From April 27th to April
30th 2015, Dr. Christin Bennke (Leibniz Institute for Baltic Sea
Research, BLUEPRINT- WP6) had the opportunity to participate in a cruise of r/v
Elisabeth Mann Borgese (EMB101) to test the sampling of seawater using the
newly developed AFIS (autonomous flow injection sampler, see Figure 1). After
previous tests which showed that technical improvements were needed, this
cruise should serve to prove that the adaptation phase was successful.
AFIS is a technique
for taking water samples without altering or even destroying the metagenomic and
metatranscriptomic information within the planktonic microorganisms in the
sample. This can be accomplished by the injection of a chemical fixative
consisting of a phenol-ethanol mix directly at the depth of sampling.
The RNA of
the microorganisms reacts very fast on environmental changes. The idea is to
use this information for new monitoring strategies, especially for autonomous
measurements. But the functioning of adequate sampling techniques is crucial
for such a plan.
EMB 101 cruise samples for nutrient analyses, chlorophyll a, microbial cell
counts and DNA as well as RNA were taken along the vertical salinity gradient
at the Baltic Sea stations Darss Sill and Arkona Bassin in parallel. And then,
for the first time, in-situ samples were taken by the improved AFIS.
There were only four days of ship time, so everyone on board was nervous
whether the testing would work making the cruise a success. But AFIS turned out
to be reliable now: All three AFIS worked perfectly and samples are now ready
for further laboratory analysis ashore.
These developments are fundamental steps towards
standardized nucleic acid sampling protocols (BLUEPRINT-WP6), which are
necessary to reveal and compare functional roles of the seawater microbes under
different environmental settings.