PDA Agar Research Articles

Fungi as Endophytes in Artemisia thuscula: Juxtaposed Elements of Diversity and Phylogeny.

Artemisia is a plant genus highly studied for its medicinal applications. The studies on the associated fungal endophytes are scarce. Ten plants specimens of Artemisia thuscula from Tenerife and La Palma were sampled to isolate the endophytic fungi. Identification of the endophytic fungi was based on morphology, Internal Transcribed Spacer (ITS) and Large Subunit (LSU) regions sequencing and indicates 37 fungal species affiliated to 25 fungal genera. Colonization rate varied among plants (CR = 25% to 92.11%). The most dominant colonizers found were Alternaria alternata (CF = 18.71%), Neofusicoccum sp. (CF = 8.39%) and Preussia sp. (CF = 3.23). Tendency for host specificity of most endophytic fungal species was observed. Sorensen–Dice index revealed that of 45 cases in the matrix, 27 of them were of zero similarity. Further, only one case was found to have 57% similarity (TF2 and TF7) and one case with 50% similarity (TF1 and TF4). The rest of the cases had values ranging between 11% and 40% similarity. Diversity indices like Brillouin, Margalef species richness, Simpson index of diversity and Fisher’s alpha, revealed plants from La Palma with higher values than plants from Tenerife. Three nutrient media (i.e., potato dextrose agar―PDA, lignocellulose agar―LCA, and tomato juice agar―V8) were used in a case study and revealed no differences in terms of colonization rate when data was averaged. Colonization frequency showed several species with preference for nutrient medium (63% of the species were isolated from only one nutrient medium). For the phylogenetic reconstruction using the Bayesian method, 54 endophytic fungal ITS sequences and associated GenBank sequences were analyzed. Ten orders (Diaporthales, Dothideales, Botryosphaeriales, Hypocreales, Trichosphaeriales, Amphisphaeriales, Xylariales, Capnodiales, Pleosporales and Eurotiales) were recognized. Several arrangements of genera draw the attention, like Aureobasidium (Dothideales) and Aplosporella (Botryosphaeriales) which are clustered with a recent ancestor (BS = 0.97).

Medios de cultivo a partir de residuos agroindustriales sólidos para el crecimiento de la levadura saccharomyces cerevisiae

El presente trabajo se llevó acabo para evaluar la promoción del crecimiento de diferentes medios de cultivos naturales frente a los medios comerciales PDA y Agar nutritivo en la cepa de Saccharomyces cerevisiae activada de levadura seca. La promoción del crecimiento fue evaluada con el Índice de Crecimiento Absoluto (ICA) en los diferentes medios de cultivos naturales y utilizando el método ecométrico. Los análisis ICA para comparar el crecimiento de la cepa en los diferentes medios naturales demostraron que el crecimiento fue muy poco, pero la explicación estuvo en que la cepa de S. cerevisiae estaba con varios repiques previos y habia perdido su vitalidad, ya que ni siquiera el medio de cultivo estandar PDA arrojo un ICA altamente productivo.

Antifungal Potentialities of Chitosan and Trichoderma in Controlling Botrytis cinerea, Causing Strawberry Gray Mold Disease

Strawberry gray mold disease caused by Botrytis cinerea (Pers.) is one of the most critical diseases attacking strawberry fruits especially at the post-harvest stage. This study compared the effectiveness of two types of Chitosan, bioagent’s filtrates and fungicides in controlling the gray mold of strawberry. The commercial and synthesized in vitro Chitosan were tested on radial growth of B.cinerea on PDA agar plates and on infected four fruits cultivars strawberry. The results showed that the two types of Chitosan were significantly decreased infection of B. cinerea especially on un-wounded fruits that have been treated by dipping method. Biological control agents were used as culture filtrates for control strawberry gray mold pathogen both on wounded and unwounded fruits, the disease incidence was inhibited significantly in comparing to control treatment. Chemical fungicides were also used in these trials for controlling the gray mold disease. The results obtained confirm the superiority of fungicides in controlling the disease in comparing the commercial and synthesized Chitosan well as biocontrol agents.

