The accumulation of vitamin B₁₂ by Klebsiella sp. No. 101 grown on methanol was investigated furthermore. Addition of urea together with ammonium sulfate or ammonium nitrate was more effective than other nitrogen sources tested. Simultaneous addition of metal ions such as ferrous, calcium and manganese, and addition of amino acids such as alanine, valine, leucine, cysteine, cystine, phenylalanine, tyrosine and proline promoted the bacterial growth and vitamin B₁₂ production. Optimal pH for vitamin B₁₂ production was near 7.0. pH adjustment and methanol feeding were effective for the growth and the vitamin formation. Vitamin B₁₂ production was decreased by addition of CN-B₁₂ to the medium at the concentrations more than 100μg per liter.

This article cannot obtain the latest cited-by information.