Stable isotopes (C, N, O, H) of feathers collected in an Italian alpine region, during postbreeding migration

Over the last 20 years the analysis of stable isotope ratios of carbon, nitrogen, oxygen, hydrogen and sulphur have gradually become a formidable tool for the animal ecologists (Hobson and Wassenaar, 1997; Marra et al., 1998; Inger and Bearhop, 2008). In particular many studies have been developed on tracking the movement and the diet of birds in time and space, fundamental to understanding their ecology, but also inherently difficult to determine. The aim of this study was to deepen the origin and behaviour of migratory bird species crossing the Trentino area, an Italian alpine region, during the post-nuptial migration period, and monitored by a long term study by ringing activities (Progetto Alpi, Pedrini et al. 2008). About 800 samples of feathers from 48 local bird species were collected during 2010 – 2012 years. Analysis of d13C, d15N, d18O and dD were performed on these samples using an Isotope Ratio Mass Spectrometer (IRMS) interfaced with an Elemental Analyser or a pyrolyser after a pre-treatment of the feathers (cleaning with diethyl ether:methanol 2:1, equilibration to ambient humitity for 4 days and, for d18O and dD a final drying step wth P2O5 for another 4 days). A first survey of the obtained data is presented in this work. As expected, the first statistical elaboration/’look’ of them confirmed that 13C can be used to trace the importance of different carbon pools to a consumer (e.g. C3, C4 or CAM plants, marine algae) whereas d15N vary as a function of a variety of biological, geochemical and anthropogenic processes and is a very effective tracer of trophic level. In particular, it was interesting to note that the specie Loxia curvirostra showed particularly high d13C and low d15N values probably due to the eating of conifer seeds and whereas the specie Motacilla flava, that bases its diet primarily on worms and insects, presented high d15N values. On the other hand d18O values mainly depends by geographical/diet factors whereas dD values are strongly affected by the geographical characteristics of the regions in which the birds grown or emigrated. The specie Troglodytes troglodytes, which is mainly sedentary, showed the higher dD values, whereas Carduelis spinus, which during autumn migrates from the north of Europe to the Mediterranean area, presented the lower values. As regards d18O, interesting was the very high values presented by Anthus pratensis specie. Further elaborations/studies by adopting a multi-isotope approach could surely increase the resolution of migratory origins

Inulin reduces production of TMA during fermentation of red meat by the human gut microbiota in vitro

Objective: Certain metabolites produced by the gut microbiota, like the biogenic amine Triethylamine (TMA) appear to increase the risk of cardiovascular disease upon colonic fermentation of choline or L-carnitine. Here, we investigated the ability of the prebiotic inulin to impact gut microbiota protein fermentation and production of potentially toxic metabolites using NMR based metabonomics and in vitro faecal batch cultures. Methods: Fermentation of meat digested using an in vitro digestion process were conducted using 24 h pH-controlled anaerobic batch cultures and fresh faeces from 5 healthy human donors (n=5). For each donor, faecal fermentations of the negative control (no substrate), inulin (1% w/v), beef (0.5% w/v) and beef + inulin (1.5% w/v) were run over 24 h. Cell free supernatant samples taken at 0, 5, 10 and 24 h fermentation were analyzed with proton magnetic resonance spectroscopy (1H-MRS) and multivariate analysis (MVA) to determine the change in metabolite profiles. Fecal microbiota composition is being analyzed by fluorescent in situ hybridization and 16S rRNA community profiling. Results: Metabonomic analysis suggested that inulin improved faecal microbiota protein metabolism, by increasing the consumption of amino acids, such as tryptophan and phenylalanine, but at the same time reducing the production of potentially toxic metabolites including TMA, 5-Aminopentanoate (a precursor of cadaverine) and phenol. Conclusions: In the presence of inulin, fermentation of meat by the gut microbiota was associated with reduced production of toxic metabolites. This supports the notion that increased consumption of fermentable fiber or prebiotics like inulin may be one means of reducing the production of harmful metabolites by the gut microbiota

d18O as authenticity thresholds in differentiating tomato passata from diluted tomato paste

