Biocrystalline structures in the nucleoids of the stationary and dormant prokaryotic cells

Abstract

Compaction and biocrystallization of the nucleoid are presently considered as a necessary and important stage in the transformation of the cell ultrastructure during change of microbial cultures strategies from growth to survival. Nucleoid biocrystallization in the stationary phase cells is achieved due to structural regularity of the DNA complexes with the histone-like Dps protein. Our experiments with Escherichia coli mutants, overproducers of the Dps protein, confirmed nucleoid biocrystallization in the late stationary phase cells. Since nucleoid biocrystallization was revealed in E. сoli cells without Dps overproduction at late stages of starvation, it is constitutive in the cycle of development of microbial populations. The present work concentrated on detection of the nucleoid biocrystalline structure in (1) long-starved (21 day in the chemostat mode) bacterial cells (genera Arthrobacter and Pseudomonas), (2) dormant ametabolic (anabiotic) cells of such prokaryotes as archaea and non-spore-forming bacteria, (3) endospores of bacilli, (4) streptomycete exospores, and (5) in the cells surviving in permafrost for (2‒3 Ma). The topics discussed include nucleoid biocrystallization as a necessary stage of maturation of the dormant microbial cells providing for survival and preservation of the species, dynamics of nucleoid biocrystallization during maturation of the dormant cells, and its possible role for the preservation of genetic information in the case of autolysis of most of the cells in a developing culture.