Enzimas hidrolíticas de fungos endofíticos isolados de Eichhornia crassipes (Marth.) Solms de ocorrência no Rio Tarumã-Açu-Amazônia Central

Abstract

Aquatic macrophytes can be colonized by endophytic fungi, microorganisms that inhabit the internal tissues of plants and play important ecological roles with biotechnological potential, especially through the production of bioactive metabolites such as extracellular enzymes. The present study investigated the production of hydrolytic enzymes synthesized by endophytic fungi that colonize Eichhornia crassipes (Marth.) Solms, which occurs in the lower course of the Tarumã-Açu River. Aquatic macrophytes were collected in two samples in the lower course of the Tarumã-Açu River, in Manaus-AM. Isolation was performed at the Biotechnology Laboratory - ILUM (EST/UEA) and in two stages: antisepsis of leaf and bulb fragments of the plant; and inoculation of the fragments in 5 equidistant points of Petri dishes containing PDA+EL medium added with the antibiotics Tetracycline and Ampicillin. Three treatments were established at different temperatures, with the control treatment at room temperature and the treatments at 18 °C and 24 °C carried out in B.O.D. incubators at controlled temperature. Each treatment was performed in triplicate and monitored for 15 days. For the enzymatic tests of amylase, protease and lipase, solid selective media were used with three-point subtraction and for the qualitative determination of the enzymatic activities, the Enzymatic Index (IE) was taken into account. A total of 18 endophytic fungi were isolated, with 7 isolates from the first collection (Colonization Rate equal to 22%) and 11 from the second collection (Colonization Rate equal to 36%). The Relative Frequency (Rf) for the leaves was 55.5% while for the bulb it was 44.4%. Of these isolates, 11 were characterized by their macro and micromorphology, four were characterized at the genus level because they presented reproductive structures: Penicillium spp. and Helicosporium sp., two fungi presented reproductive structures to which it was not possible to define the genus they belonged, and five did not present reproductive structures, being defined as Mycelia sterilia. Of the 11 endophytic fungi qualitatively analyzed for the production of extracellular enzymes (amylase, protease and lipase), only the strains of the genus Penicillium (E.F 1.3.1; E.F. 1.1.1; E.B 2.2.1) resulted positive for protease production, the fungus Mycelia sterilia (E.B 1.4.1) was positive for amylase, however, none of the fungi tested presented a positive enzymatic index for lipase. Therefore, these results suggest that these endophytic fungi isolated from E. crassipes may be promising for hydrolytic enzyme production activities. Keywords: Amazon; Endophytic fungi; Enzymes; Aquatic macrophytes