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Dive into the research topics where Georg Steinert is active.

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Featured researches published by Georg Steinert.


Marine Biotechnology | 2014

Application of Diffusion Growth Chambers for the Cultivation of Marine Sponge-Associated Bacteria

Georg Steinert; Susanna Whitfield; Michael W. Taylor; Carsten Thoms; Peter J. Schupp

Marine sponges contain dense and diverse microbial communities, which are renowned as a source of bioactive metabolites. The biological activities of sponge-microbe natural products span a broad spectrum, from antibacterial and antifungal to antitumor and antiviral applications. However, the potential of sponge-derived compounds has not been fully realized, due largely to the acknowledged “supply issue.” Most bacteria from environmental samples have resisted cultivation on artificial growth media, and cultivation of sponge-associated bacteria has been a major focus in the search for novel marine natural products. One approach to isolate so-called “uncultivable” microorganisms from different environments is the diffusion growth chamber method. Here, we describe the first application of diffusion growth chambers for the isolation of cultivable and previously uncultivated bacteria from sponges. The study was conducted by implanting diffusion growth chambers in the tissue of Rhabdastrella globostellata reef sponges. In total, 255 16S rRNA gene sequences were obtained, with phylogenetic analyses revealing their affiliations with the Alpha- and Gammaproteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. Fifteen sequences represented previously uncultivated bacteria belonging to the Bacteroidetes and Proteobacteria (Alpha and Gamma classes). Our results indicate that the diffusion growth chamber approach can be successfully applied in a natural, living marine environment such as sponges.


PeerJ | 2016

In four shallow and mesophotic tropical reef sponges from Guam the microbial community largely depends on host identity

Georg Steinert; Michael W. Taylor; Peter Deines; Rachel L. Simister; Nicole J. de Voogd; Michael Hoggard; Peter J. Schupp

Sponges (phylum Porifera) are important members of almost all aquatic ecosystems, and are renowned for hosting often dense and diverse microbial communities. While the specificity of the sponge microbiota seems to be closely related to host phylogeny, the environmental factors that could shape differences within local sponge-specific communities remain less understood. On tropical coral reefs, sponge habitats can span from shallow areas to deeper, mesophotic sites. These habitats differ in terms of environmental factors such as light, temperature, and food availability, as well as anthropogenic impact. In order to study the host specificity and potential influence of varying habitats on the sponge microbiota within a local area, four tropical reef sponges, Rhabdastrella globostellata, Callyspongia sp., Rhaphoxya sp., and Acanthella cavernosa, were collected from exposed shallow reef slopes and a deep reef drop-off. Based on 16S rRNA gene pyrosequencing profiles, beta diversity analyses revealed that each sponge species possessed a specific microbiota that was significantly different to those of the other species and exhibited attributes that are characteristic of high- and/or low-microbial-abundance sponges. These findings emphasize the influence of host identity on the associated microbiota. Dominant sponge- and seawater-associated bacterial phyla were Chloroflexi, Cyanobacteria, and Proteobacteria. Comparison of individual sponge taxa and seawater samples between shallow and deep reef sites revealed no significant variation in alpha diversity estimates, while differences in microbial beta diversity (variation in community composition) were significant for Callyspongia sp. sponges and seawater samples. Overall, the sponge-associated microbiota is significantly shaped by host identity across all samples, while the effect of habitat differentiation seems to be less predominant in tropical reef sponges.


Frontiers in Microbiology | 2017

Predicting the HMA-LMA Status in Marine Sponges by Machine Learning

Lucas Moitinho-Silva; Georg Steinert; Shaun Nielsen; Cristiane C.P. Hardoim; Yu Chen Wu; Grace P. McCormack; Susanna López-Legentil; Roman Marchant; Nicole S. Webster; Torsten Thomas; Ute Hentschel

The dichotomy between high microbial abundance (HMA) and low microbial abundance (LMA) sponges has been observed in sponge-microbe symbiosis, although the extent of this pattern remains poorly unknown. We characterized the differences between the microbiomes of HMA (n = 19) and LMA (n = 17) sponges (575 specimens) present in the Sponge Microbiome Project. HMA sponges were associated with richer and more diverse microbiomes than LMA sponges, as indicated by the comparison of alpha diversity metrics. Microbial community structures differed between HMA and LMA sponges considering Operational Taxonomic Units (OTU) abundances and across microbial taxonomic levels, from phylum to species. The largest proportion of microbiome variation was explained by the host identity. Several phyla, classes, and OTUs were found differentially abundant in either group, which were considered “HMA indicators” and “LMA indicators.” Machine learning algorithms (classifiers) were trained to predict the HMA-LMA status of sponges. Among nine different classifiers, higher performances were achieved by Random Forest trained with phylum and class abundances. Random Forest with optimized parameters predicted the HMA-LMA status of additional 135 sponge species (1,232 specimens) without a priori knowledge. These sponges were grouped in four clusters, from which the largest two were composed of species consistently predicted as HMA (n = 44) and LMA (n = 74). In summary, our analyses shown distinct features of the microbial communities associated with HMA and LMA sponges. The prediction of the HMA-LMA status based on the microbiome profiles of sponges demonstrates the application of machine learning to explore patterns of host-associated microbial communities.


