title: Comparative sequence analysis of citrate synthase and 18S ribosomal DNA from a wild and mutant strains of Aspergillus niger with various fungi.
abstract: A mutation was induced in Aspergillus niger wild strain using ethidium bromide resulting in enhanced expression of citric acid by three folds and 112.42 mg/mL citric acid was produced under optimum conditions with 121.84 mg/mL of sugar utilization. Dendograms of 18S rDNA and citrate synthase from different fungi including sample strains were made to assess homology among different fungi and to study the correlation of citrate synthase gene with evolution of fungi. Subsequent comparative sequence analysis revealed strangeness between the citrate synthase and 18S rDNA phylogenetic trees. Furthermore, the citrate synthase movement suggests that the use of traditional marker molecule of 18S rDNA gives misleading information about the evolution of citrate synthase in different fungi as it has shown that citrate synthase gene transferred independently among different fungi having no evolutionary relationships. Random amplified polymorphic DNA (RAPD-PCR) analysis was also employed to study genetic variation between wild and mutant strains of A. niger and only 71.43% similarity was found between both the genomes. Keeping in view the importance of citric acid as a necessary constituent of various food preparations, synthetic biodegradable detergents and pharmaceuticals the enhanced production of citric acid by mutant derivative might provide significant boost in commercial scale viability of this useful product.
  
  
  BACKGROUND
  CS - Citrate synthase, CA - Citric acid, RAPD - Random amplified polymorphic DNA, TAF - Total amplified fragments, PAF - Polymorphic amplified fragments, CAF - Common amplified fragments.
authors: Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA.
authors: Ghulam
authors: G
authors: Mustafa
authors: Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad-38040, Pakistan.
authors: Aisha
authors: A
authors: Tahir
authors: Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad-38040, Pakistan.
authors: Muhammad
authors: M
authors: Asgher
authors: National Institute for Biotechnology & Genetic Engineering (NIBGE) PO Box 577 Jhang Road Faisalabad, Pakistan.
authors: Mehboob-Ur
authors: MU
authors: Rahman
authors: Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad-38040, Pakistan.
authors: Amer
authors: A
authors: Jamil
keywords: Aspergillus niger; RAPD-PCR; citrate synthase; phylogenetic analysis; polymorphism