Resumo

Actinomycetes are bacteria with morphological and cell cycle distinguished from other Gram-positive bacteria, and has received particular attention since they have several endophytic strains capable of producing molecules of industrial interest such as glycohydrolases. This work aims to study the hemicellulolytic extracts of endophytic actinomycetes growth under different carbon sources. A total of 46 actinomycetes were selected on their ability to produce hemicellulases and accessory proteins. Two screenings were performed, one using the esculin gel diffusion assay (EGDA) with a 5 old days CMC culture broth supernatant. The other approach was the culture on agar plate media using beechwood xylan and liquor from sugar cane bagasse hydrotermic pretreatment. Then, 12 promising isolates were grown in steam exploded/deslignificated sugar cane bagasse plus soyabean bran (3:1) in shake flasks at 29ºC at 200 rpm. Activities of xylanase, pectinase, β-glucosidase, endoglucanase and FPase were measured and the best 4 isolates were cultivated under xylan and citrus pectin as the only carbon source. The extracts of the three different culture media were assayed for the capacity to degrade several hemicellulitics substrates. The four best actinomycetes strains selected for hemicellulases and accessory proteins producing belong to the Streptomyces genera. High levels of xylanase were measured in all the strains extracts and its production seems to be associated with the xylan presence in the media. Only two strains were able to produce enzymes with activity to β-D-glucosyl-(1→4)-β-D-glucose links of β-glucan, lichenan and CMC substrates. However, none strain were able to produce β-glucosidase under the tested conditions. In the present work it was demonstrated that endophytic actinomycetes grown on different inducers substrates and lignocellulosic residue are a potential source of hemicellulolytic enzymes to be explored for practical use.