Toxic effect on the membrane system and cell proliferation of Prorocentrum donghaiense caused by the novel algicidal fungus Talaromyces purpurogenus YL13

Abstract

A fungal strain YL13 with algicidal activity against the dinoflagellate Prorocentrum donghaiense was isolated from Wild Fox Island, Zhuhai, China, and identified as Talaromyces purpurogenus YL13 on the basis of 18S ribosomal RNA (rRNA) sequence. Strain YL13 exhibited algicidal activity through the mechanism of indirect attack, and its algicidal activity was improved from 80.3 to 96.8 % by optimization of environmental and nutrient factors with response surface methodology (RSM). Effects of strain YL13 on the membrane system and cell proliferating of P. donghaiense were investigated to elucidate the algicidal mechanism. The increase in both ATPase activities and malondialdehyde (MDA) contents suggested that the membrane in algal cells was damaged. Damage was observed in atomic force microscopy (AFM) images and the surface morphology of cells. Real-time PCR assay showed changes in the transcript abundance of proliferating cell nuclear antigen (PCNA) gene. The release of nucleic acids and changes of PCNA gene expression indicated that DNA synthesis was affected, and this influenced cell proliferation and the membrane system of P. donghaiense. The fungal supernatant might be potentially used as a bioagent for controlling harmful algae. Strain YL13 is the first record of a T. purpurogenus being algicidal to the harmful dinoflagellate P. donghaiense, and this is the first report to explore the mechanism of toxic effects on membrane system and cell proliferation of the marine T. purpurogenus against harmful P. donghaiense.