Giant number fluctuations in microbial ecologies

JOURNAL OF THEORETICAL BIOLOGY

卷:308

Article

Das, Dipjyoti¹  Das, Dibyendu¹  Prasad, Ashok² 

[1] Indian Inst Technol, Dept Phys, Bombay 400076, Maharashtra, India

[2] Colorado State Univ, Dept Chem & Biol Engn, Ft Collins, CO 80523 USA

关键词: Population dynamics;    Stochastic growth;    Mutation;    Lysis-lysogeny;    Horizontal gene transfer;   

DOI  :  10.1016/j.jtbi.2012.05.030

来源: Elsevier

【 摘 要 】

Statistical fluctuations in population sizes of microbes may be quite large depending on the nature of their underlying stochastic dynamics. For example, the variance of the population size of a microbe undergoing a pure birth process with unlimited resources is proportional to the square of its mean. We refer to such large fluctuations, with the variance growing as square of the mean, as giant number fluctuations (GNF). Luria and Delbruck showed that spontaneous mutation processes in microbial populations exhibit GNF. We explore whether GNF can arise in other microbial ecologies. We study certain simple ecological models evolving via stochastic processes: (i) bi-directional mutation, (ii) lysis-lysogeny of bacteria by bacteriophage, and (iii) horizontal gene transfer (HGT). For the case of bidirectional mutation process, we show analytically exactly that the GNF relationship holds at large times. For the ecological model of bacteria undergoing lysis or lysogeny under viral infection, we show that if the viral population can be experimentally manipulated to stay quasi-stationary, the process of lysogeny maps essentially to one-way mutation process and hence the GNF property of the lysogens follows. Finally, we show that even the process of HGT may map to the mutation process at large times, and thereby exhibits GNF. (C) 2012 Elsevier Ltd. All rights reserved.

【 授权许可】

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