Availability of Growth Delay Analysis for the Evaluation of Total Injury of Stressed Bacterial Populations

概要

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Growth delay analysis was developed for estimating total injury of a bacterial cell population, which had been subjected to bactericidal stress, using an automatic growth-recording apparatus. Integrated viability, ν, was proposed as ν=Σ^^κ__<ξ=1>n_i exp (-μλ_i), where λ_i is the increment of the lag time for the stressed cells in the i-th fraction, n_i, and μ is the specific growth rate. ν is a more general indicator for the total injury in a stressed population than the colony forming unit, which is a limited ν-value where λ_i is supposed to be either 0 or ∞. The delay time for growth of stressed bacteria referred to untreated bacteria was easily obtained using an automatic growth-recording apparatus, and shown to be-G_<10> log ν, where G_<10> is the delay time corresponding to the reduction of an inoculum size by one-tenth. The integrated viability determined under the test conditions of heated Escherichia coli was less than the relative colony forming units. The heat resistance of Bacillus subtilis FJ2 cells forming unseparative chains could be compared with that of normal cells of the wild type strain, using growth delay analysis. Availability of this method is discussed in comparison with that of the colony count method.
公益社団法人日本生物工学会の論文
1982-06-25