Fast and less thermal degradation protocol for Chromocultฎ Coliform Agar (CCA) preparation to detect E. coli
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Publication Details
Author list: Supanivatin P., Khueankhancharoen J., Saeung W., Thipayarat A.
Publication year: 2011
Journal: Thai Journal of Agricultural Science (0049-3589)
Volume number: 44
Issue number: 5
Start page: 459
End page: 465
Number of pages: 7
ISSN: 0049-3589
Languages: English-Great Britain (EN-GB)
Abstract
Effects of Chromocult® Coliform Agar (CCA) preparation methods on E. coli colony size and chromatic development were evaluated by comparing different mechanical and heat treatments. The colony growth kinetics obtained from the conventional preparation protocol (without autoclave) were assessed against that from two alternative approaches including the adjusted protocols applying autoclave sterilization and the high mechanical shear blending using fast microwave pasteurization. In this research, micro inoculation culture (MIC) technique was applied to detect E. coli using 5 μL inoculum and the incubation temperature was fixed at 35±2°C. The size expansion and chromatic changes of E. coli colonies were detected using digital image analysis. The CCA prepared using the alternative applying high shear and fast pasteurization protocol promoted more effective colony expansion of E. coli than the other two methods. The red and green color attributes were less affected by fast heating; however, the blue property of the colony showed substantial deterioration in color intensity. The overall chromatic characteristic of E .coli colonies was significantly affected by heat and preparation variation. High mechanical force helped dissolving agar media very rapidly and mitigated thermal degradation of heat sensitive components, resulting in the better nutrient assimilation of E. coli colonies. All these CCA preparation can be used interchangeably. The application of fast preparation of the CCA was of great benefit to industries where E.coli and coliforms detection are compulsory. The proposed fast CCA preparation can greatly enhance throughput and reduce complexity of the overall detection protocol.
Keywords
Chromatic, Micro inoculation culture
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