Production of lipids and proteins from marine diatoms under changing pH and silica

Abstract

Diatom algae are increasingly explored as an alternative sustainable source for functional biomolecules likes fucoxanthin, and eicosapentaenoic acid. But biomolecule quantity and quantity are influenced by growth conditions. So, effect of differential silica concentration (0-120 mg L^-1) and medium pH (5.5-9.5) on growth and cellular biochemical composition of commercially important marine diatom species were studied. Growth rate of Thalassiosira sp., Skeletonema sp., and Chaetoceros sp., was higher with 30 mg L^-1 Si at a pH of 7.5-8.5. Highest carbohydrate (153.71 mg g^-1) and protein (17.34 mg g^-1) content was found in Skeletonema sp. Silica concentration positively influenced chlorophyll and carotenoid content in a dose dependent manner. A medium pH of 8.5 and Si concentration between 60 and 120 mg L^-1 was ideal for lipid production. The optimum concentration of Si and pH for maximum biomolecule production have been reported with further scope of utilizing these conditions in commercial scale systems.

Keywords: Chrysolaminarin; Diatoms; Fucoxanthin; Functional biomolecules; Growth medium.