Three glutamic acid dialkyl ester ribitol (abbreviated as 2C8GE、2C12GE and 2C14GE) as the nonionic surfactants were synthesized with n-octyl alcohol, lauryl alcohol, and myristyl alcohol, respectively. Lactobacillus helveticus L7 with the ability to biosynthesize cis9,trans11-conjugated linoleic acid in aqueous was coated with these surfactants. Effects of the surfactants type, concentration, solvent, buffer pH, time, temperature and dry methods on the activity of enzyme in coated bacteria were studied. The optimized conditions were bacteria resuspended in pH5.8 buffer and coated with 1.0%(w/w) 2C12GE in acetone, incubated at 4℃ for 4 h, and lyophilized. The Km for lionleic acid as the substrate was 35.7 mM, and Vmax was 5.6 mM/h. The affinity of linoleic acid isomerase and linoleic acid was decreased as the bacteria were surfactant-coated.