Pang Pei Kheng and Ibrahim Che Omar

pp. 325 - 336

Abstract

Isolate USM A1 I which was identified to be Aspergillus niger was selected as a potential producer
of xylanase via a solid state fermentation system (SSF) using palm kernel cake (PKC) as substrate. The
modification of the physical conditions of the SSF system indicated that the xylanase activity was 23.97 U/g
PKC at the moisture ratio of 1:0.75 of PKC: moistening agent with the inoculum size of 1¥10⁴
 spores/ml and cultivated at the ambient temperature (28±3ºC). The supplementation of additional carbon and nitrogen
sources in the PKC medium could enhance enzyme productivity. The maximum production of xylanase and
growth obtained with the supplementation of xylose at 0.75% (w/w) were 25.40 U/g and 1.69 mg glucosamine/
g PKC. Moreover, the presence of NaNO₃ at 0.075% (w/w) as additional nitrogen source further enhanced
xylanase production to 33.99 U/g PKC although the growth remained unchanged at about 1.67 mg glucosamine/g PKC. The optimized conditions showed an increased xylanase production by 157% compared to
before the optimization of the SSF system. The xylanase productivity was 23.12 U/mg glucosamine after
optimization and 11.72 U/mg glucosamine before optimization.

Keywords

• xylanase production
• Aspergillus niger
• solid state fermentation
• palm kernel cake