133,020 research outputs found
Production of L- and D-lactic acid isomers by Lactobacillus casei subsp. casei DSM 20011 and Lactobacillus coryniformis subsp. torquens DSM 20004 in continuous fermentation
No full textWith the aim of producing L(+) and D(−) lactic acid to be employed in poly-lactic acid polymer production, for biomedical applications, the strains Lactobacillus casei subsp. casei DSM 20011 and Lactobacillus coryniformis subsp. torquens DSM 20004 were studied in a conventional chemostat mode using various dilution rates. The results obtained showed that the dilution rate influences the fermentation pattern, modifying various fermentation parameters. Nevertheless, the product and biomass yields remained constant and the ratio of the L(+) and D(−) isomers of lactic acid was not affected by the dilution rate. The optimal glucose concentration on inlet feed medium was also determined for the L. coryniformis fermentation
Production of L(+) and D(-) lactic acid isomers by Lactobacillus casei subsp. casei DSM 20011 and Lactobacillus coryniformis subsp. torquens DSM 20004 in continuous fermentation
No full textWith the aim of producing L(+) and D(-) lactic acid to be employed in poly-lactic acid polymer production, for biomedical applications, the strains Lactobacillus casei subsp. casei DSM 20011 and Lactobacillus coryniformis subsp. torquens DSM 20004 were studied in a conventional chemostat mode using various dilution rates. The results obtained showed that the dilution rate influences the fermentation pattern, modifying various fermentation parameters. Nevertheless, the product and biomass yields remained constant and the ratio of the L(+) and D(-) isomers of lactic acid was not affected by the dilution rate. The optimal glucose concentration on inlet feed medium was also determined for the L. coryniformis fermentation
Characterization of Bifidobacterium strains for use in soymilk fermentation
No full textSoybean milk, which serves as a base for a variety of beverages, contains raffinose, stachyose, pentanal and n-hexanal; theformer two may be responsible for flatulence after fermentation, whilst the latter two for a beany flavour. Twenty-seven strains of Bifidobacterium were analyzed for their a-galactosidase activity and the production of lactic and acetic acids to determine their potential for use in the production of fermented soymilk. The behaviour of three strains in soymilk was studied to determine their ability to reduce a-D-galactosyl oligosaccharides and produce lactic and acetic acids. They all were able to reduce stachyose and raffinose. Pentanal and n-hexanal were metabolized by Bifidobacterium breve MB233. These data indicate that bifidobacteria can be used for biotechnological processes that employ soymilk as the substrate. A productwith low levels of a-D-galactosyl oligosaccharides and alkylic aldehydes may be obtained
Improved cloning vectors for Bifidobacterium spp.
No full textThe recombinant plasmids pDLI41, pDGA7 and pDCO7 were constructed by cloning in pDG7, a vector based on Bifidobacterium longum replicon pMB1, the following heterologous genes: Pseudomonas fluorescens lipase, Bacillus licheniformis alpha-amylase and Streptomyces sp. cholesterol oxidase. The hybrid plasmids efficiently transformed Bifidobacterium belonging to five different species. A novel Escherichia coli-Bifidobacterium set of shuttle vectors based on the replicon pMB1 (pLF5, pCLJ15, pSPEC1) featuring chloramphenicol, erythromycin and spectinomycin resistance genetic determinants as selection marker for bifidobacteria, was developed. The plasmid pTRE3, a derivative of pLF5, was the smallest (2.8 kb) Bifidobacterium vector, possessed a convenient multicloning site and presented high structural and segregational stability
An efficient transformation system for Bifidobacterium spp.
No full textThis study describes a broad host transformation protocol that enables the uptake of plasmid DNA into 10 different species of Bifidobacterium, some of which have never been transformed before. The vector pNC7 (4·9 kb) was used to optimize the electroporation protocol. Transformation efficiencies ranged from 3·6×10−1 to 1·2×105 transformations per μg DNA. The impact of growth medium composition and electric field strength on transformation efficiency were independently optimized. Electrocompetent cells were grown in Iwata medium broth enriched with ActilightRP 16%, harvested during the early exponential growth phase, and pulsed at 12·5 kV cm−1, 100 Ω and 25 μF
Characterization and molecular cloning of Bifidobacterium longum cryptic plasmid pMB1
No full textThe small cryptic plasmid pMB1 (1.9 kb), previously isolated from Bifidobacterium longum, has been characterized by physical mapping. Two cloning vectors, pMR3 and pDG7, carrying chloramphenicol and ampicillin resistances derived from pJH101, have been electroporated in Escherichia coli
Electroporation of bifidobacteria
No full textCreating bacteria with modified genetic properties allows the specific investigation of these microorganisms. Electrotransformation is a highly efficient and easy to apply technique to introduce genetic material into bacterial cells. A strong electric field is used for this purpose.In the present manual, protocols for the transformation of about 40 strains of bacteria are described. Emphasis is placed on the individual critical procedural steps, since the practical details mainly depend on the bacterial strain under investigation. This presentation together with the theoretical introductionary chapters, allows the user to modify and adapt each protocol to his/her own experiments. Bacterial strains with relevance in the food industry, biotechnology, medical and veterinary fields, agroindustry and environmental sciences are covere
Transformation of Bacillus subtilis PB1424 by electroporation
No full textCreating bacteria with modified genetic properties allows the specific investigation of these microorganisms. Electrotransformation is a highly efficient and easy to apply technique to introduce genetic material into bacterial cells. A strong electric field is used for this purpose. In the present manual, protocols for the transformation of about 40 strains of bacteria are described. Emphasis is placed on the individual critical procedural steps, since the practical details mainly depend on the bacterial strain under investigation. This presentation together with the theoretical introductionary chapters, allows the user to modify and adapt each protocol to his/her own experiments. Bacterial strains with relevance in the food industry, biotechnology, medical and veterinary fields, agroindustry and environmental sciences are covered
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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