We present a simple and rapid method for screening nisin producers that directly identifies nisinogenic bacteria by induction of bioluminescence within the Lactococcus lactis NZ9800lux biosensor strain (Immonen and Karp, 2007, Biosensors and Bioelectronics 22, 1982-7). An overlay of putative nisinogenic colonies with the biosensor strain gives identification results within 1h. Functionality and specificity of the method were verified by screening nisin producers among 144 raw milk colonies and a panel of 91 lactococcal strains. Studies performed on strains and colonies that did not induce bioluminescence but inhibited growth of the biosensor demonstrated that only nisinogenic bacteria can cause induction. Bacteria known to produce bacteriocins other than nisin failed to induce bioluminescence, further verifying the specificity of the assay. We discovered a non-inducing but inhibitory lactococcal strain harboring a modified nisin Z gene, and demonstrated that the source of the inhibitory action is not a non-inducing variant of nisin, but a bacteriocin of lower molecular weight. The concentration of nisin producers in a raw milk sample was 1.3×102CFU/ml. We identified from raw milk a total of seven nisin Z producing L. lactis subsp. lactis colonies, which were shown by genetic fingerprinting to belong to three different groups. Among the panel of 91 lactococci, four strains were nisin A producers, and one strain harbored the modified nisin Z gene. The method presented here is robust, cost-effective and simple to perform, and avoids the pitfalls of traditional screening methods by directly specifying the identity of the inhibitory substance.

Virolainen, N., Guglielmetti, S., Arioli, S., Karp, M. (2012). Bioluminescence-based identification of nisin producers - a rapid and simple screening method for nisinogenic bacteria in food samples. INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY, 158(2), 126-132 [10.1016/j.ijfoodmicro.2012.07.007].

Bioluminescence-based identification of nisin producers - a rapid and simple screening method for nisinogenic bacteria in food samples

Guglielmetti, S
Secondo
;
2012

Abstract

We present a simple and rapid method for screening nisin producers that directly identifies nisinogenic bacteria by induction of bioluminescence within the Lactococcus lactis NZ9800lux biosensor strain (Immonen and Karp, 2007, Biosensors and Bioelectronics 22, 1982-7). An overlay of putative nisinogenic colonies with the biosensor strain gives identification results within 1h. Functionality and specificity of the method were verified by screening nisin producers among 144 raw milk colonies and a panel of 91 lactococcal strains. Studies performed on strains and colonies that did not induce bioluminescence but inhibited growth of the biosensor demonstrated that only nisinogenic bacteria can cause induction. Bacteria known to produce bacteriocins other than nisin failed to induce bioluminescence, further verifying the specificity of the assay. We discovered a non-inducing but inhibitory lactococcal strain harboring a modified nisin Z gene, and demonstrated that the source of the inhibitory action is not a non-inducing variant of nisin, but a bacteriocin of lower molecular weight. The concentration of nisin producers in a raw milk sample was 1.3×102CFU/ml. We identified from raw milk a total of seven nisin Z producing L. lactis subsp. lactis colonies, which were shown by genetic fingerprinting to belong to three different groups. Among the panel of 91 lactococci, four strains were nisin A producers, and one strain harbored the modified nisin Z gene. The method presented here is robust, cost-effective and simple to perform, and avoids the pitfalls of traditional screening methods by directly specifying the identity of the inhibitory substance.
Articolo in rivista - Articolo scientifico
Bacteriocins; Lactococcus lactis subsp. lactis/cremoris; Nisin producer; Non-functional nisin gene; Whole-cell biosensor;
English
2012
158
2
126
132
reserved
Virolainen, N., Guglielmetti, S., Arioli, S., Karp, M. (2012). Bioluminescence-based identification of nisin producers - a rapid and simple screening method for nisinogenic bacteria in food samples. INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY, 158(2), 126-132 [10.1016/j.ijfoodmicro.2012.07.007].
File in questo prodotto:
File Dimensione Formato  
Virolainen-2012-Int J Food Microbiol-VoR.pdf

Solo gestori archivio

Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Licenza: Tutti i diritti riservati
Dimensione 842.74 kB
Formato Adobe PDF
842.74 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/458447
Citazioni
  • Scopus 8
  • ???jsp.display-item.citation.isi??? 5
Social impact