Isolation and Identification of Three Bioactive Compounds from Endophytic Fungus Trichoderma sp.

The endophytic fungus Trichoderma sp. was isolated from Ocimum basilicum L. plant and cultivated in the laboratory on potato dextrose agar PDA medium. Three bioactive chemical compounds were isolated and purified from culture of Trichoderma sp. using potato dextrose agar and potato dextrose broth. An investigation of the secondary metabolites by using Thin layer chromatography, column chromatography and Gas chromatography technique was carried out ,The molecular weight of purified compounds 1, 2 and 3 were 202 KD, 137 KD and 197 KD respectively and chemical name of compound 1 is1,10-Decanedioic acid, chemical name of compound 2 is Phenol, 4-(ethylamino)-4-Ethylaminophenol and chemical name of compound3 is Pyrimido [5,4-E]-1,2,4-triazine-5,7(4ah,6H)-dione,8,8a-dihydo-4a-hydroxy-6-methyl-. The antibacterial activity of the purified compounds against two bacterial species E.coli and S. aureus were tested by using a disc diffusion agar method reaching to 32,20mm for compound 1and 24,19 mm for compound 2 and 27, 26mm for compound 3. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined by the standard serial dilution assay.

Morphological characteristics of fruit bodies and basidiospores of Wolfiporia extensa

Wolfiporia cocos is a well-known traditional medicine in China, Japan, Korea, and other Asian countries owing to its numerous therapeutic properties. With the aim to determine the morphology and genetic characteristics of W. cocosten strains of W. cocos were cultivated in vitro, and subsequently, rapid amplification of polymorphic DNA was performed. To the best of our knowledge, this is the first study to examine the morphology of fruit bodies of W. cocos in Korea. W. cocos were cultured on PDA agar at different temperatures (12, 16, 20, 24, and 28oC) under 12-hour light (600 Lux) / 12-hour dark photoperiod condition for 1 month. Appearance of fruit body was the highest at 28°C condition in all the strains investigated. Honeycomb-like structure on sclerotia was observed in Andong 01, Andong 02, Andong 03, KFRI 1104, KFRI 1105, KFRI 1106, KFRI 1107, KFRI 1108, and ASI 13007 strains of . The KFRI 1103 strain formed cosmos petal-like structure on sclerotia. The average size of basidiospores was recorded as 7.55 μm in height and 3.35 μ in width.

Investigating the degrading properties of three different strains of fungi on commonly used pesticides in Guyana

Fareed R, Ansari A, Seecharran D, Munroe L. 2017. Investigating the degrading properties of three different strains of fungi on commonly used pesticides in Guyana. Biofarmasi (Rumphius J Nat Prod Biochem) 15: 5-14. Bioremediation is the use of microbes to remove various contaminants from the environment. The present research work was carried out during 2014-15. Aspergillus niger, Aspergillus flavus and Penicillium spp. were employed for biodegradation of pesticides commonly used in Guyana. Initially, the fungi were screened for ligninolytic potential by observing decolorization/degradation of a synthetic dye (Remazol Brilliant blue) in PDA agar. The degradation of dyes was noted by the change in original colour of the dye and visual disappearance of colour from the fungustreated Petri plates. In addition, accumulation of the dye by the fungal mycelium was also noticed. The fungi were then tested for their tolerance to the pesticides Diuron, Malathion and Diazinon respectively. This was done on solid media using PDA agar with amoxillin to prevent bacterial growth. The pesticides were introduced to the fungi by way of disc diffusion. Discs of a known diameter were infused with the respective pesticides at different concentrations and placed at strategic points around the inoculated fungal mycelium. The extent of inhibition was measured by comparing the growth diameter in the sample verses growth in the control. The pesticide diazinon was found to have inhibited the fungi more when compared to Malathion and Diuron. Finally, the fungi were used to degrade the pesticides in a liquid culture-Peptone Broth. The pesticide Diuron was selected because the fungi thrived best in all concentrations of this pesticide. A concentration of the pesticide Diuron was place in flasks containing the peptone broth with mycelia discs of the respective fungal strain. The final concentration of the pesticide was determined by using High Performance Liquid Chromatography (HPLC). The concentration of the pesticide in each strain of fungi was decreased. Aspergillus niger was found to have the highest rate of pesticide degradation followed by Aspergillus flavus and Penicillium.

