Effect of pH on the production of hydrolytic enzymes of industrial interest by Bacillus licheniformis using sewage sludge as a low-cost culture médium

Management of sewage sludge has become a topic of increasing importance. This is because the treatment and final destination of these wastes are not growing at the same rate at which generated what is necessary to add the limited storage capacity of wastewater treatment plants or waste transfer centers. Current policies of different governments aims, among others, promote proecological management of sewage sludge, replacing traditional methods by new methods that lead to their stabilization and safe recycling. These methods can lead to the recovery of valuable raw materials from potentially dangerous others in order to permit their use in agriculture, industry or energy production. Moreover, exists a great enzyme market, mainly those with hydrolytic activities such as proteases, lipases or cellulases. Although its use has many advantages, the competitiveness of the enzymes compared with chemicals is limited by its high production costs. The use of a less expensive culture media and the stimulation of the production of these enzymes can significantly reduce production costs. Therefore, the use of tertiary materials as alternative substrates, available in large quantities and at lower cost, is an interesting option. In this work we have studied the effect of pH on the fermentation of sewage sludge by Bacillus licheniformis, a hydrolytic enzymes producer microorganism, in order to obtain several products for specific agronomic applications

Functional Characterization of Lysophosphatidylcholine: Acyl-CoA Acyltransferase Genes From Sunflower (Helianthus annuus L.)

Lysophosphatidylcholine acyltransferase (LPCAT, EC 2.3.1.23) is an evolutionarily conserved key enzyme in the Lands cycle that catalyzes acylation of lysophosphatidylcholine (LPC) to produce phosphatidylcholine (PC), the main phospholipid in cellular membranes. In this study, three LPCAT genes from sunflower were identified and the corresponding proteins characterized. These HaLPCAT genes encoded functionally active enzymes that were able to complement a deficient yeast mutant. Moreover, enzymatic assays were carried out using microsomal preparations of the yeast cells. When acyl specificities were measured in the forward reaction, these enzymes exhibited a substrate preference for unsaturated acyl-CoAs, especially for linolenoyl-CoA, while in the reverse reaction, linoleoyl or linolenoyl acyl groups were transferred from PC to acyl-CoA to a similar extent. Expression levels of LPCAT genes were studied revealing distinct tissue-specific expression patterns. In summary, this study suggests that the combined forward and reverse reactions catalyzed by sunflower LPCATs facilitate acyl-exchange between the sn-2 position of PC and the acyl-CoA pool. Sunflower LPCATs displayed different characteristics, which could point to different functionalities, favoring the enrichment of seed triacylglycerols (TAGs) with polyunsaturated fatty acid (PUFA)España, AEI and FEDER Project AGL2017- 83449-R. R

Ruta de la lipoxigenasa en aceituna: contribución a la biogénesis del aroma del aceite de oliva

En la presente tesis se pretendió caracterizar las enzimas de la ruta de la lipoxigenasa (lipoxigenasa, hidroperóxido liasa, alcohol deshidrogenasa y alcohol aciltransferasa) en pulpa de aceituna, como principales responsables de la síntesis del aroma del aceite de oliva vi rgen. Estas enzimas fueron detectadas y caracterizadas, encontrándose una buena correlación entre los parámetros bioquímicos de las mismas y la composición de volátiles del aceite de oliva virgen.A diferencia de otros aceites vegetales, el aceite de oliva Virgen se extrae por métodos exclusivamente físicos de frutos frescos (Alba, 1997), constituyendo un zumo natural de notables características nutricionales y organolépticas. Por no sufrir refinación, este aceite conserva su aroma natural, uno de los parámetros más apreciados por sus consumidores. Dicho aroma está formado por una compleja mezcla compuestos volátiles, entre los que se encuentras aldehídos, ésteres, alcoholes, hidrocarburos y cetonas, que han sido separados y caracterizados por GC-MS (Morales et al., 1994). De todos estos compuestos los más importantes cuantitativamente son aldehídos, alcoholes y ésteres de alcoholes de seis átomos de carbono, los cuales dan cuenta de entre el 80 y el 90% del total de la fracción de volátiles del aceite (Olías et al., 1980; Morales et al., 1995; Ranalli y De Mattia, 1997). Estos compuestos son comunes a otras especies y productos vegetales, y son responsables de los que se ha denominado olor verde, por su presencia en alta proporción en homogenados de hojas frescas (Hatanaka, 19939.Está bien establecido por experimentos de marcaje que esta serie de substancias volátiles se producen a partir de ácidos grasos poliinsaturados a través de la cascada de reacciones conocida como ruta de la lipoxigenasa (Hatanka et al., 1987). Esta ruta se induce co