Isolation and Identification of Streptomyces ramulosus from Soil and Determination of Antimicrobial Property of its Pigment

Pigment production by microorganisms is important due to more rapid growth, higher efficiency, easier extraction, and antimicrobial effects compared to other methods. The aim of the present study is to isolate and identify antibiotic pigment-producing actinomycetes from the soil of the Persian Gulf and to evaluate the antibiotic activity of their pigments in the second half of 2014. Given that pathogenic bacteria increasingly become more resistant to common antibiotics, there is a need for new antibiotics.

A total of 80 soil samples were collected from different areas and after preparing different dilutions (10-1-10-7), each sample was cultured on nutrient agar medium, specific Starch Casein Agar (SCA), and the International Streptomyces Project 2 (ISP2) media. Then, the actinomycete colonies were selected based on pigment production; pigments were extracted using sediment extraction with ethyl acetate; and the antibacterial property of their pigments were evaluated. The structure of colored extract compounds was identified by Thin layer chromatography (TLC). Molecular identification of the microorganisms was performed by 16S rRNA PCR.

The highest antibiotic effect of the pigments was observed in pathogenic bacterium S. aureus and Bacillus cereus, respectively. The lowest antimicrobial activity of the pigments was observed in Escherichia coli bacterium. All the studied fungi were resistant to the studied pigments.

Since natural pigments at an appropriate dose are healthier than the chemical ones, using them is beneficial in various industries, such as antibiotics production. Also, by determining the structure of pigments and eliminating their toxic groups, they can be used in different industries.