Komang Januartha Putra Pinatih

IDENTIFICATION OF LACTIC ACID BACTERIA ISOLATE 9A FROM BALI CATTLE’S COLON PHENOTYPICALLY

Lactic acid bacteria are the type of bacteria that has benefits in food and health industries as a biopreservative, fermentative, or probiotics. Bali cattle are known as potential host for specific lactic acid bacteria. The aim of this study is to identify phenotypically lactic acid bacteria 9A isolated from bali cattle’s colon, that producing a substance which known has potency as antimicrobial. In this study, phenotypic identification included conventional method and API 50 CHL. The result of this study showed that lactic acid bacteria isolate 9A was Streptococcus sp., whereas identification by kit API 50 CHL showed isolate 9A as Lactobacillus fermentum with 83% identity. The difference between the results of conventional method and kit API 50 CHL, may indicate the difference in sensitivity and specificity of the two methods, hence it needs further confirmation.

Regulatory elements of stx2 gene and the expression level of Shiga-like toxin 2 in Escherichia coli O157:H7

BACKGROUND/PURPOSE Shiga-like toxin (Stx) is an important factor in the pathogenesis of Escherichia coli O157:H7 infection and is responsible for some severe complications. Stx2 is usually associated with hemolytic uremic syndrome in humans. Its expression is regulated by elements located upstream of the stx2 gene, including stx2-promoter sequence, ribosome binding site, and the antiterminator q gene. The present study aimed to find the correlation between regulatory elements and the expression level of Stx2 in two local isolates of E. coli O157:H7. METHODS Two local E. coli O157:H7 strains SM-25(1) and KL-48(2), originating from human and cattle feces, respectively, and an E. coli reference strain, ATCC 43894, were investigated. The complete stx2 gene covering the sequences of promoter, ribosome binding site, and open reading frame and q gene of each strain was analyzed. The magnitude of Stx2 production was detected with a reverse passive latex agglutination method and Stx mediated cellular damage was determined with the Vero cell assay. RESULTS A comparison of the complete stx2 gene contained stx2-promoter, ribosome binding site, and q genes of two local strains KL-48(2) and SM25(1), and the E. coli ATCC 43894 showed that the amino acid sequences were identical. Both local isolates were Stx negative in the reverse passive latex agglutination test and nontoxic in the Vero cell assay. CONCLUSION The expression level of Shiga-like toxin of the two local isolates of E. coli O157:H7 did not only depend on the regulatory elements of the stx2 gene.