Antibacterial and Antifungal Polyketides from the Fungus Aspergillus unguis PSU-MF16.

Seven new polyketides including a phenol (1), two diphenyl ethers (2 and 3), two depsidones (4 and 5), and two phthalides (6 and 7) were isolated from the fungus Aspergillus unguis PSU-MF16 along with 27 known compounds. Their structures were determined by extensive spectroscopic analysis. The absolute configurations of 1 and 4-7 were established using comparative analyses of calculated and experimental ECD spectra. Among the new metabolites, 2 exhibited the best antimicrobial activity against Staphylococcus aureus, methicillin-resistant S. aureus, and Microsporum gypseum with equal MIC values of 16 µg/mL. In addition, known emeguisin A displayed potent antimicrobial activity against S. aureus, methicillin-resistant S. aureus, and Cryptococcus neoformans with equal MIC values of 0.5 µg/mL, compared with the standard drugs, vancomycin and amphotericin B. The structure-activity relationship study of the isolated compounds for antimicrobial activity is discussed.

Differential expression of immune receptors in two marine sponges upon exposure to microbial-associated molecular patterns.

The innate immune system helps animals to navigate the microbial world. The response to microbes relies on the specific recognition of microbial-associated molecular patterns (MAMPs) by immune receptors. Sponges (phylum Porifera), as early-diverging animals, provide insights into conserved mechanisms for animal-microbe crosstalk. However, experimental data is limited. We adopted an experimental approach followed by RNA-Seq and differential gene expression analysis in order to characterise the sponge immune response. Two Mediterranean species, Aplysina aerophoba and Dysidea avara, were exposed to a "cocktail" of MAMPs (lipopolysaccharide and peptidoglycan) or to sterile artificial seawater (control) and sampled 1 h, 3 h, and 5 h post-treatment for RNA-Seq. The response involved, first and foremost, a higher number of differentially-expressed genes in A. aerophoba than D. avara. Secondly, while both species constitutively express a diverse repertoire of immune receptors, they differed in their expression profiles upon MAMP challenge. The response in D. avara was mediated by increased expression of two NLR genes, whereas the response in A. aerophoba involved SRCR and GPCR genes. From the set of annotated genes we infer that both species activated apoptosis in response to MAMPs while in A. aerophoba phagocytosis was additionally stimulated. Our study assessed for the first time the transcriptomic responses of sponges to MAMPs and revealed conserved and species-specific features of poriferan immunity as well as genes potentially relevant to animal-microbe interactions.

Comprehensive optimization of precursor-directed production of BC194 by Streptomyces rochei MB037 derived from the marine sponge Dysidea arenaria.

BC194, a derivative of borrelidin (BN) that features a lower cytotoxicity than that of BN due to an altered starter unit, trans-1,2-cyclobutanedicarboxylic acid (trans-1,2-CBDA), is a potent inhibitor of angiogenesis. However, BC194 production has only been reported to occur via mutasynthesis, which requires tedious, multistep genetic manipulation. In this study, we surveyed several factors contributing to the precursor-directed biosynthesis of BC194 and provided an alternative method for the production of BC194 that is directly applicable to other BN-producing strains. First, the precursor-directed biosynthesis of BC194 by a BN-producing strain, Streptomyces rochei MB037 derived from sponge Dysidea arenaria, was carried out in modified Radix astragali (RA) medium with 5 mM trans-1,2-CBDA. Next, possible inhibitors of BN starter unit trans-1,2-cyclopentanedicarboxylic acid (trans-1,2-CPDA) biosynthesis were investigated. It was found that potassium ferricyanide was a possible inhibitor of 3,4-dihydroxyphenylacetate 2,3-dioxygenase (DHPAO) and capable of suppressing the yield of BN and increasing the BC194 yield by 112.5% (from 5.2 ± 0.76 to 11.9 ± 0.59 mg/L). BC194 yield was further enhanced in the presence of 50 mM trans-1,2-CBDA, reaching 20.2 ± 0.62 mg/L. Furthermore, 3% macroporous adsorbent DA-201 resin was added to the fermentation broth, enabling a further 36.6% increase in BC194 production and reaching 27.59 ± 1.15 mg/L. Moreover, an efficient separation of BC194 with approximately 95% purity was developed by employing high-speed counter-current chromatography (HSCCC), achieving an improved recovery (approximately 93%).

