Isolation and identification of bioactive compound producing Rhodococcus spp. isolated from soil samples

The genus Rhodococcus is gram positive bacterium which was classified into the family of Nocardiaceae.  The organism can be isolates from different sources, with capability to degrade diverse types of pollutant. Nowadays, scientists reported a few secondary metabolites which are produced by Rhodococci. Hence, the present study tried to isolate Rhodococci from different soil samples with the capability to produce antimicrobial metabolites. For this purpose ۳۶۰ soil samples were collected from different types of soil. Then the isolates were identified and characterized using APi Coryne kit. Afterward antibacterial activity of the suspected bacteria was evaluated using well diffusion agar method against test bacteria. Furthermore, the extracted metabolites were analysed using GC-MS. The results obtained from this study indicated that ۴ out of ۹ isolates were able to produce antimicrobial metabolites. The most effective isolates were R۸۷ strain with the maximum inhibition zone of ۳۵ mm and the least effective were R۸۵ strain with zone of inhibition ۲۰ mm against E. coli. The GC-Mass chromatogram showed different special peaks and the identified compounds were cyclopenthasiloxane, Azulene, ۲-۷ octadiene, docosane, cyclohexasiloxane, Bis (۳,۵,۵ trimethyhexyl, Tetraedacane – ۲ methyl, Cycloheptasiloxane  and Heptadecanol. In general, isolation of native bacteria from environmental samples with antimicrobial property is an interesting aspect which could help us to ignore antibiotic resistant bacteria from our environment.