Antimicrobial Potential of Streptomyces spp. Isolated from the Rift Valley Regions of Ethiopia

Abstract

The study was undertaken to isolate, screen, and identify actinomycetes with antimicrobial metabolites. Twenty-one composite soil samples were randomly collected from various unique agroecological niches in the Rift Valley of Ethiopia. The soil samples were serially diluted and spread on starch casein agar medium supplemented with 50 μg/ml cycloheximide and 25 μg/ml nalidixic acid. Two hundred and forty-nine (249) actinomycetes cultures were isolated and screened by cross streaking against various human pathogens. Twenty-four isolates with pronounced antimicrobial activity were selected for identification and further screening. Among the isolates, 172 (69.1%) showed antimicrobial activities against tested pathogens. The inhibition zone of the isolates ranged from 5 ± 0.31 to >40 mm during primary screening. The antimicrobial activity of the crude extracts of promising isolates showed a statistically significant difference P < 0.05 between them and the control. The isolates RVE129 and RVE217 showed the maximum zone of inhibition at 27 ± 0.6 mm and 26 ± 0.6 mm, respectively, against S. aureus, and the results were higher than the standard drug streptomycin (25 ± 0.58 mm). The inhibition zone of crude extracts from RVE129 was at the maximum of 22 ± 0.0 mm against P . aeruginosa, almost comparable to the standard drug streptomycin (24 ± 0.58 mm). Crude extract from the isolates RVE129 and RVE187 showed higher inhibition zones of 22 ± 0.6 mm and 16 ± 0.33 mm against A. niger ATCC10535, which, however, were smaller than those obtained with the standard drug amphotericin B (29 ± 0.6 mm). Twenty-four actinomycete strains with remarkable bioactivity were characterized using various cultural, morphological, physiological, and biochemical characteristics and assigned under the genus Streptomycetes. The finding of the current study indicates that Streptomyces sp. isolated from the Rift Valley of Ethiopia was found to possess a broad spectrum of bioactivity against a range of human pathogens.

Antibacterial Activities of Secondary Metabolites Derived from Streptomyces sp. VITGV38 (MCC4869) against Selected Uropathogens

“…RVE002. 25 Analysis of the GC-MS results showed that the NIST database contained six antimicrobial compounds from the extract. Six compounds were identified in the extracts of Streptomyces sp.…”

Evaluation of molecular typing methods for some scab-causing Streptomyces strains from Turkey

“…Streptomyces are gram-positive, filamentous bacteria that form extensively branched substrate mycelium. It is also the ability to produce antibiotics or other industrially valuable secondary metabolites (Kumar et al 2007 ; Elias et al 2022 ) and some of the genus members are used as biocontrol agents against plant disease (Simizu et al 2009 ). Some S treptomyces species can also cause a plant disease called scab, which is an important problem for potato growers worldwide (Bukhalid and Loria 1997 ) and the disease significantly reduces the quality of tubers (Gutierrez et al 2022 ).…”