PECTIN LYASE PRODUCTIVITY BY A UV-IRRADIATED ASPERGILLUS ORYZAE MUTANT UNDER CARROT-KOJI PROCESS - S. Mahboob; S. Ali (Journal of Animal and Plant Sciences, 2022)
Pectin lyase has several applications in different industrial areas. The enzyme has been produced by batch fermentation while the production of mutant pectin lyase has been improved by using carrot-koji fermentation. The present work deals with the stimulation in pectin lyase activity by a UV-irradiated Aspergillus oryzae mutant-auxotroph under carrot-koji process. The physical mutagenesis was induced using ultraviolet radiations. The effect of different distance from UV source (5-30 cm) and different exposure time (10-60 min) was investigated. The final mutant derivative UV-t30 was able to produce 9.26 U/ml of pectin lyase which was significantly higher than the wild-type. Two stage submerged fermentation was carried out while using carrot peelings as a substrate. The wild-type ISL-9 and mutant strain UV-t30 of A. oryzae showed the highest production by using 2 and 1.5 g carrot peelings, respectively 48 h after incubation (seeded with 8% inoculum). The enzyme was activated by CaCl2 and (NH4)2SO4 whereas it was inhibited in the presence of Tween-80. The enzyme was further activated by mutant strain UV-t30 while inhibited by wild-type ISL-9 using KNO3. After optimization of parameters for enzyme activity, the potent mutant showed a 1.3-fold increase in the enzyme activity as compared to the wild-type. The study proved that carrot peel has nutrients which enabled A. oryzae to produce pectin lyase in koji process.
Keywords: journal article; Aspergillus oryzae; pectin lyase; mutant strain; UV radiation; auxotroph formation; koji process