Davide Spadaro | Università degli Studi di Torino (original) (raw)

Papers by Davide Spadaro

Physiologia Plantarum, 2010

Reactive oxygen intermediates (ROIs) and reactive nitrogen intermediates (RNIs) have now become w... more Reactive oxygen intermediates (ROIs) and reactive nitrogen intermediates (RNIs) have now become well established as important signalling molecules in physiological settings within microorganisms, mammals and plants. These intermediates are routinely synthesised in a highly controlled and transient fashion by NADPH-dependent enzymes, which constitute key regulators of redox signalling. Mild oxidants such as hydrogen peroxide (H2O2) and especially nitric oxide (NO) signal through chemical reactions with specific atoms of target proteins that result in covalent protein modifications. Specifically, highly reactive cysteine (Cys) residues of low pKa are a major site of action for these intermediates. The oxidation of target Cys residues can result in a number of distinct redox-based, post-translational modifications including S-nitrosylation, S-glutathionylation; and sulphenic acid, sulphinic acid and disulphide formation. Importantly, such modifications precisely regulate protein structure and function. Cys-based redox switches are now increasingly being found to underpin many different signalling systems and regulate physiological outputs across kingdoms.

Archives of Phytopathology and Plant Protection, 2011

The phylogenecity of the four Fusarium mycotoxin gene (Fum 5) that has already been deposited in ... more The phylogenecity of the four Fusarium mycotoxin gene (Fum 5) that has already been deposited in National Center for Biotechnology Information (NCBI) gene bank was studied with a comparative sequence alignment with other fungi like Aspergillus sps. Cochiliobolus sps. These results clearly indicated that the Fum 5 genes of Fusarium species were originated from Aspergillues fumigates and Cochliobolus heterostrophus. Fum 5 gene closer identity was also observed clearly with other fungal Fusarium species of Aspergillus and Gibberella species.

Mycotoxin Research, 2010

In this study, we investigated the pathogenicity and patulin production by ten strains of Penicil... more In this study, we investigated the pathogenicity and patulin production by ten strains of Penicillium expansum on various fruits (apples, apricots, kiwis, plums and peaches) at two (4°C and 25°C) different temperature regimes. All strains caused the infectious rots on all fruits at 4 and 25°C except one strain (PEX 09) at 4°C. Two strains (PEX 20 and PEX 12) out of ten produced the highest amounts of patulin on all fruits tested. The patulin production by P. expansum is high at 25°C compared to 4°C. All strains of P. expansum accumulated patulin ranging from 100–13,200 μg/kg and nine strains ranging from 100–12,100 μg/kg in all fruits at 25°C and 4°C, respectively. Among ten strains of P. expansum, strain PEX 20 produced the greatest amount of patulin on apricots (13,200 μg/kg of rotten fruit) and on apples (12,500 μg/kg) at 25°C after 9 days of incubation. At 4°C, this strain produced 12,100, 12,000, 2,100 and 1,200 μg/kg of patulin on apricots, apples, plums and peaches, respectively, after 45 days of incubation. Strain PEX 12 produced the highest amount of patulin on kiwis (10,700 μg/kg) at 25°C and 10,300 μg/kg at 4°C. Patulin production by P. expansum on peaches and plums at both temperatures were lower than other fruits. The results of this study showed that careful removal of rotten fruits is essential to produce patulin-free fruit juice, since high patulin levels in apricots, apples and kiwis could result in a level greater than 50 μg/kg of this mycotoxin in finished fruit juices, when one contaminated fruit occurs in 264, 250 and 214 fruits, respectively. So, the fruit processors should take care in not using rotten fruits for juice production to avoid the patulin problem worldwide, since this study proved that most important fruits being used for juice production and direct human consumption are susceptible to P. expansum and subsequent patulin production even at low temperatures. This is the first comprehensive report regarding patulin production by different strains of P. expansum on various fruits from Italy at different temperature regimes.

