PEER-REVIEWED ARTICLE bioresources.com Al-Rajhi et al. (2022). “Induction of hydrolytic enzymes,” BioResources 17(2), 2358-2371. 2358 Induction of Hydrolytic Enzyme Production and Antibiosis via a Culture of Dual Fungal Species Isolated from Soil Rich with the Residues of Woody Plants in Saudi Arabia Aisha M. H. Al-Rajhi, a Asmaa A. Alharbi, b Reham Yahya, c,d and Tarek M. Abdel Ghany e, * Inducing hydrolytic enzymes production and antibiosis is an attractive process for industrial applications. The approach can be used to repress pathogenic microorganisms. Using a dual culture of Aspergillus fumigatus and Aspergillus flavus, the activities of cellulase, polygalacturonase, chitinase, β-1,3-glucanases, protease, xylanase, and β-glucosidase were 1.78, 3.87, 2.98, 2.79, 6.91, 2.89 U, and 1.43 U∙mg -1 of protein. Meanwhile, the activities were 0.87, 2.78, 0.58, 1.69, 4.45, 2.06, and 0.89 U.mg -1 of protein for A. flavus alone and 0.98, 2.98, 0.87, 1.89, 4.98, 2.58, and 0.91 U.mg -1 of protein for A. fumigatus alone. The cellulase, polygalacturonase, and chitinase activities were studied at different temperatures; 40 °C and 50 °C, which were better temperatures than 20 °C in terms of enzymes activity for A. fumigatus and the dual culture compared to A. flavus. The highest antimicromial activity was observed using the dual fungal culture, where the inhibition zones were 3.13, 3.47, 2.27, 1.77, 1.03, and 2 mm compared with A. fumigatus alone or A. flavus alone, against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Aspergillus fumigatus, Mucor circinelloides, and Fusarium moniliforme, respectively. Keywords: Induction; Hydrolytic enzymes; Antibiosis; Dual culture; Fungi Contact information: a: Department of Biology, College of Science, Princess Nourah bint Abdulrahman University P.O. Box 84428, Riyadh 11671, Saudi Arabia ; b: Biology Department, Faculty of Science, Jazan University, Jazan 82817, Saudi Arabia; c: College of science and health professions, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; d: King Abdullah International Medical Research Center, Riyadh, Saudi Arabia; e: Botany and Microbiology Department, Faculty of Science, Al- Azhar University, Cairo 11725, Egypt; * Corresponding authors: tabdelghany.201@azhar.edu.eg INTRODUCTION The interactions or competition among microbial species in the environment for space and food are unique for each species. Such phenomena are considered complex mechanisms and therefore require better understanding. Numerous scientists have exploited this phenomenon for the production of enzymes and antimicrobial agents. Dullah et al. (2021) observed an increase in chitinase, cellulase, and xylanase via fungal-fungal interaction in vitro, and advised the application of these interactions for the stimulation of enzyme production. Previously, dual cultures among different fungi were evaluated to study the dynamic changes of extracellular enzymes production, e.g., 1,3 glucan synthase and superoxide dismutase (Chi et al. 2007). Biocontrol of pathogenic fungi as well as bacteria depends not only on the antifungal/antibiotic compounds but may also depend on hydrolytic enzymes to cleave the bonds in cell wall components, e.g., glucans, chitin, glycoproteins, and mannans (Bowman and Free 2006; Shaikh and Sayyed 2015; Abdel-