Isolation, Characterization, and Insecticidal Activity of Chitinase Gene (chiA) From Aspergillus niger (EM77)

Abdelall, Manal F.; Abdel Wahab, Walaa A.; Esawy, Mona A.

doi:10.21608/eajbsg.2020.122669

Isolation, Characterization, and Insecticidal Activity of Chitinase Gene (chiA) From Aspergillus niger (EM77)

Document Type : Original Article

Authors

¹ Microbial Molecular Biology Department, Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Center (ARC), 9 Gamaa St., 12619, Giza, Egypt

² Chemistry of Natural and Microbial Products Department, National Research Centre, Dokki, Giza, Egypt

10.21608/eajbsg.2020.122669

Abstract

Chitin, which is found in the structure of insect cuticles and peritrophic membranes, is degraded by the chitinase enzymes. The degradation decreases the feeding and defenses of the insect and weakens it. Therefore, chitinases are important enzymes that have potential for being used as biological control agents against harmful insects. In the present study, genes encoding exo-chitinases (e.g. chiA) have been isolated from A. niger. The partial sequence includes 1484 bp open reading frame encodes for 493 amino acid. No intron was found in the chiA of A. niger (EM77). The deduced amino acid sequence of chiA of A. niger (EM77) clearly indicated the presence of three conserved domains: ChtBD1 superfamily, chitin recognition protein, and Glyco-18 domain. Chitinase enzyme was partially-purified from the culture filtrate of A. niger (EM77) and was fractionated using ethanol concentrations (25-75%). Thus, the molecular mass of the semi-purified chitinase enzyme (~ 30 kD) was observed after purification compared with unpurified total protein. So, the molecular weight of the protein seemed to be unusual from other fungal chitinases which are around 50-70 kD. The partially-purified chitinase was evaluated as the highest activity (42.39 Units/ml) 0.5 g/l of the chitin substrate concentration at 30°C for six days. Insecticidal activity of partially-purified A. niger EM77 chitinase has been estimated against S. littoralis after 96 hours and the mortality rate of neonate larvae was 38.9%. That was because of the ability of chitinase to disrupting the peritrophic membrane of insect cells. So, chitinase producing ability of A. niger (EM77 could be serving as an effective biopesticide to control harmful pests which destroy importantly economic crops instead of hazardous chemical pesticide.

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