Haruo Shinano

Comparative Sequence Analyses of the Genes Coding for 16S rRNA of Lactobacillus casei-Related Taxa

The primary structures of the 16S rRNA genes of the type strains of Lactobacillus casei and related taxa were determined by PCR DNA-sequencing methods. The sequences of Lactobacillus casei, Lactobacillus zeae, Lactobacillus paracasei, and Lactobacillus rhamnosus were different. The Knuc values ranged from 0.0040 to 0.0126. On the basis of the Knuc values and the levels of DNA-DNA relatedness among the strains of these species, the L. casei-related taxa should be classified in the following three species: L. zeae, which includes the type strains of L. zeae and L. casei; a species that includes the strains of L. paracasei and L. casei ATCC 334; and L. rhamnosus.

Bacillus horti sp. nov., a new Gram-negative alkaliphilic bacillus

Novel Gram-negative alkaliphilic strains were isolated from soil obtained from Atsuma, Hokkaido, Japan. The isolates were strictly aerobic rods that produced subterminally located ellipsoidal spores. Chemotaxonomic characteristics of the isolates included the presence of meso-diaminopimelic acid in the cell wall and a DNA G + C content of 40.2-40.9 mol%. The major isoprenoid quinone was menaquinone-7 and the cellular fatty acid profile consisted of a significant amount of 15-C branched-chain acids, iso-C15:0 and anteiso-C15:0. The growth rate was higher at pH 8-10 than at pH 7. Comparative sequence analysis of 16S rDNA of 14 alkaliphilic Bacillus strains indicates that the isolated strain has an equidistant relationship to three already defined rRNA groups of alkaliphilic Bacillus species. Based on the morphological and physiological characteristics, as well as phylogenetic position as determined by 16S rDNA analysis and DNA-DNA relatedness data, it is concluded that these isolates should be designated as a new species, for which the name Bacillus horti is proposed. The type strain is K13T (= JCM 9943T).

Influence of sporulation medium and divalent ions on the heat resistance of Alicyclobacillus acidoterrestris spores

The influence of divalent cations on the heat resistance of spores of the thermoacidophilic spoilage bacterium Alicyclobacillus acidoterrestris was studied. The heat resistance of A. acidoterrestris spores was not affected by the presence of the different divalent cations (Ca2+, Mg2+, Ba2+, Mn2+ and Sr2+) in the sporulation medium, and by the demineralization or remineralization. And the Ca and Mn contents in A. acidoterrestris spores were scarcely changed by these treatments. However, the heat resistance of Bacillus subtilis spores was affected with the changes of Ca content in the spores. The Ca contents in A. acidoterrestris spores of the different forms were greater than the DPA content. In contrast, the DPA content in the B. subtilis spores was greater than the Ca content. These findings suggest that the presence of constant amount of Ca‐DPA and a stronger binding characteristic of divalent ions, especially Ca and Mn, is reflected in the specific heat resistance of A. acidoterrestris spores.

Specific primers for detection of Alicyclobacillus acidoterrestris by RT-PCR

K. YAMAZAKI, H. TEDUKA, N. INOUE AND H. SHINANO. 1996. The reverse transcriptionpolymerase chain reaction (RT‐PCR), after a short enrichment culture, was used to detect Alicyclobacillus acidoterrestris in acidic beverages. Two specific primers were selected from the region of V2 and V4 on 16S rRNA gene. With this primer set, 294‐bp fragments from A. acidoterrestris could be amplified. The detection limit of the RT‐PCR with the FHLP filters was about 10‐1 fg of pure total RNA per reaction. Juice samples inoculated with 104 cfu of A. acidoterrestris per ml were RT‐PCR positive without enrichment. However, after 15 h of enrichment, the samples inoculated with 2–3 cfu ml‐1 were positive. This RT‐PCR culture assay would enable rapid and specific detection of strains of A. acidoterrestris in acidic beverages.

マイワシの15℃ブライン貯蔵時における貯蔵性と菌相〔英文〕

The effects of brine on fish storage have been studied using sardine (Sardinops melanosticta) as a raw material. Samples were immersed in brine and stored for a period in which they were considered suitable for consumption, at 15•‹C. NaCl concentration in the fish muscle reached its maximum within the first three days of storage for all the samples, after which the values remained constant. Assessments for suitability for consumption were carried out during storage. They included volatile base nitrogen (VB-N), microbiological, and organoleptic tests. Samples immersed in 15% brine solution proved to be edible for up to 5 days. Microbiological tests on all of the 3 samples found Pseudomonas spp. and Moraxella spp. to be the most numerous bacterial groups on the last day of sampling.