Growth of yeast and mold on trypan blue agar in conjunction with the ISO-GRID system

Abstract

Enumeration of yeast and molds on trypan blue (at 1:10 000 dilution) in potato dextrose sugar (trypan blue agar) was compared with potato dextrose agar (PDA) plus safranin flooding procedure using the hydrophobic grid-membrane filter technique (HGMF) of the ISO-GRID system. Yeast and mold grew well on trypan blue agar, producing easily recognized blue colonies on the ISO-GRID system. Results indicated that trypan blue agar is more convenient to use than the PDA plus safranin flooding procedure and as reliable (r = 0.99) for enumerating yeast and mold of cheeses, spices and dry products, and salad samples.

RAPID METHODS FOR IDENTIFYING SEAFOOD MICROBIAL PATHOGENS AND TOXINS1

“…Fung and colleagues through the years developed a variety of miniaturized microbiological techniques to effectively analyze large numbers of bacteria (Fung and Hartman 1972; Fung and Miller 1970, 1972, 1973 Fung and Neimeic 1977), yeasts (Fung and Liang 1990; Lin and Fung 1995;Lin et al 1984;Goldschmidt el al. 1991) and molds (Hart-Thakur and Fung 1995).…”

COMPARATIVE ANALYSIS OF TRYPAN BLUE AGAR AND CONGO RED AGAR FOR THE ENUMERATION OF YEAST AND MOLD USING THE HGMF SYSTEM1

“…In the original procedure (Brodsky et al 1982) for enumerating yeast and mold by the hydrophobic grid-membrane filter (HGMF), cultures were first grown on the filters and then a dye (safranin) was applied on the filter to facilitate reading of the colonies. To directly enumerate yeast and mold from foods using the HGMF system without the need for flooding the plate with safranin, Lin et al (1984) developed a Trypan blue agar method. Slifkin and Cumbie (1988) reported using Congo red as a fluorochrome for the rapid detection of fungi under ultraviolet light (UV).…”

Automation of microbial enumeration: development of a disposable hydrophobic grid-membrane filter unit

“…The HGMF is used for enumeration of coliforms, fecal coliforms (3)(4)(5)16), Salmonella sp. (6,10), Vibrio parahaemolyticus (8), Staphylococcus sp. (2), yeasts, and molds (1,10); disinfectant testing (P. Entis and P. J. Boleszczuk, Abstr.…”

“…(6,10), Vibrio parahaemolyticus (8), Staphylococcus sp. (2), yeasts, and molds (1,10); disinfectant testing (P. Entis and P. J. Boleszczuk, Abstr. Annu.…”