TY  - JOUR
A1  - Dziallas, Claudia
A1  - Grossart, Hans-Peter
T1  - Microbial interactions with the cyanobacterium Microcystis aeruginosa and their dependence on temperature
JF  - Marine biology : international journal on life in oceans and coastal waters
N2  - Associated heterotrophic bacteria alter the microenvironment of cyanobacteria and potentially influence cyanobacterial development. Therefore, we studied interactions of the unicellular freshwater cyanobacterium Microcystis aeruginosa with heterotrophic bacteria. The associated bacterial community was greatly driven by temperature as seen by DNA fingerprinting. However, the associated microbes also closely interacted with the cyanobacteria indicating changing ecological consequence of the associated bacterial community with temperature. Whereas concentration of dissolved organic carbon in cyanobacterial cultures changed in a temperature-dependent manner, its quality greatly varied under the same environmental conditions, but with different associated bacterial communities. Furthermore, temperature affected quantity and quality of cell-bound microcystins, whereby interactions between M. aeruginosa and their associated community often masked this temperature effect. Both macro- and microenvironment of active cyanobacterial strains were characterized by high pH and oxygen values creating a unique habitat that potentially affects microbial diversity and function. For example, archaea including 'anaerobic' methanogens contributed to the associated microbial community. This implies so far uncharacterized interactions between Microcystis aeruginosa and its associated prokaryotic community, which has unknown ecological consequences in a climatically changing world.
Y1  - 2012
U6  - https://doi.org/10.1007/s00227-012-1927-4
SN  - 0025-3162
VL  - 159
IS  - 11
SP  - 2389
EP  - 2398
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Grossart, Hans-Peter
A1  - Frindte, Katharina
A1  - Dziallas, Claudia
A1  - Eckert, Werner
A1  - Tang, Kam W.
T1  - Microbial methane production in oxygenated water column of an oligotrophic lake
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - The prevailing paradigm in aquatic science is that microbial methanogenesis happens primarily in anoxic environments. Here, we used multiple complementary approaches to show that microbial methane production could and did occur in the well-oxygenated water column of an oligotrophic lake (Lake Stechlin, Germany). Oversaturation of methane was repeatedly recorded in the well-oxygenated upper 10 m of the water column, and the methane maxima coincided with oxygen oversaturation at 6 m. Laboratory incubations of unamended epilimnetic lake water and inoculations of photoautotrophs with a lake-enrichment culture both led to methane production even in the presence of oxygen, and the production was not affected by the addition of inorganic phosphate or methylated compounds. Methane production was also detected by in-lake incubations of lake water, and the highest production rate was 1.8-2.4 nM.h(-1) at 6 m, which could explain 33-44% of the observed ambient methane accumulation in the same month. Temporal and spatial uncoupling between methanogenesis and methanotrophy was supported by field and laboratory measurements, which also helped explain the oversaturation of methane in the upper water column. Potentially methanogenic Archaea were detected in situ in the oxygenated, methane-rich epilimnion, and their attachment to photoautotrophs might allow for anaerobic growth and direct transfer of substrates for methane production. Specific PCR on mRNA of the methyl coenzyme M reductase A gene revealed active methanogenesis. Microbial methane production in oxygenated water represents a hitherto overlooked source of methane and can be important for carbon cycling in the aquatic environments and water to air methane flux.
KW  - epilimnic methane peak
KW  - methanogens
Y1  - 2011
U6  - https://doi.org/10.1073/pnas.1110716108
SN  - 0027-8424
VL  - 108
IS  - 49
SP  - 19657
EP  - 19661
PB  - National Acad. of Sciences
CY  - Washington
ER  -