Assessing the effectiveness of Byssochlamys nivea and Scopulariopsis brumptii in pentachlorophenol removal and biological control of two Phytophthora species.

Bioremediation and biological-control by fungi have made tremendous strides in numerous biotechnology applications. The aim of this study was to test Byssochlamys nivea and Scopulariopsis brumptii in sensitivity and degradation to pentachlorophenol (PCP) and in biological-control of Phytophthora cinnamomi and Phytophthora cambivora. B. nivea and S. brumptii were tested in PCP sensitivity and degradation in microbiological media while the experiments of biological-control were carried out in microbiological media and soil. The fungal strains showed low PCP sensitivity at 12.5 and 25 mg PCP L(-1) although the hyphal size, fungal mat, patulin, and spore production decreased with increasing PCP concentrations. B. nivea and S. brumptii depleted completely 12.5 and 25 mg PCP L(-1) in liquid culture after 28 d of incubation at 28 °C. Electrolyte leakage assays showed that both fungi have low sensitivity to 25 mg PCP L(-1) and produced no toxic compounds for the plant. B. nivea and S. brumptii were able to inhibit the growth of the two plant pathogens in laboratory studies and reduce the mortality of chestnut plants caused by two Phytophthorae in greenhouse experiments. The two fungal strains did not produce volatile organic compounds able to reduce the growth of two plant pathogens tested.

Biosorption of pentachlorophenol by Anthracophyllum discolor in the form of live fungal pellets.

Pentachlorophenol (PCP) is an extremely dangerous pollutant for every ecosystem. In this study we have detected how PCP concentration and pH levels can influence PCP adsorption by Anthracophyllum discolor in the form of live fungal pellets. PCP adsorption was evaluated after 24 hours in KCl 0.1 M electrolyte solution with initial PCP concentrations of 5 and 10 mg L (-1) and with pH values between 4 and 9 (at intervals of 0.5). Fourier Transform Infrared Spectroscopy (FTIR) was used to identify functional groups of fungal biomass that can interact with PCP. The amount of PCP that was adsorbed by A. discolor was >80% at pH values between 5 and 5.5, whatever the concentration tested. PCP adsorption significantly decreased in liquid medium of pH > 6.0. FTIR results showed that amides, alkanes, carboxylates, carboxyl and hydroxyl groups may be important to the PCP adsorption for pellets of A. discolor. Live fungal pellets of A. discolor may be used as a natural biosorbent for liquid solutions contaminated by PCP.

Flufuran, an antifungal 3,5-disubstituted furan produced by Aspergillus flavus link.

A 3,5-disubstituted furan, named flufuran, was isolated from a culture filtrate of a strain of Aspergillus flavus obtained from a chestnut compost created in the same orchard. Flufuran was identified by spectroscopic methods, and its structure was confirmed through the preparation of some key derivatives, also used to test the antifungal activity. At a concentration of 0.2 mg/ml, assayed against three Phytophthora species, pathogenic of some forest and agrarian plants, flufuran and especially its acetyl derivative showed significant antifungal activity. Although flufuran appears to be identical to a fungal metabolite isolated previously from some Polyporus spp., its interesting antifungal activity has never been reported before.

Isolation, characterization and structure-elicitor activity relationships of hibernalin and its two oxidized forms from Phytophthora hibernalis Carne 1925.

Three alpha-elicitins, named hibernalin1, hibernalin2 and hibernalin3 (hib1, hib2 and hib3, respectively), were isolated by reverse phase-low-pressure liquid chromatography from culture filtrates of Phytophthora hibernalis Carne 1925, the causal agent of citrus lemon brown rot. Hib1 proved to be identical to syringicin previously isolated from culture filtrates of Phytophthora syringae. Hib2 and hib3 shared the same primary structure with hib1, but contained, at position 50, Met sulphoxide or sulphone, respectively. By SDS-PAGE, the three proteins showed the same electrophoretic mobility, corresponding to about 10 kDa. Exact M(r) values were obtained by MALDI-TOF-MS (10,194.82 for hib1, 10,209.33 for hib2 and 10,223.80 for hib3), while by ESI-MS an M(r) value of 10,194.90 was found for hib1 and no results for hib2 and hib3. The hibernalin forms showed a high propensity to self-association, after exposure to acetonitrile. Hib1 showed to be active in both the hypersensitivity response and electrolytes leakage assays; the sample containing hib1 and hib2 was only weakly active in the first assay and inactive in the second assay, while the sample containing all three hibernalin forms proved to be inactive in both tests. It is proposed that the different activities of the three hibernalin samples could be very likely attributed to both Met50 oxidation and aggregation.

