The effects of culture media on the production of xylan-degrading enzymes by Streptomyces chattanoogensis UAH 23

The production of 4 extracellular xylanolytic enzymes, arabinofuranosidase, endoxylanase, beta-xylosidase and acetyl esterase during the growth of Streptomyces chattanoogensis UAH 23 in basal salts media containing different carbon sources was examined. The highest enzyme activities were generally detected when arabinoxylan was used as the carbon source, with the exception of acetyl-esterase where greatest activity was detected when ball-milled straw was used as carbon source. A comparison of enzyme activities revealed that the specific activity of endoxylanase (3.15 U/mg protein) was greater than those of the other three enzyme activities (44.11, 5.77 and 2.04 mU/mg protein for acetyl-esterase, alpha-L-arabinofuranosidase and beta-xylosidase, respectively). Cellulase activity could not be detected throughout the study. Characterization of the endoxylanase activity revealed that two optima pH could be detected (7.0 and 8.0) and was stable at alkaline pH values between 6.5 and 8.5. The optimum temperature was 55 degrees C with the enzyme stable for one hour at 60 degrees C. Activity staining of non denatured polyacrylamide gels containing culture supernatants revealed the presence of two active endoxylanase bands. The result suggest that two endoxylanase enzymes with different pH optimas are secreted by Streptomyces chattanoogensis UAH 23.