Peculiarities of the Formation of Cenobia in Green Microalgae (Chlorophyta) during Their Cultivation under Artificial Conditions

The strategy of cenobia formation in green algae <i>Tetradesmus dimorphus</i> (Turpin) M.J. Wynne and <i>Desmodesmus brasiliensis</i> (Bohlin) E. Hegew. and their species specificity when cultivating under optimal conditions of temperature and nutrients content were investigated. The culture of <i>T. dimorphus</i> during the entire exposure was characterized by a consistently lower number of cenobia (1.0%) compared to <i>D. brasiliensis</i> (81.2-93.6%). In <i>D. brasiliensis</i>, four-celled cenobia dominated in the first half of exposure, while two-celled forms - in the second half of exposure. The rate of decay of cenobial forms indicates that <i>T. dimorphus </i>is characterized by induced protection, and <i>D. brasiliensis</i> - by constitutive protection. The specific growth rate and biomass growth of these species were statistically at the same level. The cell volume in the culture of <i>T. dimorphus</i> tended to increase during exposure, while that of <i>D. brasiliensis</i> tended to decrease slightly.