Rapid Enumeration of Bacteria with Growth Ability in Foods by Microcolony Method

Abstract

The microcolony method is based on microscopic observation of the early stage of colony formation on laboratory media, which allows rapid and accurate enumeration of bacteria with growth ability via epifluorescence microscopy or microcolony automated counting system. In this study, the microcolony method was used to estimate the number of viable bacteria in various foods. The optimized protocol generated results on number of bacteria with growth ability in ground meat, precut vegetables, frozen spinach, precut melon, soybean curd, Chinese noodles, bean cake, white sauce, steamed cake within 24 hours. The accuracy of estimates by the microcolony method could be obtained by comparing the conventional plate counts. The results of this study showed that the microcolony method provides a useful tool to enumerate bacteria with growth ability in foods more rapidly and accurately than conventional plate counting.