Analysis of morphogenesis of the nocardioform organism Oerskovia xanthineolytica.
Depending on the nutritional and physicochemical conditions of growth the shape of Oerskovia xanthineolytica varied within a broad range. In different exponentially growing cultures five morphological types could be distinguished. In liquid cultures with increasing growth rate Oerskovia grew either as rods, filaments or branched filaments, whereas for the agar-microcultures pseudomycelia, but under reduced aeration mycelia were typical. The morphogenetic parameters of each type were determined, such as frequencies of septation and cell separation and - since wall extension was found to occur by the synthesizing activity of elongation sites (e-sites), their frequency, position and elongation rate as well. The cell length varied between 1 and about 20 micron, roughly correlated to the specific growth rate, but was also influenced by the composition and the consistence of the medium. The longest cells were found within the faster growing cultures, forming branched filaments, mycelia or pseudomycelia. During transition to the stationary growth phase these forms fragmented into rods by increase of the frequency of septation and cell separation. Increased cell length was accompanied by a reduced frequency of e-site formation which was compensated by an enhancement of their synthesizing activity. The rate of envelope synthesis varied with the morphological type from 0.12 to 9.60 micron/h. In agar-microcultures these values were much higher than in liquid media. In liquid cultures the e-sites preferentially were situated at one (rod) or the 2 cell poles (filaments), but during faster growth additional e-sites were formed within the cylindrical part of the envelope, thus leading to branching. In pseudomycelia the e-sites were formed laterally at the poles. In mycelia the poles did not receive e-site-activity, which instead occurred remote from the cell poles, also causing branching. This means that branching is either the result of the formation of more than two (up to 7) e-sites per cell (fast growing liquid cultures) or of a specific lack of transforming the poles into e-sites, (weakly aerated agar-cultures). The separation of sister cells was correlated to the transformation of poles into e-sites.
D003470:Culture Media; D009024:Morphogenesis; D009618:Nocardiaceae / Q000166:cytology / Q000254:growth & development*
D003470:Culture Media