Ammonium and attachment of Rhodopirellula baltica

Abstract

A dimorphic life cycle has been described for the planctomycete Rhodopirellula baltica SH1(T), with juvenile motile, free-swimming cells and adult sessile, attached-living cells. However, attachment as a response to environmental factors was not investigated. We studied the response of R. baltica to nitrogen limitation. In batch cultures, ammonium limitation coincided with a dominance of free-swimming cells and a low number of aggregates. Flow cytometry revealed a quantitative shift with increasing ammonium availability, from single cells towards attached cells in large aggregates. During growth of R. baltica on glucose and ammonium in chemostats, an ammonium addition caused a macroscopic change of the growth behaviour, from homogeneous growth in the liquid phase to a biofilm on the borosilicate glass wall of the chemostat vessel. Thus, an ammonium limitation-a carbon to nitrogen supply ratio of 30:1-sustained free-living growth without aggregate formation. A sudden increase in ammonium supply induced sessile growth of R. baltica. These observations reveal a response of Rhodopirellula baltica cells to ammonium: they abandon the free-swimming life, attach to particles and form biofilms.

Developing Techniques for the Utilization of Planctomycetes As Producers of Bioactive Molecules

“…The known species belonging to the order Phycisphaerales have small genomes with few secondary metabolite related clusters while species of the order Planctomycetales were found to comprise large genomes with many secondary metabolite related genes ( Jeske et al, 2013 ). Among Planctomycetales, only the cultivation of R. baltica in a small-scale custom-made chemostat was described thus far ( Frank et al, 2011 ). However, such experiments were not performed with the intention to obtain secondary metabolites.…”

Bioinformatic analyses of integral membrane transport proteins encoded within the genome of the planctomycetes species, Rhodopirellula baltica

“…At distinct stages in its life-cycle, R. baltica produces both holdfast material in the sessile stage and flagella in its motile ‘swarmer’ (or more accurately ‘swimmer’) stage. The transition between these two states is influenced by nitrogen availability; nitrogen limitation promotes the motile state while nitrogen excess promotes biofilm formation [27]. …”

Cell surface proteome of the marine planctomycete Rhodopirellula baltica

“…Biotin, protein found in biotinylation experiment; Prot K , protein found in proteinase K experiment; SP , signal peptide prediction; new SP , newly proposed SP []; TMHMM, number of predicted transmembrane helices; pSortb, predicted locations by PSORTb v.2.0; Gel, protein was identified in earlier proteome analysis [], 2D, protein found in 2D gel analysis; CW, protein found in cell wall protein analysis.…”

“…When the population density rises above a certain level, planctomycete cells aggregate to form rosettes []. A switch between swarmer and attached cells was also found to be caused by changing environmental conditions (ammonium limitation []). In native habitats, adult R. baltica cells attach firmly onto snow particles by a unique hold stalk structure [].…”

“…This marine bacterium was isolated from the water column of the Kieler Bight, a bay in the southwestern Baltic Sea []. R. baltica is a marine aerobic, heterotrophic bacterium [], which shows at least two different life styles, either as free‐swimming or as sessile, attached‐living cells []. Continuing our proteomic study [] on R. baltica SH1 T , we used a “protein shaving” approach applying proteinase K and a biotinylation method to address the surface proteome of intact cells.…”