PTR-ToF-MS for the online monitoring of alcoholic fermentation in wine: assessment of VOCs variability associated with different combinations of Saccharomyces/non-Saccharomyces as a case-study

7openInternationalItalian coauthor/editorThe management of the alcoholic fermentation (AF) in wine is crucial to shaping product quality. Numerous variables (e.g., grape varieties, yeast species/strains, technological parameters) can affect the performances of this fermentative bioprocess. The fact that these variables are often interdependent, with a high degree of interaction, leads to a huge ‘oenological space’ associated with AF that scientists and professionals have explored to obtain the desired quality standards in wine and to promote innovation. This challenge explains the high interest in approaches tested to monitor this bioprocess including those using volatile organic compounds (VOCs) as target molecules. Among direct injection mass spectrometry approaches, no study has proposed an untargeted online investigation of the diversity of volatiles associated with the wine headspace. This communication proposed the first application of proton-transfer reaction-mass spectrometry coupled to a time-of-flight mass analyzer (PTR-ToF-MS) to follow the progress of AF and evaluate the impact of the different variables of wine quality. As a case study, the assessment of VOC variability associated with different combinations of Saccharomyces/non-Saccharomyces was selected. The different combinations of microbial resources in wine are among the main factors susceptible to influencing the content of VOCs associated with the wine headspaces. In particular, this investigation explored the effect of multiple combinations of two Saccharomyces strains and two non-Saccharomyces strains (belonging to the species Metschnikowia pulcherrima and Torulaspora delbrueckii) on the content of VOCs in wine, inoculated both in commercial grape juice and fresh grape must. The results demonstrated the possible exploitation of non-invasive PTR-ToF-MS monitoring to explore, using VOCs as biomarkers, (i) the huge number of variables influencing AF in wine, and (ii) applications of single/mixed starter cultures in wine. Reported preliminary findings underlined the presence of different behaviors on grape juice and on must, respectively, and confirmed differences among the single yeast strains ‘volatomes’. It was one of the first studies to include the simultaneous inoculation on two non-Saccharomyces species together with a S. cerevisiae strain in terms of VOC contribution. Among the other outcomes, evidence suggests that the addition of M. pulcherrima to the coupled S. cerevisiae/T. delbrueckii can modify the global release of volatiles as a function of the characteristics of the fermented matrixopenBerbegal, C.; Khomenko, I.; Russo, P.; Spano, G.; Fragasso, M.; Biasioli, F.; Capozzi, V.Berbegal, C.; Khomenko, I.; Russo, P.; Spano, G.; Fragasso, M.; Biasioli, F.; Capozzi, V

On-line tracking of the human gut microbial metabolism: high-throughput screening during colonic in-vitro fermentation

The human gut encloses a large community of bacteria producing a wide range of volatile organic compounds (VOCs) when fermenting undigestible substrates. This study aims to provide a high throughput method to study in real-time the gut microbial volatilome when the microbiota process undigestible dietary substrates. Background: Small metabolites from the human gut microbiota are recognized as the intermediates of the microbiome-host cross-talk [1]. The research on the human gut metabolome is mainly based on discrete sampling representing discontinuous ‘snapshot’ of these complex biological systems [2]. The aim of this research work is to enhance the current understanding of the dynamics of the gut microbiota by integrating non-invasive and continuous analytical methods with in-vitro gut simulators, to monitor in real-time, the progression of small molecules released into the headspace [2,3] Methodology: Automated Head space-Solid Phase Micro Extraction coupled with Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) and Static Headspace- Proton Transfer Reaction-Time of Flight-Mass Spectrometry (SHS-PTR-ToF-MS) are used for the purpose of this investigation. The objective is to screen and monitor a specific set of masses of interest, to gain system level mechanistic insights on primary metabolism of the gut microbial consortia. Results: This methodology enabled the continuous monitoring of multiple metabolites in time, including short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) derived from 24h oat bran fermentation. A mixture of -odd and -even chain acids were co-released into the culture headspace after 4 hours of fermentation and their relative abundance increased in time over 24 hours. The production of multiple MCFAs from the substrate is most likely a community optimization strategy to maximize ATP production from oat degradation by means of reverse beta-oxidation which involves the utilization of fermentation intermediates, such as propanol and acetate. Furthermore, the untargeted screening allowed the detection of low abundant sulfur metabolites, thiophenes, which, to our knowledge, were never investigated before as gut microbial metabolites (GMMs). Conclusion: By integrating non-invasive and continuous analytical methods with an in-vitro gut simulator, it was possible to monitor in real-time the progression of two important class of small molecules released by the microbial consortia into the headspace. The collected information can be jointly integrated to shed light on the dynamics of bacterial foraging of complex undigestible substrates (e.g. bran from cereals). Overall, these results confirm the idea to consider the bacterial headspace as a highly dynamic chemical system that contains information on microbial community behavio

Reflectivity and velocity radar data assimilation for two flash flood events in central Italy: A comparison between 3D and 4D variational methods

