Actinobacteria Isolation from Forest Soils and Determination of Biological Activities

Abstract

Actinobacteria bacterial group has one of the most populous population in microorganisms thatextends very different and extensive habitats on earth especially the main character of the natural soilhabitats. Since old times, bioactive metabolites of soil microorganisms have been studied and the resultshave provided that metabolites of these microorganisms have significant benefits to science, medicine,agriculture, and the pharmaceutical industry. In this study, isolation of Actinobacteria strains from forestsoils, identification of morphological and molecular features, extraction of the bioactive metabolite ofisolates and determination the antimicrobial, antibiofilm, and cytotoxic activities of bioactive extract weretested. The microbiological isolation methods for collected forest soil samples were used and after thedetermination of their morphological and molecular features, isolates were defined as Brevibacterium spp.that is a member of Actinobacteria. The antibiotic resistance of the isolates was determined by differentmethods and different concentrations of standard antibiotics. The chromium tolerance of isolates was alsodetermined. The bioactive metabolites of isolates were produced in a modified medium and extracted. Theantimicrobial, antibiofilm, cytotoxic activities of bioactive metabolites were determined against standardmicroorganisms and Artemia salina larvae were used as a test organism for cytotoxic tests. In the presentstudy, results provided information about Actinobacteria that were isolated from forest soils. Isolates haveantibiotic resistance and chromium tolerance abilities. Moreover, it has been shown that the Actinobacteriagroup is the largest bioactive metabolite producing group in terms of both antibacterial and antifungalactivity and also contains a wide range of other compounds such as antibiofilm and cytotoxic compounds.The antimicrobial (MIC) concentrations of bioactive metabolites were detected 2500 μg/mL for standardbacteria cultures and 1250 μg/mL for yeasts. The antibiofilm (MBEC) value was determined at 1250 μg/mL.The 2500 μg/mL concentration of the extract was found to be the effective cytotoxic value. The resultsprovide Brevibacterium spp. isolates have industrial and pharmaceutical potential and more detailedpharmaceutical researches are planned.