TY  - JOUR
A1  - Grote, Jessica
A1  - Krysciak, Dagmar
A1  - Petersen, Katrin
A1  - Güllert, Simon
A1  - Schmeisser, Christel
A1  - Förstner, Konrad U.
A1  - Krishnan, Hari B.
A1  - Schwalbe, Harald
A1  - Kubatova, Nina
A1  - Streit, Wolfgang R.
T1  - The Absence of the N-acyl-homoserine-lactone Autoinducer Synthase Genes tral and ngrl Increases the Copy Number of the Symbiotic Plasmid in Sinorhizobium fredii NGR234
JF  - Frontiers in Microbiology
N2  - Plant-released flavonoids induce the transcription of symbiotic genes in rhizobia and one of the first bacterial responses is the synthesis of so called Nod factors. They are responsible for the initial root hair curling during onset of root nodule development. This signal exchange is believed to be essential for initiating the plant symbiosis with rhizobia affiliated with the Alphaproteobacteria. Here, we provide evidence that in the broad host range strain Sinorhizobium fredii NGR234 the complete lack of quorum sensing molecules results in an elevated copy number of its symbiotic plasmid (pNGR234a). This in turn triggers the expression of symbiotic genes and the production of Nod factors in the absence of plant signals. Therefore, increasing the copy number of specific plasmids could be a widespread mechanism of specialized bacterial populations to bridge gaps in signaling cascades.
KW  - Sinorhizobium fredii
KW  - plasmid copy number
KW  - plant symbioses
KW  - quorum sensing (QS)
KW  - RNA sequencing (RNA-Seq)
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165185
VL  - 7
IS  - 1858
ER  - 
TY  - JOUR
A1  - Krohn-Molt, Ines
A1  - Alawi, Malik
A1  - Förstner, Konrad U.
A1  - Wiegandt, Alena
A1  - Burkhardt, Lia
A1  - Indenbirken, Daniela
A1  - Thieß, Melanie
A1  - Grundhoff, Adam
A1  - Kehr, Julia
A1  - Tholey, Andreas
A1  - Streit, Wolfgang R.
T1  - Insights into microalga and bacteria interactions of selected phycosphere biofilms using metagenomic, transcriptomic, and proteomic approaches
JF  - Frontiers in Microbiology
N2  - Microalga are of high relevance for the global carbon cycling and it is well-known that they are associated with a microbiota. However, it remains unclear, if the associated microbiota, often found in phycosphere biofilms, is specific for the microalga strains and which role individual bacterial taxa play. Here we provide experimental evidence that \(Chlorella\) \(saccharophila\), \(Scenedesmus\) \(quadricauda\), and \(Micrasterias\) \(crux-melitensis\), maintained in strain collections, are associated with unique and specific microbial populations. Deep metagenome sequencing, binning approaches, secretome analyses in combination with RNA-Seq data implied fundamental differences in the gene expression profiles of the microbiota associated with the different microalga. Our metatranscriptome analyses indicates that the transcriptionally most active bacteria with respect to key genes commonly involved in plant–microbe interactions in the Chlorella (Trebouxiophyceae) and Scenedesmus (Chlorophyceae) strains belong to the phylum of the α-Proteobacteria. In contrast, in the Micrasterias (Zygnematophyceae) phycosphere biofilm bacteria affiliated with the phylum of the Bacteroidetes showed the highest gene expression rates. We furthermore show that effector molecules known from plant-microbe interactions as inducers for the innate immunity are already of relevance at this evolutionary early plant-microbiome level.
KW  - microbiology
KW  - microalga-bacteria interaction
KW  - phycosphere biofilm
KW  - metagenomics
KW  - metatranscriptomics
KW  - metaproteomics
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173701
VL  - 2017
IS  - 8
ER  -