Listeria monocytogenes remains one of the most serious foodborne pathogens facing food manufacturers, and environmental monitoring for Listeria species is central to keeping it out of production. A newly published evaluation by Kikkoman Biochemifa has now put Easy Plate™ LS head to head against the established laboratory media, and the results are worth a look.
What Was Tested
Easy Plate™ LS is a ready-to-use (RTU) film medium that detects and enumerates Listeria species in just 24 hours, with no media preparation or sterilisation required. The study evaluated its selectivity against five alternatives:
- Three conventional agar media — ALOA, PALCAM, and a chromogenic agar
- Two other commercially available ready-to-use media (referred to as RTU-A and RTU-B)
The inclusivity study covered 28 Listeria monocytogenes strains plus 20 strains of other Listeria species. The exclusivity study assessed 28 non-target strains. Each strain was enriched overnight, diluted in BPW, inoculated at roughly 100 CFU per plate, and incubated at 35–37°C, with readings taken at 24, 28 and 48 hours.
The Results
Every medium detected all L. monocytogenes strains within 24 hours. The real difference showed up with the other Listeria species:
- Easy Plate™ LS: 75% recovery (15/20) at 24 hours, rising to 85% (17/20) at 28 hours
- RTU-A and RTU-B: approximately 50% recovery at 24 hours
- ALOA: 90% (18/20) — the highest recovery of the group
- PALCAM and chromogenic agar: 65–70% at 24 hours
In other words, Easy Plate™ LS clearly outperformed the competing ready-to-use media and sat close behind traditional ALOA agar — while remaining far simpler to use. A few species, including L. seeligeri, L. ivanovii and L. grayi, needed extended incubation for optimal recovery.
Selectivity was equally strong. In the exclusivity study, Easy Plate™ LS, RTU-A and ALOA showed no growth of non-target strains through to 48 hours. Some of the other media allowed Enterococcus and Bacillus species to grow under prolonged incubation — a common source of false positives that costs time and triggers unnecessary investigations.
Why This Matters for Your Monitoring Programme
Environmental monitoring only works if the results can be trusted and returned quickly. This evaluation shows Easy Plate™ LS delivers high selectivity and reliable detection of Listeria species while minimising false-positive growth. Practically, that means:
- Results in 24 hours — faster decisions on product release and corrective action
- No media preparation or sterilisation — less labour, less equipment, less room for error
- Fewer false positives — non-target organisms suppressed through 48 hours
- Space and waste savings — the stackable film format uses a fraction of the space of petri dishes
The Bottom Line
For food manufacturers running routine environmental monitoring for Listeria, Easy Plate™ LS offers laboratory-grade selectivity in a format that any trained operator can use, with no media prep and results the next day. It is a straightforward way to strengthen a Listeria control programme without adding laboratory overhead.
Easy Plate™ LS is available in Australia from FMCG Industry Solutions, backed by our team of qualified microbiological specialists.
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