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Cyanobacteria are oxygenic phototrophs that have an essential role in soil N2 fixation, fertility, and water retention. Cyanobacteria are also natural sources of bioactive metabolites beneficial to improve plant vigor and potentially active against fungal plant pathogens. Therefore, we studied the antifungal activity of water extract (WE) and phycobiliproteins (PBPs) from Anabaena minutissima strain BEA 0300B against the fungal plant pathogen Botrytis cinerea on tomato fruits and in vitro. The water extract and PBPs were characterized by using FT-IR and FT-Raman spectroscopies. Both water extract (5 mg/mL) and PBPs (ranged from 0.3 to 4.8 mg/mL) reduced disease incidence and disease severity on tomato fruits and mycelium growth and colony forming units in vitro. For mycelium growth, a linear PBP dose-response was found. Tomato fruits were also characterized by FT-IR and FT-Raman spectroscopies in order to evaluate structural modifications induced by pathogen and PBP treatment. PBPs preserved cutin and pectin structures by pathogen challenge. In conclusion, A. minutissima can be considered a potential tool for future large-scale experiments for plant disease control.

Cadophora luteo-olivacea represents a critical problem for kiwifruit in the post-harvest phase, mainly for its little note epidemiology. The study presented some results about the possibility of preserving kiwifruit from skin pitting symptoms using alternative methods to fungicides. By in vitro assays, antagonist mechanisms of action against pathogen isolates were tested. Trichoderma harzianum (Th1) showed the highest inhibitory activity against C. luteo-olivacea isolates by volatile, non-volatile, and by dual culture assay, displaying an inhibition respectively by 90%, 70.6%, and 78.8%, and with respect to Aureobasidium pullulans (L1 and L8) by 23.3% and 25.8%, 50% and 34.7%, and 22.5% and 23.6%, respectively. Further, the sensitivity on CFU and mycelial growth of C. luteo-olivacea isolates to fludioxonil, and CaCl2 was tested, displaying interesting EC50 values (0.36 and 0.92 g L−1, 22.5 g L−1, respectively). The effect of Brassica nigra defatted meal was tested as biofumigation assays and through FT-IR (Fourier-Transform Infrared) spectroscopy. The above-mentioned treatments were applied in vivo to evaluate their efficacy on kiwifruits. Our data demonstrated that alternative solutions could be considered to control postharvest pathogens such as C. luteo-olivacea.

20 pags., 5 figs., 3 tabs. This article belongs to the Special Issue Peptides and Proteins as Innovative Biomaterials, The surface-enhanced Raman scattering (SERS) spectra of three amphiphilic oligopeptides derived from EAK16 (AEAEAKAK) were examined to study systematic amino acid substitution effects on the corresponding interaction with Ag colloidal nanoparticles. Such self-assembling molecular systems, known as “molecular Lego”, are of particular interest for their uses in tissue engineering and as biomimetic coatings for medical devices because they can form insoluble macroscopic membranes under physiological conditions. Spectra were collected for both native and gamma-irradiated samples. Quantum mechanical data on two of the examined oligopeptides were also obtained to clarify the assignment of the prominent significative bands observed in the spectra. In general, the peptide–nanoparticles interaction occurs through the COO groups, with the amide bond and the aliphatic chain close to the colloid surface. After gamma irradiation, mimicking a free oxidative radical attack, the SERS spectra of the biomaterials show that COO groups still provide the main peptide–nanoparticle interactions. However, the spatial arrangement of the peptides is different, exhibiting a systematic decrease in the distance between aliphatic chains and colloid nanoparticles.

Despite their economic and ecological interests, Poaceae are affected by the low availability of iron in calcareous soils. Several studies focused on the capacity of this family to secrete phytosiderophores and organic acids as a mechanism of tolerance to iron deficiency. This work aimed at studying the physiological responses of two Poaceae species; Hordeum vulgare (cultivated barley) and Polypogon monspenliensis (spontaneous species) to iron deficiency, and evaluate especially the release of phytosiderophores and organic acids. For this purpose, seedlings of these two species were cultivated in complete nutrient solution with or without iron. The biomass production, iron status, phytosiderophores and organic acids release by roots were studied. The results demonstrated that Polypogon monspenliensis was relatively more tolerant to iron deficiency than Hordeum vulgare. Polypogon monspenliensis had the ability to secrete a higher amount of phytosiderophores and organic acids, especially citric, acetic, oxalic and malic acids, compared to Hordeum vulgare. We propose this spontaneous species as a forage plant in calcareous soils and in intercropping systems with fruit trees to prevent iron chlorosis.

