, whereas the predominant species in PKM, PKIM, and PCM were Enterobacter xiangfangensis, Lactobacillus helveticus, and E. xiangfangensis, respectively. Weighted and unweighted principal coordinate analyses showed a clear clustering pattern with good separation and only minor overlapping. In addition, a pure culture method was performed to obtain lactic acid bacteria resources in dairy samples according to the results of SMRT sequencing. A total of 102 LAB strains were identified and Lb. helveticus (68.63%) was the most abundant, in agreement with SMRT sequencing results. Our results revealed that the bacterial communities of traditional dairy foods are complex and vary by type of fermented dairy product. The PMA treatment induced significant changes in bacterial community structure.     

Identification of Lactobacillus from koumiss by conventional and molecular methods

Lactobacilli are considered to be one of the most important potential probiotics in the dairy industry. Twelve strains of Lactobacillus were isolated from home-made koumiss samples, a traditionally fermented mare milk in China. The isolates were identified based on physiological and biochemical characteristics and analysis of 16S RNA sequences. They were proven to be Lactobacillus helveticus, Lactobacillus fermentum, Lactobacillus casei and Lactobacillus plantarum. The results demonstrated that both methods were essential to identify an isolate accurately.     

Enzymatic activity of lactic acid bacteria (with antimicrobial properties) isolated from a traditional Spanish cheese

Twenty-four strains of lactic acid bacteria (LAB) isolated from a traditional Spanish cheese (Genestoso cheese) were evaluated for their enzymatic activities (acidifying and proteolytic abilities and carboxypeptidase, aminopeptidase, dipeptidase, caseinolytic and esterase activities), in order to select indigenous strains of technical interest for the manufacture of cheese. These strains were selected on the basis of their antimicrobial activity relative to five reference strains and were identified as Lactococcus lactis subsp. lactis (thirteen strains), Leuconostoc mesenteroides (two strains), Leuconostoc pseudomesenteroides (one strain), Lactobacillus paracasei (two strains), Lactobacillus plantarum (one strain) and Enterococcus faecalis (five strains).     

Isolation of novel homopolysaccharide-producing lactic acid bacteria from Romanian raw milk and fermented dairy products

Traditionally fermented foods can be a rich source of diverse lactic acid bacteria (LAB) with interesting functional properties, such as exopolysaccharide (EPS) production. The objectives of this study were to map the mucoid and/or ropy LAB isolated from raw milk and traditionally fermented dairy products, collected in different regions of Romania, to study the species diversity within the samples and to further explore the EPS-producing capacity of the isolates. Seventy-three LAB strains were isolated and identified through (GTG)₅-PCR genomic fingerprinting and SDS-PAGE of whole-cell proteins. Lactococcus lactis was the most frequently encountered species, followed by Lactobacillus plantarum, Leuconostoc spp., and Enterococcus spp. Nine strains produced homopolysaccharides (HoPS, glucose monomers), namely L. lactis 1.8; Leuc. citreum 1.10, 1.11, 1.12, 2.8, and 4.11; Leuc. mesenteroides 21.2; Leuc. pseudomesenteroides 20.6; and Weisella confusa/cibaria 38.2, six of them in the concentrations above 10 g/L, both in milk and MRS medium supplemented with sucrose. In all EPS, the glucose constituents were connected by different α-linkages, among which α-1,6-linkages were the most prevalent.     

Natural populations of lactic acid bacteria isolated from vegetable residues and silage fermentation

Natural populations of lactic acid bacteria (LAB) and silage fermentation of vegetable residues were studied. Fifty-two strains of LAB isolated from cabbage, Chinese cabbage, and lettuce residues were identified and characterized. The LAB strains were gram-positive and catalase-negative bacteria, which were divided into 6 groups (A to F) according to morphological and biochemical characteristics. The strains in group A were rods that did not produce gas from glucose and formed the d and l isomers of lactate. Groups B and C were homofermentative cocci that formed l-lactic acid. Groups D, E, and F were heterofermentative cocci that formed d-lactic acid. Based on 16S rDNA gene sequence analysis, group A to F strains were identified as Lactobacillus plantarum, Lactococcus piscium, Lactococcus lactis, Leuconostoc citreum, Weissella soli and Leuconostoc gelidum, respectively. The prevalent LAB, predominantly homofermentative lactobacilli, consisted of Lactobacillus plantarum (34.6%), Weissella soli (19.2%), Leuconostoc gelidum (15.4%), Leuconostoc citreum (13.5%), Lactococcus lactis (9.6%), and Lactococcus piscium (7.7%). Lactobacillus plantarum was the dominant member of the LAB population in 3 types of vegetable residues. These vegetable residues contained a high level of crude protein (20.2 to 28.4% of dry matter). These silages prepared by using a small-scale fermentation system were well preserved, with low pH and a relatively high content of lactate. This study suggests that the vegetable residues contain abundant LAB species and nutrients, and that they could be well preserved by making silage, which is a potentially good vegetable protein source for livestock diets.     

