TY  - JOUR
A1  - Schellenberg, Johannes
A1  - Reichert, Jessica
A1  - Hardt, Martin
A1  - Klingelhöfer, Ines
A1  - Morlock, Gertrud
A1  - Schubert, Patrick
A1  - Bižić, Mina
A1  - Grossart, Hans-Peter
A1  - Kämpfer, Peter
A1  - Wilke, Thomas
A1  - Glaeser, Stefanie P.
T1  - The bacterial microbiome of the long-term aquarium cultured high-microbial abundance sponge Haliclona cnidata
BT  - sustained bioactivity despite community shifts under detrimental conditions
JF  - Frontiers in Marine Science
N2  - Marine sponges host highly diverse but specific bacterial communities that provide essential functions for the sponge holobiont, including antimicrobial defense. Here, we characterized the bacterial microbiome of the marine sponge Haliclona cnidata that has been in culture in an artificial marine aquarium system. We tested the hypotheses (1) that the long-term aquarium cultured sponge H. cnidata is tightly associated with a typical sponge bacterial microbiota and (2) that the symbiotic Bacteria sustain bioactivity under harmful environmental conditions to facilitate holobiont survival by preventing pathogen invasion. Microscopic and phylogenetic analyses of the bacterial microbiota revealed that H. cnidata represents a high microbial abundance (HMA) sponge with a temporally stable bacterial community that significantly shifts with changing aquarium conditions. A 4-week incubation experiment was performed in small closed aquarium systems with antibiotic and/or light exclusion treatments to reduce the total bacterial and photosynthetically active sponge-associated microbiota to a treatment-specific resilient community. While the holobiont was severely affected by the experimental treatment (i.e., bleaching of the sponge, reduced bacterial abundance, shifted bacterial community composition), the biological defense and bacterial community interactions (i.e., quorum sensing activity) remained intact. 16S rRNA gene amplicon sequencing revealed a resilient community of 105 bacterial taxa, which remained in the treated sponges. These 105 taxa accounted for a relative abundance of 72-83% of the bacterial sponge microbiota of non-treated sponge fragments that have been cultured under the same conditions. We conclude that a sponge-specific resilient community stays biologically active under harmful environmental conditions, facilitating the resilience of the holobiont. In H. cnidata, bacteria are located in bacteriocytes, which may have contributed to the observed phenomenon.
KW  - HMA sponge
KW  - bacterial symbionts
KW  - holobiont
KW  - antimicrobial defense
KW  - quorum sensing
KW  - bacteriocytes
Y1  - 2020
U6  - https://doi.org/10.3389/fmars.2020.00266
SN  - 2296-7745
VL  - 7
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Schubert, Marcel
A1  - Preis, Eduard
A1  - Blakesley, James C.
A1  - Pingel, Patrick
A1  - Scherf, Ullrich
A1  - Neher, Dieter
T1  - Mobility relaxation and electron trapping in a donor/acceptor copolymer
JF  - Physical review : B, Condensed matter and materials physics
N2  - To address the nature of charge transport and the origin of severe (intrinsic) trapping in electron-transporting polymers, transient and steady-state charge transport measurements have been conducted on the prototype donor/acceptor copolymer poly[2,7-(9,9-dialkyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PFTBTT). A charge-generation layer technique is used to selectively address transport of the desired charge carrier type, to perform time-of-flight measurements on samples with < 200 nm thickness, and to combine the time-of-flight and the photocharge extraction by linearly increasing voltage (photo-CELIV) techniques to investigate charge carrier dynamics over a wide time range. Significant trapping of free electrons is observed in the bulk of dioctyl-substituted PFTBTT (alt-PF8TBTT), introducing a strong relaxation of the charge carrier mobility with time. We used Monte-Carlo simulation to simulate the measured transient data and found that all measurements can be modeled with a single parameter set, with the charge transport behavior determined by multiple trapping and detrapping of electrons in an exponential trap distribution. The influence of the concomitant mobility relaxation on the transient photocurrent characteristics in photo-CELIV experiments is discussed and shown to explain subtle features that were seen in former publications but were not yet assigned to electron trapping. Comparable studies on PFTBTT copolymers with chemical modifications of the side chains and backbone suggest that the observed electron trapping is not caused by a distinct chemical species but rather is related to interchain interactions.
Y1  - 2013
U6  - https://doi.org/10.1103/PhysRevB.87.024203
SN  - 1098-0121
VL  - 87
IS  - 2
PB  - American Physical Society
CY  - College Park
ER  -