Xylanases Aspergillus oryzae

Biobleaching Efficiency of Aspergillus oryzae Xylanases Produced by Solid Substrate Fermentation... 

Feruloyl esterase activity was first detected in culture filtrates of Strepto-myces olivochromogenes (49), and has thereafter also been reported for some hemicellulolytic fungi (Table III). A partially purified feruloyl esterase from S. commune liberated hardly any ferulic acid without the presence of xylanase (65). Very recently a feruloyl esterase was purified from Aspergillus oryzae (Tenkanen, M. Schuseil, J. Puls, J. Poutanen, K., /. Biotechnol, in press). The enzyme is an acidic monomeric protein having an isoelectric point of 3.6 and a molecular weight of 30 kDa. It has wide substrate specificity, liberating ferulic, p-coumaric, and acetic acids from steam-extracted wheat straw arabinoxylan. 

Fourteen Aspergillus oryzae isolates were evaluated for xylanase and cellulase production on eucalyptus pulp in SSF on two media at two initial pH values. Xylanase production varied between 561 and 4131 lU/g dry matter (DM) of initial substrate (data not shown). Isolate NRRL 447 showed the lowest productivity while strain NRRL 6270 produced the highest results. The xylanase production for the best six strains is shown in Fig.l. Most isolates produced more xylanase when the initial pH of the substrate was higher (pH 8.3). The only exception was isolate 6270 (initial pH of the substrate was pH 7.0). For the best enzyme producer (NRRL 6270), the medium composition had a significant effect on xylanase activity. 

Figure 4. Effect of different nitrogen sources on xylanase production by Aspergillus oryzae NRRL 3485 in 5SSF on eucalyptus pulp (T, 30 C initicd moisture content, 83% , initial pH, 8.3, f meiUation time, 4 d). CSL, corn steep liquor (50% iby weight).

Figure 7. Effect of initial pH of the substrate on xylanase production by Aspergillus oryzae NRRL 3485. Norhoptimized wetting solution consisted of (g/l) NH4NO3, 5 com steep liqwn (50 % dry weight), 2 KH O, 5 NaCl, / MgS04 1 trace element solutim I and II, I ml/L Optimted wetting solution consisted cf (g/l) corn steep liquor (50 % dry yreigld), 75 KH 04, 5 NaCl, I M S 4,1 t ace dement solution I arid II, I mVl (T, 30X mitiai moisture corttent, 83% , initial pH, 8.3, fermentation time, 4 d).

Figure S, Time course of xylanme, fi-xylosidase and laccase production by Aspergillus oryzae NRRL 3485 in SSF on eucalyptus pulp (a xylanase b 0-xylosidase and laccase, c pH).

Figure 9. Effect of temperature on hy ofysis ofxylan by xylanase of Aspergillus oryzae NRRL 3485. Reaction was performed at pH 6,0 for 5 min.

Figure II, Thermal stability of xylanase of Aspergillus oryzae NRRL 3485 without substrate (a) and in the presence of SSF solids (b) (pH 6.5 0,05 M citrate-phosphate buffer).

Chipeta, ZA, Preez JC, Christopher L. (2008). Effect of cultivation pH and agitation rate on growth and xylanase production by Aspergillus oryzae in spent sulphite liquor. J Ind Microbiol Biotechnol, 35, 587-594. 

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