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Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water

Received: 23 March 2022     Accepted: 8 April 2022     Published: 25 April 2022
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Abstract

The evaluation of measurement uncertainty (MU) is an important method for quantitative determinations derived by microbial cultivation, thus it could further improve the result accuracy. In this study, we aimed to evaluate the MU in total bacteria counts (TBC) in water. Experiments were carried out using Pour Plate Method. The bottom-up approach was used to access the MU of TBC and different mathematical models were set up based on microbial growth principles and test process. Two geometric and five non-geometric progression factors derived from fishbone diagram were selected in these models, especially considering the influence of the bacteria binary fission. The results showed that the calculated value of expanded uncertainty was between 82 and 120CFU/mL when the test result was 100CFU/mL with the 95% confidence level. The geometric progression factor had a greater impact on MU evaluation with almost 80% of contribution, whilst non-geometric progression factor dedicated 60%. Experimental procedures such as sample repeatability, reproducibility and inoculation time should be drawn more attention, thus the accuracy of results could be improved. These innovative models not only reasonable and reliable, but also easy to use. The achievements of this study illustrated that the MU evaluation method could also be applied for analyzing other microbial indicators in water.

Published in American Journal of Environmental Protection (Volume 11, Issue 2)
DOI 10.11648/j.ajep.20221102.14
Page(s) 32-38
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2022. Published by Science Publishing Group

Keywords

Measurement Uncertainty, Total Bacteria Count, Geometric Progression, Pour Plate Method

References
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[3] ILAC. (2021). ILAC Guidelines for measurement uncertainty in testing. ILAC-G17: 01/2021.
[4] ISO/IEC 17025: 2017. General requirements for the competence of testing and calibration laboratories.
[5] China National Accreditation Service for Conformity Assessment. CNAS-CL01-A001: 2018. Guidance on the application of testing and calibration laboratory competence accreditation criteria in the field of microbiological testing [S]. Bei Jing: China National Accreditation Service for Conformity Assessment.
[6] ISO 19036: 2019. Microbiology of the food chain — Estimation of measurement uncertainty for quantitative determinations.
[7] American Public Health Association, American Water Works Association, Water Environment Federation. (2017). Standard Methods for the Examination of Water and Wastewater (23Rd Edition).
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[9] Niemi, R. M., Niemelä, S. I. (2001). Measurement uncertainty in microbiological cultivation methods. Accreditation and Quality Assurance, 6, 372-375.
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[16] Gill W. J., Sun I. C., Seung H. C., Han X. G., Men X., Kwon H. Y., Choi Y. E., Lee O. H. (2021). Method validation of 12 kinds of food dye in chewing gums and soft drinks, and evaluation of measurement uncertainty for soft drinks. Food Chemistry, 356 (9), 129705. https://doi.org/10.1016/j.foodchem.2021.129705.
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[18] Francielle R. S. D., Felipe R. L. (2020). Top-down evaluation of the matrix effects in microbial enumeration test uncertainty. Journal of Microbiological Methods, 171 (4). https://doi.org/10.1016/j.mimet.2020.105864.
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Cite This Article
  • APA Style

    Zhi Xuan Li, Wei Ma, Yi Jun Kong, Sin Neng Chio, Chang Li Zhang, et al. (2022). Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water. American Journal of Environmental Protection, 11(2), 32-38. https://doi.org/10.11648/j.ajep.20221102.14

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    ACS Style

    Zhi Xuan Li; Wei Ma; Yi Jun Kong; Sin Neng Chio; Chang Li Zhang, et al. Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water. Am. J. Environ. Prot. 2022, 11(2), 32-38. doi: 10.11648/j.ajep.20221102.14

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    AMA Style

    Zhi Xuan Li, Wei Ma, Yi Jun Kong, Sin Neng Chio, Chang Li Zhang, et al. Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water. Am J Environ Prot. 2022;11(2):32-38. doi: 10.11648/j.ajep.20221102.14

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  • @article{10.11648/j.ajep.20221102.14,
      author = {Zhi Xuan Li and Wei Ma and Yi Jun Kong and Sin Neng Chio and Chang Li Zhang and Chi Tou Lei and She Xia Zhan},
      title = {Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water},
      journal = {American Journal of Environmental Protection},
      volume = {11},
      number = {2},
      pages = {32-38},
      doi = {10.11648/j.ajep.20221102.14},
      url = {https://doi.org/10.11648/j.ajep.20221102.14},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajep.20221102.14},
      abstract = {The evaluation of measurement uncertainty (MU) is an important method for quantitative determinations derived by microbial cultivation, thus it could further improve the result accuracy. In this study, we aimed to evaluate the MU in total bacteria counts (TBC) in water. Experiments were carried out using Pour Plate Method. The bottom-up approach was used to access the MU of TBC and different mathematical models were set up based on microbial growth principles and test process. Two geometric and five non-geometric progression factors derived from fishbone diagram were selected in these models, especially considering the influence of the bacteria binary fission. The results showed that the calculated value of expanded uncertainty was between 82 and 120CFU/mL when the test result was 100CFU/mL with the 95% confidence level. The geometric progression factor had a greater impact on MU evaluation with almost 80% of contribution, whilst non-geometric progression factor dedicated 60%. Experimental procedures such as sample repeatability, reproducibility and inoculation time should be drawn more attention, thus the accuracy of results could be improved. These innovative models not only reasonable and reliable, but also easy to use. The achievements of this study illustrated that the MU evaluation method could also be applied for analyzing other microbial indicators in water.},
     year = {2022}
    }
    

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  • TY  - JOUR
    T1  - Evaluation of Measurement Uncertainty from Pour Plate Method in Bacterial Enumeration in Water
    AU  - Zhi Xuan Li
    AU  - Wei Ma
    AU  - Yi Jun Kong
    AU  - Sin Neng Chio
    AU  - Chang Li Zhang
    AU  - Chi Tou Lei
    AU  - She Xia Zhan
    Y1  - 2022/04/25
    PY  - 2022
    N1  - https://doi.org/10.11648/j.ajep.20221102.14
    DO  - 10.11648/j.ajep.20221102.14
    T2  - American Journal of Environmental Protection
    JF  - American Journal of Environmental Protection
    JO  - American Journal of Environmental Protection
    SP  - 32
    EP  - 38
    PB  - Science Publishing Group
    SN  - 2328-5699
    UR  - https://doi.org/10.11648/j.ajep.20221102.14
    AB  - The evaluation of measurement uncertainty (MU) is an important method for quantitative determinations derived by microbial cultivation, thus it could further improve the result accuracy. In this study, we aimed to evaluate the MU in total bacteria counts (TBC) in water. Experiments were carried out using Pour Plate Method. The bottom-up approach was used to access the MU of TBC and different mathematical models were set up based on microbial growth principles and test process. Two geometric and five non-geometric progression factors derived from fishbone diagram were selected in these models, especially considering the influence of the bacteria binary fission. The results showed that the calculated value of expanded uncertainty was between 82 and 120CFU/mL when the test result was 100CFU/mL with the 95% confidence level. The geometric progression factor had a greater impact on MU evaluation with almost 80% of contribution, whilst non-geometric progression factor dedicated 60%. Experimental procedures such as sample repeatability, reproducibility and inoculation time should be drawn more attention, thus the accuracy of results could be improved. These innovative models not only reasonable and reliable, but also easy to use. The achievements of this study illustrated that the MU evaluation method could also be applied for analyzing other microbial indicators in water.
    VL  - 11
    IS  - 2
    ER  - 

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Author Information
  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

  • Laboratory and Research Centre, The Macao Water Supply Company Limited, Macao SAR, China

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