Biofilm formation by the Escherichia coli strains leads to development of chronic diseases of the gastrointestinal system and urinary tract. Thus, it is important to reveal the regulatory events resulting in biofilm formation and to find inhibiting agents. Here, we first study the influence of hexuronic acids-compo nents of pectin and intermediates of the Ashwell pathway-on expression of genes with products playing key roles in regulation of the E. coli adhesion to different surfaces and formation of biofilms. Using reverse transcription followed by quantitative PCR, it was demonstrated that D-galacturonic and D-glucuronic acids acted not equally. D-galacturonate activated expression of genes coding for the biofilm formation regulator CsgD and periplasmic chaperone of the type I fimbriae FimC 1.5-3 fold, and more than 10-fold induced expression of SsrS small rNa in biofilms, thus potentially stimulating the ability of E. coli K-12 MG1655 to colonize surfaces. However, D-galacturonate slightly inhibited formation of biofilms. D-glucuronate, in contrast, repressed csgD andfimC2.5-3 fold, as well as the gene of structural flagellinflgK, in the biofilm-forming cells. In line with this, biofilm formation in the presence of D-glucuronate was significantly lowered. It was first shown that 6S small RNA SsrS activates biofilm formation, while overproduction of CsrC small RNA activated this process even in the presence of D-glucuronate. The data obtained allows suggesting that SsrS and CsrC small RNAs played an important role in regulation of the cell switching to formation of biofilms, and hexuronates can be used as modeling agents in clinical practice.