Role of some Trace Elements (Zinc and Cobalt) in the Growth of B.C.G
Sternberg, J.; Benoit, J.C.; Mercier, A.; Paquette, J.C.
Revue Canadienne de Biologie 23: 353-365
1964
ISSN/ISBN: 0035-0915 PMID: 14237169 Document Number: 9828
Zinc65 and cobalt60 were added in trace amounts to B.C.G. culture in Sauton's medium, and the microbial requirements were respectively determined to be 2.17 p.p.m. for zinc and 0.68 p.p.m. for cobalt. Addition of fission products (caesium 137 and cerium 144) in p.p.b. (part per billion) amounts did not influence microbial growth, but led to an uptake of caesium (8.42%) and cerium (11.57%) by the growing cell. While the incorporation of zinc and cobalt indicate a metabolic integration of the minerals in some bacterial compounds, that of caesium shows probably only a lack of discrimination exerted by B.C.G. between this element and its periodic relative, potassium. The binding of rare earths suggests a chemical binding of the metal to an acidic radical, possibly the phosphates of nucleic acids. This hypothesis is confirmed by significant binding of cerium144 and strontium90 placed in contact with suspensions of non-radioactive cells; heat-killed cells bind almost the same amounts of Sr90 as living cells, and only one half of the level of cerium144 Addition of trace amounts of cobalt60 and zinc65 to Sauton media prepared with batches of growth-promoting and growth-inhibiting glycerins permitted the study of the uptake of the above minerals by the B.C.G. Addition of 67.5 p.p.m. zinc to a culture medium prepared with a non-efficient batch of glycerin succeeded in rendering the normal growth-promoting properties to the glycerin. However, the uptake of Zn65 by the cells grown in cultures with efficient or zinc-enriched glycerins, does not show any difference from the values found in cells grown on non-efficient glycerins. Studies with cobalt60 showed a significant difference in the uptake of the trace element by the cells grown in media with efficient and non-efficient glycerins. Young cultures (7 days) grown in media prepared with efficient glycerins incorporate five times more cobalt than the cells grown on media prepared with non-efficient glycerins. This leads to the supposition that trace amounts of cobalt accompanying some batches of glycerin, or brought by other mineral compounds, have a growth-promoting effect, chiefly during the first 7 days of microbial growth. The microbial requirements for cobalt, estimated at 0.5-1.5 micrograms per gram cells, are well within the range of cobalt requirements for other biological systems. Work is in progress to establish the biochemical nature of the incorporated cobalt; the possibility of a growth-promoting effect of vitamin B 12 on mycobacteria is taken into consideration.
Document emailed within 1 workday
