Effect of Rare Earth Elements on Vitamin C Fermentation by Mixed Cultures.

In recent years, the research on rare earth metals has expanded to the field of microbiology. In China, the production of Vitamin C is through mixed culture fermentation, which transforms L-sorbose to 2-keto-L-gulonic acid (2-KGA), the precursor of Vitamin C. In this study we compared the yields of 2-KGA by an acid-producing strain of Ketogulonigenium vulgare that was co-cultured with different companion bacterial strains in the presence of four light rare earth elements, lanthanum, cerium, neodymium, and samarium at selected concentrations. We found that all of the tested rare earth elements had a promoting effect on 2-KGA production at concentration up to 5 mM. At or above 10 mM, the yield of 2-KGA was reduced. When cultured separately with 5 mM of given rare earth elements, the growth of two companion bacterial strains (Bacillus megaterium 25-B and B. subtilis A9) were both significantly reduced, while that of the K. vulgare strain was enhanced. © 2014 Friends Science Publishers [ABSTRACT FROM AUTHOR]