Phylogenetic Diversity and Antimicrobial Activities of Culturable Endophytic Actinobacteria Isolated from Different Egyptian Marine Sponges and Soft Corals

A cultivation-based approach was employed to isolate and compare the endophytic culturable actinobacterial diversity associated with different Egyptian marine sponges and soft corals. A total of 13 culturable actinobacteria isolates were obtained, five of which isolated from different sponges, two (AE27 and AE32) and three (AE29, AE41 and AE46) were isolated from Haliclona sp. and Callyspongia sp. collected from Sharm El-Sheikh and Hurghada, Egypt, respectively. Eight were isolated from different five soft corals, out of them two (AE2 and AE19), two (AE3 and AE15), two (AE20 and AE23), one (AE35) and one (AE13) were isolated from Rhytisma sp., Xenia sp., Lobularia sp., and Dendronephthya sinaiensis (collected from Sharm El-Sheikh, Egypt) and the Dendronephthya hemprichi (collected from Hurghada, Egypt), respectively. The 16S rRNA genes of the 13 actinobacteria isolates were amplified and sequenced (GenBank Accession numbers JF292923 – JF292930 and JF319146 – JF319150). A BLAST analysis revealed that the 13 actinobacteria isolates belonged to three known families and genera. Six strains isolated from all sponges and soft corals belonged to the genus Streptomyces (AE15, AE19, AE20 and AE35, isolated from soft corals; Xenia sp., Rhytisma sp., Lobularia sp., and Dendronephthya sinaiensis as well as AE29 and AE41, isolated from sponges; Callyspongia sp., respectively). Six strains (AE2, AE3 and AE23, isolated from soft corals; Rhytisma sp., Xenia sp. and Lobularia sp. as well as AE27, AE32 and AE46, isolated from sponges; Haliclona sp. and Callyspongia sp., respectively) belonged to the genus Nocardiopsis. Only one isolate (AE13) derived from Dendronephthya hemprichi was belonged to the genus Pseudonocardia. The phylogenetic analysis revealed that four culturable actinobacteria strains (AE2, AE27, AE32 and AE46) were more distantly related to other previously published Nocardiopsis dassonvillei. Screening for antimicrobial activity revealed that out of the 13 culturable actinobacteria isolates, only five (AE15, AE19, AE20, AE29 and AE41) belonged to the genus Streptomyces have anticandida or anti-positive Gram bacteria activity

Bioactive Benzopyrone Derivatives from New Recombinant Fusant of Marine Streptomyces

In our searching program for bioactive secondary metabolites from marine Streptomycetes, three microbial benzopyrone derivatives (1–3), 7-methylcoumarin (1) and two flavonoides, rhamnazin (2) and cirsimaritin (3), were obtained during the working up of the ethyl acetate fraction of a marine Streptomyces fusant obtained from protoplast fusion between Streptomyces strains Merv 1996 and Merv 7409. The structures of the three compounds (1–3) were established by nuclear magnetic resonance, mass, UV spectra, and by comparison with literature data. Marine Streptomyces strains were identified based on their phenotypic and chemotypic characteristics as two different bioactive strains of the genus Streptomyces. We described here the fermentation, isolation, as well as the biological activity of these bioactive compounds. The isolated compounds (1–3) are reported here as microbial products for the first time