Abstract: The aim of this work was to screen highly pectinase producing bacteria for following laboratorial research and industrial application.The soil sample that is rich in pectin substance was collected from ramie field located in the suburbs of LingLing district for screening of pectinase producing bacteria,and 11 stains were gained by enrichment procedure and screening test successively.Strain HYL6 which produced the highest enzyme activity tested by 3,5dinitrosalicylic acid (DNS) method in 11 strains was identified as Bacillus sp.and its pectinase producing conditions were optimized by onefactor experiments and orthogonal test successively.The optimized conditions were as follows:soluble starch 5 g/L,peptone 15 g/L,pH 7,and shaking fermentation 34 hours at 36 ℃,180 rpm.The activity of pectinase produced by the strain HYL6 under the optimal conditions reached 415 U/mL.

Key words: pectinase, enzyme activity, pectinase-producing conditions