## 1 Introduction
Furthermore, its presence in food may result in recalls of contaminated products due to the unsafe status of the food, producing significant food waste and economic losses in the milk and dairy industry, which represents a dynamic global business sector, with the EU cheese market being the largest in the world [17]. In this context, its control is of great importance since, to date, there is no food safety criteria for _B. cereus_ in Europe defining the acceptability of a foodstuff in terms of its microbiological safety; rather, there is a process of hygienic criterion established instead (Commission Regulation (EC) No 2073/2005) [18] for presumptive _B. cereus_ in dried infant formulae and dried dietary foods for special medical purposes intended for infants below six months of age. Regarding current preservation strategies, the use of additives from synthetic origin to improve the shelf-life of food products has been traditionally extended. However, new trends in consumer demand towards the use of natural and sustainable preservatives are gaining momentum, encouraging the search for novel sources of compounds [19] that could also represent different complementary biopreservation strategies to those currently used [20]. Marine ecosystems harbor a high diversity of organisms with unique composition. Thus, macroalgae have been traditionally consumed over centuries as food, mainly in Asian countries, due to their high nutritional value, and have also been used as gelling and thickening agents in the cosmeceutical and agri-food sector [21]. Over the past few years, they have become increasingly popular since they represent an underexploited source of chemical structures different from those described in terrestrial organisms. They have developed complex defense mechanisms to cope with harsh environmental conditions, resulting in a great variety of novel compounds [22]. In this sense, interest in the scientific community has been focused on brown macroalgae (Phaeophyceae) because of their content in chemical structures typical from this algal group, such as phlorotannins (polyphenols), fucoxanthin (carotenoid), or fucoidans (sulphated polysaccharides) [23]. They have been reported to show a variety of bioactivities, such as antioxidant, anticancer, antifungal, anti-inflammatory [24; 25], as well as great antimicrobial potential, which make macroalgae a great source of compounds with potential as an alternative for natural food preservatives [26]. In this study, _Ericaria selaginoides_, a brown macroalgae commonly found in the North Atlantic coasts of Spain, was selected according to its antimicrobial efficacy previously observed in vitro against _B. cereus_[27]. Currently, although lots of studies have described the high in vitro antimicrobial potential of these marine organisms against foodborne pathogens and spoilage bacteria, few studies assessing this potential in food matrices have been performed so far [28] aiming to assess the functionality of macroalgae in food products. The aim of this work was to evaluate the antimicrobial potential of _E. selaginoides_ extracts as a control strategy against _B. cereus_ artificially inoculated in \"mato\", a Catalan fresh cheese chosen as a food matrix. To the best of our knowledge, it is the first time that the behavior of a foodborne pathogen, _B. cereus_, is evaluated under exposure to macroalgal extracts in a dairy matrix, such as fresh cheese, thus, helping to extend the current knowledge and establish a basis to make further applications of macroalgal extracts or their bioactive compounds feasible in the food industry as natural food preservatives.