1,720,977 research outputs found
Effect of carbon sources on the end-product profile of Anaerobiospillum succiniciproducens
No full textKinetic study on succinic acid and acetic acid formation during continuous cultures of Anaerobiospirillum succiniciproducens grown on glycerol
No full textSuccinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically grown in a glycerol-fed continuous bioreactor in order to investigate the physiological responses of the cell to different pH values (5.9, 6.2, or 6.5) and various dilution rates, D. In these experiments, A. succiniciproducens showed a pH-dependent glycerol consumption behavior. When pH was maintained at 5.9 or 6.5, glycerol started to accumulate even at a very low D of 0.027 h(-1). Succinic acid yield was not significantly affected by the pH of the culture or the Ds. However, more acetic acid formation was observed when the growth rate of A. succiniciproducens was fast on glycerol at pH 6.2 (at D a parts per thousand yen 0.15 h(-1)). The highest obtainable succinic acid/acetic acid ratio was 40:1, which was 10 times higher than that obtained by batch cultures grown on glucose. The maximum obtainable productivity of succinic acid was 2.1 g L(-1) h(-1)), which was 14 times higher than that obtained by batch culture.This work was supported by Innovative Fund
from the Ministry of Knowledge and Economics (P.C. Lee) and by
the Genome-based Integrated Bioprocess Development Project from
the Ministry of Education, Science and Technology (S. Y. Lee and
H. N. Chang)
Effects of medium components on cell growth and succinic acid production by Anaerobiospirillum succiniciproducens
No full textComparative Genome Analysis of Psychrobacillus Strain PB01, Isolated from an Iceberg
No full textA novel psychrotolerant Psychrobacillus strain PB01, isolated from an Antarctic iceberg, was comparatively analyzed with five related strains. The complete genome of strain PB01 consists of a single circular chromosome (4.3 Mb) and a plasmid (19 Kb). As potential low-temperature adaptation strategies, strain PB01 has four genes encoding cold-shock proteins, two genes encoding DEAD-box RNA helicases, and eight genes encoding transporters for glycine betaine, which can serve as a cryoprotectant, on the genome. The pan-genome structure of the six Psychrobacillus strains suggests that strain PB01 might have evolved to adapt to extreme environments by changing its genome content to gain higher capacity for DNA repair, translation, and membrane transport. Notably, strain PB01 possesses a complete TCA cycle consisting of eight enzymes as well as three additional Helicobacter pylori-type enzymes: ferredoxin-dependent 2-oxoglutarate synthase, succinyl-CoA/acetoacetyl-CoA transferase, and malate/quinone oxidoreductase. The co-existence of the genes for TCA cycle enzymes has also been identified in the other five Psychrobacillus strains
Complete microbial synthesis of crocetin and crocins from glycerol in Escherichia coli
No full textBackground: Crocin, a glycosylated apocarotenoid pigment predominantly found in saffron, has garnered significant interest in the field of biotechnology for its bioactive properties. Traditional production of crocins and their aglycone, crocetin, typically involves extraction from crocin-producing plants. This study aimed to develop an alternative biosynthetic method for these compounds by engineering the metabolic pathways of zeaxanthin, crocetin, and crocin in Escherichia coli strains.Results:<bold> </bold>Employing a series of genetic modifications and the strategic overexpression of key enzymes, we successfully established a complete microbial pathway for synthesizing crocetin and four glycosylated derivatives of crocetin, utilizing glycerol as the primary carbon source. The overexpression of zeaxanthin cleavage dioxygenase and a novel variant of crocetin dialdehyde dehydrogenase resulted in a notable yield of crocetin (34.77 +/- 1.03 mg/L). Further optimization involved the overexpression of new types of crocetin and crocin-2 glycosyltransferases, facilitating the production of crocin-1 (6.29 +/- 0.19 mg/L), crocin-2 (5.29 +/- 0.24 mg/L), crocin-3 (1.48 +/- 0.10 mg/L), and crocin-4 (2.72 +/- 0.13 mg/L).Conclusions:<bold> </bold>This investigation introduces a pioneering and integrated microbial synthesis method for generating crocin and its derivatives, employing glycerol as a sustainable carbon feedstock. The substantial yields achieved highlight the commercial potential of microbial-derived crocins as an eco-friendly alternative to plant extraction methods. The development of these microbial processes not only broadens the scope for crocin production but also suggests significant implications for the exploitation of bioengineered compounds in pharmaceutical and food industries.
Melanin biopolymer synthesis using a new melanogenic strain of Flavobacterium kingsejongi and a recombinant strain of Escherichia coli expressing 4-hydroxyphenylpyruvate dioxygenase from F. kingsejongi
Full text linkBackground
Melanins are a heterologous group of biopolymeric pigments synthesized by diverse prokaryotes and eukaryotes and are widely utilized as bioactive materials and functional polymers in the biotechnology industry. Here, we report the high-level melanin production using a new melanogenic Flavobacterium kingsejongi strain and a recombinant Escherichia coli overexpressing F. kingsejongi 4-hydroxyphenylpyruvate dioxygenase (HPPD).
