• 16S rRNA gene sequencing of mock microbial populations- impact of DNA extraction method, primer choice and sequencing platform

      Fouhy, Fiona; Clooney, Adam G; STANTON, CATHERINE; Claesson, Marcus J.; Cotter, Paul D.; European Union; Science Foundation Ireland; 603038; SFI/12/RC/2273; SFI/11/PI/1137 (Biomed Central, 24/06/2016)
      Background Next-generation sequencing platforms have revolutionised our ability to investigate the microbiota composition of complex environments, frequently through 16S rRNA gene sequencing of the bacterial component of the community. Numerous factors, including DNA extraction method, primer sequences and sequencing platform employed, can affect the accuracy of the results achieved. The aim of this study was to determine the impact of these three factors on 16S rRNA gene sequencing results, using mock communities and mock community DNA. Results The use of different primer sequences (V4-V5, V1-V2 and V1-V2 degenerate primers) resulted in differences in the genera and species detected. The V4-V5 primers gave the most comparable results across platforms. The three Ion PGM primer sets detected more of the 20 mock community species than the equivalent MiSeq primer sets. Data generated from DNA extracted using the 2 extraction methods were very similar. Conclusions Microbiota compositional data differed depending on the primers and sequencing platform that were used. The results demonstrate the risks in comparing data generated using different sequencing approaches and highlight the merits of choosing a standardised approach for sequencing in situations where a comparison across multiple sequencing runs is required.
    • The altered gut microbiota in adults with cystic fibrosis

      Burke, D.G.; Fouhy, Fiona; Harrison, M. J; Rea, Mary; Cotter, Paul D.; O'Sullivan, Orla; STANTON, CATHERINE; Hill, Cian J; Shanahan, Fergus; Plant, Barry J.; et al. (Biomed Central, 09/03/2017)
      Background Cystic Fibrosis (CF) is an autosomal recessive disease that affects the function of a number of organs, principally the lungs, but also the gastrointestinal tract. The manifestations of cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction in the gastrointestinal tract, as well as frequent antibiotic exposure, undoubtedly disrupts the gut microbiota. To analyse the effects of CF and its management on the microbiome, we compared the gut microbiota of 43 individuals with CF during a period of stability, to that of 69 non-CF controls using 454-pyrosequencing of the 16S rRNA gene. The impact of clinical parameters, including antibiotic therapy, on the results was also assessed. Results The CF-associated microbiome had reduced microbial diversity, an increase in Firmicutes and a reduction in Bacteroidetes compared to the non-CF controls. While the greatest number of differences in taxonomic abundances of the intestinal microbiota was observed between individuals with CF and the healthy controls, gut microbiota differences were also reported between people with CF when grouped by clinical parameters including % predicted FEV1 (measure of lung dysfunction) and the number of intravenous (IV) antibiotic courses in the previous 12 months. Notably, CF individuals presenting with severe lung dysfunction (% predicted FEV1 ≤ 40%) had significantly (p < 0.05) reduced gut microbiota diversity relative to those presenting with mild or moderate dysfunction. A significant negative correlation (−0.383, Simpson’s Diversity Index) was also observed between the number of IV antibiotic courses and gut microbiota diversity. Conclusions This is one of the largest single-centre studies on gut microbiota in stable adults with CF and demonstrates the significantly altered gut microbiota, including reduced microbial diversity seen in CF patients compared to healthy controls. The data show the impact that CF and it's management have on gut microbiota, presenting the opportunity to develop CF specific probiotics to minimise microbiota alterations.
    • The altered gut microbiota in adults with cystic fibrosis

