Voici les éléments 1 - 10 sur 82
- PublicationMétadonnées seulementIdentification of active oxalotrophic bacteria by Bromodeoxyuridine DNA labeling in a microcosm soil experiments(2013)
; ;Martin, Gaëtan ;David, Maude M ; ;
- PublicationMétadonnées seulementMetaproteomics and ultrastructure characterization of Komagataeibacter spp. involved in high-acid spirit vinegar production(2016)
;Andres-Barrao, Cristina ;Saad, Maged ;Cabello Ferrete, Elena ; ;Chappuis, Marie Louise ;Ortega Perez, Ruben ; ;Perret, XavierBarja, FrancoisAcetic acid bacteria (AAB) are widespread microorganisms in nature, extensively used in food industry to transform alcohols and sugar alcohols into their corresponding organic acids. Specialized strains are used in the production of vinegar through the oxidative transformation of ethanol into acetic acid. The main AAB involved in the production of high-acid vinegars using the submerged fermentation method belong to the genus Komagataeibacter, characterized by their higher ADH stability and activity, and higher acetic acid resistance (15-20%), compared to other AAB. In this work, the bacteria involved in the production of high-acid spirit vinegar through a spontaneous acetic acid fermentation process was studied. The analysis using a culture-independent approach revealed a homogeneous bacterial population involved in the process, identified as Komagataeibacter spp. Differentially expressed proteins during acetic acid fermentation were investigated by using 2D-DIGE and mass spectrometry. Most of these proteins were functionally related to stress response, the TCA cycle and different metabolic processes. In addition, scanning and transmission electron microscopy and specific staining of polysaccharide SDS-PAGE gels confirmed that Komagataeibacter spp. lacked the characteristic polysaccharide layer surrounding the outer membrane that has been previously reported to have an important role in acetic acid resistance in the genus Acetobacter.
- PublicationMétadonnées seulementEffect of organic carbon and metal accumulation on the bacterial communities in sulphidogenic sediments(2016)
;A unique geochemical setting in Lake Cadagno, Switzerland, has led to the accumulation of insoluble metal sulphides in the sedimentary record as the result of past airborne pollution. This offers an exceptional opportunity to study the effect of these metals on the bacterial communities in sediments, and in particular to investigate further the link between metal contamination and an increase in the populations of endospore-forming bacteria observed previously in other metal-contaminated sediments. A decrease in organic carbon and total bacterial counts was correlated with an increase in the numbers of endospores in the oldest sediment samples, showing the first environmental evidence of a decrease in nutrient availability as a trigger of sporulation. Proteobacteria and Firmicutes were the two dominant bacterial phyla throughout the sediment, the former in an area with high sulphidogenic activity, and the latter in the oldest samples. Even though the dominant Firmicutes taxa were stable along the sediment core and did not vary with changes in metal contamination, the prevalence of some molecular species like Clostridium sp. was positively correlated with metal sulphide concentration. However, this cannot be generalized to all endospore-forming species. Overall, the community composition supports the hypothesis of sporulation as the main mechanism explaining the dominance of endospore formers in the deepest part of the sediment core, while metal contamination in the form of insoluble metal sulphide deposits appears not to be linked with sporulation as a mechanism of metal tolerance in this sulphidogenic ecosystem.
- PublicationAccès libreExploiting the fungal highway: development of a novel tool for the in situ isolation of bacteria migrating along fungal mycelium(2015)
; ; ; ;Wick, Lukas Y. ; ;Kooli, Wafa M. ;Verrecchia, Eric P.Fungi and bacteria form various associations that are central to numerous environmental processes. In the so-called fungal highway, bacteria disperse along fungal mycelium. We developed a novel tool for the in situ isolation of bacteria moving along fungal hyphae as well as for the recovery of fungi potentially involved in dispersal, both of which are attracted towards a target culture medium. We present the validation and the results of the first in situ test. Couples of fungi and bacteria were isolated from soil. Amongst the enriched organisms, we identified several species of fast-growing fungi (Fusarium sp. and Chaetomium sp.), as well as various potentially associated bacterial groups, including Variovorax soli, Olivibacter soli, Acinetobacter calcoaceticus, and several species of the genera Stenotrophomonas, Achromobacter and Ochrobactrum. Migration of bacteria along fungal hyphae across a discontinuous medium was confirmed in most of the cases. Although the majority of the bacteria for which migration was confirmed were also positive for flagellar motility, not all motile bacteria dispersed using their potential fungal partner. In addition, the importance of hydrophobicity of the fungal mycelial surface was confirmed. Future applications of the columns include targeting different types of microorganisms and their interactions, either by enrichment or by state of the art molecular biological methods.
- PublicationMétadonnées seulementCommunity analysis of betaproteobacterial ammonia-oxidizing bacteria using the amoCAB operon(2009)
; ;Kim, Ok-Sun ;Junier, Thomas ;Ahn, Tae-Seok ;Imhoff, Johannes FWitzel, Karl-Paul
- PublicationMétadonnées seulementEffect of salinity on cyanobacterial community composition along a transect from Fuliya spring into the water of Lake Kinneret, Israel(2013)
; ;Kim, Ok-Sun ;Imhoff, Johannes F ;Witzel, Karl-PaulHadas, Ora
- PublicationMétadonnées seulementResuscitation of ten-year VBNC Klebsiella oxytoca(2008)
;Dhiaf, Amel ; ;Bakhrouf, AminaWitzel, Karl-Paul
- PublicationMétadonnées seulementPhylogenetic and functional marker genes to study ammonia-oxidizing microorganisms (AOM) in the environment(2010)
; ;Molina, Verónica ;Dorador, Cristina ;Hadas, Ora ;Kim, Ok-Sun ;Junier, Thomas ;Witzel, Karl-PaulImhoff, Johannes F
- PublicationMétadonnées seulementComparative in silico analysis of PCR primers suited for diagnostics and cloning of ammonia monooxygenase genes from ammonia?oxidizing bacteria(2008)
; ;Kim, Ok-Sun ;Molina, Verónica ;Limburg, Petra ;Junier, Thomas ;Imhoff, Johannes FWitzel, Karl-Paul
- PublicationMétadonnées seulementDistribution of denitrifying bacterial communities in the stratified water column and sediment?water interface in two freshwater lakes and the Baltic Sea(2011)
;Kim, Ok-Sun ;Imhoff, Johannes F ;Witzel, Karl-Paul