Biological Control, 2011

The efficacy of Pichia guilliermondii strain M8 against Botrytis cinerea on apples was evaluated ... more The efficacy of Pichia guilliermondii strain M8 against Botrytis cinerea on apples was evaluated under storage conditions, and its possible modes of action were investigated both in vitro and in vivo experiments. After storage at 1°C for 120 days, M8 reduced grey mold incidence from 45.3% (control) to 20.0%. In apple juice medium (AJM) and in wound-inoculated apples, M8 at 10 9 and 10 8 cells ml À1 inhibited the spore germination of B. cinerea and the grey mold development. When co-culturing B. cinerea in vitro or in vivo in the presence of the yeast, neither inactivated cells nor culture filtrate of the yeast had any effect on spore germination or germ tube elongation. In AJM, the spore germination was significantly recovered by the addition of 1% glucose, sucrose and fructose, or 0.5% and 1% of (NH 4 ) 2 SO 4 , phenylalanine and asparagine. When the pathogen and the yeast were co-incubated in apple wounds with addition of the same nutrients, the inhibition of rots was significantly reduced by the supplemental nutrients. Light microscopy revealed that the yeast strongly adhered to the hyphae and spores of B. cinerea. M8 produced hydrolytic enzymes, including b-1,3-glucanase and chitinases in minimal salt media with different carbon sources. Pretreatment with M8 at 10 8 cells ml À1 followed by washing, significantly reduced grey mold lesions, suggesting an induction of defense responses. Direct attachment, competition for nitrogen and carbon sources, secretion of hydrolytic enzymes and induction of host resistance play a role in the biocontrol mechanism of P. guilliermondii M8 against B. cinerea.

Postharvest Biology and Technology, 2004

The application of a cell suspension of the BIO126 strain of Metschnikowia pulcherrima proved to ... more The application of a cell suspension of the BIO126 strain of Metschnikowia pulcherrima proved to be highly effective in the control of blue and grey mould, two of the most severe postharvest diseases on apple fruit. The possibilities of integrating the application of the antagonist with chemicals such as acibenzolar-S-methyl (ASM), ethanol, or sodium bicarbonate and a heat treatment were investigated in this work. The fruit were stored at 23 • C for 5 days and at 4 • C for 20 days. The antagonist, applied at 10 8 cells ml −1 , proved to be the key element for the control of both pathogens, being more efficient after cold storage, with a reduction of 56.6 and 97.2% in the lesion diameter of blue and grey moulds. Ethanol and acibenzolar-S-methyl permitted a partial reduction in grey mould severity. Heat treatment and sodium bicarbonate significantly improved the efficacy of the biocontrol agent against blue mould with storage at 23 • C. To study the possibility of a single application of the biocontrol agent (10 7 cells ml −1 ) with reduced dosages of sodium bicarbonate or ethanol, the viability of the micro-organism with these chemicals was studied and a new set of experiments was established. Against both pathogens, the greater reduction in lesion diameter was obtained by treating simply with the biocontrol agent. Significant results on blue mould were provided by the application of 20% ethanol or 5% sodium bicarbonate before the biocontrol agent and by the application of BIO126 in 0.1% sodium bicarbonate. The application of the cell suspension of BIO126 M. pulcherrima, preceded or not by a pre-treatment with sodium bicarbonate or ethanol, could become a successful alternative to fungicide usage in postharvest disease control of pome fruit. The fungistatic effect of ethanol or sodium bicarbonate could be associated with the effect of the biocontrol agent, being persistent on the fruit for long periods.

International Journal of Food Microbiology, 2004

Synthetic fungicides are the primary means to control postharvest diseases of fruits. Biological ... more Synthetic fungicides are the primary means to control postharvest diseases of fruits. Biological control has emerged as one of the most promising alternatives to chemicals. During the last 20 years, several biological control agents have been widely investigated for use on different pathogens and fruit crops. Many biological control mechanisms have been suggested for use on fruit including antibiosis, parasitism, induced resistance in the host tissue and competition. With the aim of extending the use of the biofungicides, there have been many studies on the application of various combinations of control agents, and on the application integrated with chemical and physical means of protection. The formulation and application methods are key issues for the efficacy and successful outcome of the commercial product. Genetic engineering may provide a useful tool in the enhancement of the biological control efficacy. Since biofungicides are usually not as effective as pesticides, this approach should be viewed as an important component of an integrated disease management scheme given that a significant and permanent reduction of pesticide use is our goal. D

Crop Protection, 2006

... Pyrenochaeta lycopersici Schneider & Gerlach, Fusarium oxysporum Schlechtend.: Fr. f.... more ... Pyrenochaeta lycopersici Schneider & Gerlach, Fusarium oxysporum Schlechtend.: Fr. f.sp. lycopersici (Sacc.) Snyder & Hans. and F. oxysporum f.sp. radicis-lycopersici Jarvis & Shoemaker are also widespread pathogens whose severity varies with regional cultural practices. ...

