Browsing by Author "Caballero, Susana"
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Item Efficient production of acetoin by fermentation using the newly isolated mutant strain Lactococcus lactis subsp. lactis CML B4(2017-07) Roncal, Tomás; Caballero, Susana; Díaz de Guereñu, María del Mar; Rincón, Inés; Prieto-Fernández, Soraya; Ochoa-Gómez, Jose R.; Tecnalia Research & Innovation; BIOECONOMÍA Y CO2; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; TECNOLOGÍAS DE HIDRÓGENO; GENERALWith the aim of applying biotechnology to produce acetoin, a chemical that can be used as an aroma and as a building block for other compounds, several putative mutants with reduced lactic acid synthesis were obtained from a wild-type homolactic strain of L. lactis subjected to chemical mutagenesis. Among these mutants, a strain was isolated, CML B4, that showed reduced lactate dehydrogenase (LDH) and increased NADH oxidase (NOX) activities. Shaken flask cultures of this mutant strain mainly produced acetoin, increasing the levels produced compared to the wild-type strain by 15-fold. A point mutation detected in the ldh gene encoding LDH was probably the genetic defect responsible for this phenotype. In pH-controlled aerobic batch fermentation, the CML B4 strain produced more than 40 gL−1 acetoin, which was increased by up to 59 gL−1 in fed-batch fermentations, with yields close to 88 and 74%, respectively, and productivities exceeding 2 gL−1 h−1. These results indicate that this strain could be used industrially as a cell factory for the production of acetoin from bioresources.Item TOXICOLOGICAL AND ENVIRONMENTAL PROPERTIES OF A CrIII/CHOLINE CHLORIDE BASED CHROME PLATING ELECTROLYTE(FEDERACION ASOCIACIONES INGENIEROS INDUSTRIALES ESPANA, ALAMEDA DE MAZARREDO, BILBAO, 69-48009, SPAIN, 2015-03) Yurramendi, Lourdes; Caballero, Susana; Alvarez, Noelia; Izagirre, Usoa; Cano, F.J.At present, industrial application of hard chromium electroplating is based on electrolytic baths of sulphuric acid and chromium trioxide solutions in water. Toxicological and environmental properties of these chromium (VI) baths show the convenience of searching for new CrVI free formulations. Research activities have shown that chromium metallic coatings from an ionic liquid (IL) using trivalent chromium salts can be successfully produced. A highly promising CrVI free, bright, thick and hard chromium deposition process has been developed based on an ionic liquid composed of Chromium chloride and Choline chloride. Jointly with technological properties evaluation, a methodological study on environmental risk analysis and on implications in health & safety for the referred ionic liquid bath has been carried out. With that aim, experimental tests on the basis of toxicological properties, of effects on human health and of environmental effects were conducted. Comparisons of the obtained results with the behaviour of traditional baths used for the same purpose were also accomplished, showing for the ionic liquid formulation a lower toxicity and less environmental risk than for the CrVI formulation.