Bioinformatic comparison of three Embleya species and description of steffimycins production by Embleya sp. NF3.

The Embleya genus is a new member of the Streptomycetaceae family formed by only two species isolated from soil (Embleya scabrispora and Embleya hyalina). Strain NF3 is an endophytic actinobacterium obtained from the medicinal tree Amphipterygium adstringens. By 16S rRNA gene analysis, NF3 strain was identified as Embleya sp., closely related to E. hyalina. In our interest to deep into the NF3 strain features, a bioinformatic study was performed on the Embleya genus based on their genome information to produce secondary metabolites. A comparative analysis of the biosynthetic gene clusters (BGCs) of NF3 with the two released Embleya genomes revealed that NF3 has 49 BGCs, E. scabrispora DSM41855 has 50 BGCs, and E. hyalina NBRC13850 has 46 BGCs. Although bearing similar cluster numbers, the three strains shared only 25% of the BGCs information. NF3 encoded the nybomycin cluster detected in E. hyalina NBRC13850 and lacked the hitachimycin cluster present in E. scabrispora DSM41855. On the contrary, strain NF3 contained a cluster for the anthracycline steffimycin, neither encoded by E. hyalina NBRC13850 nor by E. scabrispora DSM41855. Our results and previous characterization studies supported strain NF3 as a new member of the genus Embleya. The chemical analysis of the steffimycins produced by strain NF3 showed the production of eight compounds of the steffimycins and steffimycinone families. Four of these molecules have already been described: steffimycin B, steffimycin C, 8-demethoxy-10-deoxysteffimycinone, and 7-deoxiesteffimycinone, and four are new natural products: 8-demethoxysteffimycin B, 8-demethoxy-10-deoxysteffimycin B, 7-deoxy-8-demethoxysteffimycinone, and 7-deoxy-10-deoxysteffimycinone. With this information, we proposed an alternative pathway to produce StefB. Among steffimycins, StefB was the main compound produced by this strain (29.8%) and showed the best cytotoxic activity. KEY POINTS: • The Embleya genus and its biosynthetic potential • An alternative biosynthetic pathway for steffimycins biosynthesis • Four new natural products of the steffimycin family.

Antimycobacterial activity of an anthracycline produced by an endophyte isolated from Amphipterygium adstringens.

The search for new compounds effective against Mycobacterium tuberculosis is still a priority in medicine. The evaluation of microorganisms isolated from non-conventional locations offers an alternative to look for new compounds with antimicrobial activity. Endophytes have been successfully explored as source of bioactive compounds. In the present work we studied the nature and antimycobacterial activity of a compound produced by Streptomyces scabrisporus, an endophyte isolated from the medicinal plant Amphipterygium adstringens. The active compound was detected as the main secondary metabolite present in organic extracts of the streptomycete and identified by NMR spectroscopic data as steffimycin B (StefB). This anthracycline displayed a good activity against M. tuberculosis H37Rv ATCC 27294 strain, with MIC100 and SI values of 7.8 µg/mL and 6.42, respectively. When tested against the rifampin mono resistant M. tuberculosis Mtb-209 pathogen strain, a better activity was observed (MIC100 of 3.9 µg/mL), suggesting a different action mechanism of StefB from that of rifampin. Our results supported the endophyte Streptomyces scabrisporus as a good source of StefB for tuberculosis treatment, as this anthracycline displayed a strong bactericidal effect against M. tuberculosis, one of the oldest and more dangerous human pathogens causing human mortality.

Endophytes as sources of antibiotics.

Until a viable alternative can be accessible, the emergence of resistance to antimicrobials requires the constant development of new antibiotics. Recent scientific efforts have been aimed at the bioprospecting of microorganisms' secondary metabolites, with special emphasis on the search for antimicrobial natural products derived from endophytes. Endophytes are microorganisms that inhabit the internal tissues of plants without causing apparent harm to the plant. The present review article compiles recent (2006-2016) literature to provide an update on endophyte research aimed at finding metabolites with antibiotic activities. We have included exclusively information on endophytes that produce metabolites capable of inhibiting the growth of bacterial, fungal and protozoan pathogens of humans, animals and plants. Where available, the identified metabolites have been listed. In this review, we have also compiled a list of the bacterial and fungal phyla that have been isolated as endophytes as well as the plant families from which the endophytes were isolated. The majority of endophytes that produce antibiotic metabolites belong to either phylum Ascomycota (kingdom Fungi) or to phylum Actinobacteria (superkingdom Bacteria). Endophytes that produce antibiotic metabolites were predominant, but certainly not exclusively, from the plant families Fabaceae, Lamiaceae, Asteraceae and Araceae, suggesting that endophytes that produce antimicrobial metabolites are not restricted to a reduced number of plant families. The locations where plants (and inhabiting endophytes) were collected from, according to the literature, have been mapped, showing that endophytes that produce bioactive compounds have been collected globally.

Draft Genome Sequence of an Endophytic Actinoplanes Species, Encoding Uncommon trans-Acyltransferase Polyketide Synthases.

Actinoplanesis an endophytic actinobacterium isolated from the medicinal plantAmphipterygium adstringens The strain draft genome sequence reveals a gene cluster involved in the biosynthesis of a hybridtrans-acyltransferase (AT) polyketide, an unconventional bioactive metabolite never reported before in the genusActinoplanes.