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- 1,3-Propanediol continuous production by Clostridium butyricum VP1 1718: effect of dilution rate and substrate concentrationPublication . Gonzalez-Pajuelo, M.; Ribeiro-Cruz, A. P.; Sousa- Monagas, C. M.; Andrade, J. C.; Vasconcelos, I.
- Production of 1,3-propanediol by Clostridium butyricum VPI 3266 using a synthetic medium and raw glycerolPublication . González-Pajuelo, M.; Andrade, J. C.; Vasconcelos, I.Growth inhibition of Clostridium butyricum VPI 3266 by raw glycerol, obtained from the biodiesel production process, was evaluated. C. butyricum presents the same tolerance to raw and to commercial glycerol, when both are of similar grade, i.e. above 87% (w/v). A 39% increase of growth inhibition was observed in the presence of 100 g l 1 of a lower grade raw glycerol (65% w/v). Furthermore, 1,3-propanediol production from two raw glycerol types (65% w/v and 92% w/v), without any prior purification, was observed in batch and continuous cultures, on a synthetic medium. No significant differences were found in C. butyricum fermentation patterns on raw and commercial glycerol as the sole carbon source. In every case, 1,3-propanediol yield was around 0.60 mol/mol glycerol consumed.
- Uncovering Akkermansia muciniphila resilience or susceptibility to different temperatures, atmospheres and gastrointestinal conditionsPublication . Machado, Daniela; Almeida, Diana; Seabra, Catarina L.; Andrade, José Carlos; Gomes, Ana Maria; Freitas, Ana CristinaData regarding Akkermansia muciniphila viability under stress remains scarce despite its beneficial potential. Therefore, the main goal was to assess A. muciniphila culturability when exposed to different temperatures, atmospheres and gastrointestinal simulated conditions. Cultivable cell numbers A. muciniphila remain high after refrigerated and room temperatures oxygen exposure, and gastrointestinal passage.
- Continuous cultures of Clostridium acetobutylicum: culture stability and low-grade glycerol utilisationPublication . Andrade, José Carlos; Vasconcelos, IsabelContinuous cultures of two strains of Clostridium acetobutylicum were stable for over 70 d when grown on glucose/ glycerol mixtures. Butanol was the major fermentation end-product, accounting for 43 to 62% (w/w) of total products. Low-grade glycerol [65% (w/v) purity] could replace commercial glycerol [87% (w/v) purity], leading to a similar fermentation pattern: a butanol yield of 0.34 (mol/mol), a butanol productivity of 0.42 g l−1 h−1 and a 84% (w/w) glycerol consumptionwere attained when cultures were grown at pH 6 and D = 0.05 h−1; butanol accounted for 94% (w/w) of total solvents. These values are among the highest reported in literature for C. acetobutylicum simple chemostats.
- Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivityPublication . González-Pajuelo, M.; Andrade, J. C.; Vasconcelos, I.The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around 0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate. Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate concentration of 30, 60 or 70 g l-1. Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration was increased from 30 to 60 g l-1, at D=0.05–0.3 h-1, and from 60–70 g l-1, at D=0.05 and 0.1 h-1. 30 g l-1 of 1,3-propanediol and the highest reported value of productivity, 10.3 g l-1 h-1, was achieved at D=0.30 h-1 and 60 g l-1 of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l-1 of feed glycerol and a dilution rate higher than 0.10 h-1; moreover, at D=0.30 h-1 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum.
- Production of conjugated linoleic acid by food-grade bacteria: A reviewPublication . Andrade, José C.; Ascenção, Kelly; Gullón, Patricia; Henriques, Silvino M. S.; Pinto, Jorge M. S.; Rocha-Santos, Teresa A. P.; Freitas, A. Cristina; Gomes, Ana MariaConjugated linoleic acid (CLA) is a group of isomers of linoleic acid (LA) with several potential health benefits which justifies the efforts to obtain foods with enhanced CLA contents. A possible way to obtain CLA-enriched products is via fermentation as several micro-organisms, many of which are employed in the manufacture of foods, are known to convert free LA into CLA. However, due to several constraints, the use of CLA-producing bacteria still remains challenging and continuous efforts are required. This review summarises the current knowledge on microbial CLA production by food-grade micro-organisms, its technical issues and limitations, potential applications and bioactivities.
- Fermentation of Low Grade Glycerol by Clostridium butyricum and Clostridum acetobutyllcum StrainsPublication . Gonzalez-Paluelo, M.; Andrade, J.C.; Vasconcelos, I.
- Metabolic engineering of clostridium acetobutylicum for the industrial production of 1,3-propanediol from glycerolPublication . González-Pajuelo, María; Meynial-Salles, Isabelle; Mendes, Filipa; Andrade, José Carlos; Vasconcelos, Isabel; Soucaille, PhilippeClostridium butyricum is to our knowledge the best natural 1,3-propanediol producer from glycerol and the only microorganism identified so far to use a coenzyme B12-independent glycerol dehydratase. However, to develop an economical process of 1,3-propanediol production, it would be necessary to improve the strain by a metabolic engineering approach. Unfortunately, no genetic tools are currently available for C. butyricum and all our efforts to develop them have been so far unsuccessful. To obtain a better ‘‘vitamin B12-free’’ biological process, we developed a metabolic engineering strategy with Clostridium acetobutylicum. The 1,3- propanediol pathway from C. butyricum was introduced on a plasmid in several mutants of C. acetobutylicum altered in product formation. The DG1(pSPD5) recombinant strain was the most efficient strain and was further characterized from a physiological and biotechnological point of view. Chemostat cultures of this strain grown on glucose alone produced only acids (acetate, butyrate and lactate) and a high level of hydrogen. In contrast, when glycerol was metabolized in chemostat culture, 1,3-propanediol became the major product, the specific rate of acid formation decreased and a very low level of hydrogen was observed. In a fed-batch culture, the DG1(pSPD5) strain was able to produce 1,3-propanediol at a higher concentration (1104mM) and productivity than the natural producer C. butyricum VPI 3266. Furthermore, this strain was also successfully used for very long term continuous production of 1,3-propanediol at high volumetric productivity (3 g L⁻¹ h⁻¹) and titer (788 mM).
- Antioxidative peptides: trends and perspectives for future researchPublication . Freitas, A. C.; Andrade, J. C.; Silva, F. M.; Rocha-Santos, T. A. P.; Duarte, A. C.; Gomes, Ana M. P.In recent years, much attention has been given to dietary antioxidants, especially polyphenols. Several peptides derived from protein molecules have also been found to show antioxidant capacity along with other biological properties and thus there is an increasing interest in these compounds as health promoters. This review summarizes and discusses the main sources of antioxidative peptides with focus on food-derived peptides (animal, plant and marine sources), methods of preparation, antioxidant capacity evaluation as well as their proposed mechanisms of action. A discussion of the potential health effects and comments on the different applications for these antioxidants and their potential research interest are also subject of this review.
- Akkermansia muciniphila robustness towards different temperatures, atmospheres and gastrointestinal conditionsPublication . Freitas, Ana Cristina; Machado, Daniela; Almeida, Diana; Seabra, Catarina; Andrade, José Carlos; Gomes, Ana Maria
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