Isolation and identification of high viscosity-producing lactic acid bacteria from a traditional fermented milk in Xinjiang and its role in fermentation process

Forty-four lactic acid bacteria (LAB) isolated from traditional Sayram ropy fermented milk (SRFM) in southern Xinjiang of China. Further two strains were selected based on their high viscosity-producing activity. Based on the API 50 CHL strip and 16S rDNA sequence analysis, strain MB 2-1 was a Gram-positive, rod-shaped Lactobacillus helveticus and strain MB 5-1 was identified as Streptococcus thermophilus. Both the two LAB strains were grown in the milk fermentations for pure and mixed cultures and were evaluated for their growth, acidification properties, EPS production, and ability to increase the apparent viscosity of fermented milk, respectively. L. helveticus MB 2-1 displayed a high increasing in viable cell counts and the acidifying capacity in pure cultures, whereas the relatively high EPS production and viscosity-producing capacity detected in pure culture with S. thermophilus MB 5-1 as starter culture. In addition, the mixed culture of the two strains showed a higher cell growth, EPS production, and high viscosity-producing capacity at 37?°C. Values of apparent viscosity were 4.03- and 2.41-fold higher in mixed culture than for pure cultures of L. helveticus MB 2-1 and S. thermophilus MB 5-1, respectively. There was a positive correlation between the viscosity and high molecular weight EPS production with pure and mixed cultures. Our data showed two strains combination, with high viscosity-producing and acidifying capacity, can be used in mixed cultures for the manufacture of fermented milk with improved functional properties.     

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.     

A culture-dependent and -independent approach for the identification of lactic acid bacteria associated with the production of nem chua,a Vietnamese fermented meat product

In this study, the diversity of the native lactic acid bacteria (LAB) population in nem chua, a popular traditional Vietnamese uncooked fermented meat, was described using a combination of culture-dependent and culture-independent methods. A total of two hundred seventy-three LAB isolates were subjected to a polyphasic identification approach combining (GTG)₅-PCR fingerprinting and phenylalanyl-tRNA synthase α subunit (pheS) and RNA polymerase α subunit (rpoA) gene sequence analysis. LAB associated with nem chua were identified as Lactobacillus pentosus (21%), Lactobacillus plantarum (29.7%), Lactobacillus brevis (5%), Lactobacillus paracasei (0.4%), Lactobacillus fermentum (0.7%), Lactobacillus acidipiscis (0.4%), Lactobacillus farciminis (23%), Lactobacillus rossiae (0.4%), Lactobacillus fuchuensis (0.7%), Lactobacillus namurensis (0.4%), Lactococcus lactis (0.4%), Leuconostoc citreum (9.5%), Leuconostoc fallax (1%), Pediococcus acidilactici (1%), Pediococcus pentosaceus (4%), Pediococcus stilesii (1%), Weissella cibaria (0.7%) and Weissella paramesenteroides (0.7%). Furthermore, PCR-DGGE was also applied as a culture-independent method in this study. Results indicated the presence of species of which no isolates were recovered, i.e. Lactobacillus helveticus/crispatus, Lactococcus garvieae and Vagococcus sp. Conversely, not all isolated bacteria were detected by PCR-DGGE. Principal component and discriminant analysis disclosed correlations between the different production locations and certain isolated LAB species and strains and/or DGGE bands suggesting possible influences of locally prevailing production practices on the nem chua LAB microbiota.     

Development of a pentaplex PCR assay for the simultaneous detection of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, L. helveticus, L. fermentum in whey starter for Grana Padano cheese

A pentaplex PCR assay for the rapid, selective and simultaneous detection of Lactobacillus helveticus, L. delbrueckii subsp. lactis, L. delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and L. fermentum, was developed. The target sequences were a group of genes coding for beta-galactosidase production (S. thermophilus and L. delbrueckii subsp. bulgaricus), for cell-enveloped associated proteinase synthesis (L. helveticus), for dipeptide transport system production (L. delbrueckii subsp. lactis) and for arginine-ornithine antiporter protein production (L. fermentum). The analytical specificity of the assay was evaluated with 5 reference strains and 140 lactic acid bacterial strains derived from raw milk cheeses and belonging to the Lactobacillus, Streptococcus, Lactococcus and Enterococcus genera. The identification limit for each target strain was 10³ CFU/ml. This new molecular assay was used to investigate the LAB population by direct extraction of DNA from the 12 whey cultures for Grana Padano. The pentaplex PCR assay revealed a good correspondence with microbiological analyses and allowed to identify even minor LAB community members which, can be out-competed in vitro by numerically more abundant microbial species.     

