Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Bioactivity Screening and Gene-Trait Matching across Marine Sponge-Associated Bacteria.

Marine sponges harbor diverse microbial communities that represent a significant source of natural products. In the present study, extracts of 21 sponge-associated bacteria were screened for their antimicrobial and anticancer activity, and their genomes were mined for secondary metabolite biosynthetic gene clusters (BGCs). Phylogenetic analysis assigned the strains to four major phyla in the sponge microbiome, namely Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes.

Diketopiperazines and other bioactive compounds from bacterial symbionts of marine sponges.

Humanity faces great challenges, such as the rise of bacterial antibiotic resistance and cancer incidence. Thus, the discovery of novel therapeutics from underexplored environments, such as marine habitats, is fundamental. In this study, twelve strains from the phylum Firmicutes and thirty-four strains from the phylum Proteobacteria, isolated from marine sponges of the Erylus genus, collected in Portuguese waters, were tested for bioactivities and the secondary metabolites were characterised.

Cercospora sp. as a source of anti-aging polyketides targeting 26S proteasome and scale-up production in submerged bioreactor.

From a large screening of microbial extracts for the discovery of proteasome modulating natural products, the fungal strain Cercospora sp. (CF-223709) was selected as the most promising for further investigation. Different liquid cultures of the strain were initially screened for their anti-oxidant activity (DPPH, ABTS) and for their cytotoxicity against the A2058, HepG2 and CCD25sk cell lines.

Activation of Secondary Metabolite Gene Clusters in by the PimM Regulator of .

Expression of non-native transcriptional activators may be a powerful general method to activate secondary metabolites biosynthetic pathways. PAS-LuxR regulators, whose archetype is PimM, activate the biosynthesis of polyene macrolide antifungals and other antibiotics, and have been shown to be functionally preserved across multiple strains. In this work we show that constitutive expression of in ATCC 27064 significantly affected its transcriptome and modifies secondary metabolism.

MDN-0185, an Antiplasmodial Polycyclic Xanthone Isolated from Micromonospora sp. CA-256353.

A potent antiplasmodial polycyclic xanthone, MDN-0185 (1), was isolated from an unidentified species of the genus Micromonospora. The planar structure of 1 was established as a seven-ring polycyclic xanthone with partial structures very similar to two known natural products, namely, xantholipin and Sch 54445. Using ROESY correlations, the relative stereochemistry of the two independent stereoclusters of compound 1 could be determined.

Discovery of New Compounds Active against Plasmodium falciparum by High Throughput Screening of Microbial Natural Products.

Due to the low structural diversity within the set of antimalarial drugs currently available in the clinic and the increasing number of cases of resistance, there is an urgent need to find new compounds with novel modes of action to treat the disease. Microbial natural products are characterized by their large diversity provided in terms of the chemical complexity of the compounds and the novelty of structures. Microbial natural products extracts have been underexplored in the search for new antiparasitic drugs and even more so in the discovery of new antimalarials.

Occurrence, distribution, dereplication and efficient discovery of thiazolyl peptides by sensitive-resistant pair screening.

Natural products have been major sources of antibacterial agents and remain very promising. Frequent rediscoveries of known compounds hampers progress of new discoveries and demands development and utilization of new methods for rapid biological and chemical dereplication. This paper describes an efficient approach for discovery of new thiazolyl peptides by sensitive-resistant pair screening and dereplication in a time and cost-effective manner at industrial scale.

Sponge-derived Kocuria and Micrococcus spp. as sources of the new thiazolyl peptide antibiotic kocurin.

Forty four marine actinomycetes of the family Microccocaceae isolated from sponges collected primarily in Florida Keys (USA) were selected from our strain collection to be studied as new sources for the production of bioactive natural products. A 16S rRNA gene based phylogenetic analysis showed that the strains are members of the genera Kocuria and Micrococcus. To assess their biosynthetic potential, the strains were PCR screened for the presence of secondary metabolite genes encoding nonribosomal synthetase (NRPS) and polyketide synthases (PKS).

Chemical and physical modulation of antibiotic activity in emericella species.

The addition of epigenetic modifying agents and ion-exchange resins to culture media and solid-state fermentations have been promoted as ways to stimulate expression of latent biosynthetic gene clusters and to modulate secondary metabolite biosynthesis. We asked how combination of these treatments would affect a population of screening isolates and their patterns of antibiosis relative to fermentation controls. A set of 43 Emericella strains, representing 25 species and varieties, were grown on a nutrient-rich medium comprising glucose, casein hydrolysate, urea, and mineral salts.

Isolation and structural elucidation of cyclic tetrapeptides from Onychocola sclerotica.

Three new cyclic tetrapeptides (1-3) have been isolated from the crude fermentation extract of Onychocola sclerotica. The planar structures of 1-3 were elucidated by detailed spectroscopic analyses using one- and two-dimensional NMR experiments and high-resolution mass spectrometry. The absolute configuration of the amino acid residues in each cyclotetrapeptide was established by Marfey's method.

Current approaches to exploit actinomycetes as a source of novel natural products.

For decades, microbial natural products have been one of the major sources of novel drugs for pharmaceutical companies, and today all evidence suggests that novel molecules with potential therapeutic applications are still waiting to be discovered from these natural sources, especially from actinomycetes. Any appropriate exploitation of the chemical diversity of these microbial sources relies on proper understanding of their biological diversity and other related key factors that maximize the possibility of successful identification of novel molecules. Without doubt, the discovery of platensimycin has shown that microbial natural products can continue to deliver novel scaffolds if appropriate tools are put in place to reveal them in a cost-effective manner.

Bacterial diversity from benthic mats of Antarctic lakes as a source of new bioactive metabolites.

During the MICROMAT project, the bacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes was accessed for the discovery of novel antibiotics. In all, 723 Antarctic heterotrophic bacteria belonging to novel and/or endemic taxa in the α-, β- and γ-subclasses of the Proteobacteria, the Bacteroidetes branch, and of the high and low percentage G+C Gram-positives, were isolated, cultivated in different media and at different temperatures, and then screened for the production of antimicrobial activities. A total of 6348 extracts were prepared by solid phase extraction of the culture broths or by biomass solvent extraction.

Discovery of bacterial fatty acid synthase inhibitors from a Phoma species as antimicrobial agents using a new antisense-based strategy.

Fatty acids are essential for bacterial growth and viability, with the type II fatty acid synthesis (FAS II) pathway being a potential antibacterial target. A new, selective, and highly sensitive whole cell-based antisense strategy has been designed to screen for natural product inhibitors of FabH/F of the FAS II pathway using a high-throughput two-plate agar-based differential sensitivity assay (FabF(2)p). An antisense assay along with the FASII enzyme prepared from Staphylococcus aureus was used for bioactivity-guided fractionation, leading to the isolation of phomallenic acids A-C (1-3) from a leaf litter fungus identified as Phoma sp.

Discovery of FabH/FabF inhibitors from natural products.

Condensing enzymes are essential in type II fatty acid synthesis and are promising targets for antibacterial drug discovery. Recently, a new approach using a xylose-inducible plasmid to express antisense RNA in Staphylococcus aureus has been described; however, the actual mechanism was not delineated. In this paper, the mechanism of decreased target protein production by expression of antisense RNA was investigated using Northern blotting.