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Articles by I. Saadoun
Total Records ( 5 ) for I. Saadoun
  S. Aghighi , G.H. Shahidi Bonjar , R. Rawashdeh , S. Batayneh and I. Saadoun
  This is the first report of antifungal activity of Iranian Actinomycetes isolates against Alternaria solani Sorauer, Alternaria alternata (Fr.) Keissler, Fusarium solani (Mart.) Sacc., Phytophthora megasperma Drechsler, Verticillium dahliae Klebahn and Saccharomyces cerevisiae Meyen ex Hansen. Biological control of plant diseases has received worldwide attention in recent years mainly as a response to public concern about the use of hazardous chemicals in the environment. Soil Actinomycetes particularly Streptomyces spp. enhance soil fertility and have antagonistic activity against wide range of soil-borne plant pathogens. In search for soil Actinomycetes having antifungal activity against plant fungal-pathogens, 110 isolates were screened from which 14 isolates were found active at least against one of the tested fungi. Streptomyces plicatus strain101, Frankia sp. strain 103 and Streptomyces sp. strain 44 had the widest antifungal spectra of activity. Antifungal genes from these strains may be proper candidates for genetic engineering of plants for increased tolerance against the tested cosmopolitan fungal pathogens.
  Aghighi S , G.H. Shahidi Bonjar and I. Saadoun
  This is the first report on antifungal activity of a new strain of Streptomyces plicatus (strain101) against four Iranian phytopathogenic isolates of Verticillium dahliae. In the recent decades, biological control of plant diseases has received more attention mainly as a response to public concern about the use of hazardous chemicals in the environment. Soil Actinomycetes particularly Streptomyces spp. enhance soil fertility and have antagonistic activity against wide range of soil-borne plant pathogens. In search for metabolites of soil Actinomycetes having antifungal activity against four isolates of the cosmopolitan pathogen, Verticillium dahliae Klebahn, 110 isolates were screened. Among all, strain101 that was identified as a new strain of S. plicatus, showed high level of activity in Agar disk and Well-diffusion methods. S. plicatus was propagated in submerged cultures and active crude was prepared upon which some biological characterizations performed. The active metabolite (s) is polar, soluble in H2O and methanol but insoluble in chloroform, dichloromethane or hexane. Antifungal activity composed of two types, mycelial inhibition, inhibition of microsclerotia and melanin production. Antifungal gene from S. plicatus Strain 101 may be a useful candidate for genetic engineering of agriculturally important crop plants for increased tolerance against V. dahliae.
  S. Shahrokhi , G.H. Shahidi Bonjar and I. Saadoun
  This is the first report of antifungal activity of Iranian actinomycete isolates against Rhizoctonia solani Kuhn AG-3 (Teleomorph: Thanatephorus cucumeris [(Frank) Donk]). Biological control offers an environmentally friendly alternative to the use of antimicrobials for controlling plant diseases. A collection of about 200 actinomycete strains was screened for the ability to produce metabolites that inhibit R. solani growth in vitro. The Streptomyces olivaceus strain 115 showed strong in vitro antagonistic activity against R. solani in agar disc and Well-diffusion methods by producing extracellular antifungal metabolites. The strain No. 115 was propagated in submerged cultures and active crude was prepared upon which some biological characterization performed. The active metabolite(s) is polar, soluble in H2O and methanol but insoluble in chloroform, dichloromethane or hexane. Thermal inactivation point of active phase of S. olivaceus strain 115 was 80°C. Antifungal active phase of S. olivaceus strain 115 tolerate range of pH (6-9). Antifungal gene from strain 115 may be a useful candidate for genetic engineering of agriculturally important crop for increased tolerance against R. solani.
  S. Zamanian , G.H. Shahidi Bonjar and I. Saadoun
  This is the first report of antibacterial activity of Iranian actinomycetes isolates against Erwinia carotovora subsp. carotovora (Jones) Dye. E. carotovora subsp. carotovora is a soil born destructive plant pathogen with worldwide economical importance. Chemical measures have lost their attractiveness because of development of resistant strains of pathogens and due to undesirable effects on environment. Therefore, the studies on biological control of plant pathogens in soil have gained great importance worldwide. Actinomycetes, by virtue of their wide distribution, filamentous growth in soil, their ability to colonize the root surface and the rhizosphere, inhibitory effect on microorganisms and their ability to produce copious amounts of secondary metabolites especially antibiotics, role as a influential biological control agents have received special attentions. In order to obtain antibacterial antagonists from soil actinomycetes, a survey performed as follows. Soil samples taken from agricultural soils of Kerman. Serial dilutions provided and cultured in Casein Glycerin Agar (CGA). Over 110 isolates were screened among which one isolate showed high level of activity in Agar disk and Well diffusion methods against E. carotovora subsp. carotovora and identified as a new strain of Streptomyces plicatus (strain 101). This strain was propagated in submerged cultures and active crude was prepared upon which some biological characterization performed. High concentration of antibacterial agent was detected in 10th to 11th day in shake cultures. The active substance was water-soluble and insoluble in chloroform, hexan and dichloromethane. Minimal Inhibitory Concentration (MIC), by solving the crude extract in the dimethylsulfoxide plus methanol (v/v, 1:1) was determined as 5 mg mL-1. Longevity in vitro (LIV) of active crude of S. plicatus strain 101 against E. carotovora subsp. carotovora in soluble state determined about 30 days at room temperature. In thermal inactivation point studies, active crude retained activity up to 135°C. Antibacterial genes from this strain may be proper candidate for genetic engineering of plants for increased tolerance against the tested cosmopolitan bacterial pathogen.
  G.H. Shahidi Bonjar , S. Zamanian , S. Aghighi , P. Rashid Farrokhi , M.J. Mahdavi and I. Saadoun
  Ralstonia solanacearum has worldwide economical importance because of its destructive and soil-borne nature. Clearly chemical measures have lost their attractiveness because of development of resistant strains and undesirable effects on our environment. Consequently, biological control of pathogens is gaining great importance worldwide. To investigate for proper biocontrol agents and to obtain antibacterial antagonists from Iranian soil Actinomycetes, a vast survey was performed. Over 170 isolates of soil Actinomycetes were isolated and screened among which one isolate showed high level of activity in Agar disk and Well diffusion methods against R. solanacearum. It was identified as Streptomyces coralus strain 63. High concentration of antibacterial agent was detected at 8-11th day in shake cultures. Longevity in vitro of the active crude in soluble state determined about 40 days at room temperature. In thermal inactivation point studies, active crude retained activity up to 93°C. Antibacterial activity of the antagonists found in this study highlights their importance as candidates for further investigation in biological control of tested pathogenic bacteria.
 
 
 
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