The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. http://http://dspace.unitus.it:80 2013-05-24T22:15:30Z 2013-05-24T22:15:30Z Barghini, Paolo Di Gioia, Diana Fava, Fabio Ruzzi, Maurizio http://hdl.handle.net/2067/1495 2011-09-26T07:57:58Z 2006-12-31T23:00:00Z

Title: Vanillin production using metabolically engineered Escherichia coli under non-growing conditions Authors: Barghini, Paolo; Di Gioia, Diana; Fava, Fabio; Ruzzi, Maurizio Abstract: Vanillin is one of the most important aromatic flavour compounds used in the food and cosmetic industries. Natural vanillin is extracted from vanilla beans and is relatively expensive. Moreover, the consumer demand for natural vanillin highly exceeds the amount of vanillin extracted by plant sources. This has led to the investigation of other routes to obtain this flavour such as the biotechnological production from ferulic acid. Studies concerning the use of engineered recombinant Escherichia coli cells as biocatalysts for vanillin production are described in the literature, but yield optimization and biotransformation conditions have not been investigated in details.

2006-12-31T23:00:00Z Crognale, Silvia Barghini, Paolo Di Matteo, Paola Federici, Federico Ruzzi, Maurizio http://hdl.handle.net/2067/1505 2011-10-10T23:05:33Z 2007-12-31T23:00:00Z

Title: Optimization of capsaicin acylase production from Streptomyces mobaraensis in bench-top fermenter Authors: Crognale, Silvia; Barghini, Paolo; Di Matteo, Paola; Federici, Federico; Ruzzi, Maurizio Abstract: Capsaicin, the major pungent principle in hot pepper fruit, can be hydrolyzed enzymatically to vanillylamine (a natural precursor of vanillin) using a specific acylase from Streptomyces mobaraensis. Production of this enzyme using strain DSM40847 was studied under batch fermentation conditions in stirred tank (STR) and airlift (AR) bioreactors. The process performance in both fermentation devices was different with respect to biomass, enzyme concentration and specific yield (enzyme activity/biomass content); in particular the specific yield was lower in the AR (5.7 mU/g of biomass) than in the STR (6.25 mU/g of biomass). Experiments carried out in STR bioreactors at controlled (DO = 20% of saturation) and uncontrolled dissolved oxygen concentration, and constant stirred speeds (300, 450 and 600 rpm) demonstrated that the DO level has no remarkable effect on the production of the capsaicin-hydrolyzing enzyme, which is mainly produced in a cell-associated form.

2007-12-31T23:00:00Z Calisti, Cecilia Ficca, Anna Grazia Barghini, Paolo Ruzzi, Maurizio http://hdl.handle.net/2067/1499 2011-09-22T10:27:03Z 2007-12-31T23:00:00Z

Title: Regulation of ferulic catabolic genes in Pseudomonas fluorescens BF13: involvement of a MarR family regulator Authors: Calisti, Cecilia; Ficca, Anna Grazia; Barghini, Paolo; Ruzzi, Maurizio Abstract: In Pseudomonas fluorescens BF13, the cluster of genes essential for degradation of ferulic to vanillic acid (ech, vdh and fcs) is expressed in ferulic but not in succinic grown cells. In the upstream region, we identified a gene, ferR, encoding a protein homologous to transcriptional regulators of the MarR family. A ferR knockout mutant (BF13–89) showed a 3.5-fold increase in expression of an ech-reporter gene fusion compared with the parent strain in succinic-grown cells, indicating that the ferR gene product negatively regulates expression of the ferulic catabolic operon in P. fluorescens BF13. Consistent with the increased expression of the catabolic genes in the ferR mutant, BF13-89 showed a shorter (relative to its FerR+ parent) lag phase during carbon source shift from succinic to ferulic acid. However, expression of ech-lacZ fusion did not increase in BF13–89 grown in the presence of ferulic acid, indicating that FerR has a second function as transcriptional activator. Expression of ech-lacZ in a feruloyl-CoA synthetase- eficient strain revealed unambiguously that FerR-mediated activation of the ferulic catabolic operon is dependent on the thioester product of the feruloyl-CoA synthetase reaction. Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com

2007-12-31T23:00:00Z