      Burke, D.G.; Fouhy, Fiona; Harrison, M. J; Rea, Mary; Cotter, Paul D.; O'Sullivan, Orla; STANTON, CATHERINE; Hill, Cian J; Shanahan, Fergus; Plant, Barry J.; et al. (Biomed Central, 09/03/2017)
      Background Cystic Fibrosis (CF) is an autosomal recessive disease that affects the function of a number of organs, principally the lungs, but also the gastrointestinal tract. The manifestations of cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction in the gastrointestinal tract, as well as frequent antibiotic exposure, undoubtedly disrupts the gut microbiota. To analyse the effects of CF and its management on the microbiome, we compared the gut microbiota of 43 individuals with CF during a period of stability, to that of 69 non-CF controls using 454-pyrosequencing of the 16S rRNA gene. The impact of clinical parameters, including antibiotic therapy, on the results was also assessed. Results The CF-associated microbiome had reduced microbial diversity, an increase in Firmicutes and a reduction in Bacteroidetes compared to the non-CF controls. While the greatest number of differences in taxonomic abundances of the intestinal microbiota was observed between individuals with CF and the healthy controls, gut microbiota differences were also reported between people with CF when grouped by clinical parameters including % predicted FEV1 (measure of lung dysfunction) and the number of intravenous (IV) antibiotic courses in the previous 12 months. Notably, CF individuals presenting with severe lung dysfunction (% predicted FEV1 ≤ 40%) had significantly (p < 0.05) reduced gut microbiota diversity relative to those presenting with mild or moderate dysfunction. A significant negative correlation (−0.383, Simpson’s Diversity Index) was also observed between the number of IV antibiotic courses and gut microbiota diversity. Conclusions This is one of the largest single-centre studies on gut microbiota in stable adults with CF and demonstrates the significantly altered gut microbiota, including reduced microbial diversity seen in CF patients compared to healthy controls. The data show the impact that CF and it's management have on gut microbiota, presenting the opportunity to develop CF specific probiotics to minimise microbiota alterations.
    • Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir

      Cotter, Paul D.; Slattery, Conor; O'Toole, Paul W.; Department of Agriculture, Food and Marine; Science Foundation Ireland; APC Microbiome Ireland; Vistamilk; Enterprise Ireland; European Union; 818368 (MDPI, 2019-06-01)
      Lactobacilli are among the most common microorganisms found in kefir; a traditional fermented milk beverage produced locally in many locations around the world. Kefir has been associated with a wide range of purported health benefits; such as antimicrobial activity; cholesterol metabolism; immunomodulation; anti-oxidative effects; anti-diabetic effects; anti-allergenic effects; and tumor suppression. This review critically examines and assesses these claimed benefits and mechanisms with regard to particular Lactobacillus species and/or strains that have been derived from kefir; as well as detailing further potential avenues for experimentation.
    • Antifungal Peptides as Therapeutic Agents

      Fernández de Ullivarri, Miguel; Arbulu, Sara; Garcia-Gutierrez, Enriqueta; Cotter, Paul D.; Science Foundation Ireland; European Union; Teagasc Walsh Fellowship Programme; SFI/12/RC/2273; 754535; 2015066 (Frontiers Media SA, 2020-03-17)
      Fungi have been used since ancient times in food and beverage-making processes and, more recently, have been harnessed for the production of antibiotics and in processes of relevance to the bioeconomy. Moreover, they are starting to gain attention as a key component of the human microbiome. However, fungi are also responsible for human infections. The incidence of community-acquired and nosocomial fungal infections has increased considerably in recent decades. Antibiotic resistance development, the increasing number of immunodeficiency- and/or immunosuppression-related diseases and limited therapeutic options available are triggering the search for novel alternatives. These new antifungals should be less toxic for the host, with targeted or broader antimicrobial spectra (for diseases of known and unknown etiology, respectively) and modes of actions that limit the potential for the emergence of resistance among pathogenic fungi. Given these criteria, antimicrobial peptides with antifungal properties, i.e., antifungal peptides (AFPs), have emerged as powerful candidates due to their efficacy and high selectivity. In this review, we provide an overview of the bioactivity and classification of AFPs (natural and synthetic) as well as their mode of action and advantages over current antifungal drugs. Additionally, natural, heterologous and synthetic production of AFPs with a view to greater levels of exploitation is discussed. Finally, we evaluate the current and potential applications of these peptides, along with the future challenges relating to antifungal treatments.
    • Antimicrobial antagonists against food pathogens; a bacteriocin perspective