English

The potato (Solanum tuberosum L.) is a tuberous herbaceous plant that belongs to the Solanaceae family. Several biotic and abiotic factors affecting its production include fungi such as mildew. In this present work, we proposed to evaluate the antagonistic power of Trichoderma viride against parasite Phytophthora infestans of potato tubers. We conducted two tests; for the first, in confrontation in-vitro, the direct confrontation was performed on an agar PDA medium to demonstrate the inhibitory capacity of T. viride on P. infestans. For the second test, in- vivo confrontation, we realized two methods; the first was carried out using a mycelia disk on the antagonist and the second was done by injecting the spore solution of T. viride into the potato tubers after this pathogen was applied. The results of the in- vitro test revealed that the confrontation between T. viride and the P. infestans showed the inhibitory capacity of T. viride, be it directly (68%) or remotely (58%) on the growth medium. Interesting results were also obtained in- vivo. The injection of the tubercles with a T. viride spore solution reduced the development of P. infestans with an average penetration of 3.28 mm for the T. viride and of 1.65 mm for the P. infestans. The findings of the mycelia discs method were similar to the injection method with a penetration average of 2.62 mm for T. viride and 1.81 mm for P. infestans. The test results in -vitro showed the efficiency of T. viride against P. infestans; while for in-vivo, it was proved that this antagonist possesses a very significant inhibitory effect that suppresses the spread of the pathogen. Keywords: Biological control, pathogen, confrontation, symptoms, in vivo, in vitro.

Seasonal in Physic-Chemical Quality and Microbiological of Natural Sources of Water Salvador, Bahia

The quality of water in natural sources of Salvador (Bahia, Brazil) showed a pH slightly acidic characteristic and dissolved oxygen, nitrate and phosphorus levels to below the permitted by Resolution CONAMA 357/2005 and Ordinance No. 2914/2011 of the Ministry of Health (MOH). Assessed by multivariate statistics in the dry season and rainy, total and fecal coliforms is exceeded level with most of the investigated sources confirming water contamination by E. coli. For susceptibility testing, cultures were on PDA agar supplemented with supplements Pb, Cu, and Cd. The isolates were Gram negative bacteria, in arrangement in pairs with distinct macroscopic characteristics. The sensitivity levels for heavy metals demonstrated heterogeneity of the three isolates and growth. Liquid effluents from domestic and urban sewage and solid waste (garbage) are the sources responsible for most contamination. DOI: 10.5935/1984-6835.20160044

Morphological variability of Macrophomina phaseolina (Tassi) Goid, causal agent of dry root rot disease of chickpea (Cicer arietinum L.)

To find out the best sources of nutrients for the fungal growth, different solid media were tested. Maximum radial growth was recorded on PDA and Czapek's agar with mean colony diameter of 90mm and on par with each other compared to other media tested. Carrot agar recorded maximum number of sclerotial production (48 per microscopic field) followed by PDA (46 per microscopic field) and the minimum sclerotial production was observed in Czapek's agar (39.33 per microscopic field). PDA and carrot media supported good mycelial growth and sclerotia production. The maximum sclerotial size was observed in PDA (0.5×0.4 μm) whereas Czapek's agar recorded minimum size of sclerotia (0.3×0.2 μm). Ellipsoidal shape of sclerotia was observed in Czapek's agar whereas, irregular shaped sclerotia were observed in other media. Maximum dry mycelial weight was recorded eighth day of incubation (150mg).

