applied sciences Editorial Biofilms in Focus: A Threat to Foods José Juan Rodríguez-Jerez * and Carolina Ripolles-Avila Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain * Correspondence: josejuan.rodriguez@uab.cat The world of food microbiology, and by extension that of food safety, has evolved significantly at the turn of the century. In fact, from carrying out controls on the presence or absence of pathogens in finished products, we have gone on to try to detect, not only where the pathogens are found, to apply the appropriate corrective measures to the problem, but also to look beyond. At this point, the number of publications related to biofilms, considered as forms of resistance of microorganisms in food facilities, has increased significantly. Thus, according to PubMed, since 2010, 1494 articles have been published on biofilms and food safety. Therefore, the study of biofilms is being considered as an important element to improve food safety conditions nowadays. This special issue aimed to present cutting-edge research related to the detection, evaluation, and removal of biofilms. All these without forgetting the composition of the matrix and the resistance induced, by these structures, to disinfectants and the usual systems used in the sanitization process. A total of six papers (five research papers and one review paper) in various fields, as non-thermal treatments, disinfectants tolerance, biofilm structure, ecology and adhesion mechanisms has been included in this Special Issue. Govaert et al. [1] reported that the bactericidal effect of Cold Atmospheric Plasma (CAP) was always a combination of both damage to the membrane and the DNA, caused by (i) the generation of (intracellular) ROS and RNS, (ii) a drop in pH, and/or (iii) the potential generation of a small amount of UV Citation: Rodríguez-Jerez, J.J.; Photons. Moreover, the plasma species were able to penetrate the deeper layers of the Ripolles-Avila, C. Biofilms in Focus: model biofilms and some treatment conditions resulted in an increased biofilm porosity. A Threat to Foods. Appl. Sci. 2022, 12, Skowron et al. [2] reported the efficiency of the Radiant Catalytic Ionization (RCI) method 7906. https://doi.org/10.3390/ in the reduction of bacteria number from a glass surface. Bonneville et al. [3] suggested that app12157906 biofilm behavior depends on the strain and sub-inhibitory concentrations of disinfectants Received: 28 July 2022 and may explain the ability of certain isolates to persist in niches of food processing plants. Accepted: 5 August 2022 Rodríguez-Melcón et al. [4] reported that biovolume values were similar on glass and Published: 7 August 2022 graphene, while higher values were observed for polystyrene. The highest biovolume levels were found in the biofilms formed on resin. No relationship was noted between Publisher’s Note: MDPI stays neutral cell surface hydrophobicity and biofilm-forming ability. Hascoët et al. [5], using surface with regard to jurisdictional claims in published maps and institutional affil- sensors, showed that the surfaces of an Iberian Pig Processing Plant are dominated by iations. Bacillus spp., Pseudomonas spp., different enterobacteria, Mannheimia haemolytica, Rhizobium radiobacter, Staphylococcus spp., Aeromonas spp., lactic acid bacteria, and yeasts and molds. Authors considered that the understanding of the resident microbiota on the surfaces of the food industry, and its relationship with pathogen presence is crucial. Achinas et al. [6] Copyright: © 2022 by the authors. concluded that the presence of biofilms can cause hygienic problems in the industries in Licensee MDPI, Basel, Switzerland. the case of pathogenic organisms. Microorganisms can form biofilms, which are resistant This article is an open access article to cleaning and disinfection. Biofilms are observed in processing equipment and open distributed under the terms and surfaces, resulting in food safety problems, or weakening of production efficiency. conditions of the Creative Commons Although submissions for this Special Issue have been closed, more in-depth research Attribution (CC BY) license (https:// in the field of biofilm formation, detection, and control continues to address the challenges creativecommons.org/licenses/by/ of the food safety of the future. 4.0/). Appl. Sci. 2022, 12, 7906. https://doi.org/10.3390/app12157906 https://www.mdpi.com/journal/applsci Appl. Sci. 2022, 12, 7906 2 of 2 Funding: This research received no external funding. Acknowledgments: Thanks to all the authors and peer reviewers for their valuable contributions to this Special Issue ‘Biofilms in Focus: A Threat to Foods’. We would also like to express our gratitude to all the staff and people involved in this Special Issue. Conflicts of Interest: The author declares no conflict of interest. References 1. Govaert, M.; Smet, C.; Walsh, J.L.; Van Impe, J.F.M. Influence of Plasma Characteristics on the Inactivation Mechanism of Cold Atmospheric Plasma (CAP) for Listeria monocytogenes and Salmonella Typhimurium Biofilms. Appl. Sci. 2020, 10, 3198. [CrossRef] 2. Skowron, K.; Skowron, K.J.; Bauza-Kaszewska, J.; Wałecka-Zacharska, E.; Kwiecińska-Piróg, J.; Grudlewska-Buda, K.; Wiktorczyk, N.; Gospodarek-Komkowska, E. The Antimicrobial Effect of Radiant Catalytic Ionization on the Bacterial Attachment and Biofilm Formation by Selected Foodborne Pathogens under Refrigeration Conditions. Appl. Sci. 2020, 10, 1364. [CrossRef] 3. Bonneville, L.; Ortiz, S.; Maia, V.; Brito, L.; Martínez-Suárez, J.V. Strain and Growth Conditions may Regulate Resistance of Listeria monocytogenes Biofilms to Benzalkonium Chloride. Appl. Sci. 2020, 10, 988. [CrossRef] 4. Rodríguez-Melcón, C.; Alonso-Calleja, C.; Capita, R. Architecture and Viability of the Biofilms Formed by Nine Listeria Strains on Various Hydrophobic and Hydrophilic Materials. Appl. Sci. 2019, 9, 5256. [CrossRef] 5. Hascoët, A.S.; Ripolles-Avila, C.; Guerrero-Navarro, A.E.; Rodríguez-Jerez, J.J. Microbial Ecology Evaluation of an Iberian Pig Processing Plant through Implementing SCH Sensors and the Influence of the Resident Microbiota on Listeria monocytogenes. Appl. Sci. 2019, 9, 4611. [CrossRef] 6. Achinas, S.; Charalampogiannis, N.; Willem Euverink, G.J. A Brief Recap of Microbial Adhesion and Biofilms. Appl. Sci. 2019, 9, 2801. [CrossRef]