Tomato passata is one of the ‘pillars’ of the Mediterranean diet and is a typical Italian product that by law must be obtained exclusively from fresh tomatoes. For this reason Italian law provides for use of the 18O of vegetal water to determine whether passata (Brix of up to 12) is genuine or has been obtained by diluting tomato paste (Brix higher than 12). However, the same law gives no indication of reference limits for this parameter. In this study an extensive dataset of over 1000 samples were collected in different years (from 2004 to 2012) along the Italian tomato product production chain (tap waters, juices, passata, pastes). In all the samples collected the content of water d18O was investigated. This parameter was shown to be statistically different in the four classes of products, increasing from water to juice and paste, in relation to the different degree of evaporation taking place during the preparation phase. Moreover, the d18O of vegetal water, due to the contribution of the lower 18O values of tap water during dilution, was highly effective in distinguishing genuine passata from watered down paste, also in the case of passata previously concentrated up to 11.9 Brix. On the basis of these results two lower threshold values are proposed: -1.4‰ for ‘raw’ passata and -2.9‰ for passata previously concentrated up to 11.9 Brix

Use of d18O authenticity thresholds to differentiate tomato passata from diluted tomato paste

Tomato passata, one of the ‘pillars’ of the Mediterranean diet, is a typical Italian product that by law must be obtained exclusively from fresh tomatoes. For this reason Italian law provides for use of the δ 18O of vegetal water to determine whether passata (Brix of up to 12) is genuine or has been obtained by diluting tomato paste (Brix higher than 12), although without any indication of reference limits. In this study an extensive dataset of over 1000 samples collected along the Italian tomato product production chain (tap waters, juices, passata, pastes) in different years (2004-2012), was investigated on the content of vegetal water δ18O. This parameter was shown to be statistically different in the four classes of products, increasing from water to juice and paste, in relation to the different degree of evaporation taking place during the preparation phase. Moreover, the δ18O of vegetal water, due to the contribution of the lower δ18O values of tap water during dilution, was highly effective in distinguishing genuine passata from watered down paste, also in the case of passata previously concentrated up to 11.9 Brix. In particular, two lower threshold values are proposed: -1.4‰ for ‘raw’ passata and -2.9‰ for passata previously concentrated up to 11.9 Brix. Although the use of δ18O water alone does not make it possible to discriminate between Italian and foreign products, an increasing trend in δ18O water values was shown in juices and passata samples as well as in tap waters, when moving from northern to southern Italian products, making it possible to predict good geographical discrimination for this parameter

Influence of essential oils in diet and life-stage on gut microbiota and fillet quality of rainbow trout (Oncorhynchus mykiss)

Developing fish farming to meet the demands of food security and sustainability in the 21st century will require new farming systems and improved feeds. Diet and microbe interactions in the gut is an important variable with the potential to make a significant impact on future fish farming diets and production systems. It was monitored the gut microbiota of farmed rainbow trout using 16S rRNA profiling over 51 weeks during standard rearing conditions and feeding diet with supplementation of an essential oils (MixOil) mixture from plants (at a concentration in diet of 200 mg/kg). Gut microbiota 16S rRNA profiling indicated that the fish gut was dominated by Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes. Although the dietary supplementation with MixOil had no impact on either the composition or architecture of gut microbiota, significant changes in alpha and beta diversity and relative abundance of groups of gut bacteria were evident during growth stages on test feeds, especially upon prolonged growth on finishing feed. Fish fillet quality to guarantee palatability and safety for human consumption was also evaluated. Significant differences within the gut microbiota of juvenile and adult trout under the same rearing conditions were observed, The addition of essential oil blend affected some physicochemical characteristics of trout fillets, including their resistance to oxidative damage and their weight loss (as liquid loss and water holding capacity) during the first period of storage, that are two important parameters related to product shelf life and susceptibility to spoilage. The results highlighted the need for further studies concern dietary microbiome modulation at different life stages and its influence on animal health, growth performance and final product quality