Publications by authors named "Jesús Villegas"

4 Publications

  • Page 1 of 1

Richter´s Hernia Incarcerated Bowel Hernia at 5mm Port Site.

J Minim Invasive Gynecol 2021 Nov 21. Epub 2021 Nov 21.

Department of Obstetrics and Gynecology, Division of Gynecology Oncology, Universidad Autónoma de Chihuahua, Hospital Christus Muguerza Del Parque, Chihuahua México (all authors).

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http://dx.doi.org/10.1016/j.jmig.2021.11.014DOI Listing
November 2021

Scale-up from shake flasks to pilot-scale production of the plant growth-promoting bacterium Azospirillum brasilense for preparing a liquid inoculant formulation.

Appl Microbiol Biotechnol 2013 Nov 6;97(22):9665-74. Epub 2013 Sep 6.

Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, AP. 70228, Mexico, D.F., 04510, Mexico,

Azospirillum brasilense has industrial significance as a growth promoter in plants of commercial interest. However, there is no report in the literature disclosing a liquid product produced in pilot-scale bioreactors and is able to be stored at room temperature for more than 2 years. The aim of this work was to scale up a process from a shake flask to a 10-L lab-scale and 1,000-L pilot-scale bioreactor for the production of plant growth-promoting bacterium A. brasilense for a liquid inoculant formulation. Furthermore, this work aimed to determine the shelf life of the liquid formulation stored at room temperature and to increase maize crops yield in greenhouses. Under a constant oxygen mass transfer coefficient (K L a), a fermentation process was successfully scaled up from shake flasks to 10- and 1,000-L bioreactors. A concentration ranging from 3.5 to 7.5 × 10(8) CFU/mL was obtained in shake flasks and bioreactors, and after 2 years stored at room temperature, the liquid formulation showed one order of magnitude decrease. Applications of the cultured bacteria in maize yields resulted in increases of up to 95 % in corncobs and 70 % in aboveground biomass.
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http://dx.doi.org/10.1007/s00253-013-5199-9DOI Listing
November 2013

Bioconversion of Agave tequilana fructans by exo-inulinases from indigenous Aspergillus niger CH-A-2010 enhances ethanol production from raw Agave tequilana juice.

J Ind Microbiol Biotechnol 2013 Jan 17;40(1):123-32. Epub 2012 Nov 17.

Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Circuito Escolar s/n, Ciudad Universitaria, 04510 Mexico DF, Mexico.

Agave tequilana fructans are the source of fermentable sugars for the production of tequila. Fructans are processed by acid hydrolysis or by cooking in ovens at high temperature. Enzymatic hydrolysis is considered an alternative for the bioconversion of fructans. We previously described the isolation of Aspergillus niger CH-A-2010, an indigenous strain that produces extracellular inulinases. Here we evaluated the potential application of A. niger CH-A-2010 inulinases for the bioconversion of A. tequilana fructans, and its impact on the production of ethanol. Inulinases were analyzed by Western blotting and thin layer chromatography. Optimal pH and temperature conditions for inulinase activity were determined. The efficiency of A. niger CH-A-2010 inulinases was compared with commercial enzymes and with acid hydrolysis. The hydrolysates obtained were subsequently fermented by Saccharomyces cerevisiae to determine the efficiency of ethanol production. Results indicate that A. niger CH-A-2010 predominantly produces an exo-inulinase activity. Optimal inulinase activity occurred at pH 5.0 and 50 °C. Hydrolysis of raw agave juice by CH-A-2010 inulinases yielded 33.5 g/l reducing sugars, compared with 27.3 g/l by Fructozyme(®) (Novozymes Corp, Bagsværd, Denmark) and 29.4 g/l by acid hydrolysis. After fermentation of hydrolysates, we observed that the conversion efficiency of sugars into ethanol was 97.5 % of the theoretical ethanol yield for enzymatically degraded agave juice, compared to 83.8 % for acid-hydrolyzed juice. These observations indicate that fructans from raw Agave tequilana juice can be efficiently hydrolyzed by using A. niger CH-A-2010 inulinases, and that this procedure impacts positively on the production of ethanol.
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http://dx.doi.org/10.1007/s10295-012-1211-0DOI Listing
January 2013

Activity of the enzymes involved in the synthesis of exopolysaccharide precursors in an overproducing mutant ropy strain of Streptococcus thermophilus.

FEMS Microbiol Lett 2002 Apr;209(2):289-93

Departamento de Alimentos y Biotecnología, Lab. 312, Conjunto E, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F. 04510, Mexico.

The activities of some enzymes belonging to the Leloir pathway, phosphoglucomutase, UDP-glucose pyrophosphorylase, UDP-galactose 4-epimerase and galactose 1-P uridyl transferase, were studied in a wild ropy, a non-ropy and an overproducing mutant ropy strain of Streptococcus thermophilus. These activities were assayed over successive culture transfers along with exocellular polysaccharide (EPS) production. The overproducing mutant ropy strain showed increments in polysaccharide production over successive culture transfers, as opposed to reductions in production by the wild ropy strain. The observed variations among strains in the enzyme activities that were analysed in relation to EPS production suggest their involvement in the synthesis of sugar-nucleotide EPS precursors.
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http://dx.doi.org/10.1111/j.1574-6968.2002.tb11146.xDOI Listing
April 2002
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