Assessment of antibiotics production potentials in four actinomycetes isolated from aquatic environments of the Eastern Cape Province of South Africa

摘要

Crude extracts of four actinomycetes species belonging to?Actinoplane?[NB 034],Streptomyces?[TR 007] and?Actinopolyspora?[NB 069 and TR 008]?genera were screened for antibacterial activities against a wide range of bacterial strains. The extracts showed antibacterial activities against both Gram-negative and Gram-positive test bacteria with zones of inhibition ranging between 2 and 27 mm (NB 034); 9 and 15 mm (TR 007); 8 and13 (NB 069) and 2 and 12 mm (NB 069). The minimum inhibitory concentration (MIC) of the extracts against the test bacteria ranged from 0.039 - 5 mg/ml, while the minimum bactericidal concentrations (MBC) ranged from 5 to >10 mg/ml. The extracts exhibited concentration-time dependent killing of?Staphylococcus aureus?OKOH2A and?Staphylococcus scuiri?OKOH2B with a 0.73log10?and 0.88log10reduction in viable counts respectively, while a re-growth phenomenon was exhibited byKlebsiella pneumonia?ATCC 4352?and?Escherichia coli?ATCC 25922?at MIC, 2 × MIC and 4 × MIC of?Streptomyces?(TR 007)?Actinopolyspora?(TR 008) extracts. All the active extracts exhibited bacteriostatic activities.