Effects of Salinity and pH on the Growth and Active Products-secreting of Aspergillus sp. F3 from the Mangrove Rhizosphere

Abstract:

An Aspergillus sp. strain F3 was isolated and identified from the rhizosphere soil of mangrove plant, Rhizophora stylosa Griff in Dongzhai harbor mangrove forest conservation in China. In this study, the effects of media salinity and pH on the mycelial biomass and the ability of producing antibacterial metabolites from this isolate were carefully analyzed. Results showed that this isolate can grow well on the SDA medium with higher salinity (3%~9%) and higher pH (8~10). Under the modified culturing conditions, this isolate can secret the antibacterial and antitumor metabolites. The extracts of acetic ether were about 448 mg/L of the fermentation broth. The antibacterial activities of the acetic ether extract were analyzed with bacteria and fungus. Results showed this extract can suppress the growth of Staphylococcus aureus、S. epidermidis、Sarcina lutea、Bacillus subtilis and Escherichia coli with MIC of 31.3 μg/mL, 31.3 μg/mL, 7.8 μg/mL, 7.8 μg/mL and 125.0 μg/mL, respectively. It can also suppress the growth of Candida albicans with MIC of 125.0 μg/mL. Further studies uncovered the cytotoxicity of this extract against the tumor cells, such as ECV304, Lovo and HepG2 with IC50 of 3.45 μg/mL, 4.88 μg/mL and 14.31 μg/mL respectively.