Cave Actinobacteria as Producers of Bioactive Metabolites

Abstract

Recently, there is an urgent need for new drugs due to the emergence of drug resistant pathogenic microorganisms and new infectious diseases. Members of phylum Actinobacteria are promising source of bioactive compounds notably antibiotics. The search for such new compounds has shifted to extreme or underexplored environments to increase the possibility of discovery. Cave ecosystems have attracted interest of the research community because of their unique characteristics and the microbiome residing inside including actinobacteria. At the time of writing, 47 species in 30 genera of actinobacteria were reported from cave and cave related habitats. Novel and promising bioactive compounds have been isolated and characterized. This mini-review focuses on the diversity of cultivable actinobacteria in cave and cave-related environments, and their bioactive metabolites from 1999 to 2018.

The Isolation of a Novel Streptomyces sp. CJ13 from a Traditional Irish Folk Medicine Alkaline Grassland Soil that Inhibits Multiresistant Pathogens and Yeasts

“…Other studies have shown that karst regions, i.e. regions where there is dissolution of the rocks, especially limestone, support the growth of many Streptomyces [46][47][48].…”

Taxonomy and Broad-Spectrum Antifungal Activity of Streptomyces sp. SCA3-4 Isolated From Rhizosphere Soil of Opuntia stricta

“…Actinobacteria are a large group of high G+C Gram-positive bacteria (Barka et al, 2016) and the primary sources of bioactive compounds in particular commercially available antibiotics (Barka et al, 2016; Rangseekaew and Pathom-aree, 2019). So far, more than 10,000 different bioactive compounds have been identified from Actinobacteria (Martins et al, 2019), for example, vancomycins from Amycolatopsis orientalis , rifamycin from Amycolatopsis mediterranei , teicoplanin from Actinoplanes teichomyceticus , erythromycin from Saccharopolyspora erythraea , and gentamicin from Micromonospora purpurea (Lancini and Lorenzetti, 1993; Lazzarini et al, 2000).…”

Streptomyces from traditional medicine: sources of new innovations in antibiotic discovery

“…Over the last few decades, karst and cave environments have become popular areas for bioprospecting of antimicrobial Streptomyces [48,49]. Many of these areas are often associated with traditional medicine.…”

“…Ancient texts suggest that a milky white exudate covering the surfaces of some caves called 'moonmilk' can heal multiple ailments [50]. Digging deeper, research has shown that moonmilk contains an abundance of Streptomyces that have antibacterial activity against a wide range of bacteria and fungi [49,50], and display strong growth suppression against multi-resistant Rasamsonia argillacea, a causative agent of invasive mycosis in cystic fibrosis and chronic granulomatous diseases [50]. Similar studies from the Hampoeil cave (dolomite with limestone) in Iran, linked to Palaeolithic habitation, revealed many antimicrobialproducing Streptomyces, as well as other species [51].…”