Abstract This study evaluated the production of endoxylanases by Streptomyces malaysiensis AMT-3 in submerged fermentation using by-products of the food industry at 28ºC. In shake-flasks experiments, the highest endoxylanase activity of 45.8 U.mL-1 was observed within 6 days in a medium containing (w/v) 2.5% wheat bran and 1.2% corn steep liquor. The same culture conditions were used to evaluate the enzyme production in a 2 L stirred tank reactor under different agitation (300, 450 and 600 rev.min-1) and aeration (30 and 60 L.h-1) conditions. The use of 450 rev.min-1 coupled to an aeration of 90 L.h-1 resulted on 81.3 U.mL-1 endoxylanase activity within 5 days. The effect of temperature and pH on endoxylanase activity and stability showed the highest activity at 60 ºC and pH 6.0. Zymography showed the presence of three xylanolytic bands with molecular masses of 690, 180 and 142 kDa. The results showed that the thermotolerant actinobacterial endoxylanase can be produced in high titers using by-product of the food industry.

Approximately 1.5 trillion tons are the estimated yearly biomass production, making it an essentially unlimited source of raw material for environmentally friendly and biocompatible products transformed by microorganism, specially fungi and actinomycetes. Several lignocellulosic residues, such as sisal waste and sugarcane bagasse contain starch in their structures which could become important sources for the production of amylases. This study evaluated the production of amylolytic enzymes using Streptomyces sp. SLBA-08 strain, isolated from a semi-arid soil, according to their ability to grow on soluble starch as the sole carbon source. The effect of the carbon source (sisal waste and sugarcane bagasse) on α-amylase production was studied using submerged cultivations at 30 ºC. The highest level of α-amylase activity corresponded to 10.1 U. mL-1 and was obtained using sisal waste (2.7%) and urea (0.8%) in submerged fermentation after 3 days of cultivation. The partial characterization showed the best α-amylase activity at 50ºC and pH 7.0. These results are of great importance for the use of sisal waste as a substrate for biotechnological proposes.

Brewer's spent grain and corn steep liquor or yeast extract were used as the sole organic forms for proteinase production by Streptomyces malaysiensis in submerged fermentation. The influence of the C and N concentrations, as well as the incubation periods, were assessed. Eight proteolytic bands were detected through gelatin-gel-electrophoresis in the various extracts obtained from the different media and after different incubation periods, with apparent molecular masses of 20, 35, 43, 50, 70, 100, 116 and 212 kDa. The results obtained suggest an opportunity for exploring this alternative strategy for proteinases production by actinomycetes, using BSG and CSL as economically feasible substrates.