Location: Dairy and Functional Foods
Title: Heterologous production of pediocin for the control of Listeria monocytogenes in dairy foods Authors
Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2011
Publication Date: July 1, 2011
Citation: Renye Jr, J.A., Somkuti, G.A., Garabal, J.I., Du, L. 2011. Heterologous production of pediocin for the control of Listeria monocytogenes in dairy foods. Food Control. 22:1887-1892. Interpretive Summary: Nisin is a small protein, approved for use by the FDA in products to prevent contamination by foodborne pathogens. However, the emergence of pathogens resistant to nisin requires new techniques to prevent the outbreak of foodborne illness. Lactic acid bacteria (LAB) which are considered safe for human consumption can produce additional small proteins with activity against foodborne pathogens. Since some LAB that produce these proteins are unable to grow in milk, we have developed techniques to allow the production of these bioprotective agents in bacteria that are commonly used to manufacture yogurt and cheeses. In this study, dairy LAB were modified to produce a small protein called pediocin with potent activity against Listeria, an important foodborne pathogen. The presence of nisin was required for optimal production of the pediocin which was shown to inhibit the growth of nisin-resistant pathogens such as Listeria. The results suggest that nisin and pediocin can be used together to improve strategies for producing these antimicrobial agents, leading to new approaches to food preservation to prevent bacterial contamination of dairy foods.
Technical Abstract: Pediocin is an antimicrobial peptide naturally produced by Pediococci with the potential to serve as a food-grade preservative for controlling Listeria contamination. The use of Pediococci in dairy products is limited due to their inability to ferment lactose, thus lactic acid bacteria (LAB) have been considered as potential hosts for the heterologous production of pediocin. In this study the four gene operon (papA-D) required for pediocin production was cloned on the nisin-inducible expression vector pMSP3535H3. The resulting vector, pRSNPed2, was electrotransformed into Streptococcus thermophilus, Lactococcus lactis ssp. lactis and Lactobacillus casei. Transformants containing the properly constructed vector were identified by PCR analysis and shown to inhibit the growth of Listeria monocytogenes Scott A. S. thermophilus transformants were all shown to constitutively express pediocin; however, in L. lactis and L. casei both constitutive and inducer-dependent expression was observed. In all cases nisin-induction resulted in optimal pediocin production. Transformants from each LAB host were also shown to inhibit the growth of L. monocytogenes NR30, a nisin-resistant variant of L. monocytogenes Scott A. These results suggest pediocin has the potential to serve as a hurdle component along with nisin for prevention of Listeria contamination of foods.