Screening Of Microbial Esterase-producing, Studied On The Fermentation Optimization And Properties Of Esterase Of Absidia Glauca Hagem ZZM1

The application of microbial esterase (Esterase, EC3.1.11)was increasing, especially in the field of bioconversion. In thispaper, the screening and determinant of microbial esteraseproducing,the fermentation conditions,purification and properties of theStrain ZZM1 were studied systematically.A strain named ZM1 capable of producing esterase had beenisolated from soilsamples by the methods of bromocresol purplestaining technique and the determination of esterase value. Thestrain was identified as Absidia glauca Hagem based on itsmorphological characteristics and the sequence similarity ofribosomal DNA-ITS. A strain named ZZM1 was selected after UVmutagenesis, The results proved that ZMM1 had steadytransmissibility, when ZMM1 was cultivated at 32℃for 48h with160r/min, the yields of esterase was 58.76 U/mL, 104.3% higherthan ZM1. Based on studies and comparisons among methods of screening microbial esterase, a rapid, simple and efficient ScreeningModel for microbial esterase-producing was developed.In order to investigate the optimal conditions and the principleof producing esterase by A. glauca Hagem ZZM1, the orthogonalitymethods of combination Single Factor were designed and had beenemployed for the fermentation conditions and the compostion of thefermentation medium. The results showed that the optimumcompositions medium compositions were determined as sucrose 2%,NH₄CI 0.5%, K₂HPO₄ 0.1%, MgSO₄·7H₂O 0.05%, FeSO₄·7H₂O0.001%, NaC10.1%. The optimal conditions of cultivation weredetermined as: temperature 32℃, pH 6.3, aeration 50mL culture in500 mL shake flask, rotation speed 160 r/min, and the cultivatedtime was 48 h. Under the optimum cultivation conditions, the esteraseactivity reached 87.56U/mLThe esterase produced from the culuture supernatant of A.glauca Hagem ZZM1 was purified to an apparent homogeneityidentified by SDS-PAGE through deposition of NH₄SO₄, sucroseconcentration and DEAE Cellulose 52 ion exchange chromatography.The molecular mass estimated by SDSPAGE was 41.2 kDa.The purified esterase's optimum temperature and pH was 50℃and 6.3 respectively. The esterase was stable in the pH range of5.8-6.6 or temperature under 65℃. Metal ions of Li⁺,Co²⁺, Cu²⁺,Zn²⁺,Hg²⁺⁺ (0.1 mmol/L) significantly inhibited the activityto a small entent of the enzyme. Metal ions of Mr²⁺,Ca²⁺ andFe³⁺can activate the enzyme. Purified esterase can hydrolyze diferentesterase activity and specificitics for different esters.