      O'Connor, Paula M.; Ross, R Paul; Hill, Colin; Cotter, Paul D.; Science Foundation Ireland; 12/RC/2273 (Elsevier, 03/02/2015)
      Efforts are continuing to find novel bacteriocins with enhanced specificity and potency. Traditional plating techniques are still being used for bacteriocin screening studies, however, the availability of ever more bacterial genome sequences and the use of in silico gene mining tools have revealed novel bacteriocin gene clusters that would otherwise have been overlooked. Furthermore, synthetic biology and bioengineering-based approaches are allowing scientists to harness existing and novel bacteriocin gene clusters through expression in different hosts and by enhancing functionalities. The same principles apply to bacteriocin producing probiotic cultures and their application to control pathogens in the gut. We can expect that the recent developments on bacteriocins from Lactic Acid Bacteria (LAB) described here will contribute greatly to increased commercialisation of bacteriocins in food systems.
    • Antimicrobials for food and feed; a bacteriocin perspective

      O'Connor, Paula M.; Kuniyoshi, Tais M.; Oliveira, Ricardo PS; Hill, Colin; Ross, R Paul; Cotter, Paul D.; Science Foundation Ireland; São Paulo Research Foundation; 12/RC/2273; 2015/24777-0; et al. (Elsevier, 2020-01-20)
      Bacteriocins are natural antimicrobials that have been consumed via fermented foods for millennia and have been the focus of renewed efforts to identify novel bacteriocins, and their producing microorganisms, for use as food biopreservatives and other applications. Bioengineering bacteriocins or combining bacteriocins with multiple modes of action (hurdle approach) can enhance their preservative effect and reduces the incidence of antimicrobial resistance. In addition to their role as food biopreservatives, bacteriocins are gaining credibility as health modulators, due to their ability to regulate the gut microbiota, which is strongly associated with human wellbeing. Indeed the strengthening link between the gut microbiota and obesity make bacteriocins ideal alternatives to Animal Growth Promoters (AGP) in animal feed also. Here we review recent advances in bacteriocin research that will contribute to the development of functional foods and feeds as a consequence of roles in food biopreservation and human/animal health.
    • Assessing the ability of Nisin A and derivatives thereof to inhibit Gram-negative bacteria from the genus Thermus

      Jonnala, Bhagya R. Yeluri; Feehily, Conor; O'Connor, Paula M.; Field, Des; Hill, Colin; Ross, R. Paul; McSweeney, P. L. H.; Sheehan, Diarmuid (JJ); Cotter, Paul D. (2020-12-09)
    • Atypical Listeria innocua strains possess an intact LIPI-3

      Clayton, Evelyn M; Daly, Karen M.; Guinane, Caitriona M.; Hill, Colin; Cotter, Paul D.; Ross, R Paul; Enterprise Ireland; Science Foundation Ireland; 06/IN.1/B98; 10/IN.1/B3027 (Biomed Central, 08/03/2014)
      Background: Listeria monocytogenes is a food-borne pathogen which is the causative agent of listeriosis and can be divided into three evolutionary lineages I, II and III. While all strains possess the well established virulence factors associated with the Listeria pathogenicity island I (LIPI-1), lineage I strains also possess an additional pathogenicity island designated LIPI-3 which encodes listeriolysin S (LLS), a post-translationally modified cytolytic peptide. Up until now, this pathogenicity island has been identified exclusively in a subset of lineage I isolates of the pathogen Listeria monocytogenes. Results: In total 64 L. innocua strains were screened for the presence of LIPI-3. Here we report the identification of an intact LIPI-3 in 11 isolates of L. innocua and the remnants of the cluster in several others. Significantly, we can reveal that placing the L. innocua lls genes under the control of a constitutive promoter results in a haemolytic phenotype, confirming that the cluster is capable of encoding a functional haemolysin. Conclusions: Although the presence of the LIPI-3 gene cluster is confined to lineage I isolates of L. monocytogenes, a corresponding gene cluster or its remnants have been identified in many L. innocua strains.
    • Bacteriocin-Antimicrobial Synergy: A Medical and Food Perspective

