title: Use of enhanced nisin derivatives in combination with food-grade oils or citric acid to control Cronobacter sakazakii and Escherichia coli O157:H7.
abstract: Cronobacter sakazakii and Escherichia coli O157:H7 are well known food-borne pathogens that can cause severe disease. The identification of new alternatives to heating to control these pathogens in foods, while reducing the impact on organoleptic properties and nutritional value, is highly desirable. In this study, nisin and its bioengineered variants, nisin V and nisin S29A, are used alone, or in combination with plant essential oils (thymol, carvacrol and trans-cinnamaldehyde) or citric acid, with a view to controlling C. sakazakii and E. coli O157:H7 in laboratory-based assays and model food systems. The use of nisin variants (30 μM) with low concentrations of thymol (0.015%), carvacrol (0.03%) and trans-cinnamaldehyde (0.035%) resulted in extended lag phases of growth compared to those for corresponding nisin A-essential oil combinations. Furthermore, nisin variants (60 μM) used in combination with carvacrol (0.03%) significantly reduced viable counts of E. coli O157:H7 (3-log) and C. sakazakii (4-log) compared to nisin A-carvacrol treatment. Importantly, this increased effectiveness translated into food. More specifically, sub-inhibitory concentrations of nisin variants and carvacrol caused complete inactivation of E. coli O157:H7 in apple juice within 3 h at room temperature compared to that of the equivalent nisin A combination. Furthermore, combinations of commercial Nisaplin and the food additive citric acid reduced C. sakazakii numbers markedly in infant formula within the same 3 h period. These results highlight the potential benefits of combining nisin and variants thereof with carvacrol and/or citric acid for the inhibition of Gram negative food-borne pathogens.
authors.affiliation: School of Microbiology, University College Cork, Cork, Ireland.
authors.forename: Alicia
authors.initials: A
authors.lastname: Campion
authors.affiliation: School of Microbiology, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland.
authors.forename: Ruth
authors.initials: R
authors.lastname: Morrissey
authors.affiliation: School of Microbiology, University College Cork, Cork, Ireland.
authors.forename: Des
authors.initials: D
authors.lastname: Field
authors.affiliation: APC Microbiome Institute, University College Cork, Cork, Ireland; Teagasc, Moorepark Food Research Centre, Fermoy, Co. Cork, Ireland. Electronic address: paul.cotter@teagasc.ie.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Cotter
authors.affiliation: School of Microbiology, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland. Electronic address: c.hill@ucc.ie.
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
authors.affiliation: APC Microbiome Institute, University College Cork, Cork, Ireland; College of Science, Engineering and Food Science, University College Cork, Cork, Ireland.
authors.forename: R Paul
authors.initials: RP
authors.lastname: Ross
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D057005:Bioengineering; D019343:Citric Acid / Q000494:pharmacology*; D015169:Colony Count, Microbial; D044083:Cronobacter sakazakii / Q000187:drug effects* / Q000254:growth & development; D000081007:Cymenes; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005421:Flavoring Agents / Q000494:pharmacology; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D000067030:Fruit and Vegetable Juices / Q000382:microbiology; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000382:microbiology; D027845:Malus; D039821:Monoterpenes / Q000494:pharmacology; D009561:Nisin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D010938:Plant Oils / Q000494:pharmacology*; D013943:Thymol / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000081007:Cymenes; D005421:Flavoring Agents; D005520:Food Preservatives; D039821:Monoterpenes; D010938:Plant Oils; D009561:Nisin; D019343:Citric Acid; D013943:Thymol; D000171:Acrolein; C073316:carvacrol; C102526:nisin A; C012843:cinnamaldehyde
keywords: Apple juice; C. sakazakii; E. coli O157:H7; Essential oils; Infant formula milk; Nisin