Process for the selective increase of production of antibiotic GE 2270 factor a by adding vitamin B12 to nutrient medium

摘要

A method for increasing both total antibiotic yield the selective production of factor A of the GE 2270 antibiotics consisting in the addition of vitamin B.sub.12 or its analogs having vitamin B.sub.12 -- like activity to the fermentation media of Planobispora rosea ATCC 53773 or any antibiotic GE 2270 producing mutant or variant thereof.