Five alternating polar/non-polar peptides derived from the self-assembling peptide EAK-16 (AEAEAKAK)2 were examined in comparison with the EAK-16 parent form (pept1). The peptides were studied for their possible use as biomimetic materials due to their auto-assembling properties and to the presence, in two of them, of the RGD sequence, an active modulator of cell adhesion. The use of SERS allows the detection of peptides at very low concentrations (10-5-10-6 M), a feature of extreme interest to check their presence in the aqueous environment surrounding a metal implant and to study the effects of systematic amino acid substitution along the peptide chain on the corresponding interaction with the Ag colloidal nanoparticles. Quantum-mechanical data on two of the examined peptides were carried out and were very useful for clarifying the bands assignment debated in the literature. The results indicate that, in general, the peptide-nanoparticle interaction takes place through the carboxylate groups. The SERS spectrum displays an enhancement of the bands attributed to carboxylate vibrations, indicating that these groups directly interact with the nanoparticles. The most prominent band of carboxylate groups appears at 1393 cm-1 (symmetrical COO- stretching), intensified and red shifted of about 10 cm-1, as compared to the FT-Raman spectrum. This effect can be attributed to the proximity of the COO- group to the surface and to a charge transfer mechanism. Moreover, other bands can be attributed to COO- vibrations: 909 cm-1 (C-COO- stretching), 655 cm-1 (COO- bending) and 563 cm-1 (COO- wagging). The theoretical calculations pointed out that the last two bands are mixed with amide motions. As regards the other examined peptides, the spacer substitution in the sequence is a factor able to affect the peptide-Ag particles interaction: the increase in the hydrophobic chain length (Ala substituted by 2-aminobutanoic acid) favors the interaction by NH3+ groups, although the charge transfer interaction with the COO- ions is still the main interaction with the colloid. In fact, the presence of many SERS bands attributable to the NH3+ moieties of the Lys amino acid side chains, indicates the existence of interactions between the NH3+ groups and the nanoparticles, mediated by the Cl- anions present in the colloidal solution. The substitution of Ala with an aromatic Tyr residue strongly affects the interaction mechanism: the Tyr residue lies in a position close to perpendicular to the silver surface, partly as tyrosinate ion.

Ibuprofen (IbuH), 2-(4-isobutylphenyl) propionic acid, is a well-known nonsteroidal anti-inflammatory drug and is a promising antiatherosclerotic agent. Since IbuH has demonstrated to affect cell membranes structure, the study of the interaction between the membrane components, like phospholipids, and the drug, is of paramount interest. Moreover, liposomes can be used as drug carriers. In this paper, the effect of increasing amounts of Ibuprofen at neutral and acidic pH on the behaviour of dimyristoylphosphatidylcholine (DMPC) liposomes was investigated by means of Raman and differential scanning calorimetry (DSC) techniques. The results showed that pH influenced noticeably the liposome structure. A simple ‘solution-like’ model can explain the system when small or high IbuH or IbuNa (IbuH sodium salt forming at neutral and basic pH) amounts are present (IbuH/DMPC molar ratio ≤1/8.3 or ≥1/2.2 or IbuNa/DMPC molar ratio ≤1/17.5 or ≥1/4), whereas at intermediate amounts, two DSC peaks appeared: these systems could be described as a mixture of ‘phase II’ domains inserted within a structure of smaller and further ramified ‘phase I’ domains. Both DSC and Raman data suggested IbuH can penetrate within the apolar bilayer at pH 3, while at pH 7, the setting up of polar interactions of different strength between the carboxylic groups of IbuNa and the choline head of the DMPC, hamper a further penetration of the drug. Similar results were obtained both inserting directly IbuH molecules into liposomes as well as acidifying IbuNa water solutions, suggesting a possible use of liposomes as drug carriers when polarity is pH dependent.

BACKGROUND: Metal ions are implicated in protein aggregation processes of several neurodegenerative pathologies, where the protein deposition occurs, and in the biotechnology field like the food technology where many processes in food manufacturing are based on thermal treatments. OBJECTIVE: The influence of Cu2+ or Zn2+ ions on the thermal aggregation process of Bovine beta-lactoglobulin (BLG) and Bovine Serum Albumin (BSA), two protein models, was studied with the aim of delineating the role of these ions in the protein aggregation kinetics and to clarify the related molecular mechanisms. METHODS: The protein structure changes were monitored by Raman spectroscopy, whereas the aggregate growth was followed by Dynamic Light Scattering measurements. RESULTS: Both metal ions are able to favour the BLG aggregation, whereas only Zn2+ ions have a promoter effect on the thermal aggregation of BSA. The reason of this different behaviour is that the BLG aggregation evolution is manly affected by the redistribution of charges, whereas that of BSA by the metal coordination binding which depends on metal. CONCLUSIONS: Raman spectroscopy, combined with dynamic light scattering experiments, was very useful in identifying the role played by Cu2+ and Zn2+ on the aggregation pathways of BLG and BSA. The results provide evidence for the role of histidine residues both in the redistribution of charges and in the two modes of metal binding that take place in BLG- and BSA-containing systems, respectively.