SOKOLSKI W T, STAPERT E M, FERRER E B
Appl Microbiol. 1964 Jul;12(4):327-9. doi: 10.1128/am.12.4.327-329.1964.
Suspensions of Lactobacillus leichmannii were stored in liquid nitrogen and were used as direct inocula in vitamin B(12) assays. Complete recovery of viable cells was obtained when the suspensions in basal B(12) medium were rapidly frozen by direct immersion into liquid nitrogen and rapidly thawed by agitating the suspensions in a water bath at 40 C. Greater than 90% destruction occurred when the suspensions were in saline. However, both suspensions were usable in the B(12) assay system. Assay results on a number of test materials indicated good correlation between freshly prepared suspensions and frozen suspensions in basal medium stored 3 months. Suspensions in saline stored for 1 year in liquid nitrogen showed no detectable difference from the first day after freezing. Suspensions frozen slowly at the rate of 1 degree per min from 4 to -40 C and subsequently immersed in liquid nitrogen had a longer lag period of growth and were not usable in the 18-hr assay incubation system. A major advantage of a stored inoculum for direct use in a microbiological assay is the reduced day-to-day variation in the inoculum.
赖氏乳杆菌悬液保存在液氮中，并用作维生素B₁₂测定的直接接种物。当基础B₁₂培养基中的悬液通过直接浸入液氮快速冷冻，并在40℃水浴中搅拌使其快速解冻时，可获得活细胞的完全复苏。当悬液在盐水中时，超过90%的细胞会被破坏。然而，两种悬液均可用于B₁₂测定系统。对多种测试材料的测定结果表明，新鲜制备的悬液与在基础培养基中储存3个月的冷冻悬液之间具有良好的相关性。在液氮中储存1年的盐水中的悬液与冷冻后第一天相比没有可检测到的差异。从4℃以每分钟1℃的速度缓慢冷冻至-40℃，随后浸入液氮中的悬液有较长的生长延迟期，不能用于18小时的测定培养系统。直接用于微生物测定的储存接种物的一个主要优点是接种物的日常变化减少。
