Sialic acid utilization by the soil bacterium Corynebacterium glutamicum.

The ability to use the sialic acid, N-acetylneuraminic acid, Neu5 Ac, as a nutrient has been characterized in a number of bacteria, most of which are human pathogens that encounter this molecule because of its presence on mucosal surfaces. The soil bacterium Corynebacterium glutamicum also has a full complement of genes for sialic acid catabolism, and we demonstrate that it can use Neu5 Ac as a sole source of carbon and energy and isolate mutants with a much reduced growth lag on Neu5 Ac. Disruption of the cg2937 gene, encoding a component of a predicted sialic acid-specific ABC transporter, results in a complete loss of growth of C. glutamicum on Neu5 Ac and also a complete loss of [14 C]- Neu5 Ac uptake into cells. Uptake of [14 C]- Neu5 Ac is induced by pregrowth on Neu5 Ac, but the additional presence of glucose prevents this induction. The demonstration that a member of the Actinobacteria can transport and catabolize Neu5 Ac efficiently suggests that sialic acid metabolism has a physiological role in the soil environment. [ABSTRACT FROM AUTHOR]