Draft genome sequence of the sponge-associated strain Bacillus atrophaeus C89, a potential producer of marine drugs.

Bacillus atrophaeus C89, isolated from the marine sponge Dysidea avara, is a potential producer of bioactive compounds, such as neobacillamide A and bacillamide C. Here, we present a 4.2-Mb assembly of its genome. The nonribosomal peptide synthetases (NRPSs) make it possible to produce the bioactive compounds.

Antibacterial potential of sponge endosymbiont marine Enterobacter sp at Kavaratti Island, Lakshadweep archipelago.

OBJECTIVE: To isolate antibacterial potential of sponge endosymbiotic bacteria from marine sponges at Lakshadweep archipelago. Also to identify the potent bacteria by 16s rDNA sequencing and determine the antibacterial activity against clinical pathogens by MIC. METHODS: Sponge samples was collected from sub-tidal habitats at Kavaratti Island and identified. The endosymbiotic bacteria were isolated and selected potential bacteria which show antibacterial activity in preliminary screening against clinical pathogens Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Salmonella typhi (S. typhi), Klebsiella pneumoniea (K. pneumoniea) and Streptococcus sp. by disc diffusion assay. The crude extracts of potential bacteria LB3 was tested against clinical pathogens by MIC. The LB3 strain was identified by 16s rDNA sequencing, 1 111 bp was submitted in NCBI (HQ589912) and constructed phylogenetic tree. RESULTS: Sponge sample was identified as Dysidea granulosa (D. granulosa) and potential bacteria LB3 identified as Enterobacter sp TTAG. Preliminary screening of sponge isolates against clinical pathogens, LB3 strain was selected as potential producer of secondary metabolites and crude extract was implies on MIC of LB3 have confirmed with lowest concentration of 5.0 mg/mL in broth medium influence of crude extract on growth inhibitory activity after 5 h of incubation period and completed the inhibitory activity at 15 h. CONCLUSIONS: The present study concluded that phylogenetic analysis of endosymbiotic bacteria Enterobacter sp from sponge D. granulosa of Lakshadweep islands showed significant antibacterial activity against clinical bacterial pathogens.

[Revelation and phylogenetic analysis of the predominant bacterial community associated with sponges in the South China Sea based on PCR- DGGE fingerprints].

The predominant bacterial community structure of Dysidea avara and Craniella australiensis in the South China Sea were revealed by PCR- DGGE fingerprinting in the present study. With further cloning, sequencing and phylogenetic analysis, it was found that Proteobacteria predominated in these two sponges. Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria were found in Dysidea avara and only Gammaproteobacteria found in Craniella australiensis. Although Bacteroidetes were found in both sponges, they differed in the species. These bacteria were found in sponges firstly. The bacteria in Craniella australiensis show more complex diversity than that in Dysidea avara. Because compared with Dysidea avara, Craniella australiensis include Actinobacteria, Firmicutes, etc. The bacterial community diversity in these two sponges indicates that the sponge-associated bacteria are host-specific even if the hosts are from the same marine location. DGGE fingerprint-based analysis should integrate with band cloning and sequencing, phylogenetic analysis, etc., molecular techniques to get precise results for the microbial community and diversity revelation. The research of studying sponge microbe by DGGE technique is initial work, that will accelerate the development of sponge microorganisms item.

Speciation and biosynthetic variation in four dictyoceratid sponges and their cyanobacterial symbiont, Oscillatoria spongeliae.

Four species of marine sponges (Phylum Porifera, Order Dictyoceratida), which contain the filamentous cyanobacterial symbiont Oscillatoria spongeliae, were collected from four locations in Palau. The halogenated natural products associated with the symbiont were characterized from each sample, revealing that each species contained either chlorinated peptides, brominated diphenyl ethers, or no halogenated compounds. Analysis of the host sponges and the symbionts indicated that each species of sponge contained a distinct strain of morphologically similar cyanobacteria. Although cospeciation may be present in this group, we have identified that at least one host switching event has occurred in this symbiosis. Only the strain of O. spongeliae in the sponge containing the chlorinated compounds possessed genes involved in the biosynthesis of chlorinated leucine precursors, indicating that the chemical variation observed in these animals has a genetic foundation.