On-Site Enzyme Production by Trichoderma asperellum for the Degradation of Duckweed

The on-site production of cell wall degrading enzymes is an important strategy for the development of sustainable bio-refinery processes. This study concerns the optimization of production of plant cell wall-degrading enzymes produced by Trichoderma asperellum. A comparative secretome analysis was performed on T. asperellum growing on PDA agar, wheat bran and duckweed, respectively. T. asperellum proved to be able to produce a wide enzyme profile, including both depolymerization and debranching enzymes, mainly consisting of hemi-cellulases. The secretome analysis showed specific glycoside hydrolase-induction on duckweed compared with growth on wheat bran and PDA, including a GH62 α-L-arabinofuranosidase, a promising candidate enzyme for the degradation of duckweed. The enzyme cocktail from T. asperellum proved capable of degrading pretreated duckweed, obtaining up to 60% of the theoretical glucose yield, making it a potential candidate for on-site enzyme production.

The beneficial fungus Piriformospora indica protects Arabidopsis from Verticillium dahliae infection by downregulation plant defense responses.

BackgroundVerticillium dahliae (Vd) is a soil-borne vascular pathogen which causes severe wilt symptoms in a wide range of plants. The microsclerotia produced by the pathogen survive in soil for more than 15 years.ResultsHere we demonstrate that an exudate preparation induces cytoplasmic calcium elevation in Arabidopsis roots, and the disease development requires the ethylene-activated transcription factor EIN3. Furthermore, the beneficial endophytic fungus Piriformospora indica (Pi) significantly reduced Vd-mediated disease development in Arabidopsis. Pi inhibited the growth of Vd in a dual culture on PDA agar plates and pretreatment of Arabidopsis roots with Pi protected plants from Vd infection. The Pi-pretreated plants grew better after Vd infection and the production of Vd microsclerotia was dramatically reduced, all without activating stress hormones and defense genes in the host.ConclusionsWe conclude that Pi is an efficient biocontrol agent that protects Arabidopsis from Vd infection. Our data demonstrate that Vd growth is restricted in the presence of Pi and the additional signals from Pi must participate in the regulation of the immune response against Vd.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0268-5) contains supplementary material, which is available to authorized users.

Improved production of phleichrome from the phytopathogenic fungus Cladosporium phlei using synthetic inducers and photodynamic ROS production by phleichrome

Two different diketopiperazines, cyclo-(L-Pro-L-Leu) and cyclo-(L-Pro-L-Phe), which were isolated from the culture filtrate of Epichloe typhina and found to be inducers of phleichrome production, were chemically synthesized and evaluated for use in the improved production of phleichrome from wild-type and UV-mutagenized strains (M0035) of Cladosporium phlei. When supplemented with PDA and V8 juice agar media, both inducers showed significant increases in the production of phleichrome. Phleichrome production was increased in a dose-dependent manner up to a concentration of maximum yield for both inducers. No further significant induction was observed by supplementing inducers over the concentration of maximum yield. Among the two inducers, cyclo-(L-Pro-L-Phe) showed better inducing capability than cyclo-(L-Pro-L-Leu). The maximum yield was observed from the M0035 strain grown on V8 juice media supplemented with 150 μM cyclo-(L-Pro-L-Phe), which was estimated to be 232.6 mg of phleichrome per gram of mycelia and 10.2 mg of secreted phleichrome per 20 agar-plugs. Interestingly, growth inhibition was observed on V8 juice agar media with 100, 150, and 200 μM cyclo-(L-Pro-L-Phe) but not on PDA with the same amount of inducer, which suggests that the inhibitory effect might be through the overproduction of phleichrome rather than the toxic effect of the inducer itself. Superoxide production by purified phleichrome was dramatically stimulated upon illumination, thus demonstrating photodynamic production of superoxide in vitro by phleichrome.

