111 research outputs found
Enhancing the tyosine production from acetate in Escherichia coli by optimization of glyoxylate cycle
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Optimizing flux distribution between the glyoxylate and TCA cycle for efficient tyrosine production from acetate in Escherichia coli
No full textAcetate is one of promising feedstocks owing to its cheap price and great abundance. Here, we engineered a previously reported strain, SCK1, for efficient production of tyrosine from acetate. Initially, the acetate uptake and gluconeogenic pathway were amplified to maximize the flux toward tyrosine. As flux distribution between glyoxylate and TCA cycles is critical for efficient precursor supplementation, the activity of the glyoxylate cycle was precisely controlled by expression of isocitrate lyase gene under different-strength promoters. Consequently, the engineered strain with optimal flux distribution produced 0.70 g/L tyrosine with 20% of the theoretical maximum yield which are 60% and 80% increased values of the parental strain. Our strategies would be applicable to the production of various chemicals from acetate in future.
Keywords: Flux optimization, metabolic engineering, tyrosine, acetate2
Precise tuning of the glyoxylate cycle for efficient tyrosine production from acetate in Escherichia coli
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Enhancing production of tyrosine from acetate in Escherichia coli by optimization of glyoxylate shunt pathway
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Optimization of flux distributionbetween the glyoxylate and krebs cycle for efficient tyrosine productionfrom acetate in Escherichia coli
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Precise flux redistribution between the glyoxylate and TCA cycles for efficient tyrosine production from acetate in Escherichia coli
No full text2
Optimizing Flux Distribution Between the Glyoxylate and Krebs Cycle for Efficient Tyrosine Production from Acetate in Escherichia coli
No full text1
Flux optimization between the glyoxylate and TCA cycle for efficient tyrosine production from acetate in Escherichia coli
No full text2
Collective magnetic Higgs excitation in a pyrochlore ruthenate
No full textThe emergence of scalar Higgs-type amplitude modes in systems where symmetry
is spontaneously broken has been a highly successful, paradigmatic description
of phase transitions, with implications ranging from high-energy particle
physics to low-energy condensed matter systems. Here, we uncover two successive
high temperature phase transitions in the pyrochlore magnet NdRuO
at K and K, that lead to giant phonon
instabilities and culminate in the emergence of a highly coherent excitation.
This coherent excitation, distinct from other phonons and from conventional
magnetic modes, stabilizes at a low energy of 3 meV. We assign it to a
collective Higgs-type amplitude mode, that involves bond energy modulations of
the Ru tetrahedra. Its striking two-fold symmetry, incompatible with the
underlying crystal structure, highlights the possibility of multiple entangled
broken symmetries
Network coding for speedup in switches
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 69-71).Network coding, which allows mixing of data at intermediate network nodes, is known to increase the throughput of networks. In particular, it is known that linear network coding in a crossbar switch can sustain traffic patterns that cannot be served if network coding were not allowed. Thus, network coding leads to a larger rate region in a multicast crossbar switch. This thesis quantities the gain in rate region in a multicast crossbar switch in terms of speedup. We present a graph theoretic upper bound on speedup needed to achieve 100% throughput in a multicast switch using network coding. By bounding speedup, we show the equivalence between network coding and speedup in multicast switches - i.e. network coding, which is usually implemented using software, can in many cases substitute speedup, which is often achieved by adding extra switch fabrics. This bound is based on an approach to network coding problems called the "enhanced conflict graph". We show that the "imperfection ratio" of the enhanced conflict graph gives an upper bound on speedup. In particular, we apply this result to K x N switches with traffic patterns consisting of unicasts and broadcasts only to obtain an upper bound of min(2K-1/K, 2N/N+1).by MinJi Kim.M.Eng
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