Biomass,proximate biochemical composition and fatty acid profiles associated with the growth phase of Chlorella salina Butcher and Isochrysis maritima Billard and Gayral isolated from the coastal waters of Penang,Malaysia

Choosing the right algae with the relevant properties and optimal harvest time for specific culture conditions and products is essential. As such, biomass, biochemical composition and fatty acid (FA) profile at different growth stages of locally isolated strains, suitable for aquaculture, Chlorella salina and Isochrysis maritima, were determined. Biomass and moisture content of both species were affected by the growth phase. A particular accumulation trend of proximate biochemical compounds was observed in these two strains. Protein content decreased whereby, as culture aged, more carbohydrate and lipid accumulated in C. salina and I. maritima, respectively. Variations in FA profile were exhibited in C. salina where PUFA was the highest, followed by SFA and MUFA throughout the growth phases. I. maritima had the highest SFA content, followed by PUFA and MUFA during the exponential phase. The essential PUFAs in C. salina were linoleic acid (LA) and α-linolenic acid (ALA) with a low occurrence of γ-linolenic acid (GLA; 0.49–0.78%) and docosahexaenoic acid (DHA; 0.21–0.45%). I. maritima recorded relatively high ALA (4.73–6.71%), GLA (5.05–7.80%) and DHA (5.15–7.02%) with minor presence of arachidonic acid (ARA; 0.45–0.59%) and eicosapentaenoic acid (EPA; 0.43–0.58%). Both C. salina and I. maritima are suitable for aquaculture feeds, but I. maritima was more superior by having EPA and higher DHA in their cells. Harvesting regime at a specific phase must be taken into account to achieve maximum yields of a target compound; thus, for feeding purpose, harvesting both strains at stationary phase is recommended as better PUFA compositions were obtained.