Seleção dos clones produtores de amilases e proteases presentes na biblioteca Metagenômica de Terra Preta de Índio

Abstract

In the Amazon agricultural soils are found in soil called Anthropogenic Dark Earths (ADE), a soil rich in organic matter and minerals. The biodiversity is a source of very high value of non-cultivable microorganisms that can be isolated through construction of metagenomic libraries, using vectors of large fragments, with the goal of finding new biocatalytic enzymes. Enzymes widely used in the industrial market are amylase and protease, are applied in industry: chemical, pharmaceutical, textile, detergent and food industries. Amylases degrade starch into smaller units of saccharides, as proteases catalyze the hydrolysis of peptide bonds. The aim of this study was to isolate and partially characterize enzymes amylase and protease of clones isolated from a selection of functional metagenomic library of TPI in the Amazon region. In this study were isolated 1.344 clones, only 4 producing halo of starch hydrolysis and 3 proteolytic clones belonging to metagenomic library constructed with total DNA extracted from microorganisms present in soil samples of the TPI, were partially characterized the enzymes produced by 4 clones amilolytic and 1 proteolytic clone. After isolation, the clones were inoculated in culture medium Luria Bertani (LB) at 37ºC under agitation of 150 rpm and subjected to assays at pHs of 3 to 10 and temperatures ranging from 25 to 100ºC for up to 90 of incubation. Amylases had its highest production in 24 h (4.3 U/mL) and its activity was optimal at neutral pH to slightly alkaline, the clone P1C4 showed the highest production at 70°C (6.93 U/mL), since the clones P5C4 and P6C12 reported higher thermostability at 80°C, these results indicate that the gene for alpha-amylase to be cloned encoding a thermostable enzyme, such as the enzyme produced by Bacillus liqueniformis. Since the clone P3A3 produced 26.3 U/mL protease in 10 hours of production, its activity was optimal at neutral pH, and its optimum temperature at 30ºC (56.0 U/mL) and its thermostability was demonstrated in 50°C (22,0 U/mL). These features contribute to the implementation of these enzymes in industrial sectors as in food production, chemical industry and production of detergents. The enzymes isolated in this study demonstrated new features and performance when compared to enzymes described today, which proves the efficiency of the construction of metagenomic libraries for isolation of new bioproducts.