Abstract: By natural fermentation mung bean sour liquid as the research object,using plate screening techniques isolated five strains with starch flocculation activity of acid producing bacteria from sour liquid.By group morphology,individual morphological observation,physiological and biochemical experiments and 16S rDNA sequence analysis strain LLY11 with the highest flocculation activity were identificated.The strain was identified as Acetobacter indonesiensis and named as Acetobacter indonesiensis LLY11.The culture conditions were optimized by single factor experiments,the best culture condition was glucose 1%,beef paste 2%,initial pH5.0,culture temperature 30 ℃,under this culture condition,the growth curve of LLY11 strain was determined. It was determined that the strain began to enter logarithmic period from 12 h,appeard secondary growth and reached the highest value at 24 h and 42 h,and then entered the decline stage.