Abstract
The species of the Bacillus cereus group have the ability to adhere to and form biofilms on solid surfaces, including stainless steel, a material widely used in food industries. Biofilms allow for recontamination during food processing, and the “clean-in-place” (CIP) system is largely used by industries to control them. This study thus proposes to evaluate the efficacy of peracetic acid and sodium hypochlorite against biofilms induced on stainless-steel surfaces. The SAMN07414939 isolate (BioProject PRJNA390851), a recognized biofilm producer, was selected for biofilm induction on AISI 304 stainless steel. Biofilm induction was performed and classified into three categories: TCP (Tindalized, Contaminated, and Pasteurized milk), TCS (Tindalized milk Contaminated with Spores), and TCV (Tindalized milk Contaminated with Vegetative cells). Subsequently, the coupons were sanitized simulating a CIP procedure, on a pilot scale, using alkaline and acid solutions followed by disinfectants (peracetic acid and sodium hypochlorite). Microorganism adhesion on the surfaces reached 6.3 × 105 to 3.1 × 107 CFU/cm-2. Results did not show significant differences (p > 0.05) for surface adhesion between the three tested categories (TCP, TCS, and TCV) or (p > 0.05) between the two disinfectants (peracetic acid and sodium hypochlorite). Microbial populations adhered to the stainless-steel coupons are equally reduced after treatment with peracetic acid and sodium hypochlorite, with no differences in the control of B. cereus s.s. biofilms on AISI 304 stainless-steel surfaces.
Highlights
Biofilm formation is a complex process consisting of a string of molecular and physiological events that take place throughout several stages including adherence, formation of microcolonies, tridimensional structuring, and maturation (Watnick and Kolter, 2000)
The present study aimed to evaluate the efficiency of two types of disinfectants used in the CIP system on biofilms induced by spores and vegetative cells of Bacillus cereus s.s. formed on stainless-steel surfaces that were in contact with experimentally tindalized milk
The average B. cereus s.s. populations in biofilms adhered to A coupons ranged from 6.3 × 105 to 3.1 × 107 CFU/cm2, with no significant differences (p > 0.05) between the three categories under study; i.e., there was no difference between adhesion of spores and vegetative cells
Summary
Biofilm formation is a complex process consisting of a string of molecular and physiological events that take place throughout several stages including adherence, formation of microcolonies, tridimensional structuring, and maturation (Watnick and Kolter, 2000). Biofilms have an extracellular matrix that constitutes a stable structure that protects bacteria against the action of sanitizing agents, making their control more difficult and allowing for persistent recontamination of food products (Simões et al, 2006; Salustiano et al, 2009; Majed et al, 2016). Another mechanism related to the biofilm persistence is considered the different gene expression in the multicellular population, cause some cells enter in a dormant or persistent state, manifesting a non-inherited resistance or tolerance to different antimicrobials (Wood et al, 2013; Singh et al, 2017)
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