processes Article Dynamics of the Bacterial Community Associated with Phaeodactylum tricornutum Cultures Fiona Wanjiku Moejes 1 ID , Antonella Succurro 2,3,*,† ID , Ovidiu Popa 2,4,†, Julie Maguire 1 and Oliver Ebenhöh 2,4,* ID 1 Bantry Marine Research Station, Gearhies, Bantry P75 AX07, Co. Cork, Ireland;
[email protected] (F.W.M.);
[email protected] (J.M.) 2 Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany;
[email protected] 3 Botanical Institute, University of Cologne, Zülpicher Strasse 47b, 50674 Cologne, Germany 4 Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany * Correspondence:
[email protected] (A.S.);
[email protected] (O.E.) † These authors contributed equally to this work. Received: 17 October 2017; Accepted: 28 November 2017; Published: 7 December 2017 Abstract: The pennate diatom Phaeodactylum tricornutum is a model organism able to synthesize industrially-relevant molecules. Commercial-scale cultivation currently requires large monocultures, prone to bio-contamination. However, little is known about the identity of the invading organisms. To reduce the complexity of natural systems, we systematically investigated the microbiome of non-axenic P. tricornutum cultures from a culture collection in reproducible experiments. The results revealed a dynamic bacterial community that developed differently in “complete” and “minimal” media conditions. In complete media, we observed an accelerated “culture crash”, indicating a more stable culture in minimal media. The identification of only four bacterial families as major players within the microbiome suggests specific roles depending on environmental conditions. From our results we propose a network of putative interactions between P.