Assessment of physiological responses of bacteria to chlorine and UV disinfection using a plate count method, flow cytometry, and viability PCR

2021 ◽  
Author(s):  
Elaine Li Ching Chiang ◽  
Seunguk Lee ◽  
Carl Angelo Medriano ◽  
Liyan Li ◽  
Sungwoo Bae
Keyword(s):  
Flow Cytometry ◽  
Physiological Responses ◽  
Plate Count ◽  
Uv Disinfection ◽  
Count Method ◽  
Plate Count Method

Comparison between the EC plate count test at 21 °C and an accelerated plate count method for assessing the keeping quality of pasteurized milk

1992 ◽  
Vol 59 (3) ◽  
pp. 431-436 ◽  
Author(s):  
Sarah A. Langford ◽  
Rohan G. Kroll
Keyword(s):  
Plate Count ◽  
Gram Negative ◽  
Rapid Methods ◽  
Pasteurized Milk ◽  
Psychrotrophic Bacteria ◽  
Commercial Interest ◽  
Count Method ◽  
Keeping Quality ◽  
Plate Count Method

The keeping quality of properly refrigerated pasteurized milk and cream is primarily determined by post-pasteurization contamination by Gram-negative psychrotrophic bacteria (Phillips et al. 1981; Schröder et al. 1982). Reliable and rapid methods of assessing the levels of contamination by these organisms are therefore of commercial interest.

INDIVIDUAL PLOT STUDIES OF VARIATION IN NUMBERS OF BACTERIA IN SOIL: II. THE ERRORS OF THE PROCEDURE

1942 ◽  
Vol 20c (9) ◽  
pp. 444-456 ◽  
Author(s):  
Norman James ◽  
Marjorie L. Sutherland
Keyword(s):  
Environmental Factors ◽  
Large Error ◽  
Plate Count ◽  
Crop Season ◽  
Count Method ◽  
Plate Count Method ◽  
Chief Interest ◽  
The One

Data on the errors of the plate count method are presented. They are based on changes in numbers of bacteria during the crop season in plots supporting different crops. Duplicate samples were used at each step in the procedure. This provides information on variations associated with sampling, which contribute to the error of the plot estimate on any date.A large portion of the differences among estimates from each plot made on different dates is explained by correlations among numbers of bacteria and changes in environmental factors. Obviously, a large error masks a small relationship.This may be minimized by (1) careful sampling and the use of duplicates at each step in the procedure and (2) collecting data for correlating bacteria with changes in many environmental factors other than the one of chief interest m the investigation.

Impedance Measurement as an Alternative to the Plate Count Method for Estimating the Total Count of Bacteria in Raw Milk

1987 ◽  
Vol 50 (8) ◽  
pp. 665-668 ◽  
Author(s):  
F. F. J. NIEUWENHOF ◽  
J. D. HOOLWERF
Keyword(s):  
Standard Deviation ◽  
Microbiological Quality ◽  
Impedance Measurement ◽  
Raw Milk ◽  
Plate Count ◽  
Impedance Method ◽  
Count Method ◽  
Plate Counts ◽  
Plate Count Method

An improved impedance method is described with a good standard deviation of repeatability (sm = 0.05 log unit) and a fair standard deviation of the estimate of the plate count from the detection time [(sy)x = 0.33 log unit]. Compared with the standard deviation of repeatability of the plate count method (0.07 log unit), the standard deviation of repeatability of the impedance method described is a significant improvement. The impedimetric experiments were done with a Bactometer M123. The detection times as measured by this instrument were compared with the plate counts at 30°C for samples of raw refrigerated farm milk. With this technique a good indication of the microbiological quality of raw milk can be obtained within 15 h.

Study on the Detection of Total Colony in Medical and Health Environment Based on ATP Bioluminescence

2018 ◽  
Vol 24 (2) ◽  
Author(s):  
Zhe Li
Keyword(s):  
Culture Method ◽  
Pass Rate ◽  
Plate Count ◽  
Count Method ◽  
Atp Bioluminescence ◽  
Bioluminescence Assay ◽  
Plate Count Method ◽  
The Difference ◽  
Atp Bioluminescence Assay ◽  
Bioluminescence Method

