Lactobacillus属細菌のプロトプラスト形成に及ぼす糖質の影響

供試した6種のLactobacillus属細菌は, sucroseが存在する場合のみM-1酵素に感受性を示すものと, sucrose存在の有無に関係なく感受性を示すものに大別された. sucrose非存在下でM-1酵素耐性を示すL. rhamnosusを用いてM-1酵素処理時のsucrose添加効果に解析を加えた.本菌の細胞壁画分および加熱処理菌は, sucrose非存在下でもM-1酵素感受性を示した.生菌に対するM-1酵素作用のカイネティクスを求めると, Vmaxはsucrose添加で変化を受けないのに対して, Kmはsucroseの添加量に応じて低下した.このことは, sucrose添加により何らかのカバー構造が破壊されてペプチドグリカンがM-1酵素の作用を受けるようになった事を示している.以上のごとく, M-1酵素感受性の研究は,ペプチドグリカンの細胞壁中での分布様式を明らかにすると同時に,新しい細胞表層解析手段を提供するものと思われる.

All Lactobacillus bacteria used in this experiment had the susceptibility to endo-N-acetylmuramidase (M-1 enzyme) in 0.85M sucrose solution. Three of six species, however, had the resistance to M-1 enzyme in no sugar solution. Analyses of sugar effect on M-1 enzyme action suggested that the conformational changes on cell surface structures. Cell wall fraction and heat-treated cells of L. rhamnosus were digested by M-1 enzyme without sucrose addition. The hinetics of M-1 enzyme action on intact cells of L. rhamnosus showed the constant V max value and decrease in Km values according to sucrose addition. These results suggested that the effects of sugars on M-1 enzyme action were the increased exposure of covered substrates in no sugar conditions.