First Report of Phytophthora insolita and P. inflata on Rhododendron in Ohio.

During August 2003, we conducted a statewide survey of rhododendrons to determine if Phytophthora ramorum was present in Ohio ornamental nurseries. In total, 240 samples were randomly collected in 12 nurseries throughout Ohio from rhododendrons showing foliar necrotic lesions and twig dieback symptoms. The samples yielded 51 Phytophthora spp. isolates on PARP-V8 agar. The internal transcribed spacer (ITS) region of all isolates was amplified using the universal primers ITS1 and ITS4 and was sequenced. Consensus sequences from sense and antisense were then blasted against the GenBank database, allowing for the identification to species of ˜80% of all isolates. These identifications, and the ˜20% unknowns, were confirmed using blind morphological tests on the basis of the following parameters: colony morphology; shape and dimensions of sporangia and type of papillae; dimensions of oogonia and oospores; type and position of antheridia; presence or absence of chlamydospores; presence or absence and morphology of hyphal swellings; and growth rate at 35°C according to the Revisited Tabular Key of the species of Phytophthora (1). No P. ramorum was detected among the isolates; however, P. cactorum, P. citricola, P. citrophthora, and P. nicotianae were detected. We also found two occurrences of P. inflata Caros & Tucker and one of P. insolita Ann & Ko. (P. inflata: e-value ≤e-179, identities ≥95%; P. insolita: e-value = 0.0; identities = 95%.) P. inflata was isolated from two tissue types, a dead twig and a necrotic leaf tip. P. insolita was isolated from a necrotic leaf tip. Identity of the two species was confirmed morphologically using the parameters listed above as well as the following measurements (N = 40; all in µm) (1): P. inflata - sporangia: 40 × 24 ([24 to 68] × [18 to 34]); oogonia: 34.6 (28 to 40); oospores: 30.8 (25 to 38); P. insolita - sporangia: 42 × 28 ([34 to 56] × [22 to 38]); oogonia: 32 (26 to 36); oospores: 26 (22 to 30). Koch's postulates were satisfied by inoculating two rhododendron plants (cvs. PJM and Nova Zembla) with the putative pathogens. On each plant, each of three leaves was pierced with a dissecting needle and was inoculated by placing a 0.5-cm-diameter plug of mycelium that was taken from the margin of a colony actively growing on PARP-V8 agar on the wound. The inoculum was retained using clear adhesive tape. A similar procedure was used for twigs. Controls consisted of inoculations with sterile PARP-V8 agar medium. Both cultures of P. inflata and P. insolita produced necrotic lesions in all inoculations on both tissue types within 1 week, and they were reisolated from the margins of lesions on PARP-V8. The lesion margin was at least 2 cm away from the inoculum plug in leaf inoculations and several centimeters in twig inoculations. To our knowledge, this is the first report of P. inflata and P. insolita occurring on rhododendron and the first time P. insolita has been reported outside of Southeast Asia where it has been recovered only from soil. Reference: (1) D. J. Stamps et al. Mycol. Pap. No. 162. CAB Int. Mycol. Inst. Wallingford, UK, 1990.

Production, characterization, and effects on tomato of humic acid-like polymerin metal derivatives from olive oil mill waste waters.

The dark polymeric organic fraction rich in potassium recovered from olive oil mill waste waters (OMWW) and named polymerin and the potassium salified deglycosylated polymerin derivative (K-SDpolymerin) were easily transformed into their metal derivatives by saturation with various metals, including Na, Cu, Zn, Mn, Fe, and Al. Saturated metal polymerins were characterized by diffuse reflectance infrared Fourier transform spectroscopy and atomic absorption spectrometry. Tests on tomato plants of the various polymerins showed that only the soluble polymerin, K-SDpolymerin, and the insoluble Mn-SDpolymerin were significantly toxic. The toxic effects of OMWW on tomato at the original concentration and diluted 1:10 were much stronger than those of any polymerin. The possible exploitation of polymerins as bioamendments and/or metal biointegrators as a functon of their phytotoxic effects, their humic acid-like nature, and their richness in macro- and micronutrient metals is also discussed.