Characterization of a novel aciduric and halotolerant aerobic denitrifying fungus Fusarium solani DS3 isolated from coastal seawater

Abstract

A novel aerobic denitrifying fungus strain was isolated from coastal seawater and identified as Fusarium solani strain DS3, which was capable of aerobic nitrogen removal and exhibited tolerance to low pH and high salinity. The removal rates of nitrate, nitrite and ammonium were 3.33, 2.56 and 5.19 mg·L−1·h−1, respectively. Detection of N2O and CO2 in headspace gas samples indicates its capability for aerobic denitrification using nitrite as electron acceptor (but not nitrate). The unabated total nitrogen in nitrate treatments in nitrogen balance revealed that nitrate was incompetent to trigger aerobic denitrification. We measured 22.02% and 11.84% of total nitrogen converted to gaseous nitrogen using around 80 mg·L−1 of nitrite and ammonium as nitrogen source, respectively. Nitrite reductase activity assay revealed that dissimilatory and assimilatory nitrite reductases worked together in nitrite reduction. The present study indicates that fungal strain DS3 is a promising candidate for nitrogen removal, especially for saline wastewater.