Image-based Automatic Counting of Bacillus cereus Colonies using Smartphone

Phongsatorn Taithong,Siriwan Wichai,Panomkhawn Riyamongkol,Rattapoom Waranusast

doi:10.14569/ijacsa.2022.0130274

Abstract

Substantial amounts of Bacillus cereus bacteria present in food indicates that the food is unsafe to eat, so counting B. cereus colonies in food samples is a common test for food cleanliness. Manual counting of B. cereus bacteria colonies requires approximately 2-5 minutes per Petri dish, depending on the number of colonies present. This study presents a new smartphone-based method called Bacillus Cereus Image Counting System (BCICS, “B. kiks”) for automatic counting of B. cereus colonies. BCICS uses image processing techniques including Projection Profiling, Circle Hough Transformation, Adaptive Thresholding, and Power-Law Transformation to achieve high image clarity and then uses the Connected-Component Labeling (CCL) technique to correctly count the colonies, including overlapping colonies. These techniques are built into a convenient Android smartphone application. Results of counting the colonies with BCICS were compared with results of hand counting the same dishes. The accuracy rate of each dish count was calculated, as well as the average dish accuracy across all dishes. BCICS counted total colonies with an accuracy of 90.14%, which is close to that of hand counting accuracy since hand counting itself commonly involves an error rate of 5-10%. Importantly, the application took only 3-5 seconds to count one Petri dish, which is more than 74 times faster than the time required for manual counting.

Highlights

IntroductionB. cereus, is an aerobic spore-forming bacterium that naturally inhabits soils and plants [1,2]
Bacillus cereus, or B. cereus, is an aerobic spore-forming bacterium that naturally inhabits soils and plants [1,2]
Substantial amounts of Bacillus cereus bacteria present in food indicates that the food is unsafe to eat, so counting B. cereus colonies in food samples is a common test for food cleanliness

Summary

Introduction

B. cereus, is an aerobic spore-forming bacterium that naturally inhabits soils and plants [1,2]. B. cereus is one of the most important foodborne pathogenic bacteria, and it can cause two types of food poisoning. The first, emetic syndrome, is characterized by nausea and vomiting and occurs within a few hours of consumption of contaminated food. The second, diarrheal syndrome, is characterized by abdominal pain and diarrhea [3] and occurs within 3-4 hours of consumption of contaminated food. Besides B. cereus, other members of the Bacillus group of bacteria can cause food poisoning outbreaks through consumption of raw fruits and vegetables, and this is a major concern in food safety [4-6]. In Slovakia, B. cereus colonies in pasteurized milk at 30°C are not allowed to exceed a total dish count of 3 × 104 CFU/ml. When pasteurized milk is incubated for 5 days at 6°C, the total dish count must not exceed 5 × 104 CFU/ml. When pasteurized milk is incubated for 5 days at 6°C, the total dish count must not exceed 5 × 104 CFU/ml. [7]

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Conclusion