Research Article ISSN 2250-0480 VOL 8 / ISSUE 1 /JANUARY 2018 L-21 Life science Botany EFFECT OF ZINC STRESS ON BIOCHEMICAL PROFILING IN DUNALIELLA SALINA TEOD. AND SPIRULINA PLATENSIS GOMO. GAJENDRA PAL SINGH 2 , MANOJ KUMAR 1 AND AMRIT DAIYA 1 1 Research scholar, Algal biotechnology lab, Department of Botany, University of Rajasthan, Jaipur, Rajasthan, 304502, India. 2 Associate Professor, Algal biotechnology lab, Department of Botany, University of Rajasthan, Jaipur, Rajasthan, 304502, India. ABSTRACT All biomolecules like lipids, carbohydrates and fatty acid compositions of a native microalgae Dunaliella salina (Teod.) and Spirulina platensis (Gomo.) were studied in batch culture at light intensity 100 µ mol photons m -2 s -1 temperature 25 ± 1 o C and 16:8 h light and dark diurnal cycles. It was reported in our previous paper that both lipids and carbohydrate content decreased with increasing concentration of Cu stress. Similar scenario of contents was observed in lipid and carbohydrate on various treatment doses of zinc as heavy metal. GC-MS profiling of lipids showed that various compounds separated according to their retention time in which most of the compounds were Fatty Acid Methyl Ester. Further, purification of carbohydrates was confirmed by HPLC analysis using reference compounds like fructose, glucose and sucrose. The microalgae is rich deposits of essential nutrients so they could be candidate for aqua-culture feeding and/or biofuel production. KEYWORDS : Dunaliella salina; Spirulina platensis; lipids; carbohydrates; GC-MS profiling; HPLC; Zn stress. INTRODUCTION Heavy metals at toxic levels hamper normal plant functioning and act as an impediment to metabolic processes in a variety of ways, including disturbance or displacement of building blocks of protein structure, which arises from the formation of bonds between heavy metals and sulfhydryl groups 1 hindering functional groups of important cellular molecules 2 , disrupting functionality of essential metals in biomolecules such as pigments or enzymes 3 , and adversely affecting the integrity of the cytoplasmic membrane 4 , resulting in the repression of vital events in plants such as photosynthesis, respiration, and enzymatic activities. Conversely, Zn 2+ is an essential micronutrient for plants, and it is therefore essential for plant growth, development, and many metabolic processes being one of the major cofactors, together with iron and manganese, in numerous enzymes 5 . More than 1200 proteins are predicted to contain, bind, or transport Zn 2+ 6 . Furthermore, the zinc- inorganic phosphate (Pi) relationship has been observed in numerous plant species such as tomato, cotton, barley, and Arabidopsis 7 . Besides being a micronutrient, zinc is also a heavy metal and can have detrimental effects on many vital processes in plant cells. Microalgae biomass contains products with high commercial importance like proteins, lipids, carbohydrates 8 . Environmental stress condition when nutrients are limited invariably causes a steadily declining cell division rate. Surprisingly, active biosynthesis of fatty acids is maintained in some algae species under such conditions, provided there is enough light and CO 2 available for photosynthesis 9 . Their main photosynthetic pigment is phycocyanin, which is blue in colour. These bacteria also contain chlorophyll a, b and carotenoids. Some contain the pigment phycoerythrin, giving the bacteria a red or pink colour. Dunaliella species belong to the phylum Chlorophyta, order Volvocales and family Polyblepharidaceae, and are unicellular, photosynthetic and motile biflagellate microalgae morphologically distinguished by the lack of a rigid cell wall 10 . One who has grown microalgae under