Overproduction of Glucose Oxidase byAspergillus tubingensisCTM 507 Randomly Obtained Mutants and Study of Its Insecticidal Activity againstEphestia kuehniella

Abstract

In order to enhance the production of glucose oxidase (GOD), random mutagenesis of Aspergillus tubingensis CTM 507 was performed using the chemical and physical mutagens: nitric acid and UV irradiation, respectively. The majority of the isolated mutants showed good GOD production, but only some mutants presented a significant overproduction, as compared with the parent strain. The selected mutants (19 strains), showing an overproduction larger than 200%, are quite stable after three successive subcultures. Among these, six strains revealed an important improvement in submerged fermentation. The insecticidal activity of GOD produced by the wild and the selected mutant strains was evaluated against the third larval instars of E. kuehniella. Mutant strains U11, U12, U20, and U21, presenting the most important effect, displayed an LC50 value of 89.00, 88.51, 80.00, and 86.00 U/cm2, respectively, which was 1.5-fold more important than the wild strain (61 U/cm2). According to histopathology observations, the GOD enzyme showed approximately similar damage on the E. kuehniella midgut including rupture and disintegration of the epithelial layer and cellular vacuolization. The data supports, for the first time, the use of GOD as a pest control agent against E. kuehniella.

Insights into the Structures, Inhibitors, and Improvement Strategies of Glucose Oxidase

“…A study [ 62 ] revealed that N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and ethidium bromide caused the wild Aspergillus niger to change, and the enzyme activity of the mutants increased by 282% and 202%, respectively. It was believed that the random mutagenesis of Aspergillus tubingensis using nitric acid and UV irradiation can screen for some mutants, leading to a significant yield improvement [ 66 ]. Meanwhile, Khattab et al [ 63 ] selected mutants of Aspergillus niger and used them for protoplast fusion in intraspecific hybridization, resulting in fusants with higher activity than the original strain (from 114.5 to 332.1%).…”

Glucose oxidase: Applications, sources, and recombinant production

“…Therefore, they indicated that new-produced rGOX is ideal for developing bio-electrochemical instrumentations . 11,19,95 In another study, Kriaa et al 96 reported an improvement in the GOX secretion from A. tubingensis achieved by random mutagenesis. Recombinant production of GOX using various yeasts leads to the generation of hyperglycosylated variants with reduced activity.…”

“…Therefore, they indicated that new‐produced rGOX is ideal for developing bio‐electrochemical instrumentations 11,19,95 . In another study, Kriaa et al 96 . reported an improvement in the GOX secretion from A. tubingensis achieved by random mutagenesis.…”