Planctomycete Pirellula spec.

Analysis of the secretome of the planctomycete Pirellula spec. strain 1 (REGXII)


Pirellula sp. strain 1 was isolated from the water column of "Kieler Bucht". Pirellula sp. strain 1 is a marine aerobic, heterotrophic representative of the ubiquitous bacterial order Planctomycetales. Characteristics of these bacteria are the organisation of their cells into membrane defined compartments including membrane-bounded nucleoids, their budding reproduction and a complete absence of peptidoglycan. The sequencing of Pirellula sp. strain 1, funded by the BMBF, has been performed at the MPI für Molekulare Genetik in Berlin and the MPI in Bremen.


Pirellula sp. strain 1 seems to be crucially involved in the degradation of complex macromolecules in the aerobic part of the water column. It is for example known that this bacterium is able to degrade the biopolymer starch to CO2. However, a comprehensive analysis of its degradation potential has not yet been performed. In close collaboration with the MPI für Marine Mikrobiologie in Bremen we will study the extracellular proteome of Pirellula sp. strain 1 under various physiological conditions (exponential growth, stationary phase caused by glucose-, N-acetylglucosamine-, nitrogen- or phosphate starvation, and oxygen limitation). We expect new insights into the eco-physiology of this bacterium. We will get new information on the expression of distinct sets of genes and the directed secretion of different proteins under changing environmental conditions. The protein profiling experiments will allow the affiliation of the appropriate genes to so-called stimulons.
Furthermore, we will get new information on extracellular polymer-degrading enzymes of Pirellula, which could be of potential biotechnological interest. In the frame of this project it is planned to characterise two extracellular hydrolytic enzymes in detail. For this purpose genes coding for these enzymes will be cloned in suitable bacterial expression systems and then overexpressed. The overproduced proteins will be purified and selected catalytic parameters will be characterised.



Prof. Dr. Rudolf Amann and Dr. Ralf Rabus, Max-Planck-Institut für Marine Mikrobiologie, Bremen



Prof. Dr. Michael Hecker, PD Dr. T. Schweder