Genetic diversity of Lactobacillus delbrueckii isolated from raw milk in Hokkaido,Japan

Lactic acid bacteria (LAB) play important roles in acid production and flavor formation in fermented dairy products. Lactic acid bacteria strains with distinct characteristics confer unique features to products. Diverse LAB have been identified in raw milk and traditional fermented milk prepared from raw milk. However, little is known about LAB in raw milk in Japan. To preserve diverse LAB as potential starters or probiotics for future use, we have isolated and identified various kinds of LAB from raw milk produced in Japan. In this study, we focused on Lactobacillus delbrueckii, one of the most important species in the dairy industry. We identified L. delbrueckii subspecies isolated from raw milk in Hokkaido, Japan, by analyzing intraspecific diversity using 4 distinct methods, hsp60 cluster analysis, multilocus sequence analysis, core-genome analysis, and whole-genome analysis based on average nucleotide identity. The subspecies distribution and a new dominant subset of L. delbrueckii from raw milk in Japan were revealed. The discovery of new strains with different genotypes is important for understanding the geographic distribution and characteristics of the bacteria and further their use as a microbial resource with the potential to express unconventional flavors and functionalities. The strains identified in this study may have practical applications in the development of fermented dairy products.     

Selection of probiotic bacteria for the fermentation of a soy beverage in combination with Streptococcus thermophilus

Lactobacillus delbrueckii subsp. lactis R0187, Lactobacillus helveticus R0052, Lactobacillus rhamnosus R0011 and Bifidobacterium longum R0175 were examined for their ability to grow in combination with Streptococcus thermophilus cultures in milk and a laboratory soy beverage (LSB; both standardized to 4.5% protein and 2.3% fat). Strains R0011 and R0187 did not rapidly acidify the soy beverage despite good growth rates on soy carbohydrates. The S. thermophilus populations in the LSB were similar to that of milk even though milk had 30% more buffering capacity. In milk but not in soy, symbiosis with respect to acidification rate was observed between S. thermophilus and L. helveticus or B. longum. The populations of L. helveticus in the fermented products were similar in pure cultures or in the presence of the streptococci. However B. longum did not compete well in the mixed culture. Fermentation conditions varied as a function of the ability of S. thermophilus strains to acidify media to a pH of 4.65 (between 8 and 24 h). The probiotic populations in the mixed culture were influenced by the S. thermophilus strain and by the time of fermentation. Variations in growth rates of the bacteria did not appear to be linked to differences in initial redox or α-amino nitrogen levels. Strain selection enabled the preparation of a mixed starter, probiotic-fermented soy beverage containing 1.1 × 10⁸ CFU/mL of L. helveticus R0052, which represented approximately 13% of the total final population.     

Identification of cultivable lactic acid bacteria isolated from Algerian raw goat's milk and evaluation of their technological properties

One hundred and fifty-eight strains of lactic acid bacteria isolated from Algerian raw goat's milk were identified and technologically characterized. Five genera were found: Lactobacillus (50.63%), Lactococcus (25.94%), Streptococcus (14.56%), Leuconostoc (7.59%) and Pediococcus (1.26%). The predominant species were Lactococcus lactis (32 strains), Streptococcus thermophilus (23 strains), Lactobacillus bulgaricus (19 strains), Lb. helveticus (16 strains) and Lb. plantarum (14 strains).Approximately 39% of the lactic acid bacteria isolated produced more than 0.6% lactic acid (w/v) after 18 h of incubation, and belonged to the Lactococcus and Lactobacillus genera. The highest proteolytic activity was approximately 3 mg tyrosine l⁻¹ for mesophilic strains and nearly 5 mg tyrosine l⁻¹ for thermophilic lactobacilli after 72 h. High aromatic activity (more than 0.8 mg diacetyl l⁻¹ after 16 h) was detected in 14% of the strains.Nine strains were used to make dairy products (a yoghurt-like product and Edam-type cheese) on a pilot scale in the laboratory. The best-liked organoleptic characteristics were noted in a yoghurt produced with a mixed culture made up of S. thermophilus (strain 16TMC+) and Lb. helveticus (strain 20TMC) and in a cheese made with a starter composed of Lc. lactis subsp. lactis (strain 10MCM) and L. lactis subsp. lactis (V.P. +) (strain 19MCM).     

