Sialic acid utilization by the soil bacterium Corynebacterium glutamicum.

Area of Science:

• Microbiology
• Bacterial Metabolism
• Biochemistry

Background:

• Sialic acids, like N-acetylneuraminic acid (Neu5Ac), are commonly utilized by human pathogens.
• The metabolic capabilities of soil bacteria regarding sialic acids are less understood.
• Corynebacterium glutamicum possesses genes for sialic acid catabolism.

Purpose of the Study:

• To investigate the ability of Corynebacterium glutamicum to use Neu5Ac as a nutrient source.
• To identify genes and mechanisms involved in Neu5Ac utilization in C. glutamicum.
• To explore the physiological role of sialic acid metabolism in soil environments.

Main Methods:

• Growth experiments using Neu5Ac as the sole carbon and energy source.
• Isolation and characterization of mutants with altered Neu5Ac utilization.
• Gene disruption of cg2937, encoding a putative sialic acid transporter.
• Radiolabeled [(14)C]-Neu5Ac uptake assays.
• Analysis of gene expression induction by Neu5Ac and glucose.

Main Results:

• C. glutamicum can efficiently use Neu5Ac as a sole carbon and energy source.
• Disruption of the cg2937 gene completely abolishes growth and [(14)C]-Neu5Ac uptake.
• Uptake of Neu5Ac is inducible by prior growth on Neu5Ac but repressed by glucose.
• Mutants with reduced growth lag on Neu5Ac were isolated.

Conclusions:

• A specific ABC transporter, encoded by cg2937, is essential for Neu5Ac uptake and catabolism in C. glutamicum.
• Sialic acid metabolism is an active process in C. glutamicum, with implications for soil ecosystems.
• The findings suggest a broader physiological role for sialic acid utilization beyond human mucosal surfaces.