2 research outputs found
In Vitro Evaluation of Enzymatic and Antifungal Activities of SoilActinomycetes Isolates and Their Molecular Identifcation by PCR
Background: Human cutaneous infection caused by a homogeneous group of keratinophilic fungi called dermatophytes. These fungi
are the most common infectious agents in humans that are free of any population and geographic area. Microsporum canis is a cause of
dermatophytosis (Tinea) in recent years in Iran and atypical strain has been isolated in Iran. Its cases occur sporadically due to M. canis
transmission from puppies and cats to humans. Since this pathogenic dermatophyte is eukaryotes, chemical treatment with antifungal
drugs may also affect host tissue cells.
Objectives: The aim of the current study was to fnd a new antifungal agent of soil-Actinomycetes from Kerman province against M. canis
and Actinomycete isolates were identifed by PCR.
Materials and Methods: A number of hundred Actinomycete isolated strains were evaluated from soil of Kerman province, for their
antagonistic activity against the M. canis. M. canis of the Persian Type Culture Collection (PTCC) was obtained from the Iranian Research
Organization for Science and Technology (IROST). Electron microscope studies of these isolates were performed based on the physiological
properties of these antagonists including lipase, amylase, protease and chitinase activities according to the relevant protocols and were
identifed using gene 16SrDNA.
Results: In this study the most antagonist of Actinomycete isolates with antifungal activity against M. canis isolates of L1, D5, Ks1m, Km2,
Kn1, Ks8 and Ks1 were shown in vitro. Electron microscopic studies showed that some fungal strains form spores, mycelia and spore chain.
Nucleotide analysis showed that Ks8 had maximum homology (98%) to Streptomyces zaomyceticus strain xsd08149 and L1 displayed 100%
homology to Streptomyces sp. HVG6 using 16SrDNA studies.
Conclusions: Our fndings showed that Streptomyces has antifungal effects against M. canis
Biocontrol potential of Trichoderma harzianum in controlling wilt disease of pistachio caused by Verticillium dahliae
Verticillium wilt caused by Verticillium dahliae, is one of the most devastating diseases in
pistachio orchards in the world including Iran. In search for an eff ective non-chemical
strategy for the management of this disease, we evaluated the biocontrol potential of Trichoderma
harzianum isolates obtained from the rhizosphere of healthy pistachio trees in
diff erent locations of the Kerman province of Iran against V. dahliae under laboratory and
greenhouse conditions. Dual culture tests in the laboratory were conducted in a completely
randomized design using 72 T. harzianum isolates. Twenty isolates showed the highest
in vitro antagonistic activity. Th e results indicated that all 20 isolates were capable of inhibiting
the mycelial growth of V. dahliae signifi cantly. Among them, isolates Tr8 and Tr19
were the most eff ective by 88.89% and 85.12% inhibition, respectively. Extracted cell free
metabolites of all eff ective isolates also inhibited the growth of V. dahliae in the culture medium
signifi cantly. According to the results, isolates Tr4 and Tr6 inhibited fungal pathogen
growth by 94.94% and 88.15% respectively, through production of non-volatile metabolites.
In the evaluation of volatile metabolites, isolates Tr5 and Tr4 were the most eff ective
by 26.27% and 24.49% growth inhibition, respectively. Based on the results of the in vitro
experiments, the fi ve most eff ective isolates were selected for evaluation under greenhouse
conditions for their biocontrol potential in controlling Verticillium wilt of pistachio. Results
of the greenhouse, (in vivo) experiments were positive and indicated that the occurrence of
wilt disease in plants treated with the antagonists alone or in combination with pathogenic
fungus was lower than in plants inoculated with pathogen alone. Th e overall results of this
study suggest that Trichoderma fungal antagonist may be an eff ective biocontrol agent for
the control of Verticillium wilt of pistachio