Inhibition of Aspergillus flavus growth and aflatoxin B1 production by olive mill wastewater

The study aimed to investigate the effect of crude olive mill wastewater (OMW) and phenolic extract from olive mill wastewater (PE) on Aspergillus flavus growth and aflatoxin B1(AFB1) production in SMKY broth medium and in maize powder. The SMKY medium and maize powder were supplemented with various concentrations of OMW and PE, inoculated with A. flavus and incubated at 28 degrees C for 7 days. The mycelia biomass (dry mycelium weight) and fungal colony diameter were determined in SMKY and maize powder, respectively. Aflatoxin B1 synthesis was quantified by direct competitive ELISA method and chemical compositions of PE were analyzed by HPLC. In SMKY medium, results showed that mycelia biomass was reduced to 50 % and 46.2 % with concentrations of 250 mg/L and 4 g/kg of the PE and OMW, respectively. Complete inhibition was obtained with 500 mg/L and 10 g/L of the PE and OMW, respectively. In maize powder, PE and OMW reduced the mycelial growth by more than 50 % with 800 mg/L and 16 g/kg, and complete inhibition was obtained at 1000 mg/kg and 20 g/kg, respectively. Aflatoxin B1 was totally inhibited in SMKY medium to witch 400 mg/L and 8 g/L of PE and OMW, respectively, had been added. Results obtained in the present study indicate the possibility of exploiting PE and crude OMW in the control of aflatoxigenic A. flavus in stored foods products.