Isolation, characterization and antimicrobial activity of <i>Streptomyces</i> strains from hot spring areas in the northern part of Jordan

Abstract

A total of 30 Streptomyces isolates (28 from soil and 2 from water) were isolated and purified from hot-springs areas in the northern part of Jordan. Four strains were thermopile. They grew at 45 and 55°C but not at 28°C. Strains were described morphologically on four different media: on glycerol yeast extract, oatmeal, yeast malt-extract and starch casein agar. White and grey color series were the most frequent series on all media. The results showed that glycerol yeast extract and starch casein were the best media for sporulation. And yeast malt-extract was the best medium for the production of soluble pigment. Physiological and biochemical tests showed that the highest number of Streptomyces isolates were able to hydrolyze tyrosine was 26 (87%). This was followed by 25 (83%) for starch, 24 (80%) for urea, 21 (70%) for casein and 10 (33%) for gelatin. Twenty two (73%) strains showed the ability to reduce nitrate and 8 (27%) strains produced melanin. Carbon source utilization showed that 26 (87%) strains were able to utilize L- arabinose, 25 (83%) strains were able to utilize meso-inositol, 8 (27%) strains were able to utilize D-sorbitol, 18 (60%) strains were able to utilize D-mannitol, 28 (93%) strains were able to utilize L-rhamnose and all isolates exhibited the ability to utilize D-fructose and D- glucose. The ability to exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus was detected among 20 and 26% of the isolates, respectively, while the ability to exhibit antifungal activity against Candida albicans was detected among 23% of the isolates. Molecular identification of the 8 antibiotics producers was carried out by PCR technique using two sets of primers specific to Streptomyces 16S rDNA gene sequences; strepB/strepE and strepB/strepF which amplified 520 and 1070 bp, respectively. All these antibiotic producer isolates showed positive results for the genus Streptomyces specific primers.

Key words: Characterization, streptomyces, antimicrobial activity, hot springs, thermophile, PCR.