Parallel studies were performed with methionineless derivatives of Escherichia 
coli 15 T(-) and Bacillus megaterium KM: T(-). Methylated bases are present in 
the total cell ribonucleic acid (RNA) of B. megaterium. The level of RNA 
methylation in E. coli is about 60% greater than that in B. megaterium. Although 
E. coli deoxyribonucleic acid (DNA) was found to contain 0.12% 5-methylcytosine 
(5-MC) and 0.24% 6-methylaminopurine (6-MA), methylated bases were not detected 
in the DNA of B. megaterium. Assuming a molecular weight of 7 x 10(9) daltons 
for B. megaterium DNA, it was calculated that this organism could not contain 
more than one molecule of 5-MC or 6-MA per genome, and that possibly no 
methylated bases were present. Methylated bases were also not detected in the 
DNA of thymine-starved B. megaterium. Crude extracts of this organism possess 
RNA methylase activity but no detectable DNA methylase activity.