Media Used for Microbiological Assay of Riboflavin using Lactobacillus casei

Comparison of Two Species of Lactobacilli as Test Organisms in Pantothenic Acid Estimation - Lactobacillus Casei and Lactobacillus Plantarum

“…A study of the data in Table III suggests that such a maximum could not be achieved in most cases with the media and conditions selected. The term "maximum acid production" appearing in the literature (8,9,14,16,26) has thus no fixed definition. The term "drift" (3, 24) is also of limited usefulness.…”

“…The basal medium was that of Roberts and Snell (21) in which glucose was increased to 3% (8,9). The greater value for slope of the logarithmic dose-response curves obtained when this medium was used with L. casei had been attributed largely to its enzyme-hydrolyzed casein content which was incorporated in the medium at the level of 2%.…”

“…In threeand four-dose assays, with 12 and 16 tubes respectively, equally divided between standard and unknown, a factorial design (6) allowed the use of factorial coefficients, simplifying tests for validity and calculations of potency and confidence limits as discussed (8,9). Two such assays yielded the following: common slope bc, 8.7 and 9.7; confidence limits, 88 to 114% (12 tubes, 2X3 assay) and 94 to 106% (16 tubes, 2X4 assay).…”

“…Moreover, the latter organism has been adopted for use in the official methods of the Pharmacopoeia of the United States XV (20) and the Association of Official Agricultural Chemists (1). L. plantarum responds to enrichment of the earlier basal media by producing much larger amounts of acid in response to maximum dosage with essential nutrients (14), as does L. casei (8,9,15,21). Changes in the media are improvements if they lengthen the linear portion of the dose-response curve, contribute to the precision and reliability of the assay, and facilitate calculations.…”

Factors Influencing Validity and Confidence Limits of Pantothenic Acid Estimation. Microbiological Assay with Lactobacillus Casei

“…Moreover, use of the enzyme-hydrolyzed casein in media containing pantothenate but lacking one of several other vitamins had provided a basis for satisfactory assays (23). When used for riboflavin assays, this medium with added glucose had allowed a long, steep doseresponse curve and a small experimental error which compared very favorably with other media used for riboflavin (4)• Preliminary experiments with the Roberts-Snell medium with graded doses of pantothenate indicated that the charcoal treatment of the casein preparation varied somewhat in the degree of removal of pantothenic acid or of other substances capable of enhancing bacterial growth. High titrations were occasionally encountered in response to zero dose (blanks).…”