ALBERT

Description: The recent application of molecular microbial ecology tools to sponge-microbe associations has revealed a glimpse into the biodiversity of these microbial communities, that is considered just ‘the tip of the iceberg’. This chapter provides an overview over these new findings with regard to identity, diversity and distribution patterns of sponge-associated microbial consortia. The sponges Aplysina aerophoba (Verongida), Rhopaloeides odorabile (Dicytoceratida) and Theonella swinhoei (Lithistida) were chosen as model systems for this review because they have been subject to both, cultivation-dependent and cultivation-independent approaches. A discussion of the microbial assemblages of Halichondria panicea is presented in the accompanying chapter by Imhoff and Stöhr. Considering that a large fraction of sponge-associated microbes is not yet amenable to cultivation, an emphasis has been placed on the techniques centering around the 16S rRNA gene. A section has been included that covers the potential of sponge microbial communities for drug discovery. Finally, a ‘sponge-microbe interaction model’ is presented that summarizes our current understanding of the processes that might have shaped the community structure of the microbial assemblages within sponges.

Description: Marine sponges are a rich source of bioactive natural products and are promising sources for drug discovery and development An impressive example is the sponge Theonella swinhoei, which has yielded more than 120 compounds belonging to diverse structural types. Many sponges also harbor highly complex consortia of symbiotic bacteria that are suspected to be the true source of at least some of the secondary metabolites. In previous work, our group demonstrated a bacterial origin of onnamide- and psymberin-type polyketides for two different sponges (1–3), but there were no insights into the producer of compounds from other natural product families. In addition, the exact taxonomic identity of sponge-associated producers remained unknown. This talk will present new insights into these two issues. Isolation of genes encoding a peptide biosynthetic pathway from the T. swinhoei metagenome demonstrated a bacterial origin. Several genes were heterologously expressed and functionally characterized, which revealed unprecedented biosynthetic transformations. The novelty of these modifications suggests the existence of a structurally distinct natural product family, for which we propose the name proteusins. Using a strategy consisting of single-cell analysis and metagenomic sequencing, we identified the bacterial producer of onnamide polyketides in T. swinhoei. Surprisingly, the data suggest the symbiont to be a chemically exceptionally prolific bacterium, producing not only onnamides but most other compounds from this sponge chemotype, including the known and two previously unknown proteusins. Further biosynthetic studies and a survey of other sponges indicate that close relatives of the producer are widespread in these animals and vary with respect to their biosynthetic capabilities. These bacteria might therefore represent the first uncultivated taxon with a metabolic richness resembling that of major cultivated bacterial natural product sources. These results reveal a key role of symbiotic bacteria in the chemistry of their sponge hosts and provide new strategies to study uncultivated symbionts in a more systematic fashion.

Description: In extranodalen Marginalzonen-B-Zell-Lymphomen vom MALT-Typ (eMZBCL) wurde für verschiedene anatomische Lokalisationen eine Assoziation mit einer durch einen spezifischen Erreger verursachten chronischen Entzündung (z. B. Helicobacter pylori im Magen) beschrieben. Für die Lunge ist eine solche Erregerassoziation bislang nicht bekannt. Mittels einer erstmalig auf diese Fragestellung angewandten sensitiven Screeningmethode (SHARP-Screening), die auf der Analyse der bakteriellen 16S-rRNA-Gene beruht, haben wir die mikrobielle Diversität von 9 eMZBCL der Lunge analysiert und mit 9 Kontrollfällen verglichen. Interessanterweise konnten in 8 der 9 eMZBCL-Fälle Bakterien der Alcaligenacea-Familie (Alcaligenes, Achromobacter, AKIW733 ) nachgewiesen werden, während keiner der 9 Kontrollfälle eine Besiedlung mit diesen Keimen zeigte. Weitere Untersuchungen, z. B. mit spezifischen PRC-Assays an größeren Fallzahlen sind nötig, um zu klären, ob Betaproteobakterien der Alcaligenacea-Familie mit der Genese von eMZBCL in der Lunge assoziiert oder sogar ursächlich beteiligt sind. Abstract For several anatomical localisations of extranodal marginal zone B-cell lymphoma of MALT type (eMZBCL), an association with chronic inflammation caused by microbiological agents (e.g. Helicobacter pylori in the stomach) has been described. In the lung, a link between lymphomagenesis and a defined causative organism is still missing. A comprehensive diversity survey using 16S-rDNA library construction followed by restriction fragment length polymorphism (RFLP) analysis, sequencing, and phylogenetic tree construction was employed for nine cases each of BALT lymphoma and control lung tissues (normal foetal lung, pneumonitis, carcinoid). This highly sensitive method, hereafter termed SHARP screening allowed for identification of the entire bacterial population in the tissue in a cultivation-independent manner. It was noteworthy that in eight of the nine cases of BALT lymphoma, bacteria of the Alcaligenaceae family (Alcaligenes, Achromobacter, AKIW733), were detected, whereas none of the control cases showed the presence of these clades. 16S-rDNA library construction in combination with RFLP screening and phylogenetic analyses, hereafter described as SHARP screening, is a cultivation-independent tool for analysing the microbial environment in chronic inflammation processes giving rise to extranodal marginal zone B-cell lymphomas of MALT-type. Betaproteobacteria of the Alcaligenaceae family may be affiliated with and possibly involved in the lymphomagenesis of BALT lymphomas.