Oxidative enzymes activity and hydrogen peroxide production in white-rot fungi and soil-borne micromycetes co-cultures

Abstract

Fungal co-cultures appear to be advantageous for ligninolytic enzyme (LE) production compared to single fungal strains. The aims of this study were (1) to determine the type of fungal interactions in the co-cultures of two white-rot fungi (WRF, Pycnoporus sanguineus and Trametes maxima) and eight soil-borne micromycetes (SBM), (2) to determine the laccase and manganese peroxidase (MnP) activities and the hydrogen peroxide (H2O2) production in two compatible fungal and micromycetic co-cultures in submerged fermentation, and (3) to understand the effect of H2O2 on LE production by WRF through a dose-response bioassay. In the co-culture of SBM and Pycnoporus sanguineus, the main interaction was deadlock at a distance, whereas T. maxima showed competitive antagonism and replaced the SBM. In the agar plates, Purpureocillium lilacinum (27.8-fold increase) and Beauveria brongniartii (9.4-fold increase) enhanced the laccase and MnP activities of P. sanguineus, and Metarhizium anisopliae (Ma129) (0.83-fold increase) and Trichoderma sp. SP6 (22.6-fold increase) similarly enhanced these activities in T. maxima. In submerged fermentation, P. lilacinum also increased the laccase and MnP activities of P. sanguineus. The laccase activity of T. maxima only increased in the co-culture with B. brongniartii. The co-cultures achieved higher H2O2 production compared to the WRF monoculture, which played a vital role in the increase of LE. The dose-response assays revealed that low concentrations of H2O2 (2.94 and 14.69 mM) enhance the laccase and MnP activities in WRF.