Hui-chung Wu

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.

Isolation and characterization of lactic acid bacteria from jiang‐sun (fermented bamboo shoots), a traditional fermented food in Taiwan

BACKGROUND In this study, lactic acid bacteria (LAB) were isolated, characterized and identified from jiang-sun (fermented bamboo shoots; a traditional fermented food in Taiwan). Samples were collected at seven time intervals from a fixed fermenting bucket during the fermentation process of jiang-sun and its initial ingredients, dochi (fermented soybeans) and bamboo shoots. RESULTS A total of 57 LAB cultures were isolated; 42 cultures were isolated from jiang-sun samples and 15 cultures were isolated from dochi and bamboo shoots. These isolates were characterized phenotypically and then divided into three groups (A-C) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Alteration of microbial populations during the fermentation process was observed. While various LAB were found in the dochi and bamboo shoots, it was mostly replaced by Lactobacillus plantarum after 1 day of fermentation. Furthermore, the antibacterial activities of the isolates were determined, and one Enterococcus faecium strain showed inhibitory activity against all the indicator strains. CONCLUSION Results suggest that L. plantarum is the main LAB present during the fermentation of jiang-sun. To our knowledge, this is the first report describing the distribution and varieties of LAB that exist in the jiang-sun fermentation process.

Weissellicin L, a novel bacteriocin from sian-sianzih-isolated Weissella hellenica 4-7

To identify and characterize novel bacteriocins from Weissella hellenica 4‐7.

Isolation and characteristics of lactic acid bacteria isolated from ripe mulberries in Taiwan

The objective of this study was to isolate, characterize, and identify lactic acid bacteria (LAB) from ripe mulberries collected in Taiwan. Ripe mulberry samples were collected at five mulberry farms, located in different counties of Taiwan. Eighty-eight acid-producing cultures were isolated from these samples, and isolates were divided into classes first by phenotype, then into groups by restriction fragment length polymorphism (RFLP) analysis and sequencing of 16S ribosomal DNA (rDNA). Phenotypic and biochemical characteristics led to identification of four bacterial groups (A to D). Weissella cibaria was the most abundant type of LAB distributed in four mulberry farms, and Lactobacillus plantarum was the most abundant LAB found in the remaining farm. Ten W. cibaria and one Lactococcus lactis subsp. lactis isolate produced bacteriocins against the indicator strain Lactobacillus sakei JCM 1157T. These results suggest that various LAB are distributed in ripe mulberries and W. cibaria was the most abundant LAB found in this study.

Screening and characterization of LAB-produced bacteriocin-like substances from the intestine of grey mullet (Mugil cephalus L.) as potential biocontrol agents in aquaculture

To isolate and characterize bacteriocin‐like inhibitory substance (BLIS)‐producing lactic acid bacteria from the intestine of grey mullet.

Isolation and characterization of lactic acid bacteria from yan-taozih (pickled peaches) in Taiwan

Two hundred cultures of lactic acid bacteria were isolated from eight yan-taozih (pickled peaches) samples, and four cultures were isolated from the main component of these samples, fresh peaches. Phenotypic and biochemical characteristics identified eight different bacterial groups (A–H) and showed that the majority of the isolates was heterofermentative lactic acid bacteria. The most common bacterial species in yan-taozih was Leuconostoc mesenteroides, although regional diversity was also observed among the lactic acid bacteria strains isolated. The antibacterial activities of the isolates were also determined, and 20 isolates were found to show inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157T. The results of the sensory evaluation suggested that the diversity of lactic acid bacteria has a great effect on the aroma and formation of taste in the food product. Our findings suggest that Leuconostoc mesenteroides is the most abundant lactic acid bacteria in yan-taozih (pickled peaches) and that lactic acid bacteria strains play an important role in affecting the aroma and taste of the food product.

Lactococcus taiwanensis sp. nov., a lactic acid bacterium isolated from fresh cummingcordia

One coccal strain, designated 0905C15(T), was isolated from fresh cummingcordia, which is the main ingredient of pobuzihi (fermented cummingcordia), a traditional fermented food in Taiwan. 16S rRNA gene sequencing results showed that strain 0905C15(T) had 98.22-98.82 % sequence similarity to that of the type strains of four Lactococcus lactis subspecies (L. lactis subsp. lactis BCRC 12312(T), L. lactis subsp. cremoris BCRC 12586(T), L. lactis subsp. hordniae BCRC 80474(T) and L. lactis subsp. tructae BCRC 80475(T)). Comparison of two housekeeping genes, recA and rpoB, revealed that strain 0905C15(T) was well separated from the reference strains of the genus Lactococcus. DNA-DNA hybridization studies indicated that strain 0905C15(T) had low DNA relatedness to the four Lactococcus lactis subspecies (9.7-15.24 %). The DNA G+C content of strain 0905C15(T) was 39.6 mol %. Based on the evidence, strain 0905C15(T) represents a novel species of the genus Lactococcus, for which the name Lactococcus taiwanensis sp. nov. is proposed. The type strain is 0905C15(T) ( = NBRC 109049(T) = BCRC 80460(T)).

