Comprehensive Investigation of Marine Actinobacteria Associated with the Sponge Halichondria panicea

Abstract

Representatives of Actinobacteria were isolated from the marine sponge Halichondria panicea collected from the Baltic Sea (Germany). For the first time, a comprehensive investigation was performed with regard to phylogenetic strain identification, secondary metabolite profiling, bioactivity determination, and genetic exploration of biosynthetic genes, especially concerning the relationships of the abundance of biosynthesis gene fragments to the number and diversity of produced secondary metabolites. All strains were phylogenetically identified by 16S rRNA gene sequence analyses and were found to belong to the genera Actinoalloteichus, Micrococcus, Micromonospora, Nocardiopsis, and Streptomyces. Secondary metabolite profiles of 46 actinobacterial strains were evaluated, 122 different substances were identified, and 88 so far unidentified compounds were detected. The extracts from most of the cultures showed biological activities. In addition, the presence of biosynthesis genes encoding polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) in 30 strains was established. It was shown that strains in which either PKS or NRPS genes were identified produced a significantly higher number of metabolites and exhibited a larger number of unidentified, possibly new metabolites than other strains. Therefore, the presence of PKS and NRPS genes is a good indicator for the selection of strains to isolate new natural products.Sponges are multicellular invertebrates and sessile filter feeders which are abundant in the oceans as well as in freshwater habitats (41). They gained great interest due to their association with a wide variety of microorganisms. These microorganisms are known to be a rich source of secondary metabolites (108), which exhibit a broad range of bioactivities such as inhibition of enzyme activities and cell division and antiviral, antimicrobial, anti-inflammatory, antitumor, cytotoxic, and cardiovascular properties (77).Numerous studies concerning specific aspects of spongebacterium associations were accomplished using distinct methods for the evaluation of the microbial diversity (mostly molecular approaches) or the bioactivities (culture-dependent methods) or biosynthetic aspects (chemical analyses and molecular approaches) of secondary metabolites of the associated bacteria (19,47,51,54,110,122,126). So far, there is less comprehensive information about the integration of this knowledge into concepts for sponge-bacterium interactions based on small molecules.We focused on Actinobacteria associated with Halichondria panicea Pallas (Porifera, Demospongiae, Halichondriida, Halichondriidae), a sponge species living in coastal habitats worldwide (9). Previous work demonstrated a phylogenetically diverse array of bacterial groups present in this sponge: representatives of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Cytophaga/Flavobacteria, the Deinococcus group, low-GϩC-content Gram-positive bacteria, Actinobacteria, and Planctomycetales were identified by means of a genetic ...

Osculum dynamics and filtration activity in small single-osculum explants of the demosponge Halichondria panicea

“…In this way, sponges may benefit from their associated microbial symbionts (Hoffmann et al 2005, 2008, Schläppy et al 2010b, which considerably contribute to the sponge host metabolism (Weisz et al 2007, Maldonado et al 2012 and references therein). Therefore, and consistent with the suggestions of Hoffmann et al (2005), H. panicea may perhaps cease its pumping activity to establish internal body anoxia to maintain its endosymbiotic community (Althoff et al 1998, Wichels et al 2006, Schneemann et al 2010. Bacteria isolated from H. panicea are potential sources of neuro-active compounds (Perovic et al 1998), suggesting that sponge-associated microbes also play a functional role in coordinating contractile behavior of the sponge host (Meech 2008, Leys 2015.…”

Evidence for Selective Bacterial Community Structuring in the Freshwater Sponge Ephydatia fluviatilis

“…Increasing research interest in the marine sponge microbiota is also due to the potential in-spongia production, by bacterial symbionts, of biologically active secondary metabolites of pharmaceutical interest [17]. Noticeable in this regard are sponge-associated Actinobacteria, well documented for their ability to produce several biologically active compounds [18][19][20][21]. Metagenomics studies have provided further evidence for bacterial secondary metabolite production in sponges [17,22].…”

Dual effect of macroalgal extracts on growth of bacteria in Western Baltic Sea

“…The bioactivity tests were modified according to Schneemann et al (2010). Assay mixtures were prepared by transferring 10 μl aliquots of methanolic solutions of extracts into a sterile 96-well microtiter plate and evaporating the solvent in a vacuum centrifuge.…”