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Articles by G.H. Shahidi Bonjar
Total Records ( 17 ) for G.H. Shahidi Bonjar
  G.H. Shahidi Bonjar
  Microbial resistance, a world health-hazard, is dramatically increasing. Evaluation of natural products to access new, safe and effective principles to rotate or substitute with the invalidated ones is one of the scientific strategies to combat drug-resistant pathogens. With this perspective, methanolic extracts of fifty plant species of 33 families which had documented uses in Iranian Traditional Medicine, were screened for antibacterial activity against five strains of each of gram negative (G-) and gram positive (G+) bacteria. Thirty samples from 28 species in 21 families had antibacterial activity at least against one of the bacterial strains. Bioactivities were evaluated by measuring Diameter of inhibition zones in Agar well diffusion assays. Among the active plants, 32.6% were active against G-, 62% against G+ and 47.3% against both G- and G+ bacteria. Dianthus coryophyllus was active against all tested G- and G+ bacteria except Micrococcus luteus. Most susceptible G- bacteria were Klebsiella pneumoniae and Bordetella bronchiseptica and least susceptible G- bacterium was Escherichia coli. In G+ bacteria, most and least susceptible were Staphylococcus aureus and M. luteus, respectively. The extracts having more traditional usages and fairly broad spectra of activity, were used to determine Minimum Inhibitory Concentrations (MIC). The least MIC, as 0.062 mg ml-1 belonged to Myrtus communis seeds against S. aureus, Bacillus cereus and B. bronchiseptica and to Terminalia chebula ripe seeds against S. aureus. The bioactive extracts were well stable at room temperature up to 18 months. Concepts including Percent Activity, Bacterial Susceptibility Index, Average Percent of Bacterial Susceptibility and Spectral Intensity Index are proposed as new approaches for interpretation of the results.
  G.H. Shahidi Bonjar
  Streptomyceticidal activity of Methyl Tert-butyl ether (MTBE) is being reported for the first time. Adverse effect of Methyl Tert-butyl ether (MTBE), the gasoline additive, against four soil-inhabitant Streptomyces spp. isolates and two plant root-pathogens was investigated. MTBE, an octane enhance is added to gasoline to reduce atmospheric concentrations of carbon monoxide and ozone. It contaminates soil and groundwater by fuel leaks and spills. Streptomyces spp. are of the major contributors to the biological buffering of soils by exerting beneficial and antagonistic activity against wide range of bacteria and fungi. To elucidate antimicrobial activity of MTBE, it was tested against four soil isolates of Streptomyces; a plant bacterial-pathogen, Erwinia carotovora and a plant root fungal-pathogen, Fusarium solani. MTBE did not reveal any growth inhibitory-activity against E. carotovora and F. solani but showed strong inhibitory effect against Streptomyces spp. isolates. The Minimum inhibitory concentration (MIC) was 1/800 of the original MTBE. Fuel leaks and spills can adversely suppress or eliminate the Streptomyces role in the soil causing alteration in the balance of soil micro flora. This change will lead to domination of microorganisms with adverse biological or ecological effects.
  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.
  M. Kalantar Zadeh , G.H. Shahidi Bonjar , P. Rashid Farrokhi , A. Ghasemi , S. Aghighi and M.J. Mahdavi
  Streptomyces scabies and S. acidiscabies, the two major phytopathogens induce potato common scab in potato growing areas of Iran. Soil Actinomycetes including 174 isolates were assayed for assessing antagonistic activity against Streptomyces scabies and S. acidiscabies. From tested isolates, S. olivaceus, strain 115 and S. plicatus, strain 101 showed high anti-scab activity revealed by bioassays in agar disk and well diffusion methods. For further biological characterizations, the active strains were grown in submerged cultures to determine growth curve and prepare crude extracts. Preliminary greenhouse studies indicated that amending soil with the S. olivaceus, strain 115 and S. plicatus strain 101 reduce crop losses due to the pathogens. Antibacterial activities of both antagonists were of bactericidal type on both pathogens with complete inhibitory effects.
  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.
