Molecular and Biochemical Screening of Local Aspergillus niger Strains Efficient in Catalase and Laccase Enzyme Production.

Ten local Aspergillus niger isolates were subjected to RAPD analysis and out of 20 random oligonucleotide primers, primer P2 (5'-ACGGCGTATG-3') was optimized to screen all ten isolates of A. niger. Results showed amplifications of different sizes in range of 150-1500 bp and isolates 658 and 880 showed 100% genomic similarity while isolate 764 showed least genomic homology (22.54%). Based on RAPD analysis representative isolates from each cluster were short listed for further downstream molecular and biochemical analysis. These isolates included 880, 764, 506, 1005 and 744. In ribotyping hyper variable region V4 of 18S rRNA gene was amplified in five isolates which were found to be genomically diverse in RAPD analysis. Results showed that amplified sequence of 18S rRNA gene was highly conserved and 100% similar with each other and to the already reported sequence (Accession No JX393054.1). In catalase test on all isolates of A. niger indicated that isolates 744, 506, 764 and 880 were the most efficient in the production of catalase enzyme, while remaining isolates except 1109 showed intermediate catalase activity. In laccase assay isolate 744 was found to be most efficient and isolate 840 was found to be least efficient, while the remaining isolates were found to be at same level in laccase assay. Results suggested that isolate 744 can be exploited further for the production of catalase and laccase enzyme at industrial scale. [ABSTRACT FROM AUTHOR]