Yi-sheng Chen

Isolation and identification of lactic acid bacteria from soil using an enrichment procedure

Aims:u2002 To survey, and identify and classify the ecological distribution of lactic acid bacteria from soil in Japan and Taiwan.

Weissellicin 110, a Newly Discovered Bacteriocin from Weissella cibaria 110, Isolated from Plaa-Som, a Fermented Fish Product from Thailand

ABSTRACT Weissella cibaria 110, isolated from the Thai fermented fish product plaa-som, was found to produce a bacteriocin active against some gram-positive bacteria. Bacteriocin activity was not eliminated by exposure to high temperatures or catalase but was destroyed by exposure to the proteolytic enzymes proteinase K and trypsin. The bacteriocin from W. cibaria 110 was purified, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the purified bacteriocin contained one protein band that was approximately 2.5 kDa in size. Mass spectrometry analysis showed the mass of the peptide to be approximately 3,487.8 Da. N-terminal amino acid sequence analysis was performed, and 27 amino acids were identified. Because it has no similarity to other known bacteriocins, this bacteriocin was defined as a new bacteriocin and termed weissellicin 110.

Durancin L28‐1A, a new bacteriocin from Enterococcus durans L28‐1, isolated from soil

Aims:u2002 To isolate, characterize and identify bacteriocins from lactic acid bacteria in soil.

Effects of prebiotic oligosaccharides and trehalose on growth and production of bacteriocins by lactic acid bacteria.

Aims:u2002 To investigate the effects of two prebiotics and trehalose on the production of bacteriocins.

Isolation and characterization of lactic acid bacteria from dochi (fermented black beans), a traditional fermented food in Taiwan.

Aims:u2002 To isolate, characterize and identify lactic acid bacteria (LAB) in dochi (fermented black beans), a traditional fermented food in Taiwan.

Characteristics of bacteriocin-like inhibitory substances from dochi-isolated Enterococcus faecium D081821 and D081833

Aims:u2002 To characterize bacteriocin‐like inhibitory substances (BLIS) from two dochi‐isolated Enterococcus faecium.

Growth-inhibition of hiochi bacteria in namazake (raw sake) by bacteriocins from lactic acid bacteria

The bacteriocins produced by Lactococcus lactis subsp. lactis C101910 (C101910) and NBRC 12007 (NBRC 12007) were used to prevent the growth of sake spoiling hiochi bacteria (Lactobacillus hilgardii, Lactobacillus fructivorans, and Lactobacillus paracasei) in namazake, which is raw (unpasteurized) sake. The bacteriocin concentrations required for decreasing the viable cell concentrations of L. hilgardii and L. fructivorans below the detection limit (1.0 x 10(2) cells/ml) in 24 h from the initial concentration of 4.0-9.5 x 10(5) cells/ml in the namazake at pH 4.5 and at 4 degrees C, were 18-35 U/ml and 5.6 U/ml for the bacteriocin from C101910 and NBRC 12007, respectively. To decrease the viable cell concentration of L. paracasei from the initial concentration of 7.5 x 10(5) cells/ml to below the detection limit (1.0 x 10(2) cells/ml) in 24 h, 350 U/ml bacteriocin from C101910 and 140 U/ml bacteriocin from NBRC 12007 were required. In experiments using McIlvaine buffer (pH 4.5) with 15% ethanol instead of namazake as the medium, the viable cell concentrations of L. hilgardii and L. paracasei decreased to less than 1.0 x 10(2) cells/ml, whereas those of L. fructivorans decreased to less than 1.0 x 10(3) cells/ml, when bacteriocins were added at the concentrations that had proven effective in namazake. The membrane depolarization assay using a fluorescent probe showed that the presence of ethanol stimulated the collapse of the membrane potential induced by bacteriocins. The ethanol induced collapse of the membrane potential suggests that the application of bacteriocins at the storage stage of namazake is more beneficial than when used in other stages of the sake brewing process.

Detection and Characterization of Weissellicin 110, a Bacteriocin Produced by Weissella cibaria

BACKGROUNDnWeissellicin 110 is the only bacteriocin reported in Weissella cibaria up to now. This bacteriocin represents several unique features. This is the first report on the gene sequence that encodes for the bacteriocin.nnnOBJECTIVESnProviding a rapid detection method to isolate the weissellicin 110 encoding gene and determination of the bacteriocin distribution were the objectives.nnnMATERIALS AND METHODSnBacteriocin from W. cibaria 860106 was purified and analyzed using mass spectrometry for proteins sequencing. The draft genome sequence of W. cibaria 860106 was generated using next generation sequencing. PCR was applied to detect the weissellicin 110 encoding gene.nnnRESULTSnThe molecular weight and partial protein sequence were obtained for the bacteriocin from W. cibaria 860106. An open reading frame (ORF) was identified as weissellicin 110 from the draft genome sequence. PCR primers were designed to amplify the weissellicin 110 encoding gene and these primers detected sequences from other 27 BLIS-producing W. cibaria strains previously isolated from either various Taiwanese fermented foods or the respective raw materials.nnnCONCLUSIONSnThe genetic information of weissellicin 110 was obtained, enabling rapid detection of the weissellicin 110 encoding gene. Results suggest that weissellicin 110 producing W. cibaria strains are widely distributed inTaiwanese fermented foods.