Colorimetric transition Of U-D-mannoside-hexadecyl (MC16)/polymeric 10,12-pentacosadivnoic acid (PDA) Langinuir-Schaefer (LS) film caused by binding Escherichia coli jm109 to alpha-D-mannoside-hexadecyl was imC investigated via UN-visible absorption spectra. The interfacial behaviors of MC16, and PDA mixture at the air/water interface exhibited a good miscibility. We demonstrated the dependence of the colorimetric response of MC16/polymeric PDA LS film on the incubation time in E. coli solution. Based on dynamical analysis of colorimetric transition caused by binding the bacterium to MC16. it was estimated that one E. coli could only bind two MC16 molecules.