Gibbsiella papilionis Kim et al. 2013 is a later heterotypic synonym of gibbsiella dentisursi Saito et al. 2013

© 2015 IUMS. Synonymy of Gibbsiella dentisursi DSM 23818T (=NUM 1720T) and Gibbsiella papilionis JCM 18389T (=LEN33T) was suspected following multilocus sequence analysis (MLSA) of both type strains in a previous classification study, where they were found to share >99.6% gene sequence similarity. The taxonomic relationship between these two strains was re-examined here using a polyphasic approach. A DNA-DNA hybridization value of 98% confirmed that the two type strains belong to a single taxon, while the phenotypic profiles were found to be nearly identical. Therefore we propose Gibbsiella papilionis as a later heterotypic synonym of Gibbsiella dentisursi, with the type strain as NUM 1720T (=DSM 23818T=JCM 17201T)

アクトミオシン ノ ゲル ケイセイ キコウ ト ビザイ コウゾウ ニ オヨボス エンノウド ナラビニ アツリョク キョウド ノ エイキョウ

低温での加圧処理により形成したアクトミオシンゲルの形成機構を明らかにするため，アクトミオシン濃度20～30mg/g，KCl濃度0～0.6M，pH6.0の条件下で200～650MPaの加圧処理を行った。また，ゲルの形成に寄与するタンパク質間相互作用やゲルの微細構造についても検討を行った。その結果，アクトミオシンはKCl濃度0.2M，pH6.0に調整し，アクトミオシンの大半を構成するミオシンをフィラメントの状態とし，0℃で200MPa以上の加圧処理を行うことによりゲルを形成した。アクトミオシンゲルのゲル強度およびワークダン値は200～300MPaで増加し，300MPaで最も高い値を示したが，400MPa以降で減少した。また，ゲル形成に寄与するタンパク質間相互作用は非共有結合を主とし，300MPa以下はイオン結合が，400MPa以上では疎水性相互作用が主要な相互作用であった。ゲルの微細構造も300MPa以下と400MPa以上では形態が異なり，架橋部は太く，密な構造へ遷移した。これらのことから，加圧処理によりアクトミオシンは低塩濃度でゲルを形成し，300～400MPaの間でタンパク質の大きな高圧変性が起こり，ゲル形成に寄与するタンパク質間相互作用が変化することにより，ゲルの物理的特性が変化することが示唆された。In this study, the mechanism of pressure-induced gel formation of actomyosin at low temperature was clarified. Actomyosin has been high-pressure processed under processing conditions with 20～30mg/g proteins, 0～0.6M KCl and pH6.0 at up to 650MPa. In addition, protein-protein interaction to contribute to gel formation of actomyosin and gel microstructure were investigated. Actomyosin was adjusted in 0.2M KCl at pH6.0, and myosin formed to the filament which constitutes most of actomyosin. This actomyosin solution formed gel by high-pressure processing at 200MPa or more at 0℃. Gel strength and Work Done of actomyosin gel increased in 200～300MPa and showed the highest value in 300MPa, however decreased 400MPa or more. Furthermore, protein-protein interaction contributing to the gel formation non-covalent bonds was primary. In the main protein-protein interaction, 300MPa or less were ionic bond, 400MPa or more were hydrophobic interaction. Gels at 300MPa or less were different from microstructure at 400MPa or more, and the microstructure changed to dense structure with increasing pressure. These results show that actomyosin formed the filament gel in low salt concentration by high-pressure processing. In these pressure-induced actomyosin gels, protein-protein interactions were caused by high pressure denaturation in 300～400MPa, and the physical characteristic of the gel changed

Bacteroides caecicola sp. nov. and Bacteroides gallinaceum sp. nov., isolated from the caecum of an Indonesian chicken

17 juin 19251925/06/17 (N336)

Characterization of the microbiota and chemical properties of pork loins during dry aging

Abstract Dry aging (DA) allows for the storage of meat without packaging at 0 to 3°C for several weeks. It enhances the production of pleasant flavors, tenderness, and juiciness in meat. Due to the long storage period and roles of indigenous microbiota in the maturation of several meat products, the microbiota of DA meat is of interest in terms of microbial contributions and food hygiene but has not yet been characterized in detail. This study identified the microbiota of pork loins during DA using culturing and culture‐independent meta‐16S rRNA gene sequencing and elucidated its characteristics. The amounts of free amino acids and profiles of aroma‐active compounds were also monitored by high‐performance liquid chromatography and gas chromatography, respectively. The meta‐16S rRNA gene sequencing revealed that Pseudomonas spp. generally dominated the microbiota throughout DA; however, the culturing analysis showed marked changes in the species composition during DA. Acinetobacter spp. were the second most dominant bacteria before DA in the culture‐independent analysis but became a minor population during DA. The cell numbers of yeasts showed an increased tendency during DA, and Debaryomyces hansenii was the only microorganism isolated from all meat samples throughout DA. Well‐known foodborne pathogens were not observed in two microbiota analyses. The amounts of free amino acids were increased by DA, and the number of aroma‐active compounds and their flavor dilution values markedly changed during DA. Most microbial isolates showed positive reactions with proteolytic and lipolytic activities, suggesting their contribution to tenderness and aroma production in DA meats