Incidence of bacteriophages infecting lactic acid bacteria (Leuconostococcaceae) associated with bread sourdough, wine and cheese making and benefit to risk assessment of lysogeny for a better control of fermentations – LYSOPLUS

Many commonly-consumed foodstuffs are fermented products, of which wine, sourdough bread and cheese are emblematic of French gastronomy. Food and beverage manufacturing are based on fermentation processes using indigenous micro-organisms, naturally occurring in complex flora. The in situ preservation of bacterial diversity along the food production chain maintains the richness and sensorial diversity of food products. In this context, a major challenge for producers is to provide measures to control fermentations, based on scientific data regarding the incidence of upstream factors (collecting of raw materials, technological routes) on microbial balance, and the understanding of bacterial dynamics during production and/or ripening processes. LYSOPLUS meets the needs of key stakeholders in different sectors (wine, bread and blue cheese) to better control their fermentation processes, through the assessment of the level and dynamics of natural bacterial antagonists, namely bacteriophages, in spontaneous fermentations.
The knowledge on how wild strains become domesticated represents a common research priority to food microbiologists. The monitoring bacterial communities by culture- and molecular dependent analysis have highlighted the specific role of indigenous lactic acid bacteria during wine-, sourdough bread- and blue cheese-making. The Leuconostocaceae family is of great interest, and comprises the three genera Oenococcus, Leuconostoc and Weissella. In some productions, food bio-preservation can be achieved with the necessary amount of selected starters to ensure consistency, safety and quality of the final product. This alternative practice minimizes spoilage and health risks, and also offers a simplified work organization. It is recognized to bring professionals threefold benefits: economical, environmental and human, and is therefore part of the sustainable development approach of the three sectors (wine, bread, blue cheese). The main issue and originality of our program is to accumulate the necessary scientific data regarding viruses infecting such bacteria in order to clarify whether bacteriophages are relevant actors which may interfere with ongoing efforts to control the final organoleptic quality of wine, sourdough bread and blue-cheese, during harvest and transformation. The project will provide a valuable technical and scientific expertise on bacteriophages, on their diversity and the nature of their interactions with bacterial hosts. Original molecular tools dedicated to the detection and monitoring of viruses, which will be applicable to the different processing steps will be delivered. LYSOPLUS will also clarify whether presence of phages is a key factor and how it may be integrated during selection, biomass production and use of starters. An analysis of the risk-benefit balance will be carried out to provide information to stakeholders as part of their industrial strategy of selection, on what position to take concerning lysogens, and on the possible requirement for phage-resistant strains. The project involves academic with historic partnerships in the past within each sector, and industries developing bacterial starters. It will offer opportunities to the major stakeholders of the three sectors to strengthen their competitiveness, in the context of a better control of fermentations, and will help placing on the market high-quality products with diversified sensorial performances, adapted to the new expectations of consumers.