降解柠檬苦素菌株的筛选鉴定及其发酵条件的优化

为解决柠檬苦素脱苦问题,筛选了可降解柠檬苦素的菌株并优化该菌株的产酶条件。从多年生橘园的土壤和发酵时期的醋醅中筛选并分离出8株可降解柠檬苦素的菌株,对较好降解柠檬苦素的C-1-5、C-1-2-2、JJ-3菌株进行形态学观察和分子生物学鉴定,在单因素实验的基础上,选JJ-3菌株进行响应面法优化的发酵工艺。筛选得到的8株菌中C-1-5、C-1-2-2、JJ-3菌株的柠檬苦素降解率分别为27%、36%、38%。鉴定C-1-5菌株为纤维菌属(Cellulomonas sp.),JJ-3菌株和C-1-2-2菌株为苍白杆菌属(Ochrobactrum sp.)。单因素优化后C-1-5、JJ-3、C-1-2-2菌株柠檬苦素降解率分别提高至65.90%、72.79%、74.66%。通过响应面试验,JJ-3菌株最佳发酵工艺条件是:pH3.5,温度30℃,氮源为硝酸铵,菌接种量3×108 CFU/mL。在此工艺条件下,柠檬苦素降解率为78.90%。优化后的菌株具有较高的降解率,可为柠檬苦素酶的研究提供帮助。

Screening and Identification of Limonin Degrading Strains and Optimization of Fermentation Conditions

In order to solve the debittering problem of limonin,strains degrading limonin were selected and the enzyme production conditions of the strains were optimized. Eight strains degrading limonin were selected and isolated from the soil of perennial orange orchards and vinegar during fermentation.C-1-5,C-1-2-2,and JJ-3 strains with better limonin degradation rates were identified by morphology and molecular biology.On the basis of single-factor experiments,JJ-3 strain was selected for fermentation optimization by response surface optimization. Among them,C-1-5,C-1-2-2,and JJ-3 strains had relatively high degradation rates of limonin,which were 27%,36%,and 38%,respectively. The C-1-5 strain was identified as Cellulomonas sp. by morphology and molecular biology. The JJ-3 strain and C-1-2-2 strain were identified as Ochrobactrum sp.by morphology and molecular biology.Through the single factor optimization,the limonin degradation rates of C-1-5,JJ-3,and C-1-2-2 strains were increased to 65.90%,72.79%,and 74.66%,respectively.Through the response surface experiment,the optimal fermentation process conditions for JJ-3 were:pH3.5,temperature 30℃,nitrogen source was ammonium nitrate,and the inoculation amount was 3×108 CFU/mL. Under this process condition,the degradation rate of limonin was 78.90%. The strains with optimized fermentation conditions had a higher degradation rate.This study can provide help for the research of enzymes degrading limonin.