Biofilms in Focus: A Threat to Foods

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Applied Biosciences and Bioengineering".

Deadline for manuscript submissions: closed (15 May 2020) | Viewed by 26057

Special Issue Editors


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Guest Editor
Departament de Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
Interests: biofilm; food safety; food microbiology; biosafety; cleaning; disinfection; sanitization; biosecurity
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Guest Editor
Food Hygiene and Inspection Unit, Department of Animal and Food Science, Faculty of Veterinary Sciences, Autonomous University of Barcelona, Bellaterra, Spain
Interests: biofilms; microbiota; foodborne pathogens; disinfectants; resistance; sublethal concentrations; gene expression; food preservation; hygiene; food safety
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The world of microbiology is changing—consumers and taxpayers are not aware of it, and neither are many of the technicians involved in food safety. Nowadays, there is a silent problem related to microbiology, and particularly, to food microbiology. That is, the biofilms formation, and its inhabitants’ resistance to cleaning, disinfection, and antibiotics.

Little by little, without being aware of it, the presence of pathogenic microorganisms on food products have been increasing. Pathogens such as Escherichia coli Shiga-toxin producers, Listeria monocytogenes, or Yersinia enterocolitica are becoming more frequent. They are microorganisms that are clearly sensitive to common disinfectants, such as sodium hypochlorite or quaternary ammonia, that have already been used in disinfection for several hundreds of years, but which are not eliminated in food facilities after the disinfection process. Is it because of a new resistance to disinfectants? Clearly not—in recommended concentrations, the justification lies in its great capacity to produce biofilms, a very effective form of resistance, which allows them to survive, grow, and colonize large areas. Bacteria’s ability to adhere to industrial surfaces and to subsequently trigger biofilm formation has significant implications within the food industry, especially for their consequences regarding public health and economic productivity. Today, L. monocytogenes is already the pathogen with the highest mortality in Europe and the United States, and one of the main causes of the pathogen contaminating a product is because of cross-contamination from surfaces. Moreover, we cannot forget the presence and interaction between pathogens and spoilage microorganisms, because of the interaction between them, which is essential in order to assure a quick and stable biofilm structure. Perhaps more time and research are needed in order to be able to include these structures as a priority in food control—meanwhile, hundreds of deaths accumulate in the statistics.

Prof. Dr. José Juan Rodríguez-Jerez
Dr. Carolina Ripolles-Avila
Guest Editors

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Keywords

  • Biofilms 
  • Cleaning 
  • Disinfection 
  • Sanitization 
  • Food microbiology
  • Food safety 
  • Pathogens 
  • Food control

Published Papers (7 papers)

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Editorial

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2 pages, 191 KiB  
Editorial
Biofilms in Focus: A Threat to Foods
by José Juan Rodríguez-Jerez and Carolina Ripolles-Avila
Appl. Sci. 2022, 12(15), 7906; https://0-doi-org.brum.beds.ac.uk/10.3390/app12157906 - 07 Aug 2022
Viewed by 813
Abstract
The world of food microbiology, and by extension that of food safety, has evolved significantly at the turn of the century [...] Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)

