Characterization of cyst cell formation in the purple photosynthetic bacterium Rhodospirillum centenum

Abstract

Rhodospirillum centenum is an anoxygenic photosynthetic bacterium that is capable of differentiating into several cell types. When grown phototrophically in liquid, cells exhibit a vibrioid shape and have a single polar flagellum. When grown on a solid surface, R. centenum will differentiate into rod-shaped swarm cells that display numerous lateral flagella. Upon starvation for nutrients, R. centenum also forms desiccation-resistant cysts. In this study, it was determined that R. centenum has heat- and desiccation-resistance properties similar to other cyst-forming species. In addition, microscopic analyses of the morphological changes that occur during cyst cell development were performed. It was observed that R. centenum typically forms multi-celled clusters of cysts that contain from four to more than 10 cells per cluster. It was also determined that cell density has a minor effect on the percentage of cyst cells formed, with cell densities of 105–107 cells per 5 μl spot yielding the highest percentage of cyst cells. The striking similarities between the life cycle of R. centenum and the life cycle exhibited by Azospirillum spp. are discussed.

Global analysis of cell cycle gene expression of the legume symbiontSinorhizobium meliloti

“…The conservation of these motifs lends support to the theory first presented in Hallez et al (23) that CtrA mediates cell division through direct regulation of minC transcription in α-proteobacteria containing the Min system and through direct regulation of ftsZ in C. crescentus and other α-proteobacteria that lack the Min system. It is intriguing that a single regulatory factor can retain its role in a process so highly conserved as cell division but simultaneously demonstrates the flexibility to modulate diverse cellular differentiation events central to the lifestyles of α-proteobacteria, which can range from cyst cell formation in Rhodospirillum centenum to intracellular pathogenesis in Brucella (49,50).…”

The predatory life cycle of Myxococcus xanthus

“…Many bacterial species undergo cell development to a dormant cell or spore under low nutrient stress (Berleman & Bauer, 2004;Bacun-Druzina et al, 2007;Lindsay et al, 2006), but most bacteria lack the morphological complexity of Myx. xanthus or the myxobacteria in general.…”

“…Although fruiting-body formation is often referred to as a developmental programme, models of population-wide, uniform decision making (Kroos, 1990;Giglio et al, 2011) seem insufficient at explaining the role of multicellular structures observed during predatory behaviour. Indeed, many bacterial species will convert a fraction of the population to dormant cells or spores under low nutrient stress (Berleman & Bauer, 2004;Bacun-Druzina et al, 2007;Lindsay et al, 2006), yet Myx. xanthus fruiting bodies have an unmatched level of cell-type segregation.…”

Gliding Motility Revisited: How Do the Myxobacteria Move without Flagella?

“…in that the entire cell converts to a myxospore, which is also the case during Rhodospirillum sp. bacterial cyst formation (6). During these developmental transitions, gene expression and the pattern of cell movements are highly regulated (112).…”