Physicochemical regeneration of high silica zeolite Y used to clean-up water polluted with sulfonamide antibiotics.

High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration, the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric (TGA-DTA), diffractometric (XRPD), and spectroscopic (FT-IR) approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material.

Detection of potato brown rot and ring rot by electronic nose: from laboratory to real scale.

A commercial electronic nose (e-nose) equipped with a metal oxide sensor array was trained to recognize volatile compounds emitted by potatoes experimentally infected with Ralstonia solanacearum or Clavibacter michiganensis subsp. sepedonicus, which are bacterial agents of potato brown and ring rot, respectively. Two sampling procedures for volatile compounds were tested on pooled tubers sealed in 0.5-1 L jars at room temperature (laboratory conditions): an enrichment unit containing different adsorbent materials (namely, Tenax(®) TA, Carbotrap, Tenax(®) GR, and Carboxen 569) directly coupled with the e-nose (active sampling) and a Radiello(™) cartridge (passive sampling) containing a generic Carbograph fiber. Tenax(®) TA resulted the most suitable adsorbent material for active sampling. Linear discriminant analysis (LDA) correctly classified 57.4 and 81.3% total samples as healthy or diseased, when using active and passive sampling, respectively. These results suggested the use of passive sampling to discriminate healthy from diseased tubers under intermediate and real scale conditions. 80 and 90% total samples were correctly classified by LDA under intermediate (100 tubers stored at 4°C in net bag passively sampled) and real scale conditions (tubers stored at 4°C in 1.25 t bags passively sampled). Principal component analysis (PCA) of sensorial analysis data under laboratory conditions highlighted a strict relationship between the disease severity and the responses of the e-nose sensors, whose sensitivity threshold was linked to the presence of at least one tuber per sample showing medium disease symptoms. At intermediate and real scale conditions, data distribution agreed with disease incidence (percentage of diseased tubers), owing to the low storage temperature and volatile compounds unconfinement conditions adopted.

Persistence and degradation of new ß-lactam antibiotics in the soil and water environment.

The development of new antibiotics with low environmental persistence is of utmost importance in contrasting phenomena of antibiotic resistance. In this study, the persistence of two newly synthesized monocyclic ß-lactam antibiotics: (2R)-1-(methylthio)-4-oxoazetidin-2-yl acetate, P1, and (2R,3R)-3-((1R)-1-(tert-butyldimethylsilanyloxy)ethyl)-1-(methylthio)-4-oxoazetidin-2-yl acetate, P2, has been investigated in water in the pH range 3-9 and in two (calcareous and forest) soils, then compared to amoxicillin, a ß-lactam antibiotic used in human and veterinary medicine. P1 and P2 persistence in water was lower than that of amoxicillin with only a few exceptions. P1 hydrolysis was catalyzed at an acidic pH whereas P2 hydrolysis takes place at both acidic and alkaline pH values. P1 persistence in soils depended mainly on their water potential (t1/2: 35.0-70.7d at wilting point; <1d at field capacity) whereas for P2 it was shorter and unaffected by soil water content (t1/2 0.13-2.5d). Several degradation products were detected in soils at both water potentials, deriving partly from hydrolytic pathways and partly from microbial transformation. The higher LogKow value for P2 compared with P1 seemingly confers P2 with high permeability to microbial membranes regardless of soil water content. P1 and P2 persistence in soils at wilting point was shorter than that of amoxicillin, whereas it had the same extent at field capacity.

Electronic nose as an innovative tool for the diagnosis of grapevine crown gall.

For the first time, a portable electronic nose was used to discriminate between healthy and galled grapevines, experimentally inoculated with two tumourigenic strains of Agrobacterium vitis. The volatile profile of target cutting samples was analysed by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry. Spectra from tumoured samples revealed the presence of styrene which is compatible with decarboxylation of cinnamic acid involved in secondary metabolism of plants. Principal Component Analysis confirmed the difference in volatile profiles of infected vines and their healthy controls. Linear Discriminant Analysis allowed the correct discrimination between healthy and galled grapevines (83.3%, cross-validation). Although a larger number of samples should be analysed to create a more robust model, our results give novel interesting clues to go further with research on the diagnostic potential of this innovative system associated with multi-dimensional chemometric techniques.