Carlos Olano

Antimicrobial resistance is one of the main global threats to human health in the 21st century due to the rapid appearance of bacterial resistance and the lack of novel bioactive compounds. Natural products, especially from Actinomycetes, remain the best source to refill the drug industry pipeline. Different strategies have been pursued to increase the chances of discovering new molecules, such as studying underexplored environments like arthropod symbionts, which represent a relevant reservoir for active metabolites. This review summarizes recent research on the identification of bioactive molecules produced by Actinomycetes associated with arthropods’ microbiome. The metabolites have been categorized based on their structural properties and host, highlighting that multidisciplinary approaches will be the key to fully understanding this complex relationship.

Three novel lipopeptides, PM130391 (1), PM130392 (2), and PM140293 (3) were obtained from cultures of Streptomyces tuirus PHM034 isolated from a marine sediment. Structural elucidation of the three compounds showed they belong to the nonribosomal peptides family, and they all contain an acylated alanine, three piperazic acids, a methylated glycine, and an N-hydroxylated alanine. The difference between the three compounds resides in the acyl chain bound to the alanine residue. All three compounds showed cytotoxic activity against human cancer cell lines. Genome sequence and bioinformatics analysis allowed the identification of the gene cluster responsible for the biosynthesis. Inactivation of a nonribosomal peptide synthase of this cluster abolished the biosynthesis of the three compounds, thus demonstrating the involvement of this cluster in the biosynthesis of these lipopeptides.