LAUSR

Abstract Background The 3M™ Petrifilm™ Rapid Yeast and Mold Count (RYM) Plate contains nutrients supplemented with antibiotics, a cold-water-soluble gelling agent, and an indicator system that facilitates yeast and mold enumeration in 48–60 h. Objective The objective of this study is to evaluate the 3M Petrifilm RYM Plate in a matrix extension study for the enumeration of yeast and mold on stainless steel, sealed concrete, and rubber surfaces. Methods The 3M Petrifilm RYM Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual, Ch. 18: Yeasts, Molds and Mycotoxins in a paired matrix study for enumeration of yeast and mold on stainless steel, sealed concrete, and rubber environmental surfaces. Results The 3M Petrifilm RYM Plate demonstrated equivalent performance to the reference method for enumeration of yeast and mold from stainless steel, sealed concrete, and rubber environmental surfaces. There were no significant statistical differences between the 3M Petrifilm RYM Plate and reference method results for the three matrixes evaluated. Conclusion The 3M Petrifilm RYM Plate is an effective plating method for enumerating yeast and mold when analyzing stainless steel, sealed concrete, and rubber surfaces. Highlights The 3M Petrifilm RYM Plate method allows the user to obtain accurate results within 48–60 h in the matrices evaluated for the presence of yeast and mold when incubated at 25 ± 1°C or 28 ± 1°C. Interpretation and colony counting was straightforward and the 3M Petrifilm RYM Plate method required no additional agar or Petri dishes, creating an easier workflow by cutting down on supplies, sample plating time, and most noticeably, occupying less space in the incubator.