Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, and Moffett Technical Center, CPC International, Inc., Summit-Argo, Illinois 60501.
Appl Environ Microbiol. 1987 Oct;53(10):2275-81. doi: 10.1128/aem.53.10.2275-2281.1987.
Unlike most Lactobacillus acidophilus strains, a specific strain, L. acidophilus IFO 3532, was found to grow in rich medium containing 1 M sodium acetate, KCl, or NaCl. This strain could also grow with up to 1.8 M NaCl or 3 M nonelectrolytes (fructose, xylose, or sorbitol) added. Thus, this strain was tolerant to osmotic pressures up to 2.8 osM. A search for an intracellular solute which conferred osmoprotection led to the identification of glycine betaine (betaine). Betaine was accumulated to high concentrations in cells growing in MRS medium supplemented with 1 M KCl or NaCl. Uptake of [C]betaine by L. acidophilus 3532 cells suspended in buffer was stimulated by increasing the medium osmotic pressure with 1 M KCl or NaCl. The accumulated betaine was not metabolized further; transport was relatively specific for betaine and was dependent on an energy source. Other lactobacilli, more osmosensitive than strain 3532, including L. acidophilus strain E4356, L. bulgaricus 8144, and L. delbrueckii 9649, showed lower betaine transport rates in response to an osmotic challenge than L. acidophilus 3532. Experiments with chloramphenicol-treated L. acidophilus 3532 cells indicated that the transport system was not induced but appeared to be activated by an increase in osmotic pressure.
与大多数嗜酸乳杆菌菌株不同，一种特定的菌株嗜酸乳杆菌IFO 3532 被发现可以在含有 1 M 醋酸钠、KCl 或 NaCl 的丰富培养基中生长。该菌株也可以在添加高达 1.8 M NaCl 或 3 M 非电解质（果糖、木糖或山梨糖醇）的情况下生长。因此，该菌株可以耐受高达 2.8 osM 的渗透压。为寻找赋予耐渗性的胞内溶质，发现了甘氨酸甜菜碱（甜菜碱）。在 MRS 培养基中添加 1 M KCl 或 NaCl 补充物生长的细胞中，甜菜碱积累到高浓度。用 1 M KCl 或 NaCl 增加培养基渗透压可刺激嗜酸乳杆菌 3532 细胞悬浮在缓冲液中的 [C]甜菜碱摄取。积累的甜菜碱没有进一步代谢；运输相对特异于甜菜碱，并且依赖于能源。其他乳杆菌，比菌株 3532 更敏感，包括嗜酸乳杆菌 E4356 株、保加利亚乳杆菌 8144 株和德氏乳杆菌 9649 株，在应对渗透压挑战时，其甜菜碱转运率低于嗜酸乳杆菌 3532 株。用氯霉素处理的嗜酸乳杆菌 3532 细胞的实验表明，该转运系统没有被诱导，但似乎是通过渗透压的增加而被激活的。
