Growth of a diatom Amphora delicatissima in dark heterotrophic culture

A diatom Amphora delicatissima Krasske strain AM9901 isolated from shore area in Chonburi Province, Thailand, was used for heterotrophic growth studies. It was found that this diatom could grow in total darkness using modified Guillard (F/2) algal culture medium supplied with 1 gC/L glucose or acetic acid as a sole carbon source. Growth rates were increased when organic carbon and nutrient sources such as meat extract, peptone and yeast extract according to nutrient broth medium were added into the modified algal medium. Increasing of glucose concentration from 1 to 4 gC/L provided higher growth rate than normal photoautotrophic culture condition with a specific growth rate of 0.96/day and maximum cells concentration of 7.4x105 cells/mL. However, higher glucose concentrations (8, 12 and 16 gC/L) showed an inhibition effect to growth of A. delicatissima.