Population and resistance patterns of Salmonella Typhimurium and Staphylococcus aureus biofilms to sublethal chemical disinfection under mono-and dual-species multi-strain conditions

To evaluate the possible influence of bacterial interactions encountered in mono- and dual-species multi-strain biofilms of Salmonella Typhimurium (ST) and Staphylococcus aureus (SA) on: (i) the ability of strains to develop biofilm, and (ii) their subsequent resistance to sublethal chemical disinfection

Ability of Salmonella enterica and Staphylococcus aureus to develop biofilm community on stainless steel and colonize rocket tissue

Salmonella enterica and Staphylococcus aureus are important human pathogens capable of causing a diverse array of diseases, while international organization (EFSA, FAO/WHO) report that these are among the most related microorganisms for foodborne diseases. The ability of both species to form biofilm, together with the increased number of antibiotic-resistant S. aureus strains, including ones resistant to methicillin (MRSA), are of special interest for researchers. In addition, the consumption of raw plant tissues, have been recently associated with foodborne diseases outbreaks due to cross contamination. Obviously, the ability of pathogenic strains of these species to survive on either abiotic or plant surfaces needs to be further studied

Ability of Salmonella enterica and Staphylococcus aureus to develop biofilm community on stainless steel and colonize rocket tissue

In the present study, the ability of S. Typhimurium (CDC 6516-60) and S. aureus strain COL (MRSA) to both develop a biofilm community on stainless steel (SS) and colonize rocket tissue was investigated (incubation at 20°C for 144 h). In parallel, the planktonic growth of these pathogens in Brain Heart Infusion (BHI) broth, was followed

A targeted gene expression analysis during biofilm formation by Salmonella enterica on stainless steel surfaces

In the present study, the expression of 14 genes was comparatively evaluated between planktonic and biofilm cells of S. Enteritidis. These genes were selected based on previous knowledge on their putative involvement in stress related mechanisms and other colonization implications. Biofilms were left to be formed on stainless steel coupons incubated under static conditions in brain heart growth medium at either 10 or 20°C for 6 days (144 h). Results revealed significant differential expression for the genes studied between the two growth modes (planktonic, sessile)

Interactions encountered inside dual-species biofilms formed by Salmonella Typhimurium and autochthonous microbiota recovered from leafy salads on stainless steel

In the present study, the ability of bacteria isolated from leafy salads to affect biofilm formation by Salmonella Typhimurium (ST), when all these were cultured together on stainless steel (SS) coupons, was investigated. To achieve this, isolates recovered from either rocket or spinach salads were left to form mixed culture dual-species biofilms with ST on SS coupons immerged in: (i) LB medium, (ii) rocket sterile extract, and (iii) spinach sterile extract, at 20°C

The role of biofilms in the development and dissemination of microbial resistance within the food industry

Biofilms are multicellular sessile microbial communities embedded in hydrated extracellular polymeric matrices. Their formation is common in microbial life in most environments, while those formed on food-processing surfaces are of considerable interest in the context of food hygiene. Biofilm cells express properties that are distinct from planktonic ones, in particular, notorious resistance to antimicrobial agents. Thus, a special feature of biofilms is that, once they have been developed, they are hard to eradicate, even when careful sanitization procedures are regularly applied. A great deal of ongoing research has investigated how and why surface-attached microbial communities develop such resistance, and several mechanisms are to be acknowledged (e.g., heterogeneous metabolic activity, cell adaptive responses, diffusion limitations, genetic and functional diversification, and microbial interactions). The articles contained in this Special Issue deal with biofilms of some important food-related bacteria (including common pathogens such as Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus, as well as spoilage-causing spore-forming bacilli), providing novel insights on their resistance mechanisms and implications, together with novel methods (e.g., use of protective biofilms formed by beneficial bacteria, enzymes) that could be used to overcome such resistance and thus improve the safety of our food supply and protect public health

Living biointerfaces based on non-pathogenic bacteria to direct cell differentiation

Genetically modified Lactococcus lactis, non-pathogenic bacteria expressing the FNIII7-10 fibronectin fragment as a protein membrane have been used to create a living biointerface between synthetic materials and mammalian cells. This FNIII7-10 fragment comprises the RGD and PHSRN sequences of fibronectin to bind α5β1 integrins and triggers signalling for cell adhesion, spreading and differentiation. We used L. lactis strain to colonize material surfaces and produce stable biofilms presenting the FNIII7-10 fragment readily available to cells. Biofilm density is easily tunable and remains stable for several days. Murine C2C12 myoblasts seeded over mature biofilms undergo bipolar alignment and form differentiated myotubes, a process triggered by the FNIII7-10 fragment. This biointerface based on living bacteria can be further modified to express any desired biochemical signal, establishing a new paradigm in biomaterial surface functionalisation for biomedical applications