Diversity of lactic acid bacteria associated with fresh coffee cherries in Taiwan.

A total of 102 lactic acid bacteria (LAB) were isolated from three different coffee farms in Taiwan. These isolates were classified and identified by the restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. Heterofermentative Leuconostoc, and Weissella species were the most common LAB found in two farms located at an approximate altitude of 800 m. Lactococcus lactis subsp. lactis was the most common LAB found in the remaining farm was located at an approximate altitude of 1,200 m. It is therefore suggested that the altitude and climate may affect the distribution of LAB. On the basis of phylogenetic analysis, two strains included in the genera Enterococcus were considered as two potential novel species or subspecies. In addition, a total of 34 isolates showed the antifungal activity against Aspergillus flavus. Moreover, seven Lactococcus lactis subsp. lactis strains and one Enterococcus faecalis strain were found to have bacteriocin-like inhibitory substance-producing capability. These results suggest that various LAB are associated with fresh coffee cherries in Taiwan. Some of the isolates found in this study showed potential as antifungal agents.

Enterocin T, a novel class IIa bacteriocin produced by Enterococcus sp. 812.

Enterococcus sp. 812, isolated from fresh broccoli, was previously found to produce a bacteriocin active against a number of Gram-positive bacteria, including Listeria monocytogenes. Bacteriocin activity decreased slightly after autoclaving (121 °C for 15 min), but was inactivated by protease K. Mass spectrometry analysis revealed the bacteriocin mass to be approximately 4,521.34 Da. N-terminal amino acid sequencing yielded a partial sequence, NH2-ATYYGNGVYXDKKKXWVEWGQA, by Edman degradation, which contained the consensus class IIa bacteriocin motif YGNGV in the N-terminal region. The obtained partial sequence showed high homology with some enterococcal bacteriocins; however, no identical peptide or protein was found. This peptide was therefore considered to be a novel bacteriocin produced by Enterococcus sp. 812 and was termed enterocin T.

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.

Identification of nucleotide sequence involved in Weissellicin L production.

BACKGROUND: Weissellicin L, a novel bacteriocin produced by Weissella hellenica 4-7, was previously characterized but its full amino acid sequence remain unknown. The draft genome sequencing analysis of Weissella hellenica 4-7 was performed and the open reading frame (ORF) encoding the weissellicin L was identified and clarified. FINDINGS: The obtained results indicated that the mature bacteriocin consists of 29 amino acid residues with a molecular weight of approximately 3205.64 Da. A conserved processing site of two glycine residues in positions -1 and -2 was observed in the leader peptides. The possibility that bacteriocin secretion depended on ATP-binding cassette (ABC) transporter was therefore suggested. Furthermore, primers were designed from 5' and 3' flanking sequences of the weissellicin L structural gene. PCR presented a single product and was useful to detect weissellicin L structural gene. CONCLUSIONS: To our knowledge, this is the first report describing the full amino acid sequence of Weissellicin L. A rapid method to detect weissellicin L structural gene was also reported in this study.