Novel fungal bioreactors and their bioremediation of pathogenic bacteria in the environment

The filamentous and white rot fungal species, P. ostreatus , is known to degrade pathogens in the environment when in a nutrient limiting condition or starved. By utilizing novel mycoremediation techniques, P. ostreatus could be utilized as a pre- harvest food safety measure. This study was conducted to assess the three different matrices (spent mushroom compost, reticulated polyurethane foam, and woodchips) to determine their nutrient values and capabilities in aiding white rot fungus, P. ostreatus , into ligninolytic activity to inhibit E. coli in a novel bioreactor system. Overall, woodchips were proven to be the most effective matrix at supporting ligninolytic activity and increasing bacterial inhibition. Woodchips fostered greater bacterial reduction with a reduction of 2.1 log-CFU/mL ( p < 0.0001), when compared to spent mushroom compost (reduction of 0.6 log CFU/mL) ( p =0.0325) and reticulated polyurethane foam (reduction of 1.1 log CFU/mL) ( p <0.0001). The ergosterol concentration, which is indicative of fungal growth, significantly declined between day 7 (48.1 ug/g) and day 21 (18.3 ug/g) ( p <.0001), in woodchips and the H 2 O 2 concentration was shown to also significantly decline between days 0 (0.13 μg/L) and 21 (0.05 μg/L) ( p =0.0147). Both the ergosterol concentration and the production of H 2 O 2 are indicative of P. ostreatus ’ ligninolytic activity which in turn allowed it to inhibit E. coli . The woodchip matrix showed greater potential for aiding P. ostreatus, as a nutrient limiting resource, and helping the fungi induce ligninolytic activity. This activity is key to increasing bacterial reduction and developing a novel bioremediation technique to reduce pathogens. • Novel mycoremediation techniques inhibit pathogenic bacteria • P. ostreatus can be used as a pre-harvest tool for reduction of E. coli • Woodchips may be used as a nutrient limiting resource for P. ostreatus • Woodchips aid P. ostreatus in entering ligninolytic activity • Production of ligninolytic enzymes allows P. ostreatus to inhibit E. coli