The Streptomyces flora of Jordan and its' potential as a source of antibiotics active against antibiotic-resistant Gram-negative bacteria

Detection and identification of members of the genus Streptomyces are of great value because they provide a rich source of antibiotics. Toward the goal of identifying additional novel antibiotics, a total of 292 different Streptomyces isolates were recovered from 54 soil samples collected from 28 different locations in Jordan. These were then characterized by conventional methods and assessed for their activity against two antibiotic-resistant Gram-negative isolates of Escherichia coli and Klebsiella pneumoniae. Results revealed that grey, white and yellow series isolates were the most abundant, with 15% of the Streptomyces isolates active against at least one of the test pathogens. Most of the active isolates exhibited activity against E. coli (96%), while less activity was exhibited against K. pneumoniae (18%). Overall screening revealed the characterization of six Streptomyces isolates (I₇, AC₃₂, G₁₇, Z₁₁, Bb₃₆ and AQ₁₆) which inhibited the growth of both pathogens. All were obtained from a region characterized by low-nutrient soils and harsh conditions. The unusual antibiotic profile of these isolates stressed their potential as a source of novel antibiotics.