Modification of the aggregation behaviour of the environmental Ralstonia eutropha‐like strain AE815 is reflected by both surface hydrophobicity and amplified fragment length polymorphism (AFLP) patterns

Abstract

SummaryAfter inoculation of the plasmid-free non-aggregative Ralstonia eutropha-like strain AE815 in activated sludge, followed by reisolation on a selective medium, a mutant strain A3 was obtained, which was characterized by an autoaggregative behaviour. Strain A3 had also acquired an IncP1 plasmid, pLME1, co-aggregated with yeast cells when co-cultured, and stained better with Congo red than did the AE815 strain. Contact angle measurements showed that the mutant strain was considerably more hydrophobic than the parent strain AE815, and scanning electron microscopy (SEM) revealed the production of an extracellular substance. A similar hydrophobic mutant (AE176R) could be isolated from the AE815-isogenic R. eutropha-like strain AE176. With the DNA ®ngerprinting technique repetitive extragenic palindromic-polymerase chain reaction (REP-PCR), no differences between these four strains, AE815, A3, AE176 and AE176R, could be revealed. However, using the ampli®ed fragment length polymorphism (AFLP) DNA ®ngerprinting technique with three different primer combinations, small but clear reproducible differences between the banding patterns of the autoaggregative mutants and their non-autoaggregative parent strains were observed for each primer set. These studies demonstrate that,

Ralstonia metallidurans, a bacterium specifically adapted to toxic metals: towards a catalogue of metal-responsive genes

“…The knowledge about the mechanisms of resistance to heavy metals and especially their regulation stimulated further work in microbial ecology [46–51] and in environmental biotechnology [52]. Industrial applications of metal‐resistant bacteria and their genes include the use of biosensors for monitoring the concentration of heavy metals in a variety of substrates and soils [53–58], the development of bioreactors to remove heavy metals from polluted effluents or soils [59,60], and bioaugmentation [61] and phytoremediation [62] (Y. Wang, W. Hai, J. Vander Leyden and M. Mergeay, unpublished).…”

AggA is required for aggregation and increased biofilm formation of a hyper-aggregating mutant of Shewanella oneidensis MR-1

“…Pseudomonas putida CP1 exhibits auto-aggregation during the degradation of monochlorophenols and phenol, and it has been shown that this is a response to the toxicity of the added substrates (Farrell & Quilty, 2002). Bossier et al (2000) observed that after inoculation of the non-aggregative Ralstonia eutropha-like strain AE815 into activated sludge, reisolation on selective medium yielded mutant strain A3, which was characterized by autoaggregative behaviour.…”