Isolation and Identification of some halotolerant Actinomycetes having antagonistic activities against some plant pathogens (i.e., Tobacco mosaic virus, Aspergillus Sp., Fusarium Sp.) from soil of Taif Governorate KSA

Abstract

Actinomycetes are considered one of the important bacteria due to their
ability to produce several substances as secondary metabolites, found to be
effective in the control of some plant pathogens. In this study, a number of soil
samples were collected from different locations of Taif as well as Jeddah and
Makah. This was followed by determination of the microbial total counts, i.e.,
bacteria, fungi and actinomycetes. Actinomycetes were isolated and purified and
their color groups were determined. The actinomycete isolates were identified
based on their cultural and morphological properties as Streptomycetes. The salt
tolerance range of the purified Streptomyces isolates were determined by
growing them on starch nitrate agar medium supplemented with different NaCl
concentrations ranged from 3.5 to 10.5%. The highly tolerant streptomycete
isolates were grown on a starch nitrate broth medium for 6 days under shaking
conditions at 28-30oC. Then, their antiviral and antifungal activities against TMV,
Aspergillus sp. and Fusarium sp. were determined. The halotolerant
Streptomycete isolates having antifungal and/or antiviral activities were
completely identified based on their cultural, morphological and physiological
properties. The DNA of the identified isolates was extracted and used for
determination of DNA fingerprinting of these isolates using the RAPD-PCR
molecular tool