GROWTH, PRODUCTIVITY, PIGMENTS AND OXIMATE COMPOSITION OF INDIGENOUS MARINE MICROALGAE ISOLATED FROM COX’S BAZAR COAST

Abstract

Microalgal biomass has been widely reported as great source of feed, food, biodiesel, and pigments. Suitable microalgae species for particular industrial application are selected on the basis of its growth rates, productivity, and adaptability to the laboratory conditions, pigments concentrations, and proximate profiles. Understanding the growth pattern of microalgae is crucial because it is the primary steps for any kind of operational procedure mostly biomass extractions. Present study focused on four different indigenous microalgae species (Chlorella sp., Chaetoceros sp., Nannochloropsis sp., and Tetraselmis sp.) to determine their growth, productivity, pigments and proximate composition. Experimental species were collected from previously preserved sample (isolated from Cox’s Bazar coast) of Department of Aquaculture, Faculty of Fisheries, Chattogram Veterinary and Animal Sciences University. Selected species were cultured in commercial Conway culture medium. Biomass was harvested at their stationary phase for each species for further analysis. Result indicated distinct growth phase for each species in terms of cell density and optical density which were significant at 1% level of significance. In addition, Chaetoceros sp. showed significantly (p < 0.05) higher volumetric productivity (0.61 ± 0.08 mg/L/Day), areal productivity (1.2 ± 0.17 mg/cm2/Day), and lipid productivity (0.109 ± 0.003 mg/L/Day) compare to Chlorella sp., Nannochloropsis sp., and Tetraselmis sp. On the other hand, Tetraselmis sp. produced significantly highest amount of chlorophyll a and b (2.68 ± 0.04 μg/L, 1.23 ± 0.02 μg/L) where Chaetoceros sp. produced (0.29 ± 0.01 μg/L) highest amount in case of chlorophyll c. Moreover, in case of carotenoids Nannochloropsis sp. content (1.68 ± 0.05 μg/mL) significantly (p < 0.05) higher amount compares to Tetraselmis sp. (1.51 ± 0.14 μg/mL), Chaetoceros sp. (1.36 ± 0.2 μg/mL), and Chlorella sp. (0.56 ± 0.03 μg/mL). In addition, allophycocyanin reported highest amount in all the four species rather than phycocyanin and phycoerythrin. However, Nannochloropsis sp. content significantly (p < 0.05) higher amount of phycobiliproteins than other three species (Tetraselmis sp., Chlorella sp., and Chaetoceros sp.). Besides, the results of proximate composition in this study showed that, Tetraselmis sp. content significantly (p < 0.05) higher amount of protein (57 ± 0.66% dry weight), Nannochloropsis sp. content significantly (p < 0.05) higher amount of lipid (25 ± 1.84% dry weight), whereas Chlorella sp. content significantly (p < 0.05) higher amount of carbohydrate (23 ± 1.62% dry weight) among all other XIII species. For the production of valuable biomass quality microalgae are potential candidates because of their easy culture system, and capability to grow in low cost media. In that way the production cost and contamination risk also decrease. Therefore, proper selection of microalgae’ species through proper characterization is necessary for various industries.