Breeding Of Strains With High-yielding Alkaline Pectinase And Optimization Of Its Fermentation Conditions

The wild-type strain WZ008 was isolated from decayed fruit epidermis and produces alkaline pectate lyase.A pure culture W10 producing alkaline pectinase with higher activity was obtained.It was identified to belong to the genus Paenibacillus by morphological and molecular approaches,thus named as Paenibacillus sp.WZ008.As the original strain,Paenibacillus sp.WZ008 was mutated by injection of N⁺, UV mutagenesis,⁶⁰Co-?-ray mutagenesis.The results showed that N⁺, UV,⁶⁰Co-?irradiation could enhance the activity of alkaline pectinase. After combined mutagenesis,a strain named ⁶⁰Co19 with high-yielding alkaline pectinase was abtained.The pectin lyase activity reached up to 97.8 U/mL,which was increased by 104.0%than the initial.Subculture test indicated that ⁶⁰Co19 had stable hereditary characteristics.On the shaking flask level,⁶⁰Co19 was examined with different fermentation media.Based on primary medium,the effects of carbon source,nitrogen source,mineral salts and inducer of fermentation were investigated.We also determined the optimal level of key components of the fermentation media by orthogonal experiments.After fermentation medium was optimized,another orthogonal experiment determining time, temperature,pH prior to sterilization,inoculation ratio and volume of medium in ⁶⁰Co19 fermentation showed that the optimum conditions were the volume of medium 40ml/500ml,temperature 30?,pH 7.75 prior to sterilization,inoculation ratio 18%,time 60h.