A New Micromonospora Strain with Antibiotic Activity Isolated from the Microbiome of a Mid-Atlantic Deep-Sea Sponge

To tackle the growing problem of antibiotic resistance, it is essential to identify new bioactive compounds that are effective against resistant microbes and safe to use. Natural products and their derivatives are, and will continue to be, an important source of these molecules. Sea sponges harbour a diverse microbiome that co-exists with the sponge, and these bacterial communities produce a rich array of bioactive metabolites for protection and resource competition. For these reasons, the sponge microbiota constitutes a potential source of clinically relevant natural products. To date, efforts in bioprospecting for these compounds have focused predominantly on sponge specimens isolated from shallow water, with much still to be learned about samples from the deep sea. Here we report the isolation of a new Micromonospora strain, designated 28ISP2-46^T, recovered from the microbiome of a mid-Atlantic deep-sea sponge. Whole-genome sequencing reveals the capacity of this bacterium to produce a diverse array of natural products, including kosinostatin and isoquinocycline B, which exhibit both antibiotic and antitumour properties. Both compounds were isolated from 28ISP2-46^T fermentation broths and were found to be effective against a plethora of multidrug-resistant clinical isolates. This study suggests that the marine production of isoquinocyclines may be more widespread than previously supposed and demonstrates the value of targeting the deep-sea sponge microbiome as a source of novel microbial life with exploitable biosynthetic potential.     

Experimental evidence that tryptamine alkaloids do not cause Phalaris aquatica sudden death syndrome in sheep

The acute toxicity for sheep of 3 alkaloids that occur in Phalaris acquatica was examined by intravenous and oral administration. The lowest tested dose rates that produced clinically observed signs were, for 5-methoxy dimethyltryptamine, 0.1 mg/kg body weight intravenously and 40 mg/kg orally; for gramine, 10 mg/kg intravenously and 500 mg/kg orally; and for hordenine, 20 mg/kg intravenously and 800 mg/kg orally. All induced the clinical signs observed in the nervous form of phalaris toxicity, but none induced the cardiac, sudden death, syndrome.