Purpose: This study was undertaken to assess biofilm formation by selected strains of M. bovis on different contact surfaces and in various growth media and to test the efficacy of sanitizing treatments at various temperatures for control of the biofilms formed by M. bovis on different contact surfaces.
Methods: Biofilm-forming abilities of two M. bovis strains were assessed in 150 ml Middlebrook 7H9-Tween 80 (0.1%) broth with 5% liver extract and 10% oleic albumin dextrose catalase (OADC), 5% liver extract alone, or 10% OADC alone in sterile jars containing 2 x 2 cm2coupons of steel, cement or ceramic. The jars were incubated at 37°C with agitation for 2, 3 and 4 weeks, respectively. Biofilms on the coupons were subsequently exposed to 10 ml of 2% Iodasteryl®, 0.5% Virocid® and sterile water at 28 and 85°C, respectively for 5 min. Residual biofilms on treated coupons were quantified using the crystal violet binding assay.
Results: The two M. bovis strains had a similar ability in forming biofilms on the three surfaces. More biofilms were developed in media containing 5% liver extract. Biofilm mass increased as incubation time increased till the 3rdweek. More biofilms were formed on cement than on ceramic and stainless steel surface. Sanitizing treatments at 45°C removed more biofilms than at 28°C. However, neither treatment completely eliminated the biofilms.
Significance: Choice of processing surface and temperatures used for sanitizing treatments had an impact on biofilm formation and its removal from solid surfaces.