Postharvest Biology and Technology, 2010

During the growing seasons 2007 and 2008, 210 isolates of yeasts or yeast-like fungi were obtaine... more During the growing seasons 2007 and 2008, 210 isolates of yeasts or yeast-like fungi were obtained from the carposphere of temperate fruit collected from organic orchards in Northern Italy. Through six rounds of in vivo screening, three isolates showing the highest biocontrol efficacy against Monilinia laxa on peaches were selected. By using molecular and morphological tools, the strain AP6 was identified as Pseudozyma fusiformata, the strain AP47 as Metschnikowia sp., and the strain PL5 as Aureobasidium pullulans. This research represents the first evidence about the potential use of P. fusiformata to control postharvest diseases of fruit. By co-culturing in vitro M. laxa in the presence of the three antagonists, neither the inactivated cells nor the culture filtrate of the three isolates had any significant effect on spore germination or germ tube elongation, allowing exclusion of the production of secreted toxic metabolites. The antagonistic activity of A. pullulans PL5 and P. fusiformata AP6 was dependent on the cell concentration. Metschnikowia sp. AP47 significantly inhibited spore germination at the three concentrations tested (10 6 cells/mL, 10 7 cells/mL, and 10 8 cells/mL). The efficacy of the three strains was tested on peaches stored at three different temperatures, and their effectiveness was higher at 1 • C than at 8 • C or 20 • C. In trials carried out in semi-commercial conditions with peaches inoculated by spraying 10 5 spores/mL of M. laxa and stored for 21 d at 1 • C and 96% RH, a cell concentration effect on the control of brown rot incidence was observed. AP6 and PL5 showed no significant differences in efficacy when applied at 1 × 10 8 cells/mL or at 1 × 10 7 cells/mL, indicating that they could be used at a lower concentration in potential biofungicide formulations. Finally, in an experiment in semi-commercial conditions on fruit not inoculated with the pathogen with 21 d storage at 1 • C and 96% RH, the evaluation of postharvest quality parameters, including firmness, total soluble solids, ascorbic acid content, and titratable acidity, showed that none of the three screened antagonists impaired peach quality, when applied before storage. The present study identified three antagonistic microorganisms with potential exploitation as active ingredients for the development of products for postharvest control of brown rot on peaches.

Food Control, 2011

Six antagonistic yeast strains were screened for their ability to degrade Ochratoxin A (OTA) in l... more Six antagonistic yeast strains were screened for their ability to degrade Ochratoxin A (OTA) in liquid medium amended with OTA (7.5 µgml -1 ) and inoculated with yeast cells at ambient temperature invitro conditions. Highest OTA degradation was observed when the yeast cell concentration used at 1x10 8 cells/ml. Out of six yeast strains, two strains [Metchnikowia pulcherima (MACH1) and Pichia guillemonodii (M8)] were further selected for degradation of OTA at different conditions and one strain, Rhodococcus erythropolis (AR14) was used as negative control.

Journal of Environmental Science and Health Part B-pesticides Food Contaminants and Agricultural Wastes, 2009

This investigation was undertaken to test different control strategies against Botrytis cinerea v... more This investigation was undertaken to test different control strategies against Botrytis cinerea vineyards. Two commercial vineyards, “Barbera” and “Moscato,” located in Piedmont (Northern Italy) were divided into seven plots and treated with different combinations of fungicides including fenhexamid, pyrimethanil, fludioxonil + cyprodinil, iprodione, and boscalid, a new carboxamide compound. An integrated strategy including a chemical (pyrimethanil) and a biocontrol agent (Trichoderma spp. t2/4ph1) was also included. At harvest, the percentage of bunches and berries attacked by B. cinerea and the concentration of the chemical fungicides were determined. All the pesticide residues at harvest were below the maximum residue level (MRL), except when two applications of pyrimethanil per season were applied. Boscalid was the most effective active ingredient against B. cinerea among the tested chemicals. When boscalid application was followed by a treatment with pyrimethanil, its efficacy was similar to that shown by two treatments of pyrimethanil. However, this second strategy was not feasible due to the risks of resistance development in the pathogen and to the residue accumulation as indicated by the analysis.

