Isolation of natural producing Actinobacteria using the iChip technique as a novel screening method and investigation of their antibacterial activity

Actinobacteria are a large part of soil microbial population which their number is more than one million bacteria per gram soil. Generating a broad range of active compounds as secondary metabolites such as antibiotics has invariably been important. The aim of this research was a screening of natural active compounds produced by actinobacteriausing the iChip technique. Various soil specimens were collected from different areas of Mazandaran, Golestan and Fars provinces, Iran. After thermal pretreatment, soil specimens were loaded on iChip and incubated in their own natural environment for 2 weeks. Micro colonies grown in iChip wells were transferred to fresh SCA and SMS media. In order to isolate active actinobacteria, primary screening was performed using cross streak method. The crude extract of active isolates was obtained from each grown medium, then their antibacterial activities were evaluated using disc diffusion method. Out of 87 actinobacteria isolated using the iChip technique, four isolates with most antibacterial activity against some gram-positive and gram negative pathogens were chosen. The results demonstrated that all isolates had good antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, as well as Pseudomonas aeruginosa, Enterobacter aerogenes, Shigella sonnei. Moreover, the results of the current study revealed that iChip-mediated screening for natural environments, in finding new microbial species and their domestication from nature, can potentially be sustainable.

Keywords:

Actinobacteria , IChip , Natural antibacterial compounds