Abstract
Since washed cells of Lactobacillus leichmannii ATCC 7830 frequently showed erratic results in vitamin B12 assays, a depletion technique was used to stabilize the inoculum. The method consisted of incubating the twice-washed cells at 37 C for 45 min in distilled water. Survival and growth studies indicated that the stabilizing procedure (i) did not affect cell numbers, (ii) was optimal for depleting possible carry-over of vitamin B12 or other nutrilites and reserves, and (iii) brought about a phasing of the cells of the inoculum which underwent logarithmic growth immediately on inoculation. This minimal period (45 min) was the same when the cells were incubated in dextrose-water. Survival of the cells in physiological saline was greater than in distilled water, but a longer time was required for stabilizing the inoculum in saline, which precluded its use in routine work. The prepared inoculum showed an improvement over the washed inoculum in that readings between duplicate and triplicate tubes agreed closely and the standard curves were reproducible whether acidimetric or turbidimetric methods were followed. No erratic results were noted in more than 1 year of testing.
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- ARONSON A. I., SPIEGELMAN S. On the use of chloramphenicol-inhibited systems for investigating RNA and protein synthesis. Biochim Biophys Acta. 1958 Jul;29(1):214–215. doi: 10.1016/0006-3002(58)90170-7. [DOI] [PubMed] [Google Scholar]
- HAROLD F. M. ACCUMULATION OF INORGANIC POLYPHOSPHATE IN AEROBACTER AEROGENES. I. RELATIONSHIP TO GROWTH AND NUCLEIC ACID SYNTHESIS. J Bacteriol. 1963 Aug;86:216–221. doi: 10.1128/jb.86.2.216-221.1963. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HOFF-JØRGENSEN E. Microbiological assay of vitamin B12. Methods Biochem Anal. 1954;1:81–113. doi: 10.1002/9780470110171.ch4. [DOI] [PubMed] [Google Scholar]
- HOROWITZ J., SAUKKONEN J. J., CHARGAFF E. Effect of 5-fluorouracil on a uracil-requiring mutant of Escherichia coli. Biochim Biophys Acta. 1958 Jul;29(1):222–223. doi: 10.1016/0006-3002(58)90175-6. [DOI] [PubMed] [Google Scholar]