Diversification of nitrogen sources to enhance the esterase activity during the degradation of the endocrine disruptor di(2-ethylhexyl) phthalate by Fusarium culmorum

Abstract

Di(2-ethylhexyl) phthalate (DEHP) is the most used plasticizer, which is an environmental contaminant and is reported to be an endocrine disruptor in mammals. In this research, the effect of different nitrogen sources (urea, sodium nitrate and magnesium nitrate) on the growth and esterase produced by Fusarium culmorum during the degradation of DEHP (1500 mg/L) under submerged fermentation was evaluated. Growth kinetic and enzyme yields parameters were also estimated. These results showed that DEHP induced esterase production by F. culmorum and esterase production showed a nitrogen source-dependent pattern. Number and molecular weight of esterases were similar in the different nitrogen sources analyzed, however, magnesium nitrate was the best nitrogen source for esterase production (21651 U/L), followed by urea (13460 U/L), and sodium nitrate (3762 U/L). Two esterase isoforms appeared during the first 36 h with an average molecular weight of 26 and 32.6 kDa, which might be responsible for the primary DEHP degradation and the rest of the esterases which appeared after 48 h might be involved in the final steps of the biodegradation. Development of new strategies to increase enzyme production is crucial to establish efficient methods for DEHP biodegradation to mitigate the effects of DEHP pollution and the risk of health impacts.