Regulation of carbon metabolism in <i>Chlamydia trachomatis</i>

The biological significance of glycogen accumulation and how the process is regulated in Chlamydia trachomatis remains poorly defined. C. trachomatis‐infected HeLa cells were cultured in medium containing various glucose concentrations (0, 0.1, 1 or 10 mg ml−1) or in the presence of gluconeogenic carbon sources (20 mM glutamate, 20 mM malate, 20 mM α‐ketoglutarate or 20 mM oxaloacetate), and the effects of these different culture conditions on the production of infectious chlamydial elementary bodies and glycogen accumulation were monitored. When chlamydiae were cultured in glucose concentrations greater than 1 mg ml−1, optimal growth and maximal glycogen accumulation occurred. In contrast to uninfected HeLa cells, which increased their glycogen stores when grown in the presence of high glucose concentrations, chlamydial glycogen accumulation remained essentially constant. When cultured in medium supplemented with either reduced glucose concentrations or any of the gluconeogenic carbon sources, chlamydiae still grew; however, the yield of elementary bodies was substantially decreased, and there was no significant amount of glycogen accumulated by host HeLa cells or C. trachomatis.