Diversity of phytase-producing marine yeasts

Marine yeast strains from different habitats were isolated and phytase-producing marine yeasts were screened. Of the 327 yeast strains isolated, 10 showed comparatively higher phytase activity. Physiological and biochemical characters of these 10 strains, and optimum pH and temperature of the crude phytases produced by them were examined. Partial sequences of the 18S rDNA were also analyzed. Based on the physiological and biochemical characters and phylogenetic analyses, the 10 strains were found to be closely related to Hanseniaspora uvarum (strain WZ1), Yarrowia lipolytica (strain W2B), Kodamaea ohmeri (strain BG3), Candida carpophila (strain N12C), Issatchenkia orientalis (strain YF04C), Candida tropicalis (strain MA6), Yarrowia lipolytica (strain YF08), Candida carpophila (strain NY4E), Candida tropicalis (strain YF12C), and Candida tropicalis (strain MB2). They were obtained from gut of unknown fish, gut of Holothuria scabra, gut of Hexagrammos otakii, gut of Hexagrammos otakii, gut of Synechogobius hasta, and seawater. It is interesting to note that some marine yeast strains could produce alkaline phytase. This is the first report of marine yeast strains capable of producing extracellular phytase or cell-bound phytase. The results also indicated that phytase-producing marine yeasts were diverse enough to be used in bioremediation of marine phosphorous pollution.