A Chaetoceros strain was successfully isolated to a unialgal state from Giao Thuy mangrove and identified to be of Chaetoceros muelleri species based on morphological properties and 18S rDNA sequence analysis. ASW medium together with 250/00 of salinity was found to be best suitable for the growth of this strain and was applied to its biomass production. | JOURNAL OF SCIENCE OF HNUE Natural Sci. 2010 Vol. 55 No. 6 pp. 141-148 BIOLOGICAL PROPERTIES AND BIOMASS CULTURE OF THE MICROALGAE Chaetoceros muelleri FROM GIAO THUY MANGROVE FOR USE IN AQUACULTURE Le Thi Phuong Hoa Hanoi National University of Education Nguyen Thi Hoai Ha Pham Thi Bich Dao Vietnam National University Hanoi Nguyen Ngoc Tuyen Hanoi Open University E-mail lephhoa@ Abstract. A Chaetoceros strain was successfully isolated to a unialgal state from Giao Thuy mangrove and identified to be of Chaetoceros muelleri species based on morphological properties and 18S rDNA sequence anal- ysis. ASW medium together with 250 00 of salinity was found to be best suitable for the growth of this strain and was applied to its biomass produc- tion. The fatty acid profile of C. muelleri strain was typical of most diatoms with the exception of low level of 16 0 and 14 0 acids. This strain possessed high concentration of polyunsaturated fatty acids PUFAs total fatty acids which is much higher than that of C. calcitrans C. gracilis and C. muelleri in previous reports. Among these acids eicosapentaenoic acid EPA and arachidonic acid AA had significant proportion and respectively which are also higher than the above strains. The iso- lated C. muelleri strain represents a high-quality food resource and has a high potential for use in aquaculture. Keywords Chaetoceros muelleri mangrove microalgae fatty acid aqua- culture 1. Introduction Microalgae constitutes major oceanic and freshwater primary producers and have been utilized by man for hundreds of years from human and animal nutrition cosmetics to therapeutic purposes. They possess high-value compounds such as polyunsaturated fatty acids PUFAs carotenoids proteins polysaccharides and vitamins 8 11 . In aquaculture microalgae play a crucial role as they are the natural food source for many marine animals. Their consumers include bivalve 141 Le Thi Phuong Hoa Nguyen Thi Hoai Ha Pham Thi Bich Dao and