1,721,156 research outputs found
Expression of an endoxylanase gene in a tandem unit and effect of different replication mode on its structural stability in Bacillus subtils DB104
No full textCell recycled culture of succinic acid-producing Anaerobiospirillum succiniciproducens using an internal membrane filtration system
No full textCell recycled culture of succinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically carried out using an internal membrane filter module in order to examine the physiological response of A. succiniciproducens to a high-cell-density environment. The optimal growth of A. succiniciproducens and its enhanced succinic acid productivity were observed under CO2-rich conditions, established by adding NaHCO3 and Na2CO3, in the cell recycled system. A. succiniciproducens grew up to 6.50 g-DCW/l, the highest cell concentration obtained so far, in cell recycled cultures. The cells did not change their morphology, which is known to be easily changed in unfavorable or stress environments. The maximum productivity of succinic acid was about 3.3 g/l/h, which is 3-3 times higher than those obtained in batch cultures. These results can serve as a guide for designing highly efficient cell recycled systems for succinic acid at a commercial level.This work was supported by the Genome-based Integrated
Bioprocess Development Project of the Ministry of Science
and Technology through the Korea Science and Engineering
Foundation. Further support by the LG Chem Chair
Professorship (SYL) is appreciated
Kinetic Study of Organic Acid Formations and Growth of Anaerobiospirillum succiniciproducens During Continuous Cultures
No full textSuccinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically grown in glucose-fed continuous cultures using glucose as a carbon source, and the metabolic flexibility of A. succiniciproducens in response to varying glucose concentrations and dilution rates was examined. Both succinic acid (SA) and acetic acid (AA) formation was growth-associated, and their growth-rate-related coefficients (K(SA/X), K(AA/X)) and nongrowth-rate-related coefficients (K'(SA/X), K'(AA/X)) were slightly influenced by glucose concentrations. A high glucose concentration (38 g/l) and high growth rate (0.63 h(-1)) did not induce by-product formation.This work was supported by a grant from Research
Promotion Program funded by Gyeonggi Province and by
Priority Research Centers Program through the National
Research Foundation of Korea (NRF) funded by the Ministry
of Education, Science and Technology (20090093826) (PC
Lee) and by the Genome based Integrated Bioprocess
Development Project from the Ministry of Education,
Science and Technology (SY Lee and HN Chang)
Succinic Acid Production by Anaerobiospirillum succiniciproducens ATCC 29305 Growing on Galactose, Galactose/Glucose, and Galactose/Lactose
No full textSuccinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically grown on galactose, galactose/glucose, or galactose/lactose in order to study its galactose fermentation. Unlike a previous report, A. succiniciproducens was found to efficiently metabolize galactose as the sole carbon source at a rate of 2.4 g/g-DCW/h and produced succinic acid with as high a yield of 87% as with using glucose. When glucose and galactose were present, A. succiniciproducens metabolized both sugars simultaneously. Furthermore, when lactose and galactose coexisted, lactose did not inhibit the galactose fermentation of A. succiniciproducens. Therefore, co-utilization of galactose and other sugars can improve the productivity and economy of bio-based succinic acid processes.This work was supported by grants from Ajou University
to PCL and by the Genome-based Integrated Bioprocess
Development Project of the Ministry of Science and
Technology through the Korea Science and Engineering
Foundation. Further support by the LG Chem Chair
Professorship (SYL) is appreciated
Molecular cloning and characterization of an endoxylanase gene of Bacillus sp. in Escherichia coli
No full textA gene encoding an endoxylanase of Bacillus sp. was cloned acid expressed in Escherichia coli. The entire nucleotide sequence of a 1,620 bp SmaI fragment containing the endoxylanase gene was determined. The endoxylanase gene was 639 bp long and encoded 213 amino acids which showed up to 96% amino acid homology with other endoxylanases. The encloxylanase produced by E. coli harboring pKJX4 was purified by ion-exchange chromatography (DE-52 and CM-Si) and its N-terminal sequence was determined to be Ala-Gly-Thr-Asp-Tyr-Trp-Gln-Asn-Trp-Thr-Asp-Gly-Gly-Gly-Thr. The endoxylanase expressed in E. coli was identical to that of the riginal Bacillus sp, whose molecular weight was approximately 20,400. Most of the produced endoxylanase was localized in the periplasmic space of E. coli. When the endoxylanase was reacted with 2% oat spelts xylan (w/v) at 40 degrees C for 10 h, the major product was xylobiose which is known to be a selective growth stimulant to one of the healthy intestinal microflora, Bifidobacteria. (C) 1998 Elsevier Science Inc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of medium components on the growth of Anaerobiospirillum succiniciproducens and succinic acid production
No full textSeveral factors affecting cell growth and succinic acid production by Anaerobiospirillum succiniciproducens were examined by cultivating cells under various conditions. Maximum specific growth rate in the flask cultivation increased with increasing initial glucose concentration up to 20 g/l glucose. The distribution of fermentation products was not affected by glucose concentration, and the ratio of fermentation products (g-acetic acid/g-succinic acid) was similar (1:4) for all glucose concentrations. Other carbon sources including lactose, sucrose, maltose, and fructose could be utilized by A. succiniciproducens. Cell concentration and the amount of succinic acid attainable was dependent on the inoculum size. Sodium ion was essential for cell growth and succinic acid production, and its optimum concentration was 4 g/l. Cell growth and succinic acid production were slightly enhanced at the optimum magnesium ion concentration of 0.4 g/l. Among the seven different complex nitrogen sources examined by Plackett-Burman design, only poylpeptone enhanced succinic acid production. (C) 1999 Elsevier Science Ltd. All rights reserved.This research was supported by a grant from the
Ministry of Science and Technology, Korea
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