471 research outputs found
Torulaspora delbrueckii l’altra fermentazione
No full textNegli ultimi anni, ricercatori ed enologi hanno iniziato a utilizzare lieviti non-Saccharomyces per migliorare la qualità del vino o ridurre i rischi per la sicurezza alimentare. Tra i lieviti non-Saccharomyces più interessanti vi sono Kloeckera apiculata, il genere Hanseniaspora, Candida zemplinina, C. pulcherrima e C. stellata, Schizosaccharomyces pombe, Hansenula anomala, Metschnikowia pulcherrima e Lachancea thermotolerans, ma il lievito da più tempo utilizzato a livello industriale è Torulaspora delbrueckii
Annual photosynthetic response of phototrophic biofilms from an Italian wastewater treatment plant.
No full textModelling the photosynthesis and the nutrient status of aquatic phototrophic biofilms
No full textI biofilm fototrofi sono comunità di microorganismi fototrofi ed eterotrofi che crescono adesi a ogni superficie sommersa degli impianti di depurazione delle acque grazie all’energia solare, che sostiene il processo fotosintetico, e al flusso costante di acqua, che consente un apporto continuo di nutrienti inorganici. Finora, l’ecofisiologia dei biofilm fototrofi di ambiente acquatico è stata scarsamente caratterizzata in coltura. Lo scopo di questa tesi è stato quello di valutare le caratteristiche fotosintetiche, la fotoacclimatazione e la capacità di rimozione dei nutrienti dalle acque di biofilm fotosintetici di impianti di depurazione in condizioni controllate di crescita. Questo studio è parte del progetto europeo PHOBIA che ha lo scopo di sviluppare un modello concettuale unitario per i biofilms fototrofi in ambiente acquatico.
I biofilm venivano campionati dalle pareti della vasca di sedimentazione dell’impianto di depurazione delle acque reflue dell’aeroporto “Leonardo da Vinci”, Fiumicino (Roma, Italia) e messi in coltura in un prototipo di incubatore a diverse condizioni di irradianza, temperatura e velocità di flusso del terreno di coltura. L’effettiva resa quantica del fotosistema II (PSII) e curve di fotosintesi Electron Transport Rate versus Irradiance (ETR/I) erano registrate allo stadio iniziale, attivo e maturo di sviluppo dei biofilm mediante un fluorimetro PAM (Pulse Amplitude Modulated), e le clorofille, i carotenoidi e le ficobiliproteine quantificate per determinare la capacità fotosintetica e di fotoacclimatazione della comunità, e la variazione di biomassa nel tempo. Metodi spettrofotometrici erano utilizzati per quantificare l’azoto e il fosforo totali nei biofilm, con lo scopo di valutare la capacità di rimozione dei due nutrienti. Inoltre, dei campioni erano fissati per la microscopia elettronica a trasmissione e osservati per visualizzare le riserve di azoto e fosforo intracellulari.
I biofim crescevano in coltura raggiungendo un’elevata biomassa nelle varie condizioni di crescita. L’utilizzo del fluorimetro PAM consentiva di valutare rapidamente e in maniera non invasiva la capacità fotosintetica dei biofilm. La resa quantica del PSII era significativamente influenzata dalle condizioni sperimentali, con valori più elevati a irradianza crescente e a valori bassi di temperatura e flusso. I risultati delle curve ETR/I mostravano la capacità di acclimatazione dei fototrofi alle diverse condizioni di irradianza, come confermato ulteriormente dalla variazione del contenuto dei pigmenti fotosintetici. I dati spettrofotometrici rivelavano alte concentrazioni di azoto e fosforo nei biofilm a indicare che i due nutrienti venivano rapidamente sottratti dal mezzo di coltura e accumulati dai biofilm durante la crescita. Inoltre, condizioni di bassa temperatura e flusso influenzavano positivamente l’accumulo dei nutrienti. I cianobatteri e le microalghe erano attivamente coinvolti nella rimozione di azoto e fosforo come evidenziato a livello ultrastrutturale dalla presenza di granuli di cianoficina e accumuli di polifosfato, rispettivamente.
La comprensione dei processi di acclimatazione e della dinamica di rimozione dei nutrienti nei biofilm fototrofi di impianti di depurazione è di primaria importanza per lo sviluppo di un trattamento terziario alternativo e ecologicamente sicuro basato sull’impiego di comunità autoctone. In quest’ottica, il passo successivo è rappresentato dall’isolamento e coltura di specie che accoppiano elevata produttività e efficienza di rimozione dei nutrienti per la creazione in laboratorio di inoculi di biofilm da utilizzare nel processo di depurazione.Phototrophic biofilms are an ensemble of photo- and heterotrophic microorganisms which grow attached to every submerged surface of wastewater treatment plants (WWTPs) thanks to the solar energy, which support the photosynthetic processes, and to the constant water flow, which provides a continuous load of inorganic nutrients. Hitherto, the ecophysiology of aquatic phototrophic biofilms from WWTPs has been poorly characterised in culture. The aim of this thesis was to assess the photosynthetic characteristics, photoacclimation and nutrient removal ability of phototrohic biofilms from an Italian WWTP under controlled conditions. This study was part of the PHOBIA EU-Project aimed at developing a unifying model of structure and functioning of aquatic phototrotrophic biofilms.
