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Optimization of Solid State Fermentation and Leaching Process Parameters for Improvement Xylanase Production by Endophytic Streptomyces sp. ESRAA-301097

2014; OMICS Publishing Group; Volume: 06; Issue: 03 Linguagem: Inglês

10.4172/1948-5948.1000137

1948-5948

Mervat Morsy Abbas Ahmed El-Gendy,

Microbial Metabolic Engineering and Bioproduction

In the course of our searching program on the microbial endophytes of medical plants (Cympobogon proximus, Anethum graveolens, Artemisia judaica and Corchorus olitorius), the endophytic strain Streptomyces sp.ESRAA-301097 derived from Cympobogon proximus proved to be the hyper xylanase producer.Screening of various locally available agro-industrial residues as substrate support for xylanase production under SSF exhibited a mixture of wheat bran (WB); sugarcane bagasse (SCB) with corncob (CC) at a ratio of 0.5:1:1 as the efficient inducer for the induction of ESRAA-301097 xylanase production as it gave the highest enzyme productivity (2364 Ugds -1 ) at the 4th day of fermentation when compared to individual WB, SCB or CC (1167, 1241 or 1404 Ugds -1 ) after 3, 4 and 4 days of incubation.Xylanase production was enhanced to 3819 Ugds -1 after optimizing the physical process parameters including temperature 30-40°C, pH 7.0, an inoculum level of 10 7 spore gds -1 , 80-85 % initial moisture content and substrate particle size of 800 µm.An overall 23.96 % increase in enzyme production was attained with a mixture of soybean and corn steep solid as a nitrogen source but no enhancement was obtained with any of carbon or metal supplementation.Whereas xylanase yield was elucidated to 5709.2 Ugds -1 by adding Tween 20, SDS repressed its production to 750.29 Ugds -1 .The optimized leaching parameters for effective extraction of xylanase (6312.45Ugds -1 ) from the fermented solid mixture were found to be citrate buffer (0.1 M, pH 4.0) containing 0.2% Tween 80 as leaching agent, extractant volume 1:8 -1:10 (w/v), soaking time 120 min, leaching pH 4 and leaching temperature 50°C under agitation at 150 rpm.The overall level of 44.61-fold purification of Streptomyces sp.ESRAA-301097 and xylanase recovery 32.52% were achieved with specific activity of 493.48 Umg -1 .The purified enzyme showed a single protein band on SDS-PAGE indicating the monomeric nature of the enzyme with molecular weight ~31.5 kDa.Furthermore, whereas the inhibitors of cysteine protease (1, 10-phenanthroline and Dithiothreitol), metaloprotease (EDTA and EGTA) and thioprotease (iodoacetamide and p-chloromercuribenzoate) had no to minor effects on xylanase activity, the serine protease inhibitor (PMSF) markedly decreased it.