Lactococcus formosensis sp nov., a lactic acid bacterium isolated from yan-tsai-shin (fermented broccoli stems)

A coccal-shaped organism, designated 516(T), was isolated from yan-tsai-shin (fermented broccoli stems), a traditional fermented food in Taiwan. 16S rRNA gene sequencing results showed that strain 516(T) had 98.9 % sequence similarity to that of the type strain Lactococcus garvieae NBRC 100934(T). Comparison of three housekeeping genes, rpoA, rpoB and pheS, revealed that strain 516(T) was well separated from Lactococcus garvieae NBRC 100934(T). DNA-DNA hybridization studies indicated that strain 516(T) had low DNA relatedness with Lactococcus garvieae NBRC 100934(T) (46.1 %). The DNA G+C content of strain 516(T) was 38.1 mol% and the major fatty acids were C16 : 0 (22.7 %), C19 : 0 cyclo ω8c (17.9 %) and summed feature 7 (29.0 %). Based on the evidence, strain 516(T) represents a novel species of the genus Lactococcus, for which the name Lactococcus formosensis sp. nov. is proposed. The type strain is 516(T) ( = NBRC 109475(T) = BCRC 80576(T)).

Isolation and characterization of lactic acid bacteria from pobuzihi (fermented cummingcordia), a traditional fermented food in Taiwan

Lactobacillus pobuzihii is a novel species which has been previously found in pobuzihi (fermented cummingcordia), a traditional fermented food in Taiwan. However, the lactic acid bacteria (LAB) microflora in pobuzihi has not been studied in detail. In this study, LAB from pobuzihi were isolated, identified, and characterized. A total of 196 LAB were isolated; 79 cultures were isolated from the sample collected from a manufacturing factory, 38 from pobuzihi samples collected from 4 different markets, and 79 from 2 fresh cummingcordia samples. These isolates were characterized phenotypically and then divided into eight groups (A to H) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Lactobacillus plantarum was the most abundant LAB found in most samples during the fermentation of pobuzihi. On the other hand, Enterococcus casseliflavus and Weissella cibaria were, respectively, the major species found in the two fresh cummingcordia samples. A potential novel species or subspecies of lactococcal strain was found. In addition, seven L. plantarum and five W. cibaria strains showed inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157T. This is the first report describing the distribution and varieties of LAB existing in the pobuzihi during its fermentation process and the final product on the market.

Diversity of lactic acid bacteria in sian‐sianzih (fermented clams), a traditional fermented food in Taiwan

BACKGROUND Sian-sianzih (fermented clams) is a popular traditional fermented food in Taiwan. The lactic acid bacteria (LAB) microflora in sian-sianzih have not been studied in detail. In this study, LAB from sian-sianzih were isolated, characterized and identified. RESULTS A total of 186 cultures of LAB were isolated from seven sian-sianzih samples and 29 cultures were isolated from its main raw substrate: clams. The identification results revealed up to 11 distinct bacterial species belonging to five genera in sian-sianzih, and three species belonging to two genera in clams. The most common bacterial genera in sian-sianzih were Lactobacillus and Weissella, followed by Leuconostoc, Pediococcus and Lactococcus. A regional similarity in LAB, with differences in diversity, was observed in the current study. On the other hand, Lactococcus lactis subsp. lactis was the most common species found in raw clam samples. The results also suggested that greater LAB diversity could be observed in wild clams than in cultured ones. Furthermore, antibacterial activities of the isolates were determined, and one Weisella hellenica strain showed inhibitory activity against the indicator strain Lactobacilluas sakei JCM 1157(T) . A sensory assessment of seven sian-sianzih samples was also performed and the results indicated that diversity of LAB has a great effect on its aroma and taste formation. CONCLUSION The results demonstrate that various LAB species are distributed in sian-sianzih and have a great effect on the flavor of sian-sianzih.