PHYTOCHEMICAL STUDY AND ANTIMICROBIAL ACTIVITIES OF CORDIA DICHOTOMA

The present study was aimed at detecting the phytochemicals and evaluating antimicrobial activities of Cordia di chotoma known for their medicinal properties in folk medicine. Phytochemical screening wa s carried out on the leaves of Cordia dichotoma ; the results latifoliate the presence of alkaloids, proteins, carbohydrates. The assessment of antifungal activity was performed in terms of percentage of radial growth on solid medium (potatoes dextrose agar PDA) against Aspergillus flavus and Penicillium expansum . The antibacterial effect was studied by the agar direct contact method using Staphylococcus aureus , Pseudomo nas aeruginosa and Escherichia colistrains . The phytochemical estimation revealed the presence of alkaloids, flavonoids and saponosides. These phytochemicals were isolated from the plant with yields of 5.709 % of Petroleum ether extract, 6.69 % of Chlorofo rm extract, and 9.45 % of methanol extract. Finally, the results of antimicrobial activity of the aqueous extract showed a pronounced antifungal activity against the tested strains. The percentage inhibition values were found to b e in the range of 12 - 24 mm against Candida albicans and 11 to 19 mm against Aspergilus niger . The results revealed that the methanolic extract exhibited significant antimicrobial activity of concentration of 100 - 500 μ /ml respectively against tested organisms, particularly more effective against Bacilus cereus and E scherichia coli than the other extract when compared to the standard drug ( chloramphenicol).

English

Investigations into occurrence of fungus Aphanomyces frigidophilus in water of springs Dojlidy Górne, Jaroszówka and Pietrasze within the town BiaÅ‚ystok in Podlasie Province, Poland were conducted in Winter, Spring, Summer and Autumn of the year 2005. Samples were processed in the laboratory by routine methods commonly used to isolate these organisms. Bait method with the use of hemp seeds Cannabis sativa, small pieces of snake skin Natrix natrix and exuviae of shrimp Gammarus sp. as bait was applied to isolate the fungus Aphanomyces frigidophilus from the springs. The isolate was maintained on Potato Dextrose Agar PDA and stored in the culture collection of the Real Jardín Botánico CSIC Madrid, Spain. Aphanomyces frigidophilus occurred in 18 [(6)16.7%) in Winter, 3(8.3%) in Spring, 2(5.6%) in Summer, 7(19.4%) in Autumn, 2005] of the examined water samples. In Spring Dojlidy Górne it was very common and was found in all research seasons. The isolate was characterized by studding sequencing the internal transcribed spacer of nuclear DNA (ITS1+5.8S+ITS2). The results indicated the sequence comparisons of two ITS nuclear DNA for species identification: Aphanomyces frigidophilus 18S ribosomal RNA gene, partial sequence, internal transcribed spacer 1, 5.8S ribosomal RNA gene, and internal transcribed spacer 2, complete sequence and 28S ribosomal RNA gene, partial sequence. The results indicated the sequence of our isolate corresponded to the species Aphanomyces frigidophilus (AY647192, version AY647192.1; GI: 48766837).   Key words: Aphanomyces frigidophilus, snake skin of Natrix natrix and exuviae of shrimp Gammarus sp.

Spectroscopic and biological approach in the characterization of a novel 14-membered [N4] macrocyclic ligand and its Palladium(II), Platinum(II), Ruthenium(III) and Iridium(III) complexes

A novel, tetradentate nitrogen donor [N4] macrocyclic ligand, i.e. 3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[12,0,07-12] cosa-1(22),2,5,7,9,11,13,16,18,20-decaene(L), has been synthesized and characterized by elemental analyses, IR, Mass, and 1H NMR spectral studies. Complexes of Pd(II), Pt(II), Ru(III) and Ir(III) have been prepared and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral and thermal studies. On the basis of molar conductance the complexes may be formulated as [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl and [Ir(L)Cl2]Cl. The complexes are insoluble in most common solvents, including water, ethanol, carbon tetrachloride and acetonitrile, but soluble in DMF/DMSO. The value of magnetic moment indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moment corresponding to one unpaired electron. The magnetic moment of Ru(III) complex is 1.73 B.M. at room temperature. The antimicrobial activities of ligand and its complexes have been screened in vitro, as growth inhibiting agents. The antifungal and antibacterial screening were carried out using Food Poison and Disc Diffusion Method against plant pathogenic fungi and bacteria Alternaria porri, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa respectively. The compounds were dissolved in DMSO to get the required solutions. The required medium used for these activities was PDA and nutrient agar.

