EFFICIENCY OF DETERGENTS IN THE REMOVAL OF ESCHERICHIA COLI BIOFILMS ON STAINLESS STEEL SURFACES

Abstract

Escherichia coli is a pathogen associated with foodborne diseases. E. coli may be present in the food industry through biofilms in poor hygienic conditions. The objective of this research was to evaluate the efficiency of detergents for the removal of E. coli biofilms from a stainless steel surface. AISI 304, finishing number 4 stainless steel coupons (8 mm x 8 mm x 1 mm dimensions) were aseptically immersed in microtubes containing 1 ml of Mueller Hinton broth (MH) contaminated with 105 CFU / ml E. coli and incubated at 35 °C for 24 hours for biofilm formation. Then, each coupon was submitted to different procedures of hygiene: cleaning with enzymatic detergent for 5 min at 40 ° C and cleaning with 1% alkaline detergent for 5 min at room temperature. After the cleaning steps, each coupon was transferred to a microtube containing 1 mL of 0.85% saline solution and agitated for 2 min to release the biofilm. Afterwards, serial dilutions and agar plating (MH) were performed for the quantification of the detached cells. The control coupons (without detergents) were not given cleaning agents and their counts were used to calculate the number of decimal reduction due to the hygiene processes. The treatment with the enzymatic detergent showed a reduction of 1.31 log CFU / cm2 . The alkaline detergent reduced (3.70 log UFC / cm2 ) the E. coli counts of the stainless steel surface. No sanitation method tested completely removed the microbial biofilm from the stainless-steel surface.