Some Effects of Zinc on the Utilization of Carbon Sources by Monascus Purpureus

SUMMARY

In Czapek-Dox media (5% D-glucose) zinc uptake by Monascus purpureus was correlated with an increase in both phosphate and D-glucose uptake, increased growth, and increased production of carbon dioxide and ethyl alcohol. Added zinc also increased growth and reduced the economic coefficient when either D-arabinose, d-xylose, D-glucose, D-fructose, sucrose, maltose, starch, or ethyl alcohol was the sole carbon source. Fatty acids or amino acids did not serve as sole sources of carbon even in the presence of an otherwise optimum zinc concentration. A particular combination of amino acids (glycine, L-leucine, and L-tryptophan) added as a supplement to media with ethyl alcohol or the carbohydrates listed above stimulated growth to an equal or much greater extent than did the addition of zinc. This combination of amino acids also stimulated growth with D-galactose, glycerol, D-mannitol, D-sorbitol, or DL-glyceric acid, none of which supported growth with added zinc alone. All substrates which supported significant increases in growth over controls when supplemented with glycine, L-leucine, and L-tryptophan, also supported an additional and often dramatic increase in growth when supplied both these amino acids and added zinc. By contrast, neither of six Krebs-cycle acids, seven fatty acids, seven amino acids, dihydroxyacetone, pyruvate, nor DL-lactate served as a sole source of carbon for growth of M. purpureus, with or without the amino acid supplement and added zinc. These data demonstrate zinc involvement in both carbohydrate and amino acid utilization by M. purpureus, and suggest zinc involvement in regulatory processes integrating carbohydrate and nitrogen metabolism during growth.