      Mathur, Harsh; Field, Des; Rea, Mary; Cotter, Paul D.; Hill, Colin; Ross, R Paul; Science Foundation Ireland; SFI/12/RC/2273 (Frontiers, 29/06/2017)
      The continuing emergence of multi-drug resistant pathogens has sparked an interest in seeking alternative therapeutic options. Antimicrobial combinatorial therapy is one such avenue. A number of studies have been conducted, involving combinations of bacteriocins with other antimicrobials, to circumvent the development of antimicrobial resistance and/or increase antimicrobial potency. Such bacteriocin-antimicrobial combinations could have tremendous value, in terms of reducing the likelihood of resistance development due to the involvement of two distinct mechanisms of antimicrobial action. Furthermore, antimicrobial synergistic interactions may also have potential financial implications in terms of decreasing the costs of treatment by reducing the concentration of an expensive antimicrobial and utilizing it in combination with an inexpensive one. In addition, combinatorial therapies with bacteriocins can broaden antimicrobial spectra and/or result in a reduction in the concentration of an antibiotic required for effective treatments to the extent that potentially toxic or adverse side effects can be reduced or eliminated. Here, we review studies in which bacteriocins were found to be effective in combination with other antimicrobials, with a view to targeting clinical and/or food-borne pathogens. Furthermore, we discuss some of the bottlenecks which are currently hindering the development of bacteriocins as viable therapeutic options, as well as addressing the need to exercise caution when attempting to predict clinical outcomes of bacteriocin-antimicrobial combinations.
    • Bacteriocins: Novel Solutions to Age Old Spore-Related Problems?

      Egan, Kevin; Field, Des; Rea, Mary; Ross, R Paul; Hill, Colin; Cotter, Paul D.; Department of Agriculture, Food and the Marine, Ireland; Science Foundation Ireland; DAFM 13/F/462; TIDA 14/TIDA/2286; et al. (Frontiers Media S. A., 08/04/2016)
      Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria, which have the ability to kill or inhibit other bacteria. Many bacteriocins are produced by food grade lactic acid bacteria (LAB). Indeed, the prototypic bacteriocin, nisin, is produced by Lactococcus lactis, and is licensed in over 50 countries. With consumers becoming more concerned about the levels of chemical preservatives present in food, bacteriocins offer an alternative, more natural approach, while ensuring both food safety and product shelf life. Bacteriocins also show additive/synergistic effects when used in combination with other treatments, such as heating, high pressure, organic compounds, and as part of food packaging. These features are particularly attractive from the perspective of controlling sporeforming bacteria. Bacterial spores are common contaminants of food products, and their outgrowth may cause food spoilage or food-borne illness. They are of particular concern to the food industry due to their thermal and chemical resistance in their dormant state. However, when spores germinate they lose the majority of their resistance traits, making them susceptible to a variety of food processing treatments. Bacteriocins represent one potential treatment as they may inhibit spores in the post-germination/outgrowth phase of the spore cycle. Spore eradication and control in food is critical, as they are able to spoil and in certain cases compromise the safety of food by producing dangerous toxins. Thus, understanding the mechanisms by which bacteriocins exert their sporostatic/sporicidal activity against bacterial spores will ultimately facilitate their optimal use in food. This review will focus on the use of bacteriocins alone, or in combination with other innovative processing methods to control spores in food, the current knowledge and gaps therein with regard to bacteriocin-spore interactions and discuss future research approaches to enable spores to be more effectively targeted by bacteriocins in food settings.
    • Bactofencin A, a New Type of Cationic Bacteriocin with Unusual Immunity

      O'Shea, Eileen F.; O'Connor, Paula M.; O'Sullivan, Orla; Cotter, Paul D.; Ross, R Paul; Hill, Colin; Department of Agriculture, Food and the Marine, Ireland; Science Foundation Ireland; 04R; 07/CE/B1368 (American Society for Microbiology, 29/10/2013)
      Bacteriocin production is an important probiotic trait of intestinal bacteria. In this study, we identify a new type of bacteriocin, bactofencin A, produced by a porcine intestinal isolate Lactobacillus salivarius DPC6502, and assess its potency against pathogenic species including Staphylococcus aureus and Listeria monocytogenes. Genome sequencing of the bacteriocin producer revealed bfnA, which encodes the mature and highly basic (pI 10.59), 22-amino-acid defensin-like peptide. Matrixassisted laser desorption ionization–time of flight (MALDI-TOF) mass spectral analysis determined that bactofencin A has a molecular mass of 2,782 Da and contains two cysteine residues that form an intramolecular disulfide bond. Although an ABC transporter and transport accessory protein were also present within the bacteriocin gene cluster, a classical bacteriocin immunity gene was not detected. Interestingly, a dltB homologue was identified downstream of bfnA. DltB is usually encoded within the dlt operon of many Gram-positive bacteria. It is responsible for D-alanylation of teichoic acids in the cell wall and has previously been associated with bacterial resistance to cationic antimicrobial peptides. Heterologous expression of this gene conferred bactofencin A-specific immunity on sensitive strains of L. salivarius and S. aureus (although not L. monocytogenes), establishing its role in bacteriocin immunity. An analysis of the distribution of bfnA revealed that it was present in four additional isolates derived from porcine origin and absent from five human isolates, suggesting that its distribution is host specific. Given its novelty, we anticipate that bactofencin A represents the prototype of a new class of bacteriocins characterized as being cationic, with a DltB homologue providing a cognate immunity function.
    • Beneficial modulation of the gut microbiota