Research

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30 pages, 8190 KiB  
Article
Influence of Plasma Characteristics on the Inactivation Mechanism of Cold Atmospheric Plasma (CAP) for Listeria monocytogenes and Salmonella Typhimurium Biofilms
by Marlies Govaert, Cindy Smet, James L. Walsh and Jan F. M. Van Impe
Appl. Sci. 2020, 10(9), 3198; https://0-doi-org.brum.beds.ac.uk/10.3390/app10093198 - 04 May 2020
Cited by 10 | Viewed by 2323
Abstract
This research aimed to take a next step towards unravelling the CAP inactivation mechanism for mature (Listeria monocytogenes (Gram positive) and Salmonella Typhimurium (Gram negative)) model biofilms, which will support the further optimization this novel technology. More specifically, we examined how the [...] Read more.
This research aimed to take a next step towards unravelling the CAP inactivation mechanism for mature (Listeria monocytogenes (Gram positive) and Salmonella Typhimurium (Gram negative)) model biofilms, which will support the further optimization this novel technology. More specifically, we examined how the inactivation mechanism was influenced by the applied processing conditions, i.e., by the electrode configuration, the composition of the gas flow, and the power of the discharge. For each combination of plasma characteristics, we examined if the applied CAP treatment had an effect on (i) the cell membrane, (ii) the intracellular DNA, and (iii) the EPS matrix. In addition, we assessed which (reactive) CAP species were responsible for this lethal/damaging effect and whether these species were able to diffuse into the deeper layers of the biofilms. The results indicated that the inactivation mechanism was indeed influenced by the applied processing conditions. Nevertheless, the bactericidal effect of 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 photons. Moreover, the plasma species were able to penetrate into the deeper layers of the model biofilms and some treatment conditions resulted in an increased biofilm porosity. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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15 pages, 1774 KiB  
Article
The Antimicrobial Effect of Radiant Catalytic Ionization on the Bacterial Attachment and Biofilm Formation by Selected Foodborne Pathogens under Refrigeration Conditions
by Krzysztof Skowron, Karolina Jadwiga Skowron, Justyna Bauza-Kaszewska, Ewa Wałecka-Zacharska, Joanna Kwiecińska-Piróg, Katarzyna Grudlewska-Buda, Natalia Wiktorczyk and Eugenia Gospodarek-Komkowska
Appl. Sci. 2020, 10(4), 1364; https://0-doi-org.brum.beds.ac.uk/10.3390/app10041364 - 17 Feb 2020
Cited by 3 | Viewed by 3179
Abstract
The decontamination of food contact surfaces is a major problem for the food industry. The radiant catalytic ionization (RCI) method, based on the ionization process, may be an alternative for conventional decontamination procedures. The advantage of this technique is the possibility of its [...] Read more.
The decontamination of food contact surfaces is a major problem for the food industry. The radiant catalytic ionization (RCI) method, based on the ionization process, may be an alternative for conventional decontamination procedures. The advantage of this technique is the possibility of its application to household refrigerating appliances and industrial cold rooms. This study aimed to assess the effect of RCI on the reduction of Campylobacter jejuni, Listeria monocytogenes, and Salmonella Enteritidis from the biofilms formed on a glass surface under refrigeration conditions. Bacterial biofilms were exposed to RCI for 24 h and after 12 (variant I) and 72 h (variant II) of the glass surface contamination. In the last variant (III), the contaminated meat was placed on the glass surface in the refrigerator and subjected to RCI treatment for 72 h. The significantly highest values of absolute reduction efficiency coefficient E were found for the bacterial attachment stage of biofilm formation (variant I). The research proves the efficiency of the RCI method in the reduction of bacteria number from a glass surface. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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10 pages, 550 KiB  
Article
Strain and Growth Conditions may Regulate Resistance of Listeria monocytogenes Biofilms to Benzalkonium Chloride
by Lourenço Bonneville, Sagrario Ortiz, Vera Maia, Luisa Brito and Joaquín V. Martínez-Suárez
Appl. Sci. 2020, 10(3), 988; https://0-doi-org.brum.beds.ac.uk/10.3390/app10030988 - 03 Feb 2020
Cited by 6 | Viewed by 3113
Abstract
Listeria monocytogenes is one of the main foodborne pathogens. The formation of biofilms by L. monocytogenes contributes to its resistance to disinfectants, which represents a serious risk for food production plants. The aim of this study was to compare the effect of sub-inhibitory [...] Read more.
Listeria monocytogenes is one of the main foodborne pathogens. The formation of biofilms by L. monocytogenes contributes to its resistance to disinfectants, which represents a serious risk for food production plants. The aim of this study was to compare the effect of sub-inhibitory concentrations of benzalkonium chloride (BAC) (1.25 or 2.5 mg/L) on biofilm production and on biofilm reduction after exposure to an inhibitory concentration of BAC (1280 mg/L) in two isogenic L. monocytogenes strains: the BAC-sensitive wild-type strain S2-1 and its BAC-resistant mutant derivative S2BAC, which presented a multidrug resistance phenotype. The biofilm-forming ability of the strains under different BAC concentrations was evaluated by the resazurin method using polystyrene microplates. The biofilm reduction after BAC exposure was evaluated by using stainless steel coupons (SSCs). When the resazurin method was used, S2BAC produced significantly more biofilm in the presence of a sub-inhibitory concentration of BAC compared to that in the culture medium without BAC (p < 0.05). When the SSC method was used, the presence of sub-inhibitory concentrations of BAC resulted in a higher resistance of the biofilm for S2BAC compared to that in the culture medium without BAC (p < 0.05). This was not observed with the sensitive S2-1 strain. These results suggest that biofilm behavior depends on the strain and sub-inhibitory concentrations of disinfectants and may explain the ability of certain isolates to persist in niches of food processing plants. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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12 pages, 1882 KiB  
Article
Architecture and Viability of the Biofilms Formed by Nine Listeria Strains on Various Hydrophobic and Hydrophilic Materials
by Cristina Rodríguez-Melcón, Carlos Alonso-Calleja and Rosa Capita
Appl. Sci. 2019, 9(23), 5256; https://0-doi-org.brum.beds.ac.uk/10.3390/app9235256 - 03 Dec 2019
Cited by 11 | Viewed by 4056
Abstract
Biofilms are a key factor in the persistence of Listeria in food processing plants, representing a potential source of foodstuff contamination. Nine Listeria strains (eight Listeria monocytogenes and one Listeria ivanovii) were studied by confocal laser scanning microscopy (CLSM) for their ability [...] Read more.
Biofilms are a key factor in the persistence of Listeria in food processing plants, representing a potential source of foodstuff contamination. Nine Listeria strains (eight Listeria monocytogenes and one Listeria ivanovii) were studied by confocal laser scanning microscopy (CLSM) for their ability to form biofilm on glass, polystyrene, graphene and resin after 120 h of incubation at 12 °C. The relationship between cell surface hydrophobicity and biofilm formation was also investigated. On comparing the data for all the strains, similar (P > 0.05) biovolume values were obtained on glass (average 3.39 ± 1.69 µm3/µm2) and graphene (2.93 ± 1.14 µm3/µm2), while higher (P < 0.05) values were observed for polystyrene (4.39 ± 4.14 µm3/µm2). The highest (P < 0.01) biovolume levels were found in the biofilms formed on resin (7.35 ± 1.45 µm3/µm2), which also had the smallest biomass of inactivated cells (0.38 ± 0.37 µm3/µm2 vs. 1.20 ± 1.12 µm3/µm2 on the remaining surfaces; P < 0.001). No relationship was noted between cell surface hydrophobicity and biofilm-forming ability. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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14 pages, 2631 KiB  
Article
Microbial Ecology Evaluation of an Iberian Pig Processing Plant through Implementing SCH Sensors and the Influence of the Resident Microbiota on Listeria monocytogenes
by Anne-Sophie Hascoët, Carolina Ripolles-Avila, Alfons Eduard Guerrero-Navarro and José Juan Rodríguez-Jerez
Appl. Sci. 2019, 9(21), 4611; https://0-doi-org.brum.beds.ac.uk/10.3390/app9214611 - 30 Oct 2019
Cited by 14 | Viewed by 2623
Abstract
There is a whole community of microorganisms capable of surviving the cleaning and disinfection processes in the food industry. These persistent microorganisms can enhance or inhibit biofilm formation and the proliferation of foodborne pathogens. Cleaning and disinfection protocols will never reduce the contamination [...] Read more.
There is a whole community of microorganisms capable of surviving the cleaning and disinfection processes in the food industry. These persistent microorganisms can enhance or inhibit biofilm formation and the proliferation of foodborne pathogens. Cleaning and disinfection protocols will never reduce the contamination load to 0; however, it is crucial to know which resident species are present and the risk they represent to pathogens, such as Listeria monocytogenes, as they can be further used as a complementary control strategy. The aim of this study was to evaluate the resident surface microbiota in an Iberian pig processing plant after carrying out the cleaning and disinfection processes. To do so, surface sensors were implemented, sampled, and evaluated by culture plate count. Further, isolated microorganisms were identified through biochemical tests. The results show that the surfaces are dominated by Bacillus spp., Pseudomonas spp., different enterobacteria, Mannheimia haemolytica, Rhizobium radiobacter, Staphylococcus spp., Aeromonas spp., lactic acid bacteria, and yeasts and molds. Moreover, their probable relationship with the presence of L. monocytogenes in three areas of the plant is also explained. Further studies of the resident microbiota and their interaction with pathogens such as L. monocytogenes are required. New control strategies that promote the most advantageous profile of microorganisms in the resident microbiota could be a possible alternative for pathogen control in the food industry. To this end, the understanding of the resident microbiota on the surfaces of the food industry and its relation with pathogen presence is crucial. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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Review

