Sequencing and characterization of the porcine α-galactosidase A gene: towards the generation of a porcine model for Fabry disease

Purification and characterization of α-galactosidase isolated from Klebsiella pneumoniae in the human oral cavity

The enzyme α-Galactosidase (α-D-galactoside galactohydrolase [EC 3.2.1.22]) is an exoglycosidase that hydrolyzes the terminal α-galactosyl moieties of glycolipids and glycoproteins. It is ubiquitous in nature and possesses extensive applications in the food, pharma, and biotechnology industries. The present study aimed to purify α-galactosidase from Klebsiella pneumoniae, a bacterium isolated from the human oral cavity. The purification steps involved ammonium sulfate precipitation (70 %), dialysis, ion exchange chromatography using a DEAE-cellulose column, and affinity monolith chromatography. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis was used to determine the molecular weight of the purified enzyme. The kinetic constants, Michaelis constant (Km) and maximal velocity (Vmax), for this enzyme were determined by using p-nitrophenyl-α-D-galactopyranoside as substrate. The results showed that the purification fold, specific activity, and yield were 126.52, 138.58 units/mg, and 21.5 %, respectively. The SDS-PAGE showed that the molecular weight of the purified enzyme was 75 kDa. The optimum pH and temperature of the purified α-galactosidase were detected at pH 6.0 and 50 °C, respectively. The kinetic constants, Michaelis constant (Km) and maximal velocity (Vmax), for this enzyme were 4.6 mM and 769.23 U/ml, respectively. α-galactosidase from Klebsiella pneumoniae was purified and characterized. (SDS-PAGE) analysis showed that the purified enzyme appeared as single band with a molecular weight of 75 kDa.

Comparative sequence analysis of citrate synthase and 18S ribosomal DNA from a wild and mutant strains of Aspergillus niger with various fungi

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.

ABBREVIATIONS

CS - Citrate synthase, CA - Citric acid, RAPD - Random amplified polymorphic DNA, TAF - Total amplified fragments, PAF - Polymorphic amplified fragments, CAF - Common amplified fragments.

Gamma radiation induced mutagenesis in Aspergillus niger to enhance its microbial fermentation activity for industrial enzyme production

α- and β-Galactosidases find application in food processing, health and nutrition. Aspergillus niger is one of the potent producer of these enzymes and was genotypically improved using gamma-ray induced mutagenesis. The mutant-derivative produced two-fold higher α- and β-galactosidases. For testing genetic variability and its relationship with phenotypic properties of the two organisms, DNA samples of the mutant and parental strains of A. niger were amplified with 28 deca-nucleotide synthetic primers. RAPD analysis showed significantly different pattern between parental and mutant cultures. The mutant derivative yielded homogeneous while parental strain formed heterogeneous amplification patterns. Seven primers identified 42.9% polymorphism in the amplification products, indicating that these primers determined some genetic variability between the two strains. Thus RAPD was found to be an efficient technique to determine genetic variability in the mutant and wild organisms. Both wild and mutant strains were analyzed for their potential to produce galactosidases. Comparison of different carbon sources on enzyme yield revealed that wheat bran is significant (P < 0.01) effective producer and economical source followed by rice bran, rice polishing and lactose. The mutant was significantly better enzyme producer and could be considered for its prospective application in food, nutrition and health and that RAPD can be effectively used to differentiate mutant strain from the parental strain based on the RAPD patterns.