GigaScience | 2017

The Sponge Microbiome Project

Lucas Moitinho-Silva; Shaun Nielsen; Amnon Amir; Antonio González; Gail Ackermann; Carlo Cerrano; Carmen Astudillo-García; Cole Easson; Detmer Sipkema; Fang Liu; Georg Steinert; Giorgos Kotoulas; Grace P. McCormack; Guofang Feng; James J. Bell; Jan Vicente; Johannes R. Björk; José M. Montoya; Julie B. Olson; Julie Reveillaud; Laura Steindler; Mari Carmen Pineda; Maria V. Marra; Micha Ilan; Michael W. Taylor; Paraskevi N. Polymenakou; Patrick M. Erwin; Peter J. Schupp; Rachel L. Simister; Rob Knight

Abstract Marine sponges (phylum Porifera) are a diverse, phylogenetically deep-branching clade known for forming intimate partnerships with complex communities of microorganisms. To date, 16S rRNA gene sequencing studies have largely utilised different extraction and amplification methodologies to target the microbial communities of a limited number of sponge species, severely limiting comparative analyses of sponge microbial diversity and structure. Here, we provide an extensive and standardised dataset that will facilitate sponge microbiome comparisons across large spatial, temporal, and environmental scales. Samples from marine sponges (n = 3569 specimens), seawater (n = 370), marine sediments (n = 65) and other environments (n = 29) were collected from different locations across the globe. This dataset incorporates at least 268 different sponge species, including several yet unidentified taxa. The V4 region of the 16S rRNA gene was amplified and sequenced from extracted DNA using standardised procedures. Raw sequences (total of 1.1 billion sequences) were processed and clustered with (i) a standard protocol using QIIME closed-reference picking resulting in 39 543 operational taxonomic units (OTU) at 97% sequence identity, (ii) a de novo clustering using Mothur resulting in 518 246 OTUs, and (iii) a new high-resolution Deblur protocol resulting in 83 908 unique bacterial sequences. Abundance tables, representative sequences, taxonomic classifications, and metadata are provided. This dataset represents a comprehensive resource of sponge-associated microbial communities based on 16S rRNA gene sequences that can be used to address overarching hypotheses regarding host-associated prokaryotes, including host specificity, convergent evolution, environmental drivers of microbiome structure, and the sponge-associated rare biosphere.


Marine Biotechnology | 2015

Diversity of Actinobacteria Associated with the Marine Ascidian Eudistoma toealensis

Georg Steinert; Michael W. Taylor; Peter J. Schupp

Ascidians have yielded a wide variety of bioactive natural products. The colonial ascidian Eudistoma toealensis from Micronesia has been identified as the source of a series of staurosporine derivatives, though the exact origin of these derivatives is still unknown. To identify known staurosporine-producing microbes associated with E. toealensis, we analyzed with 16S rRNA gene tag pyrosequencing the overall bacterial community and focused on potential symbiotic bacteria already known from other ascidians or other marine hosts, such as sponges. The described microbiota was one of very high diversity, comprising 43 phyla: two from archaea, 34 described bacterial phyla, and seven candidate bacterial phyla. Many bacteria, which are renowned community members of other ascidians and marine holobionts, such as sponges and corals, were also part of the E. toealensis microbial community. Furthermore, two known producers of indolocarbazoles, Salinispora and Verrucosispora, were found with high abundance exclusively in the ascidian tissue, suggesting that microbial symbionts and not the organism itself may be the true producers of the staurosporines in E. toealensis.


Scientific Reports | 2017

Host-specific assembly of sponge-associated prokaryotes at high taxonomic ranks

Georg Steinert; Sven Rohde; Dorte Janussen; Claudia Blaurock; Peter J. Schupp

Sponges (Porifera) are abundant and diverse members of benthic filter feeding communities in most marine ecosystems, from the deep sea to tropical reefs. A characteristic feature is the associated dense and diverse prokaryotic community present within the sponge mesohyl. Previous molecular genetic studies revealed the importance of host identity for the community composition of the sponge-associated microbiota. However, little is known whether sponge host-specific prokaryotic community patterns observed at 97% 16S rRNA gene sequence similarity are consistent at high taxonomic ranks (from genus to phylum level). In the present study, we investigated the prokaryotic community structure and variation of 24 sponge specimens (seven taxa) and three seawater samples from Sweden. Results show that the resemblance of prokaryotic communities at different taxonomic ranks is consistent with patterns present at 97% operational taxonomic unit level.


