LEWIN, J. C. (1953). J. gen. Microbial. 9, 305-313. Heterotrophy in Diatoms

SUMMARY: Forty-two bacteria-free cultures of pennate diatoms from fresh water or soil were tested for ability to grow heterotrophically with glucose as the sole carbon source. Thirteen of these isolates proved capable of growth under these conditions. They comprised seven isolates of NawicUlu pelliculosa, five of other Merent species of Nawieula, and one of Nitzschiu ( 3) fontiCola. One isolate of NavicUla pellieubsa was tested for its ability to grow hetero-trophically on any one of sixty organic compounds. Only glucose, glycerol, and fructose were found to be effective in supporting growth. Glucose was metabolized both in the dark, and in the light in the absence of CO,. Glycerol and fructose were not utilized in the dark, but supported growth in the light in the absence of CO,. There is apparently no previous record that any chlorophyllous diatom has been cultivated successfully in the dark. Miquel (1892) found that certain species of diatoms which he obtained in pure culture would not develop either in the dark or in semi-darkness on organic nutrient solutions, although they retained the power of proliferation when returned to the light after severa