Comparison of Traditional Culture Method with DOX System for Detecting Coliform and <i>Escherichia coli</i> from Vegetables

Abstract

The methods of sanitary inspection performed primarily by traditional culture methods are time consuming, laborious, and require complicated laboratory techniques. A number of instrumental methods have been introduced for the rapid determination of viable cells based on the metabolic activities of microorganisms. The DOX system is one of the newly developed rapid inspection methods. It has three independent incubators that hold 60 vials each can estimate viable bacterial cell number by measuring the respiration speed of microorganisms and also has a high correlation between the detection time (Dt) and the viable bacterial cell number. We made a quantification analysis of coliform, and identified the presence of Escherichia coli from various kinds of vegetable samples. A total of 131 vegetable samples were tested to compare the plate count of coliform to the count using the DOX method. The correlation coefficient for the estimation of coliform-bacterial cell number was 0.85, which theoretically suggested that the DOX system was able to detect one cell of coliform-bacteria after 17.7 h of incubation. Among the 131 samples, 20 samples were confirmed for the presence of E. coli-positive cells using the UV-lamp method. This study suggested that the DOX system performs better than the conventional method for the routine inspection of coliform and E. coli from vegetable samples. Therefore, this system could be useful for the rapid detection of coliform and E. coli from vegetable samples with minimum labor and cost.

Development of a Screening Method and Device for the Detection of Escherichia coli from Agri-Food Production Environments and Fresh Produce

“…However, the growth of E. coli in Colilert-18 was obviously suppressed at 44°C. Other studies have reported that the Colilert system is a highly sensitive detection method that is capable of detecting 1 CFU/100 ml of E. coli [9,11,12]. It is known that 37°C is optimal for growth of E. coli because stressed E. coli cells can recover at this temperature [23].…”

“…The Colilert-18 assay system allows detection of E. coli within 18 h, and this rapid and simple method has been adopted for water analysis by the US Environmental Protection Agency [6] and the Korean Ministry of Environment [7]. The Colilert-18 assay system has been validated on different matrices, including raw meat, fresh-cut products, and water from marine and other sources [8][9][10][11][12][13]. Many researchers have reported that E. coli analysis based on enzyme reaction is very easy and efficient.…”

Efficacy of vermicomposting for recycling organic portion of hospital wastes using Eisenia fetida: standardization of cow manure proportion to increase enzymatic activities and fungal biomass

“…To determine the total coliform count by conventional method, 1.0 ml of the stomached mixture was poured on X-GAL (Nissui Co. Ltd., Tokyo) agar plates, and blue colonies were counted after the plates were incubated at 37°C overnight (Kawasaki et al 2003). …”

Evaluation of a Microbial Sensor as a Tool for Antimicrobial Activity Test of Cosmetic Preservatives

“…In this study, we propose a quick method to evaluate the antimicrobial activity using a microbial cellimmobilized oxygen electrode termed microbial sensor , by which a antimicrobial activity measurement could be completed within 30 min. Oxygen electrodes have been used for detection of microbial respiration in industrial samples Kawasaki et al, 2003 . On the other hand, by immobilizing the microbial cells on an oxygen electrode, the electrode could also serve as a toxicoid sensor by detecting the inhibition effect on microbial respiration Ikebukuro et al, 1996 .…”