Noreddine Benkerroum

Bacteriocin Activity By Lactobacillus Curvatus Cwbi-B28 To Inactivate Listeria Monocytogenes In Cold-Smoked Salmon During 4 Degrees C Storage

The inhibition effectiveness of a bacteriocin produced by Lactobacillus curvatus CWBI-B28 against Listeria monocytogenes was investigated in cold-smoked salmon during storage at 4 degrees C. Three bacteriocin-based strategies for the control of L. monocytogenes in foods (i.e., producing bacteriocin in situ, spraying with partially purified bacteriocin, and packaging in bacteriocin-coated plastic film), plus a newly developed method that uses cell-adsorbed bacteriocin (i.e., a suspension of producer cells on which maximum bacteriocin has been immobilized by pH adjustments), were assessed. Although all the approaches inactivated L. monocytogenes in cold-smoked salmon, various efficacy levels were observed. The behavior of L. monocytogenes was similar in samples treated with either partially purified bacteriocin or in situ bacteriocin production. In both of these cases, the counts of the pathogen declined to below the detectable limit of 0.7 log CFU/cm2 within the first week, but a approximately 0.95- and 1.3-log increase, respectively, occurred after day 14. The bioactive packaging film resulted in a slower inactivation of the pathogen but prevented any subsequent increase in the CFU throughout 22 days of storage at 4 degrees C. Application of the cell-adsorbed bacteriocin was shown to be the most effective means, as it resulted in a complete inactivation of the pathogen within 3 days, and no increase in Listeria counts occurred up to 22 days.

Effectiveness of cell-adsorbed bacteriocin produced by Lactobacillus curvatus CWBI-B28 and selected essential oils to control Listeria monocytogenes in pork meat during cold storage.

Aims:  To study the effectiveness of a combination of cell‐adsorbed bacteriocin (CAB; a suspension of producer cells on which maximum bacteriocin has been immobilized by pH adjustments) of a Lactobacillus curvatus strain with oregano or savory essential oil to control Listeria monocytogenes in pork meat at 4°C.

Antilisterial Bacteriocin-Producing Strain Of Lactobacillus Curvatus Cwbi-B28 As A Preservative Culture In Bacon Meat And Influence Of Fat And Nitrites On Bacteriocins Production And Activity

The objectives of this study were to evaluate the effectiveness of a bacteriocin-producing Lactobacillus curvatus CWBI-B28 to inhibit the growth of Listeria monocytogenes in de Man, Rogosa and Sharp (MRS) broth and in bacon meat. A co-culture of L. monocytogenes with the Bac strain in MRS broth, resulted in a reduction of the pathogen counts by 4.2 log cycles after 24h of incubation at 37°C. In bacon, the counts of L. monocytogenes was reduced to below the detectable limit (<10cfu/g) in samples inoculated with the Bac strain within 1 or 2 weeks in absence or presence of nitrites (210mg/kg), respectively. However, a week later, a re-growth of the pathogen has occurred. In contrast, no such reduction in Listeria cfus was observed in samples treated with the Bac derivative of Lb. curvatusCWBI-B28. Nonetheless, the extent of inhibitory effect of the Bac strain against L. monocytogenes in bacon was somewhat reduced in the presence of nitrites. A separate study on the influence of nitrites and fats on growth and bacteriocin production by Lb. curvatus CWBI-B28 revealed that the curing agent affects the growth of the Bac strain and, thereby bacteriocin production and activity only at concentrations (>5%) far beyond those allowed in the meat industry. Fat content did not affect the bacterial growth even at the highest concentration used (i.e. 50%), however, it interfered significantly with the detection of AUs and the antilisterial activity. Use of the Bac Lb. curvatus CWBI-B28 has proven efficient in controlling L. monocytogenes in bacon despite the slight antagonistic effect of nitrites, however the efficacy was dramatically reduced upon extended period of storage at 4°C.

Purification and characterization of three novel plasmid-born bacteriocins (curvalicins 28) produced by Lactobacillus curvatus CWBI-B28

Hakim Ghalfi, Noreddine Benkerroum*, Marc Ongena, Jozef Van Beeumen, Bernard Wathelet, Isabel Vandenberghe, Maryam Bensaid and Philippe Thonart Unite de Bio-Industries, Faculte Universitaire des Sciences Agronomiques de Gembloux, 2 Passage de Deportes, B-5030, Gembloux, Belgium; Departement des Sciences Alimentaires et Nutritionnelles, Institut Agronomique et Veterinaire Hassan II, Instituts, 10101, Rabat, Morocco; Centre Wallon de Bio-Industries, Universite de liege, Bâtiment B40, 4000, Liege, Belgium; Laboratory of Protein Biochemistry and Protein Engineering, Faculty of Sciences, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium; Unite de Chimie Biologique Industrielle, Faculte Universitaire des Sciences Agronomiques de Gembloux, 2 Passage de Deportes, B-5030, Gembloux, Belgium; *Author for correspondence (e-mail: nbenkerroum@yahoo.fr; phone: +212 37 77 17 59; fax: +212 37 77 81 35)