HYPOXANTHINE AND ALLANTOIN AS NITROGEN SOURCES FOR THE GROWTH OF SOME FRESHWATER GREEN ALGAE

Abstract

Six freshwater green algae, viz. Scenedesmus obliquus, Scenedesmus pannonicus, Chlorella glucotropa, Crucigenia tetrapedia, Tetradesmus cumbricus and Stichococcus mirabilis, were examined for their ability to utilize hypoxanthine and allantoin as sole nitrogen sources for growth in light. All the six algae could utilize both hypoxanthine and allantoin for growth. None of the algae needed any significant period of adaptation and growth was often as rapid on hypoxanthine/allantoin as it was on nitrate. Higher concentrations (3 mat) of the purines inhibited the growth of Stichococcus mirabilis and Crucigenia tetrapedia, possibly because of the formation of intracellular pools of the purines. Activity of the enzyme nitrate reductase was not markedly affected by growth on either hypoxanthine or allantoin. It is concluded that the ready utilization of hypoxanthine and allantoin indicates the operation of the standard pathway of purine catabolism, i.e. hypoxanthine → xanthine → uric acid → allantoin → end products, in these algae. Copyright © 1983, Wiley Blackwell. All rights reserved