Biochemical Composition and Ecophysiological Characteristics of the Diatom Nitzschia sp. at Different Stages of the Life Cycle

Abstract

The work analyzes the biochemical composition and the influence of some abiotic factors on cells of Nitzschia sp. strains at different stages of the life cycle. The results of the experiment showed the ability of cells to grow in the salinity range of 10–60‰ at the pre-reproductive stage and in the range of 4–60‰ at the reproductive stage which indicates a relatively wide salinity tolerance of the studied species. The optimal salinity (25‰) and illumination (2.95 klx) for a 12-h photoperiod were found to be the same for both parent and daughter cells. The light saturation coefficient for them was 1.4 klx, indicating high energy efficiency of photosynthesis. Analysis of the biochemical composition of two Nitzschia sp. strains in the reproductive and pre-reproductive stages of the life cycle was carried out. During the accumulative cultivation a high content of monoenoic and polyenoic acids was observed. In general, the amount of saturated fatty acids (UFAs) was higher in parental cells, and the amount of monounsaturated fatty acids (MUFAs) was higher in post-initial cells. The quantity of polyunsaturated fatty acids (PUFAs) was almost the same in both cultures. The ω-6/ω-3 ratio showed a predominance of ω-3 fatty acids in both parental and daughter strains. Nitzschia sp. represents an interest for biotechnology given its biochemical composition and fairly high energy efficiency when grown in culture. However, it is extremely important to take into account the phase of the life cycle of the strains in order to obtain individual valuable products.