In this paper, the application of ATP fluorescence in the detection of colonies in the health environment of hospitals was studied. Firstly, the principle of ATP bioluminescence method was described. Then, ATP bioluminescence and plate count method were used to test the density of the surface of the objects in selected area, taking the time points 2 hours after disinfection as the time nodes. The results showed that the difference between the qualified rate of ATP bioluminescence assay and the plate count method was statistically significant {P<0.01}. Therefore, ATP bioluminescence method was highly correlated with bacterial culture method. The correlation coefficient of pass rate of the two methods was 0.782, which indicated that there was a positive correlation between the two test results. Besides, the detection results showed that ATP bioluminescence method had higher sensitivity than plate counting method. Therefore, ATP bioluminescence method was more suitable for the rapid detection of the colony of hospital health environment, and helps the hospital to better manage its environmental hygiene conditions. 

scholarly journals Multiregional Evaluation of the SimPlate Heterotrophic Plate Count Method Compared to the Standard Plate Count Agar Pour Plate Method in Water

2000 ◽  
Vol 66 (1) ◽  
pp. 453-454 ◽  
Author(s):  
R. Wayne Jackson ◽  
Karen Osborne ◽  
Gary Barnes ◽  
Carol Jolliff ◽  
Dianna Zamani ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Water Samples ◽  
Plate Count ◽  
Heterotrophic Plate Count ◽  
Plate Method ◽  
Standard Plate Count ◽  
Plate Count Agar ◽  
Count Method ◽  
Standard Plate ◽  
Plate Count Method

ABSTRACT A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35°C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0.95;y = 0.99X + 0.06).

scholarly journals Fluorescence Assay for Evaluating Microbicidal Activity of Hand Antiseptics

2015 ◽  
Vol 81 (21) ◽  
pp. 7443-7447
Author(s):  
Rosa M. Lopez-Gigosos ◽  
Alberto Mariscal ◽  
Eloisa Mariscal-Lopez ◽  
Mario Gutierrez-Bedmar ◽  
Joaquin Fernandez
Keyword(s):  
Plate Count ◽  
Content Type ◽  
E Coli ◽  
Glucuronidase Activity ◽  
Count Method ◽  
Fluorescence Methods ◽  
Fluorescence Level ◽  
Assay Time ◽  
Plate Count Method ◽  
Time Required

ABSTRACTWe developed a fluorescent β-d-glucuronidase activity (BGA)-based assay for detecting and quantifyingEscherichia coliin samples to assess the biocide efficacy of hand antiseptics. The fluorescence level is proportional to the number of viableE. coliorganisms present. We compared our assay results to those of theE. coliplate count method specified by the European standard for testing hygienic hand rub disinfectant products (EN1500). The plate count method requires excessive handling and materials and is not valid if the number of organisms per plate is too low or high for counting in many of the samples. We optimized the fluorescent assay based on the cleavage of 4-methylumbelliferyl-β-d-glucuronide by adding 4-nitrophenyl-β-d-glucuronide, a nonfluorogenic BGA substrate, to induce glucuronidase activity and reduce assay time. Furthermore, our method can be automated and eliminates the need for multiple dilutions. Fluorescence was temporally monitored, and the time required to reach a specific value of fluorescence was correlated with the initial number of viableE. coliorganisms on the samples. There was a positive correlation (P< 0.05) with a high correlation coefficient (R2= 0.82) between theE. colicounts by plate count and fluorescence methods. Reported effects in fluorescent BGA were compared to the EN1500 plate count method with five hand disinfectants. We found our method more advantageous, because it was as sensitive as the EN1500 method, requires less time to complete, and is less expensive and less laborious than conventional plating techniques.

scholarly journals Application of the Micro Biological Survey analytical method for the determination of bacterial load in cow raw milk

2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Alessandra Cornacchia ◽  
Maria Antonietta Saletti ◽  
Violeta Di Marzio ◽  
Romolo Salini ◽  
Cristina Marfoglia ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Bacterial Load ◽  
Colorimetric Method ◽  
Independent Set ◽  
Raw Milk ◽  
Plate Count ◽  
Experimental Conditions ◽  
Biological Survey ◽  
Plate Count Method

The aim of this study was to evaluate the performance of “Micro Biological Survey – MBS Test” in the enumeration of bacterial load in cow raw milk. The MBS test is based on a colorimetric method recently developed and patented by “Roma Tre” University, Italy. The evaluation of the performance of the MBS method was carried out by comparison with plate count at 30°C (gold standard) and flow cytometry. Thirteen independent set of experiments were performed analyzing a total of 104 samples of cow raw milk with the selected methods. Results obtained using the MBS method are comparable with those obtained with the plate count method at 30°C (CFU/mL) and flow cytometry technology; in particular, the results obtained with the MBS method are very close to plate count’s at 30°C. On the other hand, there are statistically significant differences between these two methods’ and flow cytometry technology’s results that could be due to the different experimental conditions.

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