" Candidatus Mesochlamydia elodeae” (Chlamydiae: Parachlamydiaceae ), a novel chlamydia parasite of free-living amoebae

Vannella sp. isolated from waterweed Elodea sp. was found infected by a chlamydia-like organism. This organism behaves like a parasite, causing the death through burst of its host. Once the vannellae degenerated, the parasite was successfully kept in laboratory within a Saccamoeba sp. isolated from the same waterweed sample, which revealed in fine through electron microscopy to harbor two bacterial endosymbionts: the chlamydial parasite we introduce and another endosymbiont initially and naturally present in the host. Herein, we provide molecular-based identification of both the amoeba host and its two endosymbionts, with special focus on the chlamydia parasite. High sequence similarity values of the 18S rDNA permitted to assign the amoeba to the species Saccamoeba lacustris (Amoebozoa, Tubulinea). The bacterial endosymbiont naturally harbored by the host belonged to Sphingomonas koreensis (Alpha-Proteobacteria). The chlamydial parasite showed a strict specificity for Saccamoeba spp., being unable to infect a variety of other amoebae, including Acanthamoeba, and it was itself infected by a bacteriophage. Sequence similarity values of the 16S rDNA and phylogenetic analysis indicated that this strain is a new member of the family Parachlamydiaceae, for which we propose the name "Candidatus Mesochlamydia elodeae.

DEEP—A tool for differential expression effector prediction

High-throughput methods for measuring transcript abundance, like SAGE or microarrays, are widely used for determining differences in gene expression between different tissue types, dignities (normal/malignant) or time points. Further analysis of such data frequently aims at the identification of gene interaction networks that form the causal basis for the observed properties of the systems under examination. To this end, it is usually not sufficient to rely on the measured gene expression levels alone; rather, additional biological knowledge has to be taken into account in order to generate useful hypotheses about the molecular mechanism leading to the realization of a certain phenotype

THE BOSS EXPERIMENT OF THE EXPOSE-R2 MISSION: BIOFILM VERSUS PLANKTONIC CELLS

In the BOSS experiment (biofilm organisms surfing space), which was performed in the context of the successfully finalized EXPOSE-R2 mission, an international consortium of scientists investigated the ability of a variety of organisms to survive in space and on Mars as a function of their life style. The question in focus is whether there are different strategies for individually living microorganisms (planktonic state) compared to a microbial consortium of the same cells (biofilm state) to cope with the unique mixture of extreme stress factors including desiccation, gamma-, ionizing- and UV radiation in this environment. Biofilms, in which the cells are encased in a self-produced matrix of excreted extracellular polymeric substances, are one of the oldest clear signs of life on Earth. Since they can become fossilized they might also be detected as the first life forms on other planets and moons of the solar system and are therefore ideal candidates for astrobiological investigations. As an example for the organisms that attended the EXPOSER2 mission the results of the ight and mission ground reference analysis of Deinococcus geothermalis are presented. Deinococcus geothermalis is a non-spore-forming, gram-positive, orange-pigmented representative of the Deinococcus family which is unparalleled in its poly-extreme resistances to a variety of environmental stress factors on Earth. The results demonstrate that Deinococcus geothermalis remains viable in the desiccated state over almost 2 years, whereas culturability was preserved in biofilm cells at a significantly higher level than in planktonic cells. Furthermore, cells of both sample types were able to survive simulated space and Martian conditions and showed high resistance towards extra-terrestrial UV radiation. Additionally results of cultivation-independent investigations of pigment stability, membrane integrity, enzyme activity, ATP content and DNA integrity will be discussed.To conclude, biofilms exhibit an enhanced rate of survival compared to their planktonic counterparts when exposed to space and Martian conditions. This seems to indicate an advantage of living as a biofilm when facing the poly-extreme conditions of space or Mars. The findings will contribute to the understanding of the opportunities and limitations of life under the extreme environmental conditions of space or other planets as function of the state of life and aims to contribute to the understanding of the adaptation mechanisms that allow microorganisms to survive in extreme environments, possibly including space and the surface of Mars

Mikrobiologische Trinkwasserqualität in der Wasserverteilung bei veränderten Temperaturen aufgrund des Klimawandels

Aufgrund des Klimawandels kann es zu einer Erwärmung der oberen Bodenzonen und indirekt dadurch auch zu einer Beeinflussung der Trinkwassertemperatur im Verteilernetz kommen. Es ist bekannt, dass dies unter Umständen zu mikrobiologischen Veränderungen in Form einer Aufkeimung (Erhöhung der Koloniezahlen) führen kann. Ob dies jedoch auf ein erhöhtes Risiko der Einistung, des Verbleibs oder sogar der Vermehrung hygenisch relevanter Bakterien zutrifft, wird im Rahmen des vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Projekts dynaklim am IWW in Kooperation mit der Universität Duisburg-Essen untersucht

Sicherung der Trinkwasserqualität bei der Wasserverteilung bei veränderten Bodentemperaturen

