Browsing by Keyword "Microbiology"
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Item Effect of polyphenol content on the antimicrobial activity of natural extracts from agro-industrial by-products(2015-01-01) Sanz-Puig, María; Pina-Pérez, María Consuelo; Saenz, Jessica; Marañón, Izaskun; Rodrigo, Dolores; Martínez-López, Antonio; Alimentación SostenibleThe main objective of the present study was to investigate the effect of the conditions of extraction by Accelerated Solvent Extraction (ASE) technology on the bioactive antimicrobial activity of extracts from by-products of cauliflower, broccoli, orange, and mandarin. The antimicrobial activity of extracts, with concentrated phenol content, was evaluated against four of the most important foodborne pathogens: Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, Bacillus cereus, and Listeria monocytogenes. The largest phenol content (1252.12 +/- 38.29 mu g gallic acid/mL) was recovered from cauliflower extract. Cauliflower and mandarin extracts were effective against both Gram-positive and Gram-negative bacteria, showing the highest inhibition zones, 16 1 mm and 17 +/- 0.4 mm respectively, against 105 cfu/mL S. Typhimurium. The antimicrobial effectiveness of the extracts was influenced by the ASE extraction conditions, initial contamination level, and microbial strain.Item Effects of in situ Remediation With Nanoscale Zero Valence Iron on the Physicochemical Conditions and Bacterial Communities of Groundwater Contaminated With Arsenic(2021-03-17) Castaño, Ana; Prosenkov, Alexander; Baragaño, Diego; Otaegui, Nerea; Sastre, Herminio; Rodríguez-Valdés, Eduardo; Gallego, José Luis R.; Peláez, Ana Isabel; Tecnalia Research & InnovationNanoscale Zero-Valent Iron (nZVI) is a cost-effective nanomaterial that is widely used to remove a broad range of metal(loid)s and organic contaminants from soil and groundwater. In some cases, this material alters the taxonomic and functional composition of the bacterial communities present in these matrices; however, there is no conclusive data that can be generalized to all scenarios. Here we studied the effect of nZVI application in situ on groundwater from the site of an abandoned fertilizer factory in Asturias, Spain, mainly polluted with arsenic (As). The geochemical characteristics of the water correspond to a microaerophilic and oligotrophic environment. Physico-chemical and microbiological (cultured and total bacterial diversity) parameters were monitored before and after nZVI application over six months. nZVI treatment led to a marked increase in Fe(II) concentration and a notable fall in the oxidation-reduction potential during the first month of treatment. A substantial decrease in the concentration of As during the first days of treatment was observed, although strong fluctuations were subsequently detected in most of the wells throughout the six-month experiment. The possible toxic effects of nZVI on groundwater bacteria could not be clearly determined from direct observation of those bacteria after staining with viability dyes. The number of cultured bacteria increased during the first two weeks of the treatment, although this was followed by a continuous decrease for the following two weeks, reaching levels moderately below the initial number at the end of sampling, and by changes in their taxonomic composition. Most bacteria were tolerant to high As(V) concentrations and showed the presence of diverse As resistance genes. A more complete study of the structure and diversity of the bacterial community in the groundwater using automated ribosomal intergenic spacer analysis (ARISA) and sequencing of the 16S rRNA amplicons by Illumina confirmed significant alterations in its composition, with a reduction in richness and diversity (the latter evidenced by Illumina data) after treatment with nZVI. The anaerobic conditions stimulated by treatment favored the development of sulfate-reducing bacteria, thereby opening up the possibility to achieve more efficient removal of As.Item Waste-derived volatile fatty acids as carbon source for added-value fermentation approaches(2021-05-01) Chalima, Angelina; de Castro, Laura Fernandez; Burgstaller, Lukas; Sampaio, Paula; Carolas, Ana Lúcia; Gildemyn, Sylvia; Velghe, Filip; Ferreira, Bruno Sommer; Pais, Celia; Neureiter, Markus; Dietrich, Thomas; Topakas, Evangelos; De Castro, Laura Fernandez; Tecnalia Research & Innovation; Alimentación SostenibleThe establishment of a sustainable circular bioeconomy requires the effective material recycling from biomass and biowaste beyond composting/fertilizer or anaerobic digestion/bioenergy. Recently, volatile fatty acids attracted much attention due to their potential application as carbon source for the microbial production of high added-value products. Their low-cost production from different types of wastes through dark fermentation is a key aspect, which will potentially lead to the sustainable production of fuels, materials or chemicals, while diminishing the waste volume. This article reviews the utilization of a volatile fatty acid platform for the microbial production of polyhydroxyalkanoates, single cell oil and omega-3 fatty acids, giving emphasis on the fermentation challenges for the efficient implementation of the bioprocess and how they were addressed. These challenges were addressed through a research project funded by the European Commission under the Horizon 2020 programme entitled ‘VOLATILE—Biowaste derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks’.