Study on breeding of high-yield strains for production of lactulose by compound mutation

High-yield strains for production of lactulose were bred by compound mutation, with a view of providing technical support for the biological(enzymatic) synthesis of lactulose. By using Kluyveromyceslactis(JN-187) as the original strain, UV mutagenesis was performed to breed Mutant Strain JU74-09 with the highest hydrolysis activity; then, with Mutant Strain JU74-09 as the original strain, nitrosoguanidine(NTG) mutagenesis was performed to breed Mutant Strain JN91-08 with the highest transglycosylation activity. The results of 7 passage experiments showed that Mutant Strain JN91-08 had good genetic stability. All these proved that UV mutagenesis combined with nitrosoguanidine(NTG) mutagenesis is an effective mutation method of breeding strains for production of lactulose.