Biofilms were collected from the walls of the sedimentation tank (ST) of the Leonardo da Vinci Airport WWTP, Fiumicino (Rome, Italy) and cultured in an incubator prototype at different irradiance, temperature and flow regime. Effective quantum yield of photosystem II (ΔF/Fm') and Electron Transport Rate versus Irradiance (ETR/I) curves were recorded at initial, active and mature stages of biofilm development by means of a Pulse Amplitude Modulated (PAM) fluorometer, and the chlorophylls, carotenoids and phycobiliproteins quantified to determine the community photosynthetic and photoacclimation ability, and phototrophic biomass variation over time. In order to assess the nutrient removal ability, spectrophotometric methods were used to quantify the total nitrogen (N) and phosphorus (P) content in cultured biofilms. Samples were also fixed for transmission electron microscopy (TEM) and observed to visualise intracellular N and P reserves.
Biofilms were able to grow in culture attaining high biomass in the different conditions tested. PAM-fluorescence technique provided a rapid and non-invasive assessment of the photosynthetic performance. ΔF/Fm' was significantly affected by the different conditions tested, with higher values obtained at increasing growth irradiance, low temperature and low flow. Data obtained by ETR/I curves recordings demonstrated the acclimation ability of phototrophs to varying irradiance as further confirmed by the variation of photosynthetic pigments. Spectrophotometric data revealed high N and P concentrations in the biofilms indicating that the two nutrients were rapidly removed from the medium and stored by the biofilms during growth. In addition, low temperature and flow positively influenced P retention in the biofilms. Cyanobacteria and microalgae were actively involved in N and P removal and accumulation as evidenced at ultrastructural level by the occurrence of cyanophycin granules and polyphosphate bodies, respectively.
Understanding acclimation processes and nutrient removal dynamics in WWTP phototrophic biofilms is of major importance to the development of alternative and environmentally sound tertiary water treatment exploiting autochthonous communities. On this basis, the following step is represented by the isolation and culturing of species that couple high productivity and nutrient removal efficiency for the laboratory creation of biofilm inocula to be used in the depuration process
Malolactic bacteria from Trentino and their use in immobilized form
No full textThe immobilization of Oenococcus oeni strain PN4 with a new technology, and its use to perform malolactic fermentation (MLF) in wine is described. The immobilization was achieved with a two-steps process. Cells were entrapped in Ca-alginate microbeads, then coated with an organo-silica membrane obtained by two sol-gel treatments. The resulting material improves the physico-chemical features of alginate, avoids cell leakage during fermentation, and protects them from antimicrobial compounds. Experimental malolactic fermentations were carried out in microvinification scale; the activity of immobilized cells did not differ from that of free cells. The use of immobilized bacteria allowed some innovative approach at the MLF: i)the simultaneous alcoholic and malolactic fermentations in must by free yeast and immobilized bacteria; ii)the serial fermentation of subsequent wine lots with the same biomass of immobilized bacteria, for at least 45 days; iii)the achievement of MLF in a wine added with lysozyme, to suppress wild lactic bacteria and their potential spoilage
Phototrophic biofilms in wastewaters: application of transmission electron microscopy techniques to bioremediation studies.
No full textLieviti e alcol da problema a soluzione?
No full textAttraverso la microbiologia è possibile contribuire alla riduzione del grado alcolico dei vini
Promoting seed germination of Bunias erucago, a Mediterranean leafy vegetable
No full textKnowledge of germination and propagation requirements are crucial for the use of plant genetic resources. Here, we compare different treatments to improve the germination of Bunias erucago (Cruciferae), a Mediterranean vegetable herb of growing commercial interest. Its cultivation is limited by the poor germination shown by the seeds which are enclosed in indehiscent silicles. To improve the germination, we investigated four treatments: (1) presoaking silicles in water for 48 hours; (2) scarification of silicles with sandpaper; (3) seed extraction; and (4) seed exposure to gibberellic acid (GA(3)). The same treatments (except the GA(3) treatment) were also used to investigate seedling emergence under glasshouse conditions. In the absence of treatments and/or soaking in water, there was very low final germination ( 90%, respectively. Scarification was the most effective treatment in a horticultural context, since the brittleness of seeds makes their extraction too delicate and time-consuming. The seedling emergence results confirmed those of seed germination in the laboratory, underlining the effectiveness of the treatments for plant cultivation. Seed germination performance varied among wild populations, underlining the importance of provenance when using wild plants as new crops
Oenological characterisation of indigenous strains of S. cerevisiae isolated in a biodynamic winery in the Cortona DOC area
No full textGenotypic and technological characterisation of the S. cerevisiae population isolated in a biodynamic winery in the Cortona DOC area was performed to gain better knowledge of the variables that influence winemaking. The oenological performance of 11 S. cerevisiae strains was evaluated with physiological tests; strain typing was performed through analysis of interdelta sequences and 26S rDNA sequencing. The analysis revealed a remarkable variability in terms of S. cerevisiae strains, despite the homogeneity of wine features, underlining the high levels of biodiversity characterising biodynamic agriculture. Some strains were found in wines of different vintages, suggesting the presence of an established microbiota in the winery. Oenological tests demonstrated that while some yeasts provided reliable oenological performance, other strains were not able to accomplish prompt and effective alcoholic fermentation, or were characterised by spoilage characteristics, such as excessive production of volatile phenols or acetic acid. Indigenous strains of S. cerevisiae could be a useful instrument for reliable winemaking without altering the native microbiota of each oenological environment. However, characterisation of their oenological suitability, and the application of practices able to drive the evolution of microbiota, must be employed to reduce the risk of wine spoilage
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