Reduction of Listeria monocytogenes in queso fresco cheese by a combination of listericidal and listeriostatic GRAS antimicrobials.
Single and combined effects of three GRAS (generally recognized as safe) antimicrobials including, bacteriophage P100 (phage P100), lauric arginate (LAE), and potassium lactate-sodium diacetate mixture (PL-SD) were evaluated against Listeria monocytogenes cold growth in queso fresco cheese (QFC). The fate of phage P100 when exposed to LAE (200 ppm) or PL-SD (2.8% PL and 0.2% SD) was determined at 4°C and 30°C in a broth model. Phage P100 was found to be stable in the presence of these antimicrobial agents as plaque forming units (PFU) did not vary between control, LAE or PL-SD treatments. When 9 log CFU/ml of stationary phase cells of L. monocytogenes was exposed to these antimicrobials in tryptic soy broth, there was a 3 to 5 log CFU/ml reduction with phage P100 and a complete 9 log CFU/ml reduction with LAE but no measurable reduction with PL-SD after 24h at 4°C or 30°C. In QFC, the L. monocytogenes populations increased from the initial 3.5 log CFU/cm(2) to 7.7 log CFU/cm(2) in 28 days at 4°C. Treatment with 7.8 log PFU/cm(2) of phage P100 or 200 ppm of LAE showed strong listericidal effect initially by reducing L. monocytogenes counts by 2 to 3.5-4 log CFU/cm(2) while there was a subsequent regrowth of L. monocytogenes at 4°C. Treatment with PL-SD showed strong listeriostatic effect without decreasing L. monocytogenes counts but growth was prevented for 28 days at 4°C. Only the combined treatment of listericidal phage P100 or LAE with listeriostatic PL-SD reduced the initial L. monocytogenes counts by 2-4 log CFU/cm(2) and also kept the L. monocytogenes counts at that reduced level in QFC for 28 days at 4°C.
Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
Kamlesh A
KA
Soni
Monil
M
Desai
Ademola
A
Oladunjoye
Frederick
F
Skrobot
Ramakrishna
R
Nannapaneni
D000085:Acetates / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001435:Bacteriophages / Q000187:drug effects / Q000502:physiology; D002611:Cheese / Q000382:microbiology*; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005511:Food Handling; D005516:Food Microbiology / Q000379:methods*; D006801:Humans; D007773:Lactates / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology* / Q000821:virology
D000085:Acetates; D000900:Anti-Bacterial Agents; D007773:Lactates; C548838:sodium diacetate; C031371:N(alpha)-lauroylarginine ethyl ester; D001120:Arginine