The potential of fungal co-cultures as biological inducers for increased ligninolytic enzymes on agricultural residues.
Dual cultivation or co-cultivation of fungi and the exploitation of interspecific interaction, even antagonism, show considerable promise as a strategy in enhancing enzyme production. The aim of this work was to investigate the phenomenon of antagonistic invasion as a strategy to possibly accelerate secondary metabolism in ligninolytic fungi and thereby to increase enzyme activity. Ten different fungal strains were cultivated on various substrates like corn cob, wheat straw and sugar cane bagasse and evaluated for the effects of invasion antagonistic interaction on enzyme production. Monoculture enzyme activities were compared with co-culture enzyme activities. However, strains such as Trichoderma sp. KN10, Rhizopus microsporus KN2, Fomitopsis sp. KN1 and Coriolopsis sp. KN6 demonstrated strong tendencies of invasion and replacement in co-cultures. Also, significant changes in morphology and concomitant increase in enzyme activity were demonstrated in a majority of these interactions with remarkable results observed with invasions involving Trichoderma sp. KN10. Analysis of mean values of enzyme activity showed dual culture interactions involving KN10 with values for manganese peroxidase production approximately at 1.46 U/mL compared to monoculture of 0.06 U/mL. Furthermore, dual culture laccase values were approximately 0.09 U/mL compared to monocultures of 0.05 U/mL. Overall, the highest enzyme activity was observed using wheat straw reflecting similar patterns of invasion interactions. This study demonstrates that dual cultivation of fungi with the appropriate substrates results in improved production of biotechnologically relevant enzymes.