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.