Micro ecosystems from feed industry surfaces: a survival and biofilm study of Salmonella versus host resident flora strains

Abstract

BackgroundThe presence of Salmonella enterica serovars in feed ingredients, products and processing facilities is a well recognized problem worldwide. In Norwegian feed factories, strict control measures are implemented to avoid establishment and spreading of Salmonella throughout the processing chain. There is limited knowledge on the presence and survival of the resident microflora in feed production plants. Information on interactions between Salmonella and other bacteria in feed production plants and how they affect survival and biofilm formation of Salmonella is also limited. The aim of this study was to identify resident microbiota found in feed production environments, and to compare the survival of resident flora strains and Salmonella to stress factors typically found in feed processing environments. Moreover, the role of dominant resident flora strains in the biofilm development of Salmonella was determined.ResultsSurface microflora characterization from two feed productions plants, by means of 16 S rDNA sequencing, revealed a wide diversity of bacteria. Survival, disinfection and biofilm formation experiments were conducted on selected dominant resident flora strains and Salmonella. Results showed higher survival properties by resident flora isolates for desiccation, and disinfection compared to Salmonella isolates. Dual-species biofilms favored Salmonella growth compared to Salmonella in mono-species biofilms, with biovolume increases of 2.8-fold and 3.2-fold in the presence of Staphylococcus and Pseudomonas, respectively.ConclusionsThese results offer an overview of the microflora composition found in feed industry processing environments, their survival under relevant stresses and their potential effect on biofilm formation in the presence of Salmonella. Eliminating the establishment of resident flora isolates in feed industry surfaces is therefore of interest for impeding conditions for Salmonella colonization and growth on feed industry surfaces. In-depth investigations are still needed to determine whether resident flora has a definite role in the persistence of Salmonella in feed processing environments.

Salmonella serovars isolated for the first time in Poland, 1995–2007

“…Animal feed is a recognized source of pathogenic microorganisms for animals [16]. It is still relatively common to find evidence of contamination of domestic and imported feed and animal-feed ingredients [17][18][19][20][21][22][23][24][25][26]. Salmonella can be isolated regularly from feedstuffs and feed ingredients, including both animal and vegetable proteins, such as soya, rape, palm kernel, rice bran and cottonseed.…”

Differential Biofilm Formation and Chemical Disinfection Resistance of Sessile Cells of Listeria monocytogenes Strains under Monospecies and Dual-Species (with Salmonella enterica) Conditions

“…Evidently, bacterial pathogens, such as L. monocytogenes and S. enterica, can be entrapped in multispecies sessile communities formed on such surfaces. In addition, attachment and biofilm formation by these two species have been shown to be influenced by either the natural in situ presence of other species or just their metabolic by-products (8,10,11,24,26,27,29,32,33,37,38,39,46,58,77). For instance, the presence of Staphylococcus xylosus and Pseudomonas fragi affected the numbers of L. monocytogenes biofilm cells on stainless steel (51), while compounds present in Hafnia alvei cell-free culture supernatant inhibited the early stage of S. enterica serovar Enteritidis biofilm formation on the same material (10).…”

Invasion and Survival of Salmonella in the Environment: The Role of Biofilms

“…Dualspecies biofilms favored Salmonella growth compared to Salmonella in mono-species biofilms, where biomass increased 2.8-fold and 3.2-fold in the presence of Staphylococcus and Pseudomonas, respectively (Habimana et al, 2010). Thus contamination with Salmonella in the presence of other bacteria will only exacerbate the problem of dissemination of Salmonella.…”