Carbohydrate Requirement of Caenorhabditis Elegans and the Final Development of a Chemically Defined Medium

The carbohydrate requirement in the free-living nematode Caenorhabditis elegans was investigated. Glucose, fructose, sucrose, trehalose and glycogen were tested individually at concentrations of 0, 1.3, 6.5, 32.5, and 162.5 mg/ml as the energy source in a chemically defined medium containing C. briggsae Maintenance Medium (CbMM without glucose), 50 μg/ml cytochrome c and 50 μg/ml β-sitosterol. Potassium acetate, used as the energy source in other studies, was not added to the medium. Therefore, carbohydrate was the major energy source for the nematode. At 32.5 mg/ml, glucose was found to support the maximal population at 80,000 nematodes/ml (100%), followed by glycogen (96%) and trehalose (73%). Population was significantly reduced when fructose (46%) or sucrose (26%) was the carbohydrate source. Toxicity was shown at 162.5 mg/ml for four carbohydrates tested, except glycogen. These results suggested that all five carbohydrates can be utilized as energy sources by C. elegans; however, the degree of utilization of each carbohydrate by C. elegans varied. Since glucose was best utilized by the nematode at 32.5 mg/ml, this concentration is recommended for future use in preparation of CbMM. Based on this study, the chemically defined medium that has been used for cultivation of C. elegans can also be modified to: CbMM (1×, with 32.5 mg/ml glucose), 50 μg/ml cytochrome c and 50 μg/ml β-sitosterol. Glucose (at 32.5 mg/ml) can be used as the major energy source in a chemically defined medium for the axenic cultivation of C. elegans.