Atividade xilanásica de fungos associados ao trato digestório de insetos: potencial para obtenção de xilooligossacarídeos a partir de farelo de trigo

Abstract

Insects and fungi are very diverse groups and coexist in various terrestrial and aquatic habitats and potential interactions can occur between species of these two groups, which can be beneficial to both partners. The study of the digestive tract (DT) of insects as a habitat for fungal microorganisms is an opportunity to obtain fungal strains with biotechnological potential, in addition to being important for understanding the symbiotic relationships between these organisms. Thus, the objective of this work is to know the fungal diversity of the DT of Triplectides larvae (Trichoptera: Leptoceridae) and the biotechnological potential for the production of xylanases and obtaining xylooligosaccharides (XOS). Larvae were collected from low-order streams in the Cerrado and Amazon Forest, Brazil. The DT was analyzed to obtain fungal samples and later identification. In the first phase, the 49 fungal isolates were tested for xylanase and CMCase production, in plates. In the second phase, 33 fungal strains were tested in submerged cultivation, using wheat bran as a lignocellulosic substrate, for the simultaneous production of xylanase and XOS. Subsequently, immobilization of the xylanase enzyme was performed. As a result, the genus Penicillium was the most frequent in the DT of Triplectides (Trichoptera: Leptoceridae) larvae. In the test on plates, 78% produced CMCase and 62% produced xylanase in specimens from Cerrado. In the Amazon Forest, 35% for CMCase and 71% for xylanase. In the submerged culture test, the isolates Penicillium rubens MN737746.1, Talaromyces palmae MT521727.1 and Penicillium paxilli MN737731.1 had higher xylanase production 5.31 U/mL, 3.12 U/mL and 2.45 U/mL , respectively. And the strain Penicillium caseifulvum MT521726.1 stood out in the production of XOS (16.70 mg/mL). The immobilization of the enzyme with resin and functionalized with Glutaraldehyde showed 88% yield. The results indicate a high diversity of fungal species associated with the DT of Triplectides larvae both in streams of the Amazon Forest and in the Cerrado. Furthermore, it was observed that most fungal isolates have the ability to produce xylanolytic enzymes.