title: Quantitative assessment of viable cells of Lactobacillus plantarum strains in single, dual and multi-strain biofilms.
abstract: Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential source of contamination.
authors.affiliation: Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
authors.forename: Mónica D
authors.initials: MD
authors.lastname: Fernández Ramírez
authors.affiliation: Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kostopoulos
authors.affiliation: Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
authors.forename: Eddy J
authors.initials: EJ
authors.lastname: Smid
authors.affiliation: Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands; Wageningen Food and Biobased Research, Wageningen University and Research, Wageningen, The Netherlands.
authors.forename: Masja N
authors.initials: MN
authors.lastname: Nierop Groot
authors.affiliation: Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands. Electronic address: tjakko.abee@wur.nl.
authors.forename: Tjakko
authors.initials: T
authors.lastname: Abee
mesh_terms: D001386:Azides / Q000737:chemistry; D018441:Biofilms / Q000254:growth & development*; D002470:Cell Survival; D005506:Food Contamination; D005511:Food Handling; D005516:Food Microbiology; D048191:Lactiplantibacillus plantarum / Q000145:classification* / Q000254:growth & development*; D010933:Plankton; D011419:Propidium / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D001386:Azides; C533957:propidium monoazide; D011419:Propidium
keywords: Biofilm coculture; Competition; Food spoilage