Enhanced Production of Ligninolytic Enzymes by Mangrove Fungal Endophytes Co-cultured with Pathogenic and Beneficial Fungi

Abstract

Mangrove ecosystems host diverse fungal endophytes with potential ligninolytic activity, yet their functional roles under competitive stress remain underexplored. This study assessed 30 mangrove-derived fungal endophytes (MFE) for their ability to produce key ligninolytic enzymes — laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) — in single- and dual-culture with the pathogenic Fusarium oxysporum and beneficial Trichoderma afroharzianum. Enzyme production was evaluated using qualitative colorimetric assays and quantified through potency index (PI), a measure of enzyme efficiency relative to colony growth. Initial screening revealed that enzyme production was species-specific, with only one isolate, Schizophyllum commune RmLE-P12, producing all three enzymes. Notably, Nigrospora and Penicillium isolates exhibited strong Lac and MnP activity, respectively, and with high PI values designating them as hyper-ligninolytic strains. Under co-culture conditions, enzyme expression and growth rates varied. Some MFE showed enhanced enzyme production in response to competition or antagonistic interaction, while others exhibited reduced or suppressed activity. Interaction assays identified six types of fungal interactions, with growth halts near contact (Type C) and challenge species overgrowth (Type E) being most prevalent. Antagonism indices indicated that T. afroharzianum exerted a stronger inhibitory effect than F. oxysporum. This comprehensive analysis highlights the species-dependent ligninolytic capabilities of MFE and reveals dynamic enzyme regulation under biotic stress.