Taxonomy,Physiology And Dimethylsulfonopropionate Prouduction Of Phaeocystis Globosa Scherffel

Morphology, life cycle, physiology and dimethysulfonipropionate (DMSP) production of two strains (Hong Kong and Shantou, China) of Phaeocystis globosa were studied under laboratory conditions with batch culture method. Life cycle of P globosa is complex and heteromorphic, exhibiting alternations between two different morphological forms: free-living cells (motile and non-motile cells) and colonies. The free-living cells were showed in globose form about 39 Jtm in diameter while the colonies were different in size. The colonies of Shantou strain which were up to maximum 3.0 cm in diameter in field study were much larger than that of Hong Kong strain (1.0cm). The free-living cells reproduced by repeated bipartition and these cells were aggregated forming a colony. In these colonies, cell division and subsequent enlargement resulted in growth. When the nutrition in culture were depleted, the colonies were lysised or decayed and thousands of free-living cells were released. In batch culture the growth cycle of P globosa Hong Kong strain takes about 25 30 days and 214 days for Shantou strain. The growth rate of two strains varied from each other under three different temperatures(20 0C, 25 0C, 300C), and the optimal temperature was 250C for the growth of Hong Kong strain and 300C for Shantou strain. Their corresponding maximum specific growth rate were 0.38 and 0.48, respectively. It is concluded that temperature was one of the factors limiting the growth of two strains. The result of the Latin square experiments showed that phosphate is the most significant growth-limiting factor (P<0.01) and nitrate is the second limiting factor (P