PeerJ | 2018

Archaeal and bacterial diversity and community composition from 18 phylogenetically divergent sponge species in Vietnam

Ton That Huu Dat; Georg Steinert; Nguyen Thi Cuc; Hauke Smidt; Detmer Sipkema

Sponge-associated prokaryotic diversity has been studied from a wide range of marine environments across the globe. However, for certain regions, e.g., Vietnam, Thailand, Cambodia, and Singapore, an overview of the sponge-associated prokaryotic communities is still pending. In this study we characterized the prokaryotic communities from 27 specimens, comprising 18 marine sponge species, sampled from the central coastal region of Vietnam. Illumina MiSeq sequencing of 16S ribosomal RNA (rRNA) gene fragments was used to investigate sponge-associated bacterial and archaeal diversity. Overall, 14 bacterial phyla and one archaeal phylum were identified among all 27 samples. The phylum Proteobacteria was present in all sponges and the most prevalent phylum in 15 out of 18 sponge species, albeit with pronounced differences at the class level. In contrast, Chloroflexi was the most abundant phylum in Halichondria sp., whereas Spirastrella sp. and Dactylospongia sp. were dominated by Actinobacteria. Several bacterial phyla such as Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Deferribacteres, Gemmatimonadetes, and Nitrospirae were found in two-thirds of the sponge species. Moreover, the phylum Thaumarchaeota (Archaea), which is known to comprise nitrifying archaea, was highly abundant among the majority of the 18 investigated sponge species. Altogether, this study demonstrates that the diversity of prokaryotic communities associated with Vietnamese sponges is comparable to sponge-prokaryotic assemblages from well-documented regions. Furthermore, the phylogenetically divergent sponges hosted species-specific prokaryotic communities, thus demonstrating the influence of host identity on the composition and diversity of the associated communities. Therefore, this high-throughput 16S rRNA gene amplicon analysis of Vietnamese sponge-prokaryotic communities provides a foundation for future studies on sponge symbiont function and sponge-derived bioactive compounds from this region.


Archive | 2018

BluePharmTrain: Biology and Biotechnology of Marine Sponges

Georg Steinert; Carla Huete Stauffer; Nele Aas-Valleriani; Erik Borchert; Agneya Bhushan; Alexandra Campbell; Maryam Chaib De Mares; Margarida Costa; Johanna Gutleben; Stephen Knobloch; Robert Lee; Stephanie Munroe; Deepak Naik; Eike Edzard Peters; Ellen Stokes; Wanlin Wang; Eydís Einarsdóttir; Detmer Sipkema

BluePharmTrain is a Marie Curie Initial Training Network of 17 European academic and industrial partners collaborating to train young scientists in multidisciplinary aspects of blue biotechnology. Harvesting marine sponges for the extraction of bioactive compounds is often highly unsustainable, and the chemical synthesis of promising compounds is often either too complex or very expensive. To find sustainable and economically feasible production methods of sponge-derived compounds, individual BluePharmTrain research projects explore innovative techniques, focusing on selected sponge species shown to harbour interesting active metabolites. The different techniques include sponge cell cultivation, cultivation of microbial symbionts, next-generation sequencing approaches (i.e. metagenomics and metatranscriptomics), in situ and ex situ cultivation of sponges, life cycle characterisation, chemical structure elucidation of compounds and compound metabolic pathway description. Altogether, these consorted efforts and collaborations lead to new insights on sponge metabolism, sponge-microbe interactions and bioactive compound production.


Environmental Microbiology Reports | 2018

Coexistence of poribacterial phylotypes among geographically widespread and phylogenetically divergent sponge hosts: Phylogeny of Poribacteria among globally distributed sponge hosts

Georg Steinert; Johanna Gutleben; Akhirta Atikana; René H. Wijffels; Hauke Smidt; Detmer Sipkema


Archive | 2016

Guam Sponge Microbial OTU abundance & Taxonomy (Greengenes)

Georg Steinert; Michael W. Taylor; Peter Deines; Rachel L. Simister; De Nicole J. Voogd; Michael Hoggard; Peter J. Schupp

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Detmer Sipkema

Wageningen University and Research Centre

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Lucas Moitinho-Silva

University of New South Wales

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Shaun Nielsen

University of New South Wales

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Hauke Smidt

Wageningen University and Research Centre

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Johanna Gutleben

Wageningen University and Research Centre

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