1,721,023 research outputs found
Biomethanization and decontamination of olive mill wastewaters through an integrated anaerobic-aerobic biofilm process
No full textDue to their high COD content, olive mill wastewaters (OMWs) have to be treated before being discharged. Anaerobic digestion is one of the most promising remediation solution for OMWs as it is able to mediate both their decontamination and valorization (by the production of a CH4-rich biogas). The possibility of intensifying the performances of this process by performing it in an anaerobic digestor packed with granular active carbon was recently demonstrated. In order to further remove the COD from the effluent of the developed system, an aerobic post-treatment, constituted by a column reactor packed with silica beads, directly fed with the outlet of the anaerobic plant and colonized by the influent native microflora, was integrated to the anaerobic bioreactor. A 2 month-continuous mode experiment was carried out by feeding the integrated anaerobic-aerobic system with an amended OMW. The COD load with which the reactors were fed were 31.9 and 52.2 g/(ld) for the anaerobic and the aerobic plant, respectively. The integrated system was found to remove the 58% of the inlet COD, and the aerobic post-treatment contributed for 1⁄4 of such removal yield. In order to better understand the biological process, the composition of the bacterial communities of both the anaerobic and the aerobic reactors were characterized
Biological fate of Diuron and Sea-nine® 211 and their effect on primary microbial activities in slurries of a contaminated sediment from Venice Lagoon
No full textThe individual fate of the industrial booster biocides Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and Sea-nine® 211 (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) in a marine sediment of Porto Marghera (Venice Lagoon, Italy) was investigated, under anaerobic and aerobic conditions, in slurry-phase microcosms consisting of sediment suspended in its own overlaying water, i.e. under biogeochemical conditions which closely mimic those occurring in situ. Biocides were singly supplied as methanol solutions to a final concentration of 50 mg/kg of dry sediment. No Diuron degradation occurred throughout 3 months of incubation under any of the conditions tested. Conversely, Sea-nine®211 was promptly and completely degraded, regardless of the presence of oxygen. Under anoxic conditions, neither sulphate reduction nor methanogenesis occurred significantly in the non-amended microcosms, probably because of the very low availability of substrates in the actual site sediment and water employed. In contrast, methanogenesis occurred in the biocide amended microcosms where methanol was supplied as the carrier for biocides. No sulphate consumption was observed in the same microcosms. The large methane production observed in the parallel biocide-free control microcosms supplemented with methanol suggested that methylotrophic methanogens were the main compounds responsible for the detected activities. Diuron was found to intensify methane production, probably because it exerted an inhibitory effect on some competitors of indigenous methylotrophic methanogens
Integrated approaches for the production of vanillin
No full textVanillin is the molecule responsible for the well-known vanilla aroma, and therefore one of the most used flavour components in the food and cosmetic industries. Vanillin is mostly produced via a chemical process, with only a small fraction extracted from natural sources, namely, the bean of the orchid Vanilla planifolia. The consumer demand for natural vanillin highly exceeds the amount of vanillin extracted by plant sources and new methods for the production of natural vanillin have been attempted. Biotransformation of natural substrates into vanillin is an alternative way to produce the natural flavour. Ferulic acid can be obtained by hydrolysis of the lignin fraction of plant biomasses and converted into vanillin using engineered microorganisms. Our work has been focused on solving the major challenges in obtaining preparative bioprocesses are: the availability of methods for hydrolysis and recovery of ferulic acid from biomasess, the construction of stable and productive engineered microorganisms with high tolerance towards the vanillin produced, the optimization of fermentation/biotransformation, and finally efficient protocols for vanillin recovery.
Examples from our work will be presented with regards to different strategies for identifying an integrated approach for biotechnological vanillin production
Intermolecular electron transfer in merocyanine aggregates studied by optical and transient EPR methods
No full textExcited states of two merocyanine chromophores have been studied by means of optical and magnetic resonance techniques. The dye molecules were dissolved in solvents of different polarity and cast in thin films on quartz surfaces. The optical absorption and emission spectra of both molecules indicate a little charge-transfer character in the S-0-S-1 transition. The cast films contain monomers and H type aggregates. EPR spectra have been obtained by time resolved techniques at low temperature after illumination of the sample. EPR spectra of isolated molecules in frozen solutions are typical of triplet excited states generated by spin-orbit promoted intersystem crossing. Two signals are observed in EPR spectra of the cast films, with a narrow line in emission superimposed on a very weak molecular triplet lineshape. The polarization and lineshape analysis suggest that a radical ion pair with a lifetime of the order of microseconds is formed by intermolecular charge migration following the photoinduced electron-transfer reaction between the donor and acceptor moieties of the chromophore
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Selection of hydrolytic enzymes with antifouling activity in seawater
No full textBiofouling represents a severe problem for the shipping industry that needs to have more environmental friendly paints, since several biocides currently used in antifouling coatings are going to be banned by the European legislation because of their poor biodegradability and high toxicity1. Since biofouling starts with the formation of a monolayer of bacterial cells which adhere to surface via biopolymers, hydrolytic enzymes able to degrade natural polymers might prevent bacterial adhesion and biofouling maturation, and might therefore represent potential environmental-friendly antifouling agents2. In this work, the activity and stability of a group of commercially available hydrolytic enzymes in synthetic marine water were characterized, and their ability to reduce biofilm formation by a natural marine microbial community was investigated.
A protease, a glycosidase and a lipase were found to display a remarkable specific activity in synthetic marine water (pH 8.0, 25°C), corresponding to 98%, 140% and 62% of their specific activity in buffer under the same conditions, respectively. Mixtures of the 3 enzymes displayed comparable specific activities, except for the lipase activity, that was reduced by 23% in the presence of the protease. In addition, glycosidase and lipase exhibited half lives higher than 56 days in synthetic marine water at 20°C, whereas half life of the protease was 20 days. Finally, none of the three enzymes was able to prevent biofilm formation on microtitre plates by a marine microbial community. However, the mixture of the three enzymes inhibited biofilm growth by 90% as compared to the untreated control, whereas the planctonic growth of microbial community was not affected by enzymes addition.
1EU Biocidal Product Directive, http://ec.europa.eu/environment/biocides/index.htm
2Kristensen et al. 2008. Biotechnology Advances 26, 471–48
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