      Cotter, Paul D. (Elsevier, 2016-03-29)
      As the scientific community continues to develop an ever-greater understanding of the composition and function of the human gut microbiota, and the role of specific microbial populations in health and disease, attention has turned to the tools that are at our disposal with respect to altering these microbes in a beneficial way. The options available include the use of diet, probiotics/prebiotics, antimicrobials and, potentially, exercise. Here, our recent investigations of the relationship between protein, bacteriocin producing probiotics and exercise and the gut microbiota and, in turn, health will be described.
    • Beneficial modulation of the gut microbiota

      Cotter, Paul D. (Elsevier, 2016-03-29)
      As the scientific community continues to develop an ever-greater understanding of the composition and function of the human gut microbiota, and the role of specific microbial populations in health and disease, attention has turned to the tools that are at our disposal with respect to altering these microbes in a beneficial way. The options available include the use of diet, probiotics/prebiotics, antimicrobials and, potentially, exercise. Here, our recent investigations of the relationship between protein, bacteriocin producing probiotics and exercise and the gut microbiota and, in turn, health will be described.
    • Beneficial modulation of the gut microbiota

      Cotter, Paul D. (Elsevier BV, 2016-04-01)
      As the scientific community continues to develop an ever-greater understanding of the composition and function of the human gut microbiota, and the role of specific microbial populations in health and disease, attention has turned to the tools that are at our disposal with respect to altering these microbes in a beneficial way. The options available include the use of diet, probiotics/prebiotics, antimicrobials and, potentially, exercise. Here, our recent investigations of the relationship between protein, bacteriocin producing probiotics and exercise and the gut microbiota and, in turn, health will be described.
    • Beneficial modulation of the gut microbiota

      Walsh, Calum J.; Guinane, Caitriona M.; O'Toole, Paul W.; Cotter, Paul D.; Science Foundation Ireland; 11/PI/1137 (Elsevier, 26/03/2014)
      The human gut microbiota comprises approximately 100 trillion microbial cells and has a significant effect on many aspects of human physiology including metabolism, nutrient absorption and immune function. Disruption of this population has been implicated in many conditions and diseases, including examples such as obesity, inflammatory bowel disease and colorectal cancer that are highlighted in this review. A logical extension of these observations suggests that the manipulation of the gut microbiota can be employed to prevent or treat these conditions. Thus, here we highlight a variety of options, including the use of changes in diet (including the use of prebiotics), antimicrobial-based intervention, probiotics and faecal microbiota transplantation, and discuss their relative merits with respect to modulating the intestinal community in a beneficial way.
    • Bioactivity in Whey Proteins Influencing Energy Balance

      McAllan, Liam; Cotter, Paul D.; Roche, Helen M.; Korpela, Riitta; Nilaweera, Kanishka (OMICS Publishing Group, 30/03/2012)
      Obesity develops due to energy (food) intake exceeding energy expenditure. Nutrients that reduce the positive energy balance are thus being considered as therapies to combat obesity. Here, we review the literature related to the physiological, cellular and endocrine effects of intake of whey proteins, namely α-lactalbumin, β-lactoglobulin, glycomacropeptide and lactoferrin. Moreover, we discuss how dietary composition and obesity may influence whey protein effects on the above parameters. Evidence suggests that intake of whey proteins causes a decrease in energy intake, increase in energy expenditure, influence insulin sensitivity and glucose homeostasis and alter lipid metabolism in the adipose, liver and muscle. These physiological changes are accompanied by alterations in the plasma levels of energy balance related hormones (cholecystokinin, ghrelin, insulin and glucagon-like peptide-1) and the expression of catabolic and anabolic genes in the above tissue in the direction to cause a negative energy balance.
    • Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