Phytophthora Crown and Root Rot of Zucchini Squash in Almería, Spain.

Zucchini (Cucurbita pepo) is intensively cropped in approximately 4,500 ha of plastic houses in southern Spain. In 2008 to 2009, Consul, Cronos, and Tosca zucchini plants showed symptoms of leaf wilting, basal stem necrosis, and plant death. Incidences of dead plants were 20 to 30% and these plants were distributed in clusters. Phytophthora capsici Leonian was isolated from the basal stems of symptomatic plants, using PDA and cornmeal agar amended with a pimaricin, ampicillin, and rifampicin. Five resultant isolates (PCl-211, PCl-221, PCl-611, PCl-612, and PCl-811) on lima beans agar (LBA) produced white mycelia with lemon-shaped and papillate sporangia borne on long pedicels, but no oospores or chlamydospores. These isolates had an identical ribosomal DNA ITS sequence, matching with that of P. capsici in GenBank. The sequences of two representative isolates, PCl-211 and PCl-811, were deposited in GenBank with accession nos. KC662328 and KC688317, respectively. The pathogenicity of these five isolates was tested on zucchini cv. Consul in 1-liter containers filled with vermiculite in May and September of 2009. Plants were inoculated at the 2 to 3 true-leaf stage. Plates with LBA fully covered with colony of each isolate were separately blended and homogenized with 300 ml of sterile distilled water. Inocula were poured around stem at 50 ml per plant. Each experiment had three replicates and four plants per replicate. Treatments with different isolates were arranged in a randomized complete block design. In both experiments, 12 uninoculated plants served as controls. Test plants were maintained for a month following inoculation in a greenhouse with mean temperatures ranging from 21.9 to 27.9°C and from 20.7 to 24.6°C for the May and September experiments, respectively. The first wilting occurred 5 days after inoculation. At the end of the May experiment, all control plants and those inoculated with PCl-221 remained asymptomatic while 83.3% of those inoculated with PCl-211 and 100% of those with the other isolates were dead. Inoculated plants exhibited crown and root rots, excluding the secondary roots. In the September experiment, 83.3% and 33.3% of plants inoculated with PCl-211 and PCl-221, respectively, were symptomatic, while all plants inoculated with the other isolates were dead. The control plants remained healthy. The pathogen was consistently recovered from symptomatic plants in both experiments. Although P. capsici was reported in peppers (Capsicum annuum) in several provinces of Spain (1), to our knowledge, this is the first report of P. capsici as the causal agent of crown rot in zucchini plants in plastic houses in the Almería Province of Spain, one of the world's largest concentrations of greenhouses. Reference: (1) J. L. Andrés et al. Span J Agric Res 3:326, 2005.

First Report of Fusarium sporotrichioides Causing Foliar Spots on Forage Corn in Chile.

