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A new strategy to control the molecu...
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Shi, Fengying.
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A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media.
紀錄類型:
書目-語言資料,印刷品 : Monograph/item
正題名/作者:
A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media./
作者:
Shi, Fengying.
面頁冊數:
170 p.
附註:
Adviser: Richard A. Gross.
Contained By:
Dissertation Abstracts International57-10B.
標題:
Biology, Microbiology. -
電子資源:
http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9708446
ISBN:
0591157195
A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media.
Shi, Fengying.
A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media.
- 170 p.
Adviser: Richard A. Gross.
Thesis (Ph.D.)--University of Massachusetts Lowell, 1995.
Polyethylene glycol (PEG) was found to be a useful tool in the molecular weight control of Poly($\beta$-hydroxybutyrate) (P3HB) produced by Alcaligenes eutrophus in nitrogen free media with fructose as the carbon source. The lower the PEG molecular weight, the more dramatic the molecular weight decrease of synthesized P3HB; the molecular weight of P3HB from PEG-106 amended media was less than half of that from PEG-1000 supplemented media. Hydroxyl terminal groups of PEG with relatively low molecular weight played an important role in the molecular weight control of P3HB. In contrast, when PEG-10,000 was introduced to the polymer accumulation media, the molecular weight of obtained P3HB increased to about twice that of P3HB synthesized in PEG deficient media. Monomethoxy substituted PEG, CH$\sb3
ISBN: 0591157195Subjects--Topical Terms:
1017734
Biology, Microbiology.
A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media.
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A new strategy to control the molecular weights and compositions of PHAS produced by Alcaligenes eutrophus (ATCC 17699) by the addition of poly(ethylene glycol) to the cultivation media.
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170 p.
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Adviser: Richard A. Gross.
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Source: Dissertation Abstracts International, Volume: 57-10, Section: B, page: 6062.
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Thesis (Ph.D.)--University of Massachusetts Lowell, 1995.
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Polyethylene glycol (PEG) was found to be a useful tool in the molecular weight control of Poly($\beta$-hydroxybutyrate) (P3HB) produced by Alcaligenes eutrophus in nitrogen free media with fructose as the carbon source. The lower the PEG molecular weight, the more dramatic the molecular weight decrease of synthesized P3HB; the molecular weight of P3HB from PEG-106 amended media was less than half of that from PEG-1000 supplemented media. Hydroxyl terminal groups of PEG with relatively low molecular weight played an important role in the molecular weight control of P3HB. In contrast, when PEG-10,000 was introduced to the polymer accumulation media, the molecular weight of obtained P3HB increased to about twice that of P3HB synthesized in PEG deficient media. Monomethoxy substituted PEG, CH$\sb3
$o
-PEG-OH-350, and free PEG with similar chain length had equal effects on P3HB production and molecular weight control. When both hydroxyl terminal groups of tetraethylene glycol (TEG) were capped by methoxy functionalities, the resulting dimethoxy TEG, CH$\sb3
$o
-TEG-OCH$\sb3$, had little effect on P3HB molecular weight change. This was in direct contrast to the result by HO-TEG-OH or PEG-200. Polyethylene oxide with dicarboxyl terminal groups, HOOC-PEG-COOH-600 had virtually the same effects on P3HB production and molecular weight control.
520
$a
When 4-hydroxybutyric acid was used as the sole carbon source in the second stage media, polyesters with 4-hydroxybutyrate (4HB) repeat units were formed. The addition of PEG-200 from 0 to 2% increased the 4HB content in the polymer from 66 to 86 mol%. Proton nuclear magnetic resonance ($\sp1
$h
NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) analyses of the polyhydroxyalkanoates (PHAs) produced in 4% PEG-200 medium showed that the polymer product was a mixture of polyesters with complex components. Also the two dimentional homonuclear ($\sp1
$h
NMR) correlated (COSY) spectrum confirmed that a PHA-PEG diblock copolymer was formed. The PEG-200 uptake in A. eutrophus cells was unusually high, which was related to the formation of PHA-PEG diblock copolymers. The fractionation of the PHA in acetone separated the mixture to acetone soluble (AS) and insoluble (AIS) two fractions. The AS and AIS fractions are composed of 4HB and 3HB enriched chain segments respectively. PEGs with different molecular weights and different terminal functionalities were studied as to the effects of PHA compositional manipulation. In some of the nitrogen free media amended by PEGs, such as PEG-300 or CH$\sb3
$o
-PEG-OH-350 reinforced the novel 3-hydroxyvaleryl-CoA biosynthetic pathway, in that PHA with 3HV repeat units was formed at a relatively low concentration of PEG eve in PEG deficient media.
520
$a
The scale-up fermentations of A. eutrophus in PEG deficient media, 4% PEG-106, 1,4-butanediol, PEG-1000 and ethylene glycol supplemented media were carried out. The resulting PHAs were fractionized in acetone and the AS and AIS fraction were analyzed by GPC and $\sp1
$h
NMR. It was found that all of PHAs were polyesters mixtures with very different compositions. AS fractions always had lower molecular weight than the corresponding AIS fractions.
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http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9708