Diversity and Bioactive Potential of Actinobacteria Isolated from a Coastal Marine Sediment in Northern Portugal

Abstract

Natural compounds have had increasing applications in the biotechnological sector, with a large fraction of these substances being channeled to the pharmaceutical industry due to their important pharmacological properties. The discovery of new bioactive molecules with novel mechanisms of action constitutes a promising solution for the design of alternative therapeutic solutions. Actinobacteria are a large group of morphologically and physiologically diverse bacteria well known for their production of biotechnologically relevant compounds. The Portuguese coast is scantly explored in terms of Actinobacteria diversity and respective bioactive potential, offering a good opportunity to find new Actinobacteria taxa and bioactive natural products. In this study, we investigated the Actinobacteria diversity associated with a sediment sample collected from the intertidal zone of a beach in northern Portugal, through a cultivation-dependent approach, and screened its antimicrobial and cytotoxic potential. A total of 52 Actinobacteria strains were recovered from the marine sediment, with the largest fraction of the isolates belonging to the genus Micromonospora. Bioactivity screening assays identified crude extracts of six Streptomyces strains active against C. albicans, exhibiting minimum inhibition concentration (MIC) values in the range of 3.90–125 μg mL−1. Twenty-five Actinobacteria crude extracts (obtained from strains of the genera Micromonospora, Streptomyces and Actinomadura) exhibited significant effects on the viability of at least one tested cancer cell line (breast ductal carcinoma T-47D and liver hepatocellular carcinoma HepG2). The Actinobacteria extracts demonstrating activity in the antimicrobial and/or cytotoxic assays were subjected to metabolomic analysis (Mass spectrometry (MS)-based dereplication and molecular networking analyses), indicating the presence of four clusters that may represent new natural products. The results obtained demonstrate the importance of bioprospecting underexplored environments, like the Portuguese coast, for enhancing the discovery of new natural products, and call attention to the relevance of preserving the natural genetic diversity of coastal environments.

Biodiversity of Secondary Metabolites Compounds Isolated from Phylum Actinobacteria and Its Therapeutic Applications

“…The isolates’ greatest fraction were from the genus Micromonospora , from which six Streptomyces strains were active against Candida. albicans , with minimum inhibitory concentration (MIC) values ranging from 3.90 to 125 µg mL −1 [ 2 ].…”

“…Global demand for new chemotherapeutic compounds and antibiotics with high bioactivity and low toxicity has increased recently due to the emergence of life-threatening microorganisms and multidrug resistance agents among viruses, bacteria and fungi [ 1 ]. Additionally, the detection of secondary metabolites molecules with unique modes of action established various therapeutic agents’ strategies for treating many illnesses [ 2 ]. To be more specific, endophytic Actinobacteria are microorganisms that represent a new production source of a large number of secondary metabolites, including alkaloids, beta-lactams, sulfonamides, aminoglycosides, glycopeptides, siderophores, quorum-sensing molecules, immunosuppressants, polyene macrolides, saccharides, pyrazoloisoquinolinones, butenolides, nucleosides and degradative enzymes [ 3 ].…”

Inhibition of Intestinal Lipid Absorption by Cyanobacterial Strains in Zebrafish Larvae

“…For liquid chromatography-high-resolution electrospray ionization tandem mass spectrometry (LC-HRESI-MS/MS, Thermo Fisher Scientific, Waltham, MA, USA), the fractions were dissolved in UPLC/MS grade acetonitrile at a concentration of 1 mg/mL, and 5 µL was injected per sample. Experimental conditions are described in detail in Ribeiro et al (2020) [41].…”

Potential Anti-Obesity, Anti-Steatosis, and Anti-Inflammatory Properties of Extracts from the Microalgae Chlorella vulgaris and Chlorococcum amblystomatis under Different Growth Conditions

“…A total of 40 µl of each sample replica (DMSO, 10 mg/mL) was dried and then resuspended to a concentration of 1 mg/mL in acetonitrile for LC-MS. Experimental conditions are described in Ribeiro et al [49]. The chromatographic step was carried out in an ACE UltraCore 2.5 Super C18 column (75 mm × 2.1 mm, Advanced Chromatography Technologies, Aberdeen, United Kingdom).…”