  G.H. Shahidi Bonjar , M.H. Fooladi , M.J. Mahdavi and A. Shahghasi
  Rapid emergence of antibacterial resistance is well documented as a serious problem worldwide. This situation shows that the potencies of prevalent antibiotics are decreasing steadily. This situation implies the need for searching new antimicrobials to replace with invalidated ones or use in antibiotic rotation programs. In a four years study, from 1,300 soil Actinomycete isolates collected from different localities of Kerman, Hormozgan, Sistan and Baloochestan, south and south east Provinces of Iran, Streptomyces sp. isolate No. 419 showed widest antibacterial activity. The active principle named as Broadspectrim. It showed antibacterial activity against wide range of G+ and G- bacteria as Bacillus anthracis, Bacillus subtilis, Citrobacter diversus, Citrobacter freundii, Corynebacterium diphtheriae, Enterobacter sp., Escherichia coli, Klebsiella pneumoniae, Micrococcus luteum, Proteus vulgaris, Proteus rettgeri, Proteus mirabilis, Proteus morganii, Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas syringae pv syringae, Salmonella Para Typhi A, B, C, D, Salmonella typhi, Sarcinia sp., S. marcescens, Shigella dysentery, S. flexneri, S. sonnei, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Vibrio cholera Eltor (INABA) and Xanthomonas sp. but Shigella flexneri and Staphylococcus albus were resistant to it.
  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.
  G.H. Shahidi Bonjar and Sonia Aghighi
  Among soil-borne fungi, cosmopolitan phytopathogen, Verticillium dahliae Klebahn is responsible for high yield losses in many plant species. Except for solarization in mediterranean countries and except in the few cases where disease-resistant cultivars are available, control of Verticillium wilt in commercial crops has been highly dependent on the application of preplant soil fumigants. Research to develop alternative control measurements should focus on biological approaches aimed at shifting the composition of soil microbial communities to suppress Verticillium. The merits of role of actinomycetes in biological control of soil-borne fungal-pathogens are known, however actinomycetes microflora of the Iranian soils has not been very well explored in searching for biofungicide agents. At the present research, in vitro studies of some biological effects of two Iranian strains of actinomycetes, Streptomyces plicatus strain 101 and Frankia sp. strain 103, are presented. Both strains revealed enzymatic activity and inhibited production of microsclerotia in V. dahliae. Treating the crude extract with chloroform, denaturized enzymatic activity of both strains. Thermal inactivation point of active phases of S. plicatus was 70 and 90°C and in Frankia sp. was determined as 60°C. Antifungal active phases of S. plicatus tolerate wide range of pH (5-13) but in Frankia sp. active phase tolerates pH 7-9. These two strains may be useful candidates for involving in integrated control programs of Verticillium vascular wilting.
  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.
  S.A. Ayatollahi Mousavi , E. Khalesi , G.H. Shahidi Bonjar , S. Aghighi , F. Sharifi and F. Aram
  Rapid identification of Candida species in clinical laboratory is becoming increasingly important since the incidence of Candidiasis continues to rise as the hospital surveys show. Molecular techniques utilizing amplification of target DNA provide quick and precise methods for diagnosis and identification of Candida species. In this study, using universal primers, the ITS1-ITS4 region was amplified. The restriction enzyme MspI digests this region and was used to identify of C. albicans, C. glabrata, C. krusei, C. tropicalis and C. guilliermondii. Electrophoretically, ribosomal DNA of C. guilliermondii produced three bands whereas the other species gave two bands upon digestion. Accordingly these enzymes behave as valuable application tools in molecular diagnosis of Candida species in Candidiasis maladies and can be substituted with the classical diagnosis of the pathogen.
  G.H. Shahidi Bonjar
  Aspergillus flavus was isolated from kernels of early splits in pistachio nuts (Pistacia vera L.) from three orchards in vicinity of Kerman, Iran in 2002 and 2003. Pistachio nuts with early splits have split nuts in which their kernels invade by molds before harvest. A. flavus recovered from 12.5% of kernels with early splits at early and 25% from cracked seedless shells at late periods of season. Aflatoxins were detected in early splits of all three orchards. The results indicate that a major route for contamination of pistachio nuts with the toxins originates from early split nuts and cracked seedless shells. Since these are distinct from normal nuts, they should be removed and properly disposed of during processing.
  G.H. Shahidi Bonjar
  This is the first report showing the anti-yeast activities of different Iranian plants. Plants used in herbal-medicine were collected from South-East regions of Iran. Methanolic extracts were prepared and evaluated in Agar well-diffusion test against three yeast species of Saccharomyces cerevisiae, Candida albicans and C. utilis. From 48 plant species in 34 families, 26 species in 20 families showed inhibitory effect at least against one yeast species at 20 mg ml ha-1 . Plants with high anti-yeast activity included Alpinia officinarum, Chrozophora verbasafalia , Cinnamomum zeylanicum, Dianthus coryophyllus, Helleborus nigra, Heracleum persicum, Myrtus communis, Terminalia chebula and Trachysermum copticum which were effective mostly against C. albicans and C. utilis. No plant showed high level of activity against S. cerevisiae. The lowest MIC was observed in M. communis and T. chebula as 0.31 mg ml ha-1 . Active extracts retained their activity at room temperature in both DMSO: methanol (1:1, v/v) solvent and lyophilized state up to 18 months.