Angiotensin I converting enzyme (ACE) inhibitory activity and antihypertensive effect of fermented milk

Milk was fermented with a total of 25 lactic acid bacteria to assay in vitro inhibitory activity towards angiotensin I converting enzyme (ACE). The tested strains belonged to Lactobacillus acidophilus, Lactobacillus casei, Lacobacillus helveticus, Lactobacillus jensenii, Lactobacillus reuteri, Lactobacillus rhamnosus, Lactococcus lactis ssp. lactis, Lactococcus. raffinolactis and Leuconostoc mesenteroides ssp. cremoris. The ACE inhibitory potencies of theses strains varied and seven of them showing the highest ACE inhibitory activity were selected for further studies. The development of ACE inhibitory activity during fermentation correlated with degree of hydrolysis. Modification of fermentation conditions or pH control did not affect the ACE inhibitory activity. ACE inhibitory compounds from Lb. jensenii fermented milk were isolated by reversed phase HPLC and identified by MS-analysis and amino acid sequencing. The active compounds were peptides from β-casein. The milk fermented with Lb. jensenii caused a transient reduction of blood pressure in spontaneously hypertensive rats.     

Peptide profiles and angiotensin-I-converting enzyme inhibitory activity of fermented milk products: Effect of bacterial strain,fermentation pH,and storage time

Milk was fermented to defined pH values with 13 strains of lactic acid bacteria. The products were evaluated after 1 and 7 days of cold storage, and major peptides in selected products were identified. The Streptococcus thermophilus and Lactobacillus acidophilus strains used did not give rise to products with significant angiotensin-1-converting enzyme (ACE)-inhibition. The four Lactococcus lactis strains behaved similarly in fermentation, proteolysis and ACE-inhibition. The products made with the seven Lactobacillus helveticus strains varied. The highest ACE-inhibitory activity was obtained with two highly proteolytic strains of Lb. helveticus and with the Lactococcus strains. Fermentation from pH 4.6 to 4.3 with these strains slightly increased the ACE-inhibitory activity, whilst fermentation to pH 3.5 with Lb. helveticus reduced the ACE-inhibitory activity. Cold storage dramatically increased the ACE-inhibitory activity of some products. A non-linear correlation was found between peptide amount and ACE-inhibitory activity, and peptides contributing to the ACE-inhibitory activity were identified.     

Technological characterization of lactic acid bacteria isolated from Armada cheese (a Spanish goats’ milk cheese)

Thirty-one strains of lactic acid bacteria (LAB) isolated from Armada cheese, Sobado variety, (eight strains of Lactococcus lactis subsp. lactis, four strains of Lactococcus lactis subsp. cremoris, two strains of L. lactis subsp. lactis biovar. diacetylactis, two strains of Leuconostoc mesenteroides subsp. mesenteroides, two strains of Leuconostoc mesenteroides subsp. dextranicum, five strains of Lactobacillus plantarum, six strains of Lactobacillus casei subsp. casei and two strains of Lactobacillus brevis) were screened for their acidifying capacity and enzymatic activity, that included the rapid API-ZYM system, the proteolytic activity, the amino-, di-, and carboxypeptidase activity and the caseinolytic activity. The strains of L. lactis subsp. lactis exhibited the highest acidifying and proteolytic activity. Lipase and esterase activity was practically non-existent for lactococci and lactobacilli; a certain esterase activity was observed among leuconostoc. The highest aminopeptidase activity was demonstrated by the cell-free extract (CFE) of some strains of L. plantarum, L. casei subsp. casei and L. mesenteroides subsp. dextranicum. The CFEs of L. lactis subsp. cremoris and L. lactis subsp. lactis possessed carboxypeptidase and dipeptidase activities, at levels depending on the strain. Appreciable caseinolytic activity was detected for the CFE of L. plantarum and those some lactococci.     

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

BACKGROUND: Jiang‐gua (fermented cucumbers) is a popular traditional fermented food in Taiwan. The microflora of lactic acid bacteria (LAB) in jiang‐gua have not been investigated in detail. In this study, LAB from jiang‐gua were isolated, characterised and identified. RESULTS: A total of 103 LAB were isolated; 70 cultures were isolated from jiang‐gua samples and 33 cultures were isolated from its raw substrate, cucumber. These isolates were mainly characterised phenotypically and then divided into seven groups (A‐G) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. The isolates were identified as Enterococcus casseliflavus, Leuconostoc lactis, Leuconostoc mesenteroides, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus paraplantarum, Lactococcus lactis subsp. lactis, Weissella cibaria and Weissella hellenica. The antibacterial activities of the isolates were determined and 11 Lc. lactis subsp. lactis strains showed inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157^T. CONCLUSION: Heterofermentative W. cibaria and Leu. lactis were the major LAB found in jiang‐gua samples without soy sauce. In soy sauce‐added samples, homofermentative L. pentosus and L. plantarum were the most abundant LAB. In addition, the results also suggested that HhaI and RsaI restriction enzymes could be applied to distinguish W. hellenica and Weissella paramesenteroides. Copyright © 2012 Society of Chemical Industry