Isolation of endophytic actinomycetes from psidium guajava and ziziphus mauritiana / Nurul Najwa Saleh

Endophytic microorganisms are usually bacteria, fungi or actinomycetes that inhabit the internal part of plants without causing apparent symptoms of a disease to the plants. Actinomycetes have been used for drug discovery because it produces more than 10, 000 bioactive compounds. Endophytic actinomycetes possess metabolites with a broadspectrum activity where it can be used to treat multidrug-resistant pathogens, such as Methicillin resistant Staphylococcus aureus (MRSA) whereby ethnomedicinal plants is an essential resource of isolating these endophytic actinomycetes. Therefore, the present study was designed to correlate the presence of endophytic actinomycetes in ethnomedicinal plants by isolating them from Psidium guajava and Ziziphus mauritiana. The efficacy of two surface sterilization methods and two different incubation temperatures for isolation of endophytic actinomycetes were assessed by using low based media. Two procedures were used for surface sterilization, Procedure I using 70% ethanol and Procedure II using 99% ethanol and the isolation plate was then incubated at 30°C and 37°C for one month. The method using 99% ethanol (Procedure II) in surface sterilization procedure was observed more effective in eliminating the epiphytes and incubation at 37°C was found to be practical for the isolation of endophytic actinomycetes. Based on morphological characteristics, all seven isolates were identified with Streptomyces spp and were isolated from roots of plants. From the seven isolated, 71.4% (n=5) were isolated from Z. mauritiana and 28.6% (n=2) from P. guajava. In conclusion, the isolation and optimization to enhance the growth of endophytes through surface sterilization and incubation temperature was described and it shows that the endophytic actinomycetes can potentially be harvested from ethnomedicinal plants.