UV MUTAGENESIS ENHANCE FUNCTION OF CELLOBIOHYDROLASE I GENE OF <i>ASPERGILLUS NIGER</i>

Background The need for utilizing renewable resources to meet the future demand for fuel and other value added products has increased the attention on lignocellulosic wastes. Lignocelluloses are degraded by cellulase and other lignocellulolytic enzymes produced by fungi and bacteria. Mutagenic agents have been used to achieve improvement of these strains. There is however, paucity of data on the effect of these mutagenic agents on the structure and function of cellulase genes. The aim of this study was to carry out a structural analysis on selected cellulase genes obtained from ultraviolet light mutated Aspergillus niger . Methods Fungi were isolated from decomposing wood wastes. They were genotyped by amplifying the internally transcribed spacer (ITS) regions on their DNA, sequencing the amplicons and analyzing the sequences. They were genetically modified for enhanced cellulase production using ultraviolet rays. RNA of the mutated A. niger was reverse transcribed to complementary DNA (cDNA). The selected genes; aepI, aceI, cbhI and a laccase gene, Lacc1 were amplified and sequenced. The sequences were aligned and compared with referenced sequences which included those of Trichoderma reesei and Phanerochaete chrysosporium . The sequences were also translated into amino acid and in‐silico X‐ray crystallography structure of the active site of the enzyme was constructed using MEGA5 and JPred version of Jalview softwares. Results Bioinformatics analysis of the sequence of the cbh I gene of the A. niger mutant showed that it's enzyme had strong similarity with compared industrially beneficial fungi; Trichoderma reesei and Phanerochaete chrysosporium . Amino acid changes occurred between the 8 th to the 92 nd position on the chain‐A of the enzyme. Amino acids residues in its active site had low hydropathy index. Predicted structure of cellulase from A. niger mutant revealed that alteration occurred in the β‐pleated sheets of the enzyme. Conclusion Genetic modification of Aspergillus niger resulted in enhanced cellulase enzyme activity. Support or Funding Information Central Research Laboratory, College of Medicine, University of Lagos