Project Materials

ISOLATION AND CHARACTERIZATION OF ANTIBIOTIC PRODUCING ACTINOMYCETES IN A RHIZOSPHERE ENVIRONMENT

ABSTRACT

This study was conducted to isolate and characterise antibiotic-producing actinomycetes in rhizosphere habitats using the standard microbiological approach, crowded plate method, streak plate method, and pour plate method. Starch casein agar and nutrient agar were employed to characterise the growing organisms, and tests such as gramme staining, starch hydrolysis, casein hydrolysis, lipid hydrolysis, citrate, methyl red, catalase, and indole were performed. After culturing, only 5 of the 13 isolates (from a total of 25 soil samples) showed observable development and demonstrated antibacterial action on selected species (Stapylococus aureus, Bacillus subtilis, and Escherichia coli). The total count of colony forming units ranged from 3.9×106 to 5.2×106. This study yielded five isolates, four of which were from the Streptomycetes genus (B, F, H, and M) and one from the Nocardia genus (L). Isolate B inhibited Escherichia coli with a zone of 26mm; isolates F, H, L, and M inhibited Staphylococcus aureus with zones of 8mm, 9mm, 16mm, and 9mm, respectively; and isolates B, F, H, L, and M inhibited Bacillus subtitis with zones of 5mm, 11mm, 11mm, 19mm, and 7mm, respectively. According to this study, Streptomyces are the most common antibiotic-producing actinomycetes in soil. Antibiotics should be used only when necessary to avoid antibiotic resistance in certain organisms and stored at appropriate temperatures and pressures; thus, further purification, elucidation, and characterisation are recommended to determine the quality, novelty, and commercial value of antibiotics.