Effect of wine inhibitors on free pineapple stem bromelain activity in a model wine system

The influence of potential inhibitors, naturally present in wine, on the activity of stem bromelain was investigated in order to evaluate the applicability of this enzyme for protein stabilization in white wine. Bromelain proteolytic activity was tested against a synthetic substrate (Bz-Phe-Val-Arg-pNA) in a model wine system after adding ethanol, sulfur dioxide (SO(2)), skin, seed, and gallic and ellagic tannins at the average range of their concentration in wine. All the inhibitors of stem bromelain activity tested turned out to be reversible. Ethanol was a competitive inhibitor with a rather limited effect. Gallic and ellagic tannins have no inhibitory effect on stem bromelain activity, while both seed and skin tannins were uncompetitive inhibitors. The strongest inhibition effect was revealed for sulfur dioxide, which was a mixed-type inhibitor for the enzyme activity. This study provides useful information relative to a future biotechnological application of stem bromelain in winemaking.     

A multivariate approach for anomaly separation of potentially toxic trace elements in urban and peri-urban soils: an application in a southern Italy area

Purpose

Geogenic soil enrichment and anthropogenic pollution by potentially toxic trace elements (PTEs) are two processes acting together. Although it is often difficult, it is necessary to separate the two processes for risk assessment and understanding the environmental implications. The aim of this study was to analyse the soil concentrations of various PTEs in a southern Italy area in order to: (1) determine their different correlation structure to isolate sources of variation acting at different spatial scales and (2) to define potential anomalies based on the correlation structure.

Materials and methods

In the urban and peri-urban area of Cosenza-Rende, 149 topsoil samples were collected (0.10 m) and analysed for different elements by X-ray fluorescence spectrometry. Principal component analysis and factorial kriging analysis were used to map the spatial distribution of PTEs in topsoil and to identify the main factors influencing their spatial variability.

Results and discussion

Two groups of PTEs were identified: the first group included As, Pb and Zn; and the second one Al, Co, Cr, Fe, La, Nb, Ni, Ti and V. The first group was related to anthropogenic causes, while the second one was more related to parent rock composition. The regionalized factors at different scales of variability allowed to aggregate and summarize the joint variability in the PTEs and consider the probable causes of soil pollution.

Conclusions

The study allowed analysing and quantifying the sources (environmental or anthropogenic) of variation of PTEs acting at different spatial scale and defining the spatial anomalies based on the correlation structure associated at the different spatial scales.     

Impact of the biocontrol agent Trichoderma atroviride SC1 on soil microbial communities of a vineyard in northern Italy

The fungus Trichoderma atroviride SC1 is an experimental biocontrol agent (BCA) that is active against the fungus Armillaria mellea. Following the application of Trichoderma to the surface soil of a vineyard, we used a highly specific real-time PCR, previously validated for the analysis of soil microcosms, to monitor the populations of this fungus at different soil depths over several months. The quantification obtained using this molecular method was highly correlated with laboratory assays of colony-forming units. The native communities of bacteria and fungi in the soil were analyzed using automated ribosomal intergenic spacer analysis (ARISA), and transient changes were observed following the application of T. atroviride SC1 conidia. A principal component of variance analysis demonstrated that the introduction of T. atroviride SC1 had an effect on the soil microflora during the first two weeks following inoculation. However, at later dates, environmental conditions had a higher influence on the surveyed communities than the BCA application, as confirmed through the use of the Shannon index of biodiversity. Soil depth had a strong influence on the composition and biodiversity of fungal communities.     

Characterization and antimicrobial activity of essential oils of industrial hemp varieties (Cannabis sativa L.)

The present study focused on inhibitory activity of freshly extracted essential oils from three legal (THC < 0.2% w/v) hemp varieties (Carmagnola, Fibranova and Futura) on microbial growth. The effect of different sowing times on oil composition and biological activity was also evaluated. Essential oils were distilled and then characterized through the gas chromatography and gas chromatography-mass spectrometry. Thereafter, the oils were compared to standard reagents on a broad range inhibition of microbial growth via minimum inhibitory concentration (MIC) assay. Microbial strains were divided into three groups: i) Gram (+) bacteria, which regard to food-borne pathogens or gastrointestinal bacteria, ii) Gram (?) bacteria and iii) yeasts, both being involved in plant interactions. The results showed that essential oils of industrial hemp can significantly inhibit the microbial growth, to an extent depending on variety and sowing time. It can be concluded that essential oils of industrial hemp, especially those of Futura, may have interesting applications to control spoilage and food-borne pathogens and phytopathogens microorganisms.     

Methods of assessing the incidence of Armillaria root rot across viticultural areas and the pathogen's genetic diversity and spatial–temporal pattern in northern Italy

Armillaria mellea (Vahl:Fr.) P. Kumm. is the causal agent of root rots of numerous perennial woody plants, including grapevine. In grapevine, A. mellea infections cause reduced plant vigour, poor grape quality and, in the last stage of the disease, plant death. No post-infection control agents are available for use against this disease. Disease management programmes rely solely on prophylactic measures. Therefore, knowledge of the distribution pattern of the disease over time, disease incidence and actual losses due to the disease across geographical areas is crucial. We evaluated the use of aerial photographs, surveys of growers’ experiences and field assessments to estimate the incidence of Armillaria root rot in a viticultural area (140 ha) situated in the Piana Rotaliana region (Italy). Results of the 4-year assessment were that 25% of the vineyards (36 ha) were infected by Armillaria, 2% of the cultivated vines exhibited disease symptoms and 0.25% of the vines died each autumn. The causal agent was almost exclusively A. mellea but, in two cases, Armillaria gallica was also isolated. The genetic diversity of the Italian population, according to IGS sequencing and somatic incompatibility testing, was very high, suggesting multiple pathogen introduction sites and the slow, vegetative underground spread of the fungus. Fungal clones were found within individual vineyards. Even if, within a particular area, the disease is spreading very slowly and crop losses are limited (one vine out of 400 dies each year), an effective agronomic plan for the prevention of infections should be implemented.     

Direct identification of Ehrlichia canis by a novel polymerase chain reaction method and molecular analysis of the citrate synthase (gltA) gene from various Italian strains.

Fourteen blood samples collected from dogs that were seropositive for Ehrlichia canis were examined for the presence of the citrate synthase gene using a highly specific and sensitive novel polymerase chain reaction assay. The assay detected E. canis DNA in 3 dogs. The complete nucleotide sequence of the citrate synthase gene was determined in 2 of the test-positive samples, and represents the first sequence of the gene to be derived from Italian isolates. The sequence data displayed high identity (99.2%) between the geographically separated Italian samples and the Oklahoma strain of E. canis. The high-sequence conservation revealed by molecular analysis confirmed the usefulness of the citrate synthase gene as a target for detection of E. canis.     

Adsorption and desorption of triasulfuron by soil

The adsorption and desorption of the herbicide triasulfuron [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide] by three soils, soil organic matter (H(+) and Ca(2+)-saturated), and an amorphous iron oxide were studied. Adsorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the adsorption in all of the systems. Indeed, the adsorption on soils was negatively correlated with pH. The highest level of adsorption was measured on soils with low pH and high organic carbon content. Moreover, it was found that humic acid is more effective in the adsorption compared with calcium humate (the pH values of the suspensions being 3.5 and 6, respectively). Experiments on amorphous iron oxide confirmed the pH dependence. Desorption was hysteretic on soils having high organic carbon content.