Search

In this study, two designed primers were evaluated to identify soil Streptomyces and to detect streptomycin production by strb1 targeted PCR. Potential Streptomyces-specific signatures were identified in their 16S rDNA sequences in regions located around nucleotide positions 576 and 995. Primer pair RI7/RI8 derived from these regions was investigated for its specificity in detecting and identifying Streptomyces isolates by PCR assays using DNA from pure cultures. The constructed primer pair showed high specificity in detecting and identifying Streptomyces type strains as well as soil isolates. Streptomycin-producers were detected by PCR assays through the selective amplification of streptomycin biosynthetic gene (strb1). Results suggest that PCR assay facilitates the differential identification of Streptomyces-specific antibiotic producers and a resident population of Streptomyces in Jordan with the capacity of streptomycin-production is present.

A total of 60 different Streptomyces isolates were recovered from 12 soil samples collected from the Badia region north-eastern of Jordan. These were then characterized by conventional methods and assessed for their antagonistic activity against three pathogenic and antibiotic-resistant bacteria. Results indicated that grey and white colour series were the most abundant with 30% of all isolates active against, at least, one of the test organisms;Staphylococcusaureus , Escherichia coli and Klebsiella pneumoniae. Overall screening results revealed the characterization of four Streptomyces isolates (I7, AC32, Bb36 and Z11) which inhibited the growth of all tested pathogens. The unusual antibiotic profile of these isolates underlined their potential as a source of novel antibiotics.

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.

Random amplified polymorphic DNA (RAPD) analysis has been used to determine the relatedness of 73 antibiotic-producing soil Streptomyces isolates that were recovered from different soil habitats in Jordan based on their RAPD-PCR fingerprints. Genetic polymorphisms between these isolates showed three common bands of 2777, 800 and 250 bp shared by approximately (95%) of them. Some specific bands were also observed. Further analysis of RAPD patterns with the UPGMA resulted in clustering the tested isolates into two main super clusters. Super cluster I was more homogenous than super cluster II and contained all the reference strains. However, super cluster II consists of unrelated isolates within five small groups. As RAPD fingerprints of the tested isolates linked to their phenotypes, differentiation between isolates with different cultural properties was observed.