Application of ozone during grape drying for the production of straw wine. Effects on the microbiota and compositive profile of grapes.

AIMS: Straw wine is a highly valuable oenological production, affected by relevant economical losses due to proliferation of spoilage micro-organisms during drying grapes, after being harvested. In this work, ozone was evaluated as a tool to preserve grapes during drying, in terms of both qualitative and quantitative changes induced in the epiphytic microflora. In addition, the alteration exerted by ozone on grapes' chemical composition was analysed. METHODS AND RESULTS: Grapes from four vine varieties were treated with ozone produced by a cold plasma generator during the entire drying period (6 weeks). The microflora was quantified weekly by plate counts and characterized by 454-pyrosequencing, and was compared with identical, untreated grape samples. At the end of drying, an extensive chemical characterization of the whole mass of grapes by FT-IR and GC-MS was performed. Ozone counteracted the growth of microflora by reducing the microbial population up to 3 log units. From the qualitative point of view, ozone reduced the incidence of spoilage micro-organisms, such as Acetobacter and Botrytis cinerea, among the microbiota of grapes. CONCLUSIONS: The statistical analysis discriminates grape samples based on the residual epiphytic microflora at the end of drying and not on their chemical composition. These evidences confirmed that ozone did control spoilage micro-organisms without altering the volatile profile of grapes. Chemical analysis revealed that untreated grapes are less suitable for winemaking owing to the deprivation of some valuable compounds during the microbial proliferation. SIGNIFICANCE AND IMPACT OF THE STUDY: Ozone is an emerging tool in winemaking, recently applied for controlling spoilage micro-organisms in winery. The present study describes a new application of ozone as an effective and safe alternative to chemical preservatives which are actually involved in the control of microbial alterations of grapes.

Gamma-aminobutyric acid-producing lactobacilli positively affect metabolism and depressive-like behaviour in a mouse model of metabolic syndrome.

Metabolic and neuroactive metabolite production represents one of the mechanisms through which the gut microbiota can impact health. One such metabolite, gamma-aminobutyric acid (GABA), can modulate glucose homeostasis and alter behavioural patterns in the host. We previously demonstrated that oral administration of GABA-producing Lactobacillus brevis DPC6108 has the potential to increase levels of circulating insulin in healthy rats. Therefore, the objective of this study was to assess the efficacy of endogenous microbial GABA production in improving metabolic and behavioural outcomes in a mouse model of metabolic dysfunction. Diet-induced obese and metabolically dysfunctional mice received one of two GABA-producing strains, L. brevis DPC6108 or L. brevis DSM32386, daily for 12 weeks. After 8 and 10 weeks of intervention, the behavioural and metabolic profiles of the mice were respectively assessed. Intervention with both L. brevis strains attenuated several abnormalities associated with metabolic dysfunction, causing a reduction in the accumulation of mesenteric adipose tissue, increased insulin secretion following glucose challenge, improved plasma cholesterol clearance and reduced despair-like behaviour and basal corticosterone production during the forced swim test. Taken together, this exploratory dataset indicates that intervention with GABA-producing lactobacilli has the potential to improve metabolic and depressive- like behavioural abnormalities associated with metabolic syndrome in mice.

Effects of therapeutic hypothermia on the gut microbiota and metabolome of infants suffering hypoxic-ischemic encephalopathy at birth.

Neonatal hypoxic ischemic encephalopathy (HIE) in the perinatal period can lead to significant neurological deficits in later life. Total body cooling (TBC) is a neuroprotective strategy used in the treatment of HIE and has been shown to reduce seizures and improve neurodevelopmental outcomes in treated infants. Little is known, however, about the effects of HIE/TBC on the developing gut microbiota composition and subsequent metabolic profile. Ten term infants with HIE who received TBC at 33.5°C for 72h were recruited. A control group consisted of nine healthy full term infants. Faecal samples were collected from both groups at 2 years of age and stored at -20°C. 16S rRNA amplicon Illumina sequencing was carried out to determine gut microbiota composition and 1H NMR analysis was performed to determine the metabolic profile of faecal water. The gut microbiota composition of the HIE/TBC infants were found to have significantly lower proportions of Bacteroides compared to the non-cooled healthy control group. Alpha diversity measures detected significantly lower diversity in microbial richness in the HIE/TBC infant group compared to the control infants (Shannon index, <0.05). High inter-individual variation was found in gut microbiota composition and metabolic profile of both groups. Initial principal coordinate analysis and hierarchal clustering of compounds on MetaboAnalyst 3.0 indicated no clear separation in the metabolic profile of these two infant groups. These results suggest that there is no significant impact on the gut microbial development of HIE/TBC infants compared to healthy infants at 2years of life. To our knowledge this is the first study to report the gut microbiota composition and metabolic profile of infants who have experienced HIE/TBC at birth.