Document Type : Original Article
Authors
1
Molecular Biology Research & Studies Institute, Assiut University, 71516 Assiut, Egypt.
2
Department of Botany and Microbiology, Faculty of Science, Assiut University, Assiut, 71511, Egypt
3
Department of Biology, College of Science, Sultan Qaboos University, 123, Muscat, Oman
4
Assiut University Mubasher Mycological Centre (AUMMC), Assiut University, Assiut, 71511, ERU Science & Innovation Center of Excellence, Egyptian Russian University, Badr city, 11829, Cairo, Egypt
Abstract
The accumulation of chitinous waste from crustacean shells and fungal biomass poses significant environmental challenges globally, necessitating efficient biotechnological solutions. Chitinases produced by fungi are promising candidates for addressing this problem; however, the availability of potent fungal strains and optimized conditions for maximum enzyme yield remain limited. This study evaluated the chitinase production capability of 39 fungal species, comprising 207 isolates from the genera Aspergillus (98 isolates from 26 identified species and 3 unidentified species) and Trichoderma (109 isolates from 13 identified species and 23 unidentified species) at 30 ºC. Preliminary screening results revealed that 158 isolates exhibit positive activity (66 isolates of Aspergillus and 92 of Trichoderma), while 18 showed moderate capability. Among the 66 positive Aspergillus isolates, 53 shown strong chitinase activity, 12 exhibited moderate activity, and one displayed low activity. Among the 92 positive Trichoderma isolates, 85 exhibited high chitinase activity, 6 demonstrated moderate activity, and one was a low chitinase producer. In submerged fermentation (SmF), all fungi exhibiting elevated chitinase activity were examined. The findings indicated that Aspergillus welwitschiae AUMC 994 and Trichoderma viride AUMC 1782 were the most potent strains. The optimization of chitinase activity for both strains was achieved by modifying the pH, temperature, nitrogen source, and fermentation duration. At pH 8.0 and 30 ºC, A. welwitschiae AUMC 994 exhibited peak chitinase activity of 0.04 U/mL after 4 days utilizing yeast extract as the nitrogen source. T. viride AUMC 1782 achieved the maximum chitinase activity of 0.038 U/mL at pH 9.0 and 30 ºC after 3 days, utilizing yeast extract as a nitrogen source. This work presents fungal chitinases that may serve as interesting options for biocontrol agents against significant pests.
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