In southern Chile, forage corn (Zea mays L.) is grown for feeding animals in milk diaries and livestock production. In December 2010, corn plants with small circular spots on leaves were collected from three fields located in Río Negro (Los Lagos region). Symptoms began as small, circular white to brown spots of 5 to 10 mm on different parts of the leaf and necrotic tissue with irregular brown to burgundy margins on the border and tip of the leaf. Estimated visual severity was ~5 to 40% for each leaf from field samples. Twelve small blocks of tissue were taken from the edge of necrotic spots from infected leaves, surface disinfected (2 min in 95% ethanol, 2 min in 0.5% NaOCl, followed by three rinses with sterile distilled water), and then placed on PDA and incubated for 7 days at 24 ± 1°C. Seventy five percent of the sampled tissues developed fungal colonies and a 4-mm3 block of agar that contained the advancing hyphal edge of each colony was transferred to PDA and carnation leaf agar and incubated for 10 days at 24 ± 1°C. Colonies were fast growing with pink-white and dense mycelia; with a carmine red color on the undersurface of the plate and orange sporodochia; polyphialides abundant; microconidia abundant, oval or pear-shaped or spindle-shaped, thin walled, hyaline, often with a papilla at the base, and 5.5 to 12.2 × 2.0 to 3.2 μm. Macroconidia were sickle-shaped, 3 to 5 septate, moderately curved to straight, hyaline, thick walled, and 20.5 to 42.9 × 3.5 to 5.0 μm. Morphology of colonies and conidia matched the description of Fusarium sporotrichioides Sherb. (3). Identity of the fungus was confirmed by molecular characterization of the ITS and 18SrRNA regions (universal primers ITS4/5 and NS1/2, respectively) and the β-tubulin gene (primers Bt1a/Bt1b) of three isolates. BLAST searches of the obtained sequences had between 99 to 100% homology with several isolates of F. sporotrichioides from GenBank (Accession Nos. KC866343 to KC866351). Pathogenicity tests were conducted by dispensing 10 μl of a prepared spore suspension (107 spores/ml) on corn leaves (16 leaves). Negative controls were corn leaves inoculated with sterile distilled water. Inoculated corn leaves were kept at 25 ± 1°C in glass bell jars and monitored for the onset of symptoms for 10 days. The test was conducted twice. Additionally, 20 corn plants of four hybrid lines were inoculated with ~5 ml of a spore suspension (104 macroconidia/ml) 2 months after seeding under field conditions in Valdivia, Los Ríos region, Chile. Seventy five days after sowing, similar lesions to those initially observed on field infected leaves were observed on inoculated leaves but not on water controls. Under field conditions, an extended damage on borders of basal leaves and spots on stems and cobs was observed. The pathogen was reisolated from infected tissues, thereby fulfilling Koch's postulates. F. sporotrichioides is a frequent pathogen in corn silage (1) and cereal crops (3,4), and produces trichothecene mycotoxins that cause toxicosis in animals (2,3). To our knowledge, this is the first report of F. sporotrichioides causing foliar spot on forage corn in Chile and this disease could represent a serious risk of mycotoxin contamination in this crop.

First Report of Fusarium proliferatum Causing Rot on Garlic and Onion in Argentina.

In October 2001 and January 2002, in onion fields (Allium cepa L. cv Valencianita) in the Provinces of San Juan (SJ) and Mendoza (MZ), Argentina, plants were observed with chlorosis, dry leaf tips, and bulbs showing discoloration and rot. During the summer of 2002, a tan rot with white mycelium in rot cavities was also observed in stored garlic bulbs (Allium sativum) in MZ. Four monosporic cultures obtained with a micro punch adapted microscope (three from onion CSJ1, CMZ1, CMZ2 and one from garlic AMZ1) were characterized by morphology on PDA and carnation leaf agar (2). The isolates were deposited in the fungal collection of the Plant Mycosis Laboratory of the Integrated Unit Balcarce. The isolates produced abundant aerial white mycelium and a violet to vinaceous pigmentation. Club-shaped microconidia were abundant, in chains on both mono- and polyphialides. Slender, thin-walled and relatively straight macroconidia were produced only under black light and were mostly 3-septate. Chlamydospores were absent. The isolates were identified as Fusarium proliferatum. Crosses to confirm mating populations and to identify mating types were made in triplicate on carrot agar (3) with standard tester strains D-04853 (MATD-2) and D-04854 (MATD-1) as female parents and the field isolates as male parents. Crosses were examined weekly and were scored positive only if perithecia were seen oozing a cirrhus of ascospores. The identities of these isolates were confirmed as showing positive crosses with standard tester strains of Gibberella intermedia. Pathogenicity tests were conducted with healthy 45-day-old onion seedlings (cv. Valcatorce INTA). The roots of the onion seedlings were soaked in a conidial suspension (5 × 106 conidia/ml) of each isolate (CSJ1, CMZ1, CMZ2) for 2 h; the control was soaked in sterile water (SW). Seedlings were transplanted to pots in a sterile mixture of soil and sand (v/v). Five plants were used for each of 3 replications. The plants were placed in a greenhouse and irrigated with SW. After 3 weeks, symptoms were evaluated. All inoculated plants exhibited symptoms similar to those observed in the bulbs from which the pathogen was isolated and a brown rot appeared on the basal plate of the onion, later becoming dark brown. In garlic, the inoculation consisted of a wound 4.5 mm deep and 2 mm wide in superficially sterilized garlic cloves (cv. Nieve INTA). Inside the cavity, a drop (50 μl) was placed from a suspension of 5 × 106 conidia/ml (AMZ1), then covered with a drop of paraffin. Controls used SW. The garlic cloves were incubated in hermetically sealed trays at 22 ± 3°C in darkness for 3 weeks (1). Garlic showed tan rot and white mycelium in the wound. F. proliferatum was reisolated from inoculated onion seedlings and garlic cloves. The controls did not exhibit symptoms nor were any fungi recovered when tissue was excised from the inoculation points and plated on agar. F. proliferatum was previously reported in Argentina on asparagus (4) with symptoms similar to those of onion and garlic. To our knowledge, this is the first report of F. proliferatum attacking onion and garlic in Argentina. This pathogen has the potential risk of mycotoxin accumulation in contaminated bulbs.

