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Surveillance of single‐cell behavior in different subpopulations of Ralstonia pickettii AR1 during growth and polyhydroxybutyrate production phases by flow cytometry
Author(s) -
Shakeri Shahryar,
Roghanian Rasoul,
Emtiazi Giti
Publication year - 2012
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201100042
Subject(s) - polyhydroxybutyrate , exponential growth , flow cytometry , biology , stationary phase , intracellular , population , limiting , microbiology and biotechnology , strain (injury) , biophysics , bacteria , chemistry , genetics , chromatography , physics , anatomy , mechanical engineering , demography , quantum mechanics , sociology , engineering
Most bacterial strains accumulate intracellular polyhydroxybutyrate (PHB) granules as an energy reservoir, in response to fluctuations in their microenvironment. Flow cytometry was applied for the analysis of single cells of Ralstonia pickettii AR1 in response to changes in the culture conditions. Two parameters, the PHB production‐related FL2 and side scatter (SSC) parameters, were used to monitor, distinguish and characterize different subpopulations in the growth and PHB production phases. A high SSC level was observed in the mid‐log exponential growth phase. When the nitrogen source reached a limiting level, the SSC started to decrease, in contrast to the intracellular PHB granules‐related FL2 parameter. The results show that ammonium limitation is a critical and important factor for the accumulation of reserve compounds. Four subpopulations were observed and distinguished upon entrance of the cells into the exponential growth phase. When the cells entered the late exponential growth or early stationary phase, two subpopulations had disappeared and only two, different subpopulations were dominant. One of the subpopulations with changed SSC and PHB production activity switched to another subpopulation that was only active in PHB production in the stationary phase. The whole cells of R. pickettii AR1 tended to form a homogeneous population at the end of the stationary phase. In fact, the changes in the subpopulations of a single strain are related to different physiological states of the cells. The observation of different subpopulations suggests that each subpopulation shows a specific response to changes in the surrounding microenvironment, nutrients and limiting factors. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)