Deep Subseafloor Fungi as an Untapped Reservoir of Amphipathic Antimicrobial Compounds

Abstract

The evolving global threat of antimicrobial resistance requires a deep renewal of the antibiotic arsenal including the isolation and characterization of new drugs. Underexplored marine ecosystems may represent an untapped reservoir of novel bioactive molecules. Deep-sea fungi isolated from a record-depth sediment core of almost 2000 m below the seafloor were investigated for antimicrobial activities. This antimicrobial screening, using 16 microbial targets, revealed 33% of filamentous fungi synthesizing bioactive compounds with activities against pathogenic bacteria and fungi. Interestingly, occurrence of antimicrobial producing isolates was well correlated with the complexity of the habitat (in term of microbial richness), as higher antimicrobial activities were obtained at specific layers of the sediment core. It clearly highlights complex deep-sea habitats as chemical battlefields where synthesis of numerous bioactive compounds appears critical for microbial competition. The six most promising deep subseafloor fungal isolates were selected for the production and extraction of bioactive compounds. Depending on the fungal isolates, antimicrobial compounds were only biosynthesized in semi-liquid or solid-state conditions as no antimicrobial activities were ever detected using liquid fermentation. An exception was made for one fungal isolate, and the extraction procedure designed to extract amphipathic compounds was successful and highlighted the amphiphilic profile of the bioactive metabolites.

Bacterial attachment and biofilm formation on stainless steel surface and their in vitro inhibition by marine fungal extracts

“…The marine Sarocladium spp. have also been reported to be active against E. coli (Samuel, Prince, & Prabakaran, ), while S. kiliense , endophytic fungi possessed antibacterial and antifungal properties (Lou et al, ; Navarri et al, ). The genus Penicillium is well known producer of variety of compounds with broad spectrum of biological activity and pharmacological application (Debbab, Aly, Lin, & Proksch, ).…”

Statistical optimization and valuable applications of bioactive compounds produced by marine Pseudoalteromonas piscicida

“…Antimicrobial resistant microorganisms cause killing of about 3 million people each year in the world (Navarri et al, 2016). This threat requires renewal of the traditional antibiotics Underexplored marine environment may represent an untapped reservoir of novel antimicrobial agents (Blunt et al, 2015).…”

“…Upon using tumour cell line (Caco-2) (Figure 4 C, D), the supernatant of tested compound showed a reasonable degree almost 63.8 % inhibition respectively after 72 h using the MTT assay. On the other hand, using the supernatants of the tested compound showed very low activity towards EI4 (Figure 4 A,B), (HepG2) (Figure 4 E,F) cell line and (MCF-7) (Figure 4 G,H) as detected by MTT assays where they showed only 33 % and 44.6% inhibition respectively after 72 h. Noble et al (2016) reported that secondary metabolites from the marine Pseudoalteromonas sp. inhibited the proliferation of A549 lung carcinoma cells.…”

Strategies to diversify natural products for drug discovery

“…New and complex metabolites from traditional, easy-to-collect natural sources are becoming scarce for intense chemical investigation. Nevertheless, some largely unexplored natural sources, such as endophytes, 23,24 uncultivable or poorly cultivable microorganisms, [25][26][27][28] and marine organisms in extreme growing conditions, 29,30 are attracting more attention from chemists and biologists. In recent years, developments in genomics have revealed that microorganisms have far greater potential to produce new and complex secondary metabolites.…”