Linna Tongyonk

Bacillus siamensis sp. nov., isolated from salted crab (poo-khem) in Thailand

A Gram-positive, endospore-forming, rod-shaped bacterium, strain PD-A10(T), was isolated from salted crab (poo-khem) in Thailand and subjected to a taxonomic study. Phenotypic and chemotaxonomic characteristics, including phylogenetic analyses, showed that the novel strain was a member of the genus Bacillus. The novel strain grew in medium with 0-14 % (w/v) NaCl, at 4-55°C and at pH4.5-9. The predominant quinone was a menaquinone with seven isoprene units (MK-7). The major fatty acids were anteiso-C₁₅:₀ and anteiso-C₁₇:₀. Polar lipid analysis revealed the presence of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, lysylphosphatidylglycerol, glycolipid and unknown lipids. The DNA G+C content was 41.4 mol%. The 16S rRNA gene sequence similarities between strain PD-A10(T) and Bacillus amyloliquefaciens NBRC 15535(T), Bacillus subtilis DSM 10(T), Bacillus vallismortis DSM 11031(T) and Bacillus mojavensis IFO 15718(T) were 99.5, 99.4, 99.4 and 99.2 %, respectively. Strain PD-A10(T) showed a low degree similarity of rep-PCR fingerprints and low DNA-DNA relatedness with the above-mentioned species. On the basis of the data gathered in this study, strain PD-A10(T) should be classified as representing a novel species of the genus Bacillus, for which the name Bacillus siamensis sp. nov. is proposed. The type strain is PD-A10(T) (=BCC 22614(T)=KCTC 13613(T)).

Antimutagenicity of Black Glutinous Rice and Hom Nil Rice

Black glutinous rice (Oryza sativa var. glutinosa) and Hom Nil rice (Oryza sativa) are colored rice varieties with antioxidant properties, popular among health conscious consumers. We studied the antimutagenicity of raw, cooked and fermented samples against two direct mutagens - nitrite-treated 1-aminopyrene and nitrite treated chicken essence - in an Ames assay using Salmonella typhi- murium strains TA 98 and TA 100. The extract of each sample with acid alcohol reduced the mutagenicity of both mutagens. In addition, the antimutagenicity of the extracts from the samples made of black glutinous rice was higher than that of the extracts from samples made of Hom Nil rice. The protective effects of these rice varieties might be due to the presence of some phytochemicals, including anthocyanins, which are the main antioxidant. The selected rice va- rieties might be appropriate for p