The Effect of Cobalt on the Microbial Synthesis of LLD-active Substances

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Abstract
Culture medium composed of 1% N-Z-Amine (Type A), 0.3% Difco beef extract, and water to vol. was adjusted to pH 6.8-7.0 and dispensed in 40 ml. aliquots in 250 ml. flasks; varying concns. of Co in the form of Co(NO3)2.6H2O were added to all but control flasks. All flasks were autoclaved and then inoculated from a 48-hr. shake flask culture of Streptomyces griseus and incubated at 28[degree]C with continuous shaking. After 2, 3, 4, and 5 days the concn. of the unidentified Lactobacillus lactis Dorner (LLD) growth factor in the cultures was bioassayed using vit. B12 as standard. Those flasks to which Co had been added showed up to 3 times as much LLD activity as control flasks; max. effects were obtained with as little as 1 to 2 ppm. of Co, and concns. of 20-50 ppm. caused toxic symptoms with decreased growth and LLD activity. A similar increase in LLD activity was noted in cultures of various isolates from cow manure and rumen contents, of Mycobacterium smegmatis and of Pseudomonas sp. when Co was added.