A Study on actinobacterial diversity of Hampoeil cave and screening of their biological activities

Abstract

Caves are oligotrophic, dark and less-explored environments and are considered as sources of promising microbial strains in biotechnology. Hampoeil Cave is located in massive dolomite with thin bedded limestone in northwestern of Iran. In an isolation and screening program, various samples from soil, water, floor, wall and ceiling of Hampoeil cave and its invertebrates were collected. Four various treatments and 10 different isolation media were used for the isolation of the actinobacteria. Screening of the isolates for antimicrobial activity against 10 bacteria and fungi, 5 hydrolytic enzymes production and resistance to 5 heavy metals have been performed. Among 33 various samples, 76 actinobacteria from various genera, including Streptomyces, Micromonospora, Micrococcus, Kocuria and Corynebacterium were isolated. Eighty percent of the strains had one of the studied hydrolytic enzyme activity. At least one type of antimicrobial activity was seen in 25.3% of the isolates. Resistance to one metal or more was seen in 26.32% of the isolates. The ratio of rare-actinobacteria in the oligotrophic samples to enriched samples is 20% more than Streptomyces. Percentage of strains with the highest activity in esterase, amylase, DNase, protease or lipase activity that were isolated from organic-rich environmental samples were 100, 100, 100, 82 and 82%, respectively. Also, 26.32% of the actinobacterial isolates resisted to heavy metals. It was concluded that Hampoeil cave is a good source in finding cave-living actinobacteria potent in producing hydrolytic enzymes and bioremediation.

Antibacterial potential of Actinobacteria from a Limestone Mining Site in Meghalaya, India

“…From the cultivated isolates, it showed a dominance of Streptomyces genera which comprised 76% of the total number of isolates. Recent reports on actinobacteria from limestone niches have also shown Streptomyces to be the dominant genera 8,13,44,45 . A number of novel actinobacterial strains have also been reported from other limestone niches.…”

“…Limestone-rich areas mainly dominated by a CaCO 3 environment, are under-explored ecological niches for mining of microorganisms for various metabolic properties. Recent studies have revealed that both hypogean and epigean limestone actinobacteria are potential antibiotics producers [8][9][10][11][12][13][14] . The state of Meghalaya located in the north-eastern part of India falls under the Indo-Burma Biodiversity Hotspot 15 .…”

Streptomyces Isolates from the Soil of an Ancient Irish Cure Site, Capable of Inhibiting Multi-Resistant Bacteria and Yeasts

“…We are aware that limestone areas similar to Boho have long been regarded as a rich source of antibiotic producing Streptomyces [43][44][45] [34]. Finally, a gene cluster from Streptomyces isolates McG7 and McG8 showed similarity to those previously identified for the synthesis of cyslabdan, an antimicrobial potentiator [33].…”

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

“…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].…”