The growth, development and metabolism of a new form of green unicellular algae Closteriopsis acicularis were investigated from the point of view of their potential use in the biological life support system (BLSS). Their growth and biochemical characteristics were studied as a function of nitrogen supply. During the nitrogen-deficiency cultivation the growth rate remained unchanged, cell division and biomass increment was uncoupled, and carbohydrate formation was predominant. The content of carbohydrates increased at the expense of assimilable fractions, particularly starch. These data can be used in the selection of an optimum nitrogen level for the case of algal continuous cultivation, in the calculation of material flow charts, and in the development of diets that can be provided by a BLSS incorporating Closteriopsis acicularis.