Evaluation of antifungal activity of free fatty acids methyl esters fraction isolated from Algerian Linum usitatissimum L. seeds against toxigenic Aspergillus

ObjectiveThe aim of this study was to evaluate the antifungal activity of the major fraction of fatty acids methyl esters (FAMEs) isolated from Linum usitatissimum L. seeds oil collected from Bechar department (Algeria). MethodsThe assessment of antifungal activity was carried out in terms of percentage of radial growth on solid medium (potatoes dextrose agar PDA) and biomass growth inhibition on liquid medium (potatoes dextrose broth PDB) against two fungi. ResultsThe FAMEs was found to be effective in inhibiting the radial mycelial growth of Aspergillus flavus more than Aspergillus ochraceus on all tested concentrations. The highest antifungal index was found to be (54.19%) compared to Aspergillus ochraceus (40.48%). The results of the antifungal activity of the FAMEs inhibition of biomass on liquid medium gave no discounted results, but this does not exclude the antifungal activity. ConclusionsWe can assume that the observed antifungal potency may be due to the abundance of linoleic and α-linolenic acids in linseed oil which appears to be promising to treat fungal infections, storage fungi and food spoilage in food industry field.

INHIBITORY ACTIVITY OF ALLYL ALCOHOL DERIVED FROM ALLIIN IN GARLIC AGAINST FOOD BORNE PATHOGEN CANDIDA ALBICAN

The objectives of the present study were to evaluate the antimicrobial activity of allyl alcohol produced by the thermal decomposition of garlic against food borne pathogen Albicans, and to find out the minimum inhibitory concentration of allyl alcohol in heated garlic. The initial concentration of the organism Candida was estimated by direct microscopic count (DMC) method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests were performed to observe the antimicrobial activity of allyl alcohol-a product of garlic, against Albicans at different pH levels and heating times such as: pH 4 and heating time 90 min, pH 4 and heating time 30 minutes, pH 8 and heating time 90 minutes, and pH 8 and heating time 30 minutes respectively in the YMPG broth and PDA agar, by incubating at 350C for 24 hours. Similarly HPLC method was used to determine the amount of extracted product of garlic - allyl alcohol at different pH levels. It has been observed that allyl alcohol showed comparatively more anti yeast activity at pH 4, with heating time 90 minutes, which is 1.56% at dilution 1/64. Similarly generation of allyl alcohol from heated garlic extract by HPLC test was found maximum at pH 4, and time 90 minutes that is 8.05 % as compared to other three combined variables of pH, and time. The findings of present study clearly met with the hypothesis that allyl alcohol in heated garlic had anti yeast activity, it was able to inhibit the growth of pathogen such as Albicans, by extending heating time at low pH level.