Sourdough, mainly based on wheat or rye flour and water, is a relatively complex microbial ecosystem densely inhabited by yeasts and lactic acid bacteria (LAB), which are mainly responsible for dough leavening and acidification. Within this community, LAB have received attention because of their higher diversity and greater influence on odor, aroma, shelf-life and nutritional aspects of sourdough baked goods. Sourdough LAB may originate from flour, additional ingredients, water and bakery environment. The serial fermentations, repeated for 7–15 days, lead to mature sourdough, characterized by stable numbers of LAB, and constant acidification and leavening performances. Once mature sourdough has been produced, the stability of its microbial community is debated. Some researchers reported about very stable sourdoughs, at microbial species and even strain level. Others observed that bacterial species and strains fluctuate within different time in the same sourdough. Recently, the scientific research has focused the attention to characterise genotype and functional properties of LAB inhabiting the sourdough. The aim of the STSM will be to explore the genetic makeup and functional properties of LAB community of sourdough.Total DNA will be extracted from sourdough. Colture indipendent methods and omic approaches will be adopted to investigate genotype and functional abilities of LAB. Results will help to clarify role, contribution and evolution of LAB community in the sourdough ecosystem.

1. Aim and motivation. Genome sequencing of food fermenting bacteria is a powerful tool for their taxonomic identification, to understand their ecological adaptation, and to allow their exploitation in food biotechnology.
2. Proposed contribution to the scientific objectives of the Action. The training mission will contribute to the following scientific objectives:
   1. Contribution to microbial diversity and identification of genetic microbial resources;
   2. identify potential applications of sourdough microbes.
3. Relevant methodologies and techniques. The short term training mission will provide training on the basic workflow for sequencing of bacterial genomes, including DNA isolation and quality control, assembly of reads obtained on the Illumina platform, annotation of bacterial genomes, and the functional analysis with tools that allow identification of the taxonomic position, carbohydrate active enzymes, bacteriocins, phages, and other functional features.
4. Work plan (Provisional program, Tasks to achieve the proposed aim, corresponding goals and expected achievements).
   Provisional program:
   Week 1, DNA isolation and DNA quality control.
   Week 2. Assembly and annotation of bacterial genomes. We will work with genomes that were sequenced at the University of Alberta unless participants bring sequence data to the workshop.
   Week 3 and 4. Functional analysis with suitable online tools. Our current work focuses on genes coding for antimicrobial peptides or metabolites, carbohydrate active enzymes, and determinants for resistance to chemical or physical stressors; the focus of the analysis will depend on the specific research topic of the participants.

Sourdough, mainly based on wheat or rye flour and water, is a relatively complex microbial ecosystem densely inhabited by yeasts and lactic acid bacteria (LAB), which are mainly responsible for dough leavening and acidification. These ecosystems have received attention because of their high diversity and important influence on odor, aroma, shelf-life and nutritional aspects of sourdough baked goods. Sourdough microbial community may originate from flour, additional ingredients, water and bakery environment. The serial fermentations, repeated for 7–15 days, lead to mature sourdough, characterized by stable numbers of LAB and yeasts, and constant acidification and leavening performances. Once mature sourdough has been produced, the stability of its microbial community is debated. Some researchers reported about very stable sourdoughs, at microbial species and even strain level. Others observed that species and strains fluctuate within different time in the same sourdough. Recently, the scientific research has focused the attention to elucidate the interaction between lactic acid bacteria and yeast during sourdough fermentation. The aim of the STSM will be to explore these interactions.Colture dipendent and colture indipendent methods, omic approaches and microscopy methods will be adopted for the study. Results will help to clarify the interactions between LAB and yeasts in the sourdough ecosystem.