Smittle R B, Gilliland S E, Speck M L, Walter W M
Appl Microbiol. 1974 Apr;27(4):738-43. doi: 10.1128/am.27.4.738-743.1974.
Concentrated cultures of Lactobacillus bulgaricus were prepared by resuspending cells grown in semisynthetic media in sterile 10% non-fat milk solids. The concentrated cultures were frozen in liquid nitrogen for 24 h. The cell suspensions exhibited decreased viability after storage, and the amount of death varied among the different strains tested. Storage stability of all strains examined was improved by supplementing the growth medium with sodium oleate. Radioisotopes were used to study the fate of sodium oleate with L. bulgaricus NCS1. [1-(14)C]sodium oleate was incorporated solely into the lipid portion of the cells, including both neutral and polar lipids. The fatty acid composition of L. bulgaricus NCS1, NCS2, NCS3, and NCS4 grown with and without sodium oleate was studied. The major fatty acids of strains NCS1, NCS2, and NCS3 grown without sodium oleate were dodecanoic, tetradecanoic, hexadecanoic, hexadecenoic, and octadecenoic acids. In addition to these, strain NCS4 contained C(19) cyclopropane fatty acid. The major fatty acids of all strains grown with sodium oleate were tetradecanoic, hexadecanoic, hexadecenoic, octadecenoic, and C(19) cyclopropane fatty acids. All strains grown in broth containing sodium oleate contained larger amounts of octadecenoic and C(19) cyclopropane fatty acid, and less saturated fatty acids than when grown without sodium oleate. Statistical analyses indicated that C(19) cyclopropane fatty acid was most closely related to stability of the lactobacilli in liquid nitrogen. A negative regression line that was significant at P < 0.001 was obtained when the cellular content of this fatty acid was plotted against death.
保加利亚乳杆菌的浓缩培养物是通过将在半合成培养基中生长的细胞重悬于无菌10%脱脂乳固体中来制备的。将浓缩培养物在液氮中冷冻24小时。储存后细胞悬液的活力下降，并且在所测试的不同菌株中死亡数量各不相同。通过在生长培养基中添加油酸钠提高了所有检测菌株的储存稳定性。使用放射性同位素研究油酸钠与保加利亚乳杆菌NCS1的去向。[1-(14)C]油酸钠仅掺入细胞的脂质部分，包括中性和极性脂质。研究了在添加和不添加油酸钠的情况下生长的保加利亚乳杆菌NCS1、NCS2、NCS3和NCS4的脂肪酸组成。在不添加油酸钠的情况下生长的NCS1、NCS2和NCS3菌株的主要脂肪酸是十二烷酸、十四烷酸、十六烷酸、十六碳烯酸和十八碳烯酸。除此之外，NCS4菌株含有C(19)环丙烷脂肪酸。在添加油酸钠的情况下生长的所有菌株的主要脂肪酸是十四烷酸、十六烷酸、十六碳烯酸、十八碳烯酸和C(19)环丙烷脂肪酸。与不添加油酸钠时相比，在含有油酸钠的肉汤中生长的所有菌株含有更多的十八碳烯酸和C(19)环丙烷脂肪酸，以及更少的饱和脂肪酸。统计分析表明，C(19)环丙烷脂肪酸与乳杆菌在液氮中的稳定性关系最为密切。当将这种脂肪酸的细胞含量与死亡率作图时，得到了一条在P < 0.001时显著的负回归线。
