ILLUSTRATION: LALLEMAND
PHOTO: LALLEMAND
SCIENTIFIC REVIEW ▶▶▶
Positive biofilms to guide surface microbial ecology
Increasing emphasis is put on the role and management of microbial biofilms in farm buildings, particularly in the context of reducing on-farm antimicrobial usage while safeguarding the animal microbial environment. A comprehensive review has just been published in the journal Biofilm.
BY VIRGILE GUÉNEAU, LALLEMAND ANIMAL NUTRITION AND INRAE T
he scientific review provides an overview of the en- visioned modes of action of positive biofilms used on livestock building surfaces and the resulting criteria for the selection of the appropriate micro-
organisms for this specific application. The authors further discuss the pros and cons of such a biosecurity approach as well as its influence along the food chain, from farm-to-fork.
Biofilms
A biofilm is defined as a “spatially organised community of micro-organisms fixed to a surface”. It represents the most prevalent mode of life for micro-organisms in nature and is omnipresent in all environments. Biofilms secrete a protective
extracellular matrix which can represent around 85% of the biofilm biomass. In farm buildings all surfaces — floors, walls, ceilings and equipment — are colonized by biofilms. They can be harmless, positive or negative for the animals if they contain pathogens. Before a new batch of animals enters the building, cleaning and disinfection (C&D) are necessary. However, surfaces do not remain sterile. Micro-organisms car- ried over from the animal environment and the new animals themselves, quickly start recolonizing the surfaces, forming biofilms again.
The rationale for positive biofilm Among internal biosecurity measures to limit the persistence and proliferation of pathogenic bacteria in livestock build- ings, C&D protocols are applied between each breeding cycle using, for example, biocidal products. However, several stud- ies have shown that such chemicals may not be completely effective against biofilms and only allow elimination of part of the microbiota present on farm building surfaces. It has been shown in avian farms that C&D protocols are not totally effective in eradicating the residual pathogens respon- sible for cross-contamination between different batches of animals, such as Salmonella spp., Campylobacter jejuni, Entero- coccus spp. and Escherichia coli. This reduction in the efficien- cy of C&D is directly associated with the formation of biofilms by these surface-associated communities. While various anti-biofilm approaches have been envisaged, none of these biosecurity methods is universal and combined strategies hold the most potential. A very promising approach appears to be guiding the ecology of a surface by settling positive biofilms that will colonize and physically protect the surface from pathogen multiplication: the positive biofilm strategy (Figure 1). Positive biofilms are already used in many sectors, such as food and healthcare, and show very promising results in farm building applications when used to complement C&D protocols.
Figure 1. Representation of the concept of how positive biofilms can guide microbial ecology on the surface of livestock buildings following a cleaning and disinfection protocol.
20 ▶ POULTRY WORLD | No. 6, 2022
How do positive biofilms work? Four major complementary mechanisms have been
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