STUDIES ON IMPROVEMENTS IN THE MEDIUM FOR LACTOBACILLUS ACIDOPHILUS IN THE ASSAY FOR DEOXYRIBONUCLEIC ACID1

A. J. Siedler, F. A. Nayder, B. S. Schweigert
1957 Journal of Bacteriology  
Lactobacillus (Thermobacterium) acidophilus strain R-26 has been proposed as an assay organism for the determination of deoxyribonucleic acids (Hoff-J0rgensen, 1952) . In attempting to use this organism for deoxyribonucleic acid determinations in our laboratory, it was noted that growth of the culture was very poor unless crude supplements, such as yeast extract or liver extracts, were added to the medium. The highly significant response observed with these supplements warranted further
more » ... ation. The unique requirement of L. acidophilus strain R-26 for a deoxyriboside which is not replaceable by vitamin B,2 also suggested that the use of this organism for further studies on nucleic acid metabolism would be extremely fruitful. EXPERIMENTAL METHODS The culture of L. acidophilus strain R-26 was obtained from Dr. Hoff-J0rgensen. Stock cultures were maintained on 10 per cent litmus milk medium (Difco) to which 0.1 per cent cysteine and 0.5 per cent yeast extract (Difco) were added. The inoculum medium and the original assay medium used in these studies weie the same as those ieported by Hoff-J0rgensen. The assay medium consisted of the following constituents per 100 ml of double strength medium; casein (acid hydrolyzed), 2.5 g; casein
doi:10.1128/jb.73.5.670-675.1957 fatcat:z7jbq3xpejfhtai2crh5l4br3a