Results
Melanin synthesis of F. kingsejongi strain was confirmed via melanin synthesis inhibition test, melanin solubility test, genome analysis, and structural analysis of purified melanin from both wild-type F. kingsejongi and recombinant E. coli expressing F. kingsejongi HPPD. The activity of F. kingsejongi HPPD was demonstrated via in vitro assays with 6 × His-tagged and native forms of HPPD. The specific activity of F. kingsejongi HPPD was 1.2 ± 0.03 μmol homogentisate/min/mg-protein. Bioreactor fermentation of F. kingsejongi produced a large amount of melanin with a titer of 6.07 ± 0.32 g/L, a conversion yield of 60% (0.6 ± 0.03 g melanin per gram tyrosine), and a productivity of 0.03 g/L·h, indicating its potential for industrial melanin production. Additionally, bioreactor fermentation of recombinant E. coli expressing F. kingsejongi HPPD produced melanin at a titer of 3.76 ± 0.30 g/L, a conversion yield of 38% (0.38 ± 0.03 g melanin per gram tyrosine), and a productivity of 0.04 g/L·h.
Conclusions
Both strains showed sufficiently high fermentation capability to indicate their potential as platform strains for large-scale bacterial melanin production. Furthermore, F. kingsejongi strain could serve as a model to elucidate the regulation of melanin biosynthesis pathway and its networks with other cellular pathways, and to understand the cellular responses of melanin-producing bacteria to environmental changes, including nutrient starvation and other stresses.publishe
고효율 연속 발효에 의한 유기산 제조 방법
No full textThe present invention provides a method for manufacturing organic acid by high-efficiency fermentation, which comprises the steps of continuous culture of organic acid bacteria and collection of organic acid produced from the culture employing a cell-recycle multiple-stage continuous fermentor with serially connected fermentors, each of which comprises a fermentor containing a ferment container, temperature controller, stirrer, and pH controller; pumps for efflux-circulation of media from the fermentor; and, cell separator for separation and circulation of media from the pumps. According to the present method, the high-concentration lactic acid of 90 g/L can be produced with the high productivity of 50 g/L/h, which can reduce the facility cost and production cost in the bulk manufacturing process. In addition, the present invention can be effectively applied to the production of other organic acids such as acetic acid, formic acid, citric acid, malic acid, maleic acid, fumaric acid, and succinic acid, which show the end-product inhibition
유산의 경제적 생산을 위한 고효율 발효방법
No full textThe present invention provides a method for manufacturing organic acid by high-efficiency fermentation, which comprises the steps of continuous culture of organic acid bacteria and collection of organic acid produced from the culture employing a cell-recycle multiple-stage continuous fermentor with serially connected fermentors, each of which comprises a fermentor containing a ferment container, temperature controller, stirrer, and pH controller; pumps for efflux-circulation of media from the fermentor; and, cell separator for separation and circulation of media from the pumps. According to the present method, the high-concentration lactic acid of 90 g/L can be produced with the high productivity of 50 g/L/h, which can reduce the facility cost and production cost in the bulk manufacturing process. In addition, the present invention can be effectively applied to the production of other organic acids such as acetic acid, formic acid, citric acid, malic acid, maleic acid, fumaric acid, and succinic acid, which show the end-product inhibition
Anaerobiospirillum succiniciproducens와 mannheimia sp.을 이용한 생물학적 숙신산 생산
No full text학위논문(박사) - 한국과학기술원 : 화학공학과, 2001.2, [ x, 127 p. ]Physiological and cultural characteristics of a succinate-producing Anaerobiospirillum succiniciproducens and a novel succinate-producing Mannheimia sp., isolated from bovine rumen, were studied to develop the biological systems for succinic acid production. Among several environmental and physiological factors affecting cell growth and end-product formation, the external supply of and enhanced the growth of A. succiniciproducens and its succinic acid formation. Steady-state parameters obtained by the continuous cultures of A. succiniciproducens indicated that both succinic acid production and acetic acid production were found to be growth-associated and that the formation of unwanted acetic acid reduced the succinic acid yield and cell growth. Acetic acid formation could be avoided by using glycerol as a carbon source during the batch and continuous cultures. Accordingly, a high yield and productivity of succinic acid could be obtained. Inexpensive materials such as whey, wood hydrolysate, and corn steep liquor could be effectively utilized by A. succiniciproducens. A novel succinate-producing Mannheimia sp. 55E isolated from bovine rumen is a metabolically versatile bacterium capable of growing either anaerobically and aerobically. It fermented glucose to succinic, acetic, formic, and lactic acids in response to environmental conditions. Under 100% condition, more succinic acid and less lactic acid were formed, and cells grew well. The culture pH did not affect the ratio of end-products formed under 100% condition. Whereas, under 100% condition, more lactic acid and less succinic acid were formed, and cells grew poor. Aerobically, Mannheimia sp. 55E produces lactic and acetic acids without exhausted gas and irrespective of initial glucose concentration, which indicated that this bacterium may not have tricarboxylic acid cycle (TCA). The pckA gene encoding phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in the cen...한국과학기술원 : 화학공학과
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