Bedingt durch die globale Erwärmung findet eine Erwärmung der oberen Bodenschichten durch längere Hitzeperioden in den Sommermonaten statt. Dies wird besonders in Großstädten mit vielen hochversiegelten Flächen zu erwarten sein. Diese Erwärmung der oberen Bodenschichten und eine klimabedingte Erhöhung der Rohwassertemperaturen können zu einem Anstieg der Trinkwassertemperatur in Trinkwasserverteilungsnetzen führen. Der Einfluss der Wassertemperatur auf hygienisch relevante Mikroorganismen in Trinkwasser und Trinkwasserbiofilmen wurde daher in der vorliegenden Studie untersucht

Detergent-induced cell aggregation in subpopulations of Pseudomonas aeruginosa as a preadaptive survival strategy

During growth of Pseudomonas aeruginosa strain PAO1 with the toxic detergent SDS, a part of the population actively formed macroscopic cell aggregates while the other part grew as freely suspended cells. The physiological function of aggregation for growth with SDS was investigated. Three mutants growing with SDS without aggregation were isolated: the spontaneous mutant strain N and two mutants with transposon insertions in the psl operon for exopolysaccharide synthesis. SDS-induced aggregation in strain N but not in a pslJ mutant was restored by complementation with two genes encoding diguanylate cyclases responsible for synthesis of cyclic-di-guanosine monophosphate (c-di-GMP). By expressing a c-di-GMP-specific phosphodiesterase SDS-induced aggregation of strain PAO1 was reduced.Upon exposure to SDS in the presence of the uncoupler carbonyl cyanide chlorophenylhydrazone, the aggregating strains had ca. 500-fold higher survival rates than the non-aggregating strains. Co-incubation experiments revealed that strain N could integrate into aggregates of strain PAO1 and thereby increase its survival rate more than 1000-fold.These results showed that SDS-induced aggregation involved c-di-GMP signalling with the psl operon as a possible target. Cell aggregation could serve as a pre-adaptive strategy ensuring survival and growth of P. aeruginosa populations in environments with multiple toxic chemicals

Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions

Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions. The effect of sulfatic Mars regolith simulant on cell viability during stress was investigated separately. The EPS produced by the biofilm cells contained mainly polysaccharides and proteins. To detect viable but nonculturable (VBNC) cells, cultivation-independent viability indicators (membrane integrity, ATP, 16S rRNA) were determined in addition to colony counts. Desiccation for 2 months resulted in a decrease of culturability with minor changes of membrane integrity in biofilm cells and major loss of membrane integrity in planktonic bacteria. Temperatures between -25°C and +60°C, vacuum, and Mars atmosphere affected neither culturability nor membrane integrity in both phenotypes. Monochromatic (254 nm; ‡1 kJ m⁻²) and polychromatic (200–400 nm; >5.5 MJ m⁻² for planktonic cells and >270 MJ m⁻² for biofilms) UV irradiation significantly reduced the culturability of D. geothermalis but did not affect cultivation-independent viability markers, indicating the induction of a VBNC state in UV-irradiated cells. In conclusion, a substantial proportion of the D. geothermalis population remained viable under all stress conditions tested, and in most cases the biofilm form proved advantageous for surviving space and Mars-like conditions

Tolerances of Deinococcus geothermalis Biofilms and Planktonic Cells Exposed to Space and Simulated Martian Conditions in Low Earth Orbit for Almost Two Years

Fossilized biofilms represent one of the oldest known confirmations of life on the Earth. The success of microbes in biofilms results from properties that are inherent in the biofilm, including enhanced interaction, protection, and biodiversity. Given the diversity of microbes that live in biofilms in harsh environments on the Earth, it is logical to hypothesize that, if microbes inhabit other bodies in the Universe, there are also biofilms on those bodies. The Biofilm Organisms Surfing Space experiment was conducted as part of the EXPOSE-R2 mission on the International Space Station. The experiment was an international collaboration designed to perform a comparative study regarding the survival of biofilms versus planktonic cells of various microorganisms, exposed to space and Mars-like conditions. The objective was to determine whether there are lifestyledependent differences to cope with the unique mixture of stress factors, including desiccation, temperature oscillations, vacuum, or a Mars-like gas atmosphere and pressure in combination with extraterrestrial or Marslike ultraviolet (UV) radiation residing during the long-term space mission. In this study, the outcome of the flight and mission ground reference analysis of Deinococcus geothermalis is presented. Cultural tests demonstrated that D. geothermalis remained viable in the desiccated state, being able to survive space and Mars-like conditions and tolerating high extraterrestrial UV radiation for more than 2 years. Culturability decreased, but was better preserved, in the biofilm consortium than in planktonic cells. These results are correlated to differences in genomic integrity after exposure, as visualized by random amplified polymorphic DNA–polymerase chain reaction. Interestingly, cultivation-independent viability markers such as membrane integrity, ATP content, and intracellular esterase activity remained nearly unaffected, indicating that subpopulations of the cells had survived in a viable but nonculturable state. These findings support the hypothesis of long-term survival of microorganisms under the harsh environmental conditions in space and on Mars to a higher degree if exposed as biofilm