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Marine-derived fungi are emerging as prolific workhorses of structurally novel natural products (NPs) with diverse bioactivities. However, the limitation of available selection markers hampers the exploration of cryptic NPs. Recyclable markers are therefore valuable assets in genetic engineering programs for awaking silent SM clusters. Here, both pyrG and amdS-based recyclable marker cassettes were established and successfully applied in marine-derived fungi Aspergillus sp. SCSIO SX7S7 and Spiromastix sp. SCSIO F190, respectively. Using pyrG recyclable marker, a markerless 7S7-ΔdepH strain with a simplified HPLC background was built by inactivating a polyketide synthase (PKS) gene depH and looping out the pyrG recyclable marker after depH deletion. Meanwhile, an amdS recyclable marker system was also developed to help strains that are difficult to use pyrG marker. By employing the amdS marker, a backbone gene spm11 responsible for one major product of Spiromastix sp. SCSIO F190 was inactivated, and the amdS marker was excised after using, generating a relatively clean F190-Δspm11 strain for further activation of novel NPs. The collection of two different recycle markers will guarantee flexible application in marine-derived fungi with different genetic backgrounds, enabling the exploitation of novel structures in various fungi species with different genome mining strategies. [ABSTRACT FROM AUTHOR]

Chemical epigenetic manipulation was applied to a deep marine-derived fungus, Aspergillus sp. SCSIOW3, resulting in significant changes of the secondary metabolites. One new diphenylether-O-glycoside (diorcinol 3-O-α-D-ribofuranoside), along with seven known compounds, were isolated from the culture treated with a combination of histone deacetylase inhibitor (suberohydroxamic acid) and DNA methyltransferase inhibitor (5-azacytidine). Compounds 2 and 4 exhibited significant biomembrane protective effect of erythrocytes. 2 also showed algicidal activity against Chattonella marina, a bloom forming alga responsible for large scale fish deaths. [ABSTRACT FROM AUTHOR]

The article presents graphs and other supplementary visual aids on a new dioic acid from a wbl gene mutant of deepsea-derived Streptomyces somaliensis SCSIO ZH66.

The wblAso gene functions as a global regulatory gene in a negative manner in deepsea-derived Streptomyces somaliensis SCSIO ZH66. A new dioic acid (1) as well as two known butenolides (2 and 3) were isolated from the ΔwblAso mutant strain of S. somaliensis SCSIO ZH66. The structure of 1 was elucidated by a combination of spectroscopic analyses, including MS and NMR techniques. In the cell growth inhibitory evaluation, compound 3 exhibited moderate activity against the human hepatic carcinoma cell line (Huh7.5) with an IC50 value of 19.4 µg/mL, while compounds 1 and 2 showed null activity up to 100 µg/mL. [ABSTRACT FROM AUTHOR]

Two new C-glycoside angucyclines, marangucycline A (1) and marangucycline B (2), along with three known compounds, dehydroxyaquayamycin (3), undecylprodigiosin (4) and metacycloprodigiosin (5), have been identified as products of the deep-sea sediment strain Streptomyces sp. SCSIO 11594. New structures were elucidated on the basis of HRESIMS, 1D and 2D NMR analyses and comparisons to previously reported datasets. Compounds 2 and 4 displayed in vitro cytotoxicity against four cancer cell lines A594, CNE2, HepG2, MCF-7 superior to those obtained with cisplatin, the positive control. Notably, compound 2 bearing a keto-sugar displayed significant cytotoxicity against cancer cell lines with IC50 values ranging from 0.24 to 0.56 μM; An IC50 value of 3.67 μM was found when using non-cancerous hepatic cell line HL7702, demonstrating the cancer cell selectivity of 2. Compounds 1-3 were proved to have weak antibacterial activities against Enterococcus faecalis ATCC29212 with an MIC value of 64.0 μg/mL. Moreover, 3 displayed selective antibacterial activity against methicillin-resistant Staphylococcus epidermidis shhs-E1 with an MIC value of 16.0 μg/mL. [ABSTRACT FROM AUTHOR]

Pseudonocardians A–C (2–4), three new diazaanthraquinone derivatives, along with a previously synthesized compound deoxynyboquinone (1), were produced by the strain SCSIO 01299, a marine actinomycete member of the genus Pseudonocardia, isolated from deep-sea sediment of the South China Sea. The structures of compounds 1–4 were determined by mass spectrometry and NMR experiments (1H, 13C, HSQC, and HMBC). The structure of compound 1, which was obtained for the first time from a natural source, was confirmed by X-ray analysis. Compounds 1–3 exhibited potent cytotoxic activities against three tumor cell lines of SF-268, MCF-7 and NCI-H460 with IC50 values between 0.01 and 0.21 μM, and also showed antibacterial activities on Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 and Bacillus thuringensis SCSIO BT01, with MIC values of 1–4 μg mL−1. [ABSTRACT FROM AUTHOR]