Canadian Journal of Microbiology, 2010

Few strains of Metschnikowia pulcherrima (Pitt) M.W. Miller are under development for control of ... more Few strains of Metschnikowia pulcherrima (Pitt) M.W. Miller are under development for control of postharvest pathogens on fruit. A substrate was developed to optimize the biomass production of M. pulcherrima strain BIO126. Different complex nutrient sources, with or without pH control, were tested. Growth in yeast extract provided at concentrations > or =30 g*L-1 yielded the highest biomass. The addition of two carbon sources, D-mannitol and L-sorbose, at 5 g*L-1 each, significantly improved yeast growth. The greatest amount of yeast growth occurred when pH values of the medium ranged from 5.0 to 7.5. A combination of yeast extract, D-mannitol, and L-sorbose (YEMS), probably with diauxic utilization, showed a synergistic effect, widening the exponential phase (maximum specific growth rate of 0.45 h-1) and increasing the final cell number (1.5 x 109 cells*mL-1) and dry biomass (6.0 g*L-1) in well-controlled batch fermentation. In efficacy trials on 'Golden Delicious' apples, M. pulcherrima grown in YEMS effectively reduced incidence and severity of Botrytis cinerea (51.1% and 70.8%, respectively) and Penicillium expansum (41.7% and 14.0%, respectively). Also on 'Gala' apples, the best reduction of grey and blue mould incidence was obtained with cells grown in YEMS (58.1% and 50.5%, respectively).

Postharvest Biology and Technology, 2008

A new strain of Metschnikowia pulcherrima (MACH1) was studied for its efficacy as a biocontrol ag... more A new strain of Metschnikowia pulcherrima (MACH1) was studied for its efficacy as a biocontrol agent against Botrytis cinerea, Penicillium expansum and Alternaria alternata on apples stored for 8 months at 1 • C. The results of two semi-commercial trials demonstrated the efficacy of the biocontrol strain MACH1. In order to understand the mechanism of action involved, the yeast strain was investigated for its competitive ability for iron against postharvest pathogens of apple. M. pulcherrima strain MACH1 was cultivated on PDA with different concentrations of iron (supplemented as FeCl 3 ) against A. alternata and B. cinerea. The yeast strain MACH1 produced a wider pigmented inhibition zone against both pathogens in low iron amendments while less inhibition was measured with increased iron concentrations. At the coloured inhibition zone, B. cinerea and A. alternata conidia did not germinate and mycelial degeneration was observed. In addition, a high reduction in infection by both pathogens was recorded in apples treated with M. pulcherrima strain MACH1 supplemented with low iron amendments compared to higher iron concentrations. The same experiments were carried out in vivo and in vitro against P. expansum. M. pulcherrima strain MACH1 amended with low iron concentration (5 g mL −1 FeCl 3 ), showing modest lesion diameter reduction and no effect on P. expansum under increased iron and without iron amendments. This study illustrated that iron depletion by the yeast strain MACH1 under low iron conditions could reduce the growth of some postharvest pathogens in vitro and in vivo. Although, iron depletion seems to be a primary mode of action against the postharvest pathogens studied, other mechanisms of action cannot be excluded in the biocontrol employed by M. pulcherrima strain MACH1.

Food Additives & Contaminants Part B-surveillance, 2008

Pear, peach, apricot, and mixed juices (125 samples) were purchased in Italian supermarkets and o... more Pear, peach, apricot, and mixed juices (125 samples) were purchased in Italian supermarkets and organic food shops and analysed for patulin content. An overall incidence of 34.4? was observed in the fruit juices, with a mean contamination level of 3.6 µg kg–1. No one sample exceeded 50 µg kg–1, the maximum permitted limit according to European legislation. However, 19 positive samples contained more than 10 µg kg–1 of patulin, which is the maximum level permitted for baby food. The incidence of patulin contamination was significantly higher in pear juices (64.1?) than in apricot, peach, or mixed juices. Statistical analysis (p = 0.002; Kruskal–Wallis test) showed a significantly higher level of patulin in pear (5.1 µg kg–1) and mixed juices (4.9 µg kg–1) than in the other juices. A slightly higher incidence of positive samples was found in conventional juices (35.7?) compared with the organic ones (29.6?). The magnitude between the mean contamination levels was similar in conventional (3.6 µg kg–1) and organic (3.3 µg kg–1) juices (p = 0.474; Mann–Whitney U-test). Samples were further divided based on the fruit content in fruit juices, fruit nectars, and fruit drinks. In fruit nectars the incidence of positive samples (37.8?) was slightly higher than in fruit drinks (27.2?), but the mean patulin contamination was higher in fruit drinks (5.2 µg kg–1) than in fruit nectars (3.4 µg kg–1). However, the magnitude between the two means was not statistically different (p = 0.734; Mann–Whitney U-test). Italian juices had a higher incidence of patulin (35.3?), with a lower mean content (3.5 µg kg–1), compared with the incidence (22.2?) and level (4.1 µg kg–1) foreign juices commercially available in Italy. The magnitude of the means between Italian and foreign juices was not statistically different, according to the Mann–Whitney U-test (p = 0.616). The estimated intake of patulin ranged from 0.1 to 1.5 ng kg–1 body weight for the whole population and from 0.3 to 5.1 ng kg–1 body weight for the consumers only. The highest patulin intake was estimated for consumers of pear juices, followed by consumers of mixed juices. The daily intake of patulin derived from the consumption of pear juice suggests that also pear juices, though a minor patulin source, could be monitored for their patulin content in order to control the mycotoxin contamination, especially in countries, such as Italy, where pear nectars are preferred as fruit drinks.