  G.H. Shahidi Bonjar , S. Aghighi and A. Karimi Nik
  Methanol plant-extracts of 221 species from 98 families which had documented uses in Iranian herbal-medicine were screened for antibacterial and antifungal activity against 11 standard bacterial strains and 3 fungal species at 20 mg mlG1. Eighty one samples in 39 families showed antibacterial and/or antifungal activity against at least on one of the tested microorganisms. Antimicrobial activities were evaluated by measuring the diameter of inhibition zones in agar well diffusion method. Dianthus coryophyllus was active against all tested G-ve and G+ve bacteria except Micrococcus luteus. Most susceptible G-ve bacteria were Klebsiella pneumoniae and Bordetella bronchiseptica and least susceptible was Escherichia coli. In G+ve bacteria, most and least susceptible were Staphylococcus aureus and Micrococcus luteus, respectively. Plants with high antifungal activity included Alpinia officinarum, Chrozophora verbasafalia, Cinnamomum zeylanicum, Dianthus coryophyllus, Helleborus nigra, Heracleum persicum, Myrtus communis, Terminalia chebula and Trachysermum copticum which were effective mostly against Candida albicans and C. utilis.
  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.
  Sadeghi, A. , A.R. Hessan , H. Askari , S. Aghighi and G.H. Shahidi Bonjar
  Biological control of sugar beet damping-off of Rhizoctonia solani by two Streptomyces isolates (S2 and C) was evaluated in this study. The in vitro antagonism assays showed that active isolates had inhibitory effects on mycelium growth of the three R. solani AG-4 isolates (Rs1, Rs2 and Rs3). Soil treatment either with isolate S2 or C formulation inhibited the disease completely and increased seedling stand in infected and uninfected treatments significantly (p<0.05). Compared to controls, all treatments containing bacteria had enhanced shoot and root dry weight and root density. Both bacterial isolates maintained normal growth in pH ranges of 5.6, 7.2 and 8.0 at 29°C. Isolate C grew in pH ranges 5.6, 7.2 and 8.0 at 23-37°C, isolate S2 grew at 18-37°C in pH 5.6-8.0 but did not grow in acidic medium at 37°C. When pH decreased to 5.0, growth of C decreased and S2 inhibited. To elucidate the mode of antagonism, chitinase activity and siderophore production were evaluated. Both isolates showed chitinase activity on medium containing colloidal chitin. Biosynthesis of siderophore was detectable in isolate C but not in S2. The results of this study showed that these isolates had antifungal activities by production of siderophore and chitinase.
  F. Sharifi , P. Rashid Farrokhi , G.H. Shahidi Bonjar , S. Aghighi , F. Aram and E. Khalesi
  Actinomycetes enhance soil fertility and have antagonistic activity against wide range of plant root-pathogens. These micro organisms were isolated from agricultural soils of Kerman and Fars Provinces as pure cultures. Pythium aphanidermatum, causes damping off and root and stem rots of cucurbits worldwide. From 178 Actinomycetes isolates, 43 inhibited growth of the pathogen in culture plates and two of the most active isolates exhibited biological control of the pathogen under greenhouse conditions. When plants were grown in sterile soil mix and treated both with Actinomycetes and the pathogen, the number of healthy plants increased dramatically and the symptoms on diseased plants were less severe in comparison with seedlings treated with the pathogen alone. From the collected data it was well conclusive that in greenhouse tests, soil applications of Actinomycetes controlled causal agent of damping off in cucurbit seedlings. Antifungal activity was of fungicidal type on the pathogen mycelia. Regarding biotechnological implications, the results indicate that the active isolates can be investigated for use as biofertilizers, biofungicides and use in future development of recombinant DNA in cucurbits bearing elevated resistance to damping off. Field trials of the active isolates are under investigation.
  F. Sharifi , G.H. Shahidi Bonjar , S. Aghighi , P. Rashid Farrokhi , E. Khalesi , M.J. Mahdavi and H. Taraz
  Pythium aphanidermatum, the major phytopathogen induce damping off, root and stem rots, blights of grasses and fruit and in greenhouse cucurbits growing all areas of the world. Soil Actinomycetes including 178 isolates were assayed for assessing antagonistic activity against P.aphanidermatum. From tested isolates, 43 isolates were effective but 2 isolates strains 311 and 321 showed high anti-fungal activity revealed by bioassays in agar disk and well diffusion methods. For further biological characterizations, the active strains were grown in submerged cultures to determine growth curve and prepare crude extracts. Preliminary greenhouse studies indicated that amending soil with these strains, 311 and 321; reduce crop losses due to the pathogen. Antifungal activities of both antagonists were of fungicidal type on pathogen with complete inhibitory effects.
 
 
 
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