Premium
Non‐exponential growth of Mycobacterium leprae Thai‐53 strain cultured in vitro
Author(s) -
Amako Kazunobu,
Iida Kenichiro,
Saito Mitsumasa,
Ogura Yoshitoshi,
Hayashi Tetsuya,
Yoshida Shinichi
Publication year - 2016
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/1348-0421.12454
Subject(s) - mycobacterium leprae , biology , bacteria , in vitro , microbiology and biotechnology , exponential growth , tissue culture , strain (injury) , liquid medium , cell culture , immunology , genetics , chemistry , anatomy , leprosy , mathematical analysis , mathematics , chromatography
In this study, attempts were made to culture this bacterium in media supplemented with a variety of biological materials to determine why cultivation of Mycobacterium leprae in vitro has not this far been successful. A slight increase in the number of cells in medium supplemented with human blood plasma and an extract of nude mouse tissue as observed after more than 3 months of cultivation at 30 °C. To ascertain whether this increase was real growth, the growth was analyzed by droplet digital PCR, which showed a slow increase in the copy number of cell‐associated DNA and the release of a large amount of DNA into the culture medium from bacterial cells during cultivation. These results were supported by electron microscopic examination of M. leprae in infected mouse tissues, which showed that most of the replicated bacteria had degenerated and only a few cells survived. Based on these results, it was postulated that many of the replicated cells degenerate during M. leprae growth and that only a few cells remain to participate in the next growth stage. This means that, unlike other cultivable bacteria, the growth of M. leprae is not exponential and the number of cells therefore increase extremely slowly. Thus, accurate judging of the success of M. leprae cultivation requires observation of growth over a long period of time and careful measurement of the increase in number of viable cells.