Microbiological Research, 2008

Metschnikowia pulcherrima occurs naturally on fruits, buds and floral parts of apple trees. Some ... more Metschnikowia pulcherrima occurs naturally on fruits, buds and floral parts of apple trees. Some strains are effective as biocontrol agents against postharvest decay of apples and other fruits. The usefulness of the amplified fragment length polymorphism (AFLP) technique was evaluated for the genetic analysis of 26 strains of M. pulcherrima, isolated from different sources in different geographical regions. With six AFLP primer pairs, 729 polymorphic bands were scored. The technique showed a high discriminatory power. Genetic relationships between strains were also estimated using AFLP. All the isolates from the carposphere of apple, previously tested as biocontrol agents, were grouped in a single cluster with a high bootstrap value (97), indicating robustness and reproducibility. AFLP patterns could clearly distinguish the different strains and research is in progress to use some putative specific bands for single tag sequence (STS) conversion to develop isolate-specific markers.

Postharvest Biology and Technology, 2002

Flavour and Fragrance Journal, 2010

The efficacy of plant essential oils was evaluated on apples, cv. Golden Delicious, cv. Granny Sm... more The efficacy of plant essential oils was evaluated on apples, cv. Golden Delicious, cv. Granny Smith, cv. Red Chief and cv. Royal Gala, at postharvest to control Botrytis cinerea and Penicillium expansum. The essential oils from basil (Ocimum basilicum), fennel (Foeniculum sativum), lavender (Lavandula officinalis), marjoram (Origanum majorana), oregano (Origanum vulgare), peppermint (Mentha piperita), rosemary (Rosmarinus officinalis), sage (Salvia officinalis), savory (Satureja montana), thyme (Thymus vulgaris) and wild mint (Mentha arvensis) were tested at different concentrations. All the essential oils were from mediterranean plants. The fruits were artificially wounded and inoculated with a suspension at 1 × 105 conidia/ml of each pathogen. After 12 h, emulsions at 1% and 10% of each essential oil were dropped into each inoculated wound. A tebuconazole chemical control and an inoculated control were also included. All the treated fruit were stored at 4 ± 1°C. After 15 and 30 days, the diameter of the rot around each wound was measured. The results revealed that the efficacies of the essential oils tested were cultivar- and storage time-dependent. In any case, treatments with essential oils from oregano, savory and thyme showed significant efficacy in all apple cultivars tested. Treatments with essential oil emulsions at 10% were phytotoxic for all the apple cultivars evaluated. Copyright © 2010 John Wiley & Sons, Ltd.

Food Control, 2007

A survey on the occurrence of patulin was conducted during 2005 on commercial pure apple juices (... more A survey on the occurrence of patulin was conducted during 2005 on commercial pure apple juices (53 samples) and mixed apple juices (82 samples) marketed in Italy. The current study was undertaken to investigate the possible inXuence of the agro-food production process employed (conventional or organic), of the fruit percentage in the commercial product (higher or lower than 50%) and of the type of apple juice (clear or cloudy) on the occurrence and level of patulin contamination. Patulin could be quantiWed in 34.8% of the samples ranging from 1.58 to 55.41 g kg ¡1 . With the exception of one sample, the level of patulin was lower than 50 g kg ¡1 , the maximum permitted threshold in fruit juices according to the European legislation. Mean levels of patulin were signiWcantly lower in mixed apple juices (4.54 g kg ¡1 ) than in pure apple juices (9.32 g kg ¡1 ). Levels of patulin contamination were comparable in clear and cloudy juices. A similar incidence of positive samples was found in conventional and organic apple based juices, and the magnitude between the mean contamination levels, although higher in organic (10.92 g kg ¡1 ) than in conventional juices (4.77 g kg ¡1 ), was not statistically signiWcant (p D 0.771; Mann-Whitney test). The magnitude between the means of patulin contamination in juices containing more than 50% fruit (11.26 g kg ¡1 ) and in juices with 50% or less fruit (3.35 g kg ¡1 ) was statistically signiWcant (p D 0.016; Mann-Whitney test).