Effect of chemical and microbial vitamin B^sub 12^ analogues on production of vitamin B^sub 12

Strain improvement by genetic manipulation or optimization of fermentation conditions for overproduction of vitamin B^sub 12^ has a drawback due to feed back inhibition. To resist the feed back inhibition by analogues of vitamin B^sub 12^ in Propionibacterium freudenrechii subsps. shermanii (OLP-5), we have tested with microbially separated B^sub 12^ analogues from three different strains. Microbial analogues were differentiated from commercially available vitamin B^sub 12^ by high pressure liquid chromatography and spectrophotometric method. An analogue isolated from NRRL-B-4327 was shown to increase vitamin B^sub 12^ concentration from 18.53 ± 0.15 to 31.67 ± 0.58 mg/l in OLP-5 strain. The presence of chemical analogue (ICH2 Co(DH)^sub 2^ (H2Py)^sub 4^) increased vitamin B^sub 12^ production from 16.13 ± 0.15 to 18.53 ± 0.15 mg/l in OLP-5. These findings revealed that addition of B^sub 12^ analogues in fermentation media have developed strain resistance to feed back inhibition by vitamin B^sub 12^.[PUBLICATION ABSTRACT]