      Field, Des; Begley, Maire; O'Connor, Paula M.; Daly, Karen M.; Hugenholtz, Floor; Cotter, Paul D.; Hill, Colin; Ross, R Paul; Science Foundation Ireland; 10/IN.1/B3027; et al. (PLOS, 08/10/2012)
      Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.
    • A Bioengineered Nisin Derivative to Control Biofilms of Staphylococcus pseudintermedius

      Field, Des; Gaudin, Noemie; Lyons, Francy; O'Connor, Paula M.; Cotter, Paul D.; Hill, Colin; Ross, R Paul; Science Foundation Ireland; 10/IN.1/B3027 (PLoS, 19/03/2015)
      Antibiotic resistance and the shortage of novel antimicrobials are among the biggest challenges facing society. One of the major factors contributing to resistance is the use of frontline clinical antibiotics in veterinary practice. In order to properly manage dwindling antibiotic resources, we must identify antimicrobials that are specifically targeted to veterinary applications. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many gram-positive bacteria, including human and animal pathogens such as Staphylococcus, Bacillus, Listeria, and Clostridium. Although not currently used in human medicine, nisin is already employed commercially as an anti-mastitis product in the veterinary field. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) and also against staphylococci and streptococci associated with bovine mastitis. However, newly emerging pathogens such as methicillin resistant Staphylococcus pseudintermedius (MRSP) pose a significant threat in terms of veterinary health and as a reservoir for antibiotic resistance determinants. In this study we created a nisin derivative with enhanced antimicrobial activity against S. pseudintermedius. In addition, the novel nisin derivative exhibits an enhanced ability to impair biofilm formation and to reduce the density of established biofilms. The activities of this peptide represent a significant improvement over that of the wild-type nisin peptide and merit further investigation with a view to their use to treat S. pseudintermedius infections.
    • A Bioengineered Nisin Derivative, M21A, in Combination with Food Grade Additives Eradicates Biofilms of Listeria monocytogenes

      Smith, Muireann K.; Draper, Lorraine A.; Hazelhoff, Pieter-Jan; Cotter, Paul D.; Ross, R Paul; Hill, Colin; Science Foundation Ireland; SFI/12/RC/2273 (Frontiers, 30/11/2016)
      The burden of foodborne disease has large economic and social consequences worldwide. Despite strict regulations, a number of pathogens persist within the food environment, which is greatly contributed to by a build-up of resistance mechanisms and also through the formation of biofilms. Biofilms have been shown to be highly resistant to a number of antimicrobials and can be extremely difficult to remove once they are established. In parallel, the growing concern of consumers regarding the use of chemically derived antimicrobials within food has led to a drive toward more natural products. As a consequence, the use of naturally derived antimicrobials has become of particular interest. In this study we investigated the efficacy of nisin A and its bioengineered derivative M21A in combination with food grade additives to treat biofilms of a representative foodborne disease isolate of Listeria monocytogenes. Investigations revealed the enhanced antimicrobial effects, in liquid culture, of M21A in combination with citric acid or cinnamaldehyde over its wild type nisin A counterpart. Subsequently, an investigation was conducted into the effects of these combinations on an established biofilm of the same strain. Nisin M21A (0.1 μg/ml) alone or in combination with cinnamaldehyde (35 μg/ml) or citric acid (175 μg/ml) performed significantly better than combinations involving nisin A. All combinations of M21A with either citric acid or cinnamaldehyde eradicated the L. monocytogenes biofilm (in relation to a non-biofilm control). We conclude that M21A in combination with available food additives could further enhance the antimicrobial treatment of biofilms within the food industry, simply by substituting nisin A with M21A in current commercial products such as Nisaplin® (Danisco, DuPont).