Isolation Of Actinomycetes Strains And Their Different Levels Of Resistance Against Antibiotics

This study is aimed at isolating and characterizing strains of an actinomycetes from soils. Six strains of actinomycetes were isolated from the riverside, rhizoplane and low land of Muzaffarpur district of Bihar (India). The cultural characterisation revealed the production of diffusible pigments of different colours. Heavy sporulation was noticed in some strains. Out of six strains isolated, four strains such as KS-1, KS-2, KS-3 and KS-4 were found to be mesophilic, and the other two KS-5 and KS-6 showed thermophilic when subjected to a higher temperature. The antibiotic susceptibilities of these six strains gave the idea about the sensitive and resistance nature based on the zone of inhibition against six antibiotics. Three strains (KS-1, KS-3 and KS-5) were found to be sensitive, whereas KS-2, KS-4 and KS-6 exhibited resistance to the particular antibiotic. The antibiogram of these strains such as KS-2, KS-4 and KS-6 clearly showed the different levels of resistance such as constitutive resistance, lethal dose50 and minimal inhibitory concentration within the susceptible range of different antibiotics. CR was found to be maximum (3.5 mu gmL-1) in strain KS-4 against tetracycline, the highest lethal dose (14 mu gmL-1) was noticed in KS-2 against ampicillin while Minimal Inhibitory concentration was found to be maximum (26 mu gmL-1) against streptomycin in strain KS-6.