Characterization of the high cytochalasin E and rosellichalasin producing-Aspergillus sp. nov. F1 isolated from marine solar saltern in China

A moderately halophilic fungus F1 was isolated from a marine solar saltern in Weihai, China. The identification of the fungus F1 was performed by the morphological characteristics, physiological and biochemical tests as well as phylogenetic analysis based on ITS (internal transcribed spacer)-5.8S rDNA region sequence comparison. The strain was identified as belonging to the genus Aspergillus and designated as Aspergillus sp. nov. F1. Furthermore, Aspergillus sp. nov. F1 grew well in 3-15 % (w/v) NaCl, and with increasing of salinity, the generation of secondary metabolites with cytotoxicity was also augmented. Three compounds with cytotoxicity were isolated from the ethyl acetate extract of the whole broth and mycelia of Aspergillus sp. nov. F1, and identified as ergosterol, rosellichalasin and cytochalasin E, respectively. Especially, ergosterol showed high potent cytotoxic activity to human colon cancer cell line RKO with IC50 of 3.3 +/- A 0.5 mu M. Considering the high cytochalasin production and the simple and economical fermentation of Aspergillus sp. nov. F1, the strain could be used as potential strain for large scale production of the cytochalasin E and rosellichalasin.