Sansone, Ferdinando (2021) Thermophilic microorganisms as source of molecules for biotechnological applications. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Thermophilic microorganisms as source of molecules for biotechnological applications
Date: 12 July 2021
Number of Pages: 153
Institution: Università degli Studi di Napoli Federico II
Department: Biologia
Dottorato: Biologia
Ciclo di dottorato: 33
Coordinatore del Corso di dottorato:
Date: 12 July 2021
Number of Pages: 153
Keywords: α-galactosidase; β-galactosidase; MA-13
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/10 - Biochimica
Date Deposited: 23 Jul 2021 10:51
Last Modified: 07 Jun 2023 10:41

Collection description

Background: The spore-forming lactic acid bacterium Bacillus coagulans MA-13 has been isolated from canned beans manufacturing and successfully employed for the sustainable production of lactic acid from lignocellulosic biomass. Among lactic acid bacteria, B. coagulans strains are generally recognized as safe (GRAS) for human consumption. Low-cost microbial production of industrially valuable products such as lactic acid and various enzymes devoted to the hydrolysis of oligosaccharides and lactose is of great importance to the food industry. Specifically, α- and β-galactosidases are attractive for their ability to hydrolyze not-digestible galactosides present in the food matrix as well as in the human gastrointestinal tract. Results: In this thesis, the potential of B. coagulans MA-13 as a source of metabolites and enzymes has been explored to improve the digestibility and the nutritional value of food. A combination of mass spectrometry analysis with conventional biochemical approaches has been employed to unveil the intra- and extra-cellular glycosyl hydrolases (GH) repertoire of B. coagulans MA-13 under diverse growth conditions. The highest enzymatic activity was detected on β-1,4 and α-1,6-glycosidic linkages and the enzymes responsible for these activities were unambiguously identified as a β-galactosidase (GH42) and an α-galactosidase (GH36), respectively. Whilst the former has been found only in the cytosol, the latter is localized also extracellularly. The export of this enzyme may occur through a not yet identified secretion mechanism since a typical signal peptide is missing in the α-galactosidase sequence. A full biochemical characterization of the recombinant β-galactosidase has been carried out and the ability of this enzyme to perform homo- and hetero-condensation reactions to produce galacto-oligosaccharides, has been demonstrated. Conclusions: Probiotics that are safe for human use and are capable of producing high levels of both α-galactosidase and β-galactosidase are of great importance to the food industry. In this thesis, it has been proven the ability of B. coagulans MA-13 to over-produce these two enzymes thus paving the way for its potential use in food industry.


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