The aim of this study is to provide an evaluation of the impact of two largely used data assimilation techniques, namely three- and four-dimensional variational data assimilation systems (3D-Var and 4D-Var), on the forecasting of heavy precipitation events using the Weather Research and Forecasting (WRF) model. For this purpose, two flash flood events in central Italy are analysed. The first occurred on September 14, 2012 during an Intensive Observation Period of the Hydrological cycle in the Mediterranean experiment (HyMeX) campaign, while the other occurred on May 3, 2018. Radial velocity and reflectivity acquired by C-band weather radars at Mt. Midia (central Italy) and San Pietro Capofiume (northern Italy), as well as conventional observations (SYNOP and TEMP), are assimilated into the WRF model to simulate these damaging flash flood events. In order to evaluate the impact of the 3D-Var and 4D-Var assimilation systems on the estimation of short-term quantitative precipitation forecasts, several experiments are carried out using conventional observations with and without radar data. Rainfall evaluation is performed by means of point-by-point and filtering methodologies. The results point to a positive impact of the 4D-Var technique compared to results without assimilation and with 3D-Var experiments. More specifically, the 4D-Var system produces an increase of up to 22% in terms of the Fractions Skill Score compared to 3D-Var for the first flash flood event, while an increase of about 5% is achieved for the second event. The use of a warm start initialization results in a considerable reduction in the spin-up time and a significant improvement in the rainfall forecast, suggesting that the initial precipitation spin-up problem still occurs when using 4D-Var

Disturbances in groundwater chemical parameters related to seismic and volcanic activity in Kamchatka (Russia)

International audienceStarting from 1992 geochemical data are being collected with a mean sampling frequency of three days in the form of the pH value and of the most common ions and gases in the groundwater in one deep well located in Petropavlovsk, the capital city of Kamchatka (Russia). On 1 January 1996 a strong eruption started from the Karymsky volcano, that is located about 100km far from the well, in the north-northeastern direction. At the same time, a large earthquake (M=6.9) occurred in the Karymsky area. On 5 December 1997 a very large earthquake (M=7.7) occurred offshore, at a distance of 350km from the well and towards the same direction. The analysis of the geochemical data shows clear variations in the raw temporal trends on both cases. For the first event, a clear premonitory phase appeared; for the second one, some pre-seismic variations could be revealed but permanent modifications of the chemistry of the water subsequent to the earthquake are very clear. In both cases the feature of the geochemical variations is consistent with an afflux of new water in the aquifer connected with the well and with an escape of the Carbon dioxide gas from the ground in different directions. A schematic model able to justify such a phenomenology and the connections of the geochemical variations with the previous tectonic activities is proposed

Retrospective analysis for detecting seismic precursors in groundwater argon content

We examined the groundwater Argon content data sampled from 1988 to 2001 at two wells in Kamchatka (Russia) and anomalous increases appeared clearly during June-July&nbsp;1996. On 21&nbsp;June, a shallow (1km) earthquake with <i>M</i>=7.1 occurred at a distance less than 250km from the wells and so the previous increases could be related to this earthquake and, in particular, could be considered premonitory anomalies. In order to support this raw interpretation, we analysed the data collected in details. At first we smoothed out the high frequency fluctuations arising from the errors in a single measurement. Next we considered the known external effects on the water of a well that are the slow tectonic re-adjustment processes, the meteorology and the gravity tides and we separated these effects applying band-pass filters to the Argon content raw trends. Then we identified the largest fluctuations in these trends applying the 3 σ criterion and we found three anomalies in a case and two anomalies in other case. Comparing the time occurrence of the anomalies at the two wells we found out that a coincidence exists only in the case of the premonitory anomalies we are studying. The simultaneous appearance of well definite anomalies in the residual trends of the same parameter at two different sites supports their meaning and the possibility that they are related to some large scale effect, as the occurrence of a strong earthquake. But, other earthquakes similar to the June&nbsp;1996 event took place during the Argon content measurements time and no anomaly appeared in this content. In the past, some of the authors of this paper studied the Helium content data collected in three natural springs of the Caucasus during seven years. A very similar result, that is the simultaneous appearance of clear premonitory anomalies only on the occasion of a strong (<i>M</i>=7.0) but shallow (2–4km) earthquake, was obtained. The correspondence with the case of the Caucasus validates the interpretation of the Kamchatkian anomalies as precursors

Renormalisation group corrections to neutrino mixing sum rules

Neutrino mixing sum rules are common to a large class of models based on the (discrete) symmetry approach to lepton flavour. In this approach the neutrino mixing matrix $U$ is assumed to have an underlying approximate symmetry form \tildeU_\nu, which is dictated by, or associated with, the employed (discrete) symmetry. In such a setup the cosine of the Dirac CP-violating phase $\delta$ can be related to the three neutrino mixing angles in terms of a sum rule which depends on the symmetry form of \tildeU_\nu. We consider five extensively discussed possible symmetry forms of \tildeU_\nu: i) bimaximal (BM) and ii) tri-bimaximal (TBM) forms, the forms corresponding to iii) golden ratio type A (GRA) mixing, iv) golden ratio type B (GRB) mixing, and v) hexagonal (HG) mixing. For each of these forms we investigate the renormalisation group corrections to the sum rule predictions for $\delta$ in the cases of neutrino Majorana mass term generated by the Weinberg (dimension 5) operator added to i) the Standard Model, and ii) the minimal SUSY extension of the Standard Model

The Daya Bay and T2K results on sin22\u3b813 and non-standard neutrino interactions

We show that the relatively large best fit value of sin^22\u3b813=0.14(0.17) measured in the T2K experiment for fixed values of i) the Dirac CP violation phase \u3b4=0, and ii) the atmospheric neutrino mixing parameters \u3b8(23)=\u3c0/4, |\u394m^2(32)|=2.4 710^{ 123} eV^2, can be reconciled with the Daya Bay result sin^22\u3b8(13)=0.090\ub10.009 if the effects of non-standard neutrino interactions (NSI) in the relevant \u3bd\uafe\u2192\u3bd\uafe and \u3bd\u3bc\u2192\u3bde oscillation probabilities are taken into account. \ua9 2014 The Authors