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15 pages, 1550 KiB  
Review
A Brief Recap of Microbial Adhesion and Biofilms
by Spyridon Achinas, Nikolaos Charalampogiannis and Gerrit Jan Willem Euverink
Appl. Sci. 2019, 9(14), 2801; https://0-doi-org.brum.beds.ac.uk/10.3390/app9142801 - 12 Jul 2019
Cited by 111 | Viewed by 9335
Abstract
Food and beverage industries operate their production units under stringent hygiene standards to verify high-quality products. However, the presence of biofilms can cause hygienic problems in the industries in the case of pathogenic organisms. Microorganisms can form biofilms, which are resistant to cleaning [...] Read more.
Food and beverage industries operate their production units under stringent hygiene standards to verify high-quality products. However, the presence of biofilms can cause hygienic problems in the industries in the case of pathogenic organisms. Microorganisms can form biofilms, which are resistant to cleaning and disinfection. Microorganisms in biofilms are closely packed in a matrix that acts as a barrier to cleaning and disinfection. Biofilms are observed in processing equipment and open surfaces, resulting in food safety problems or weakening of production efficiency. This review provides a recap of the biofouling process, including the production mechanisms and control techniques of microbial adhesion. Microbial adhesion and colonization are the sine qua non of the establishment of bacterial pathogenesis and this report focuses on their prevention. Full article
(This article belongs to the Special Issue Biofilms in Focus: A Threat to Foods)
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