2026-03-08T08:03:12Z https://jircas.repo.nii.ac.jp/oai

oai:jircas.repo.nii.ac.jp:02000113 2024-05-28T06:08:20Z 1704421711574:1705364280817

Screening of Bacteria Producing Vitamin B₁₂ from Tua-Nao in Thailand タイのトゥアナオよりビタミンB₁₂生産菌の分離 OKADA, Noriyuki CHETTANACHITARA, Charan DAENGSUBHA, Wiwut fermented soybeans Natto cell fusion From Tua-Nao, a non-salt fermented soybean food of Thailand, bacteria which can be utilized for the improvement of Natto bacterium by cell fusion technique were screened. Screening was carried out for vitamin B₁₂-producing bacteria which are heat-resistant and lysozyme-sensitive. Tua-Nao samples were collected at Lam Phun, Phrao, Doi Saket and Mae Hong Son in northern Thailand. Bacterial counts in Tua-Nao samples were markedly different in number and the ratio of the number of heat-resistant bacteria to the number of total bacteria was also different. Vitamin B₁₂ content varied and some samples did not contain vitamin B₁₂ at all. The lysozyme sensitivities and vitamin B₁₂-producing ability of bacteria separated from Tua-Nao samples after heating were examined. Among 120 isolates, about 20 were lysozyme-sensitive and one (TN02-13) produced vitamin B₁₂. However the isolate (TN02-13) was a mixture of two bacterial isolates (TN02-13a and TN02-13b) and TN02-13b was found to produce vitamin B₁₂ and to be lysozyme-sensitive. Thus a vitamin B₁₂-producing bacterium was obtained from Tua-Nao. This bacterium was regenerated from a protoplast form into a bacillary form. タイの無塩大豆発醗酵食品より，細胞融合による納豆菌の改良に利用可能なバクテリアを探索した。検索は，リゾチーム感受性かつ耐熱性のビタミンB₁₂生産菌を求めて行った。トゥアナオ試料は北タイのラムプーン，プラオ，ドイサケット，メーホーンソンより採取した。トゥアナトのバクテリア数は試料によりかなり異なった。耐熱性／非耐熱性の比も大きく異なった。またトゥアナオはビタミンB₁₂含量が異なるのみでなく，含まないものもあった。ビタミンB₁₂を含むトゥアナオ試料より，熱処理後バクテリアを分離し，リゾチーム感受性，ビタミンB₁₂生産能を調べた。分離株120株のうち，リゾチーム感受性を示す約20株を得，そのうちビタミンB₁₂生産能を有する1株(TN02-13)を見いだした。本菌は混合菌(TN02-13a,TN02-13b)であったが，再分離後TN02-13bにリゾチーム感受性かつビタミンB₁₂生産能があることが分かった。また本菌はプロトプラストから桿菌へ再生した。 journal article Japan International Research Center for Agricultural Sciences 1995-09-01 VoR application/pdf JIRCAS Journal 2 49 57 https://jircas.repo.nii.ac.jp/record/2000113/files/jircas_journal2-_49-57.pdf 13407686 AA11030483 https://doi.org/10.34556/0002000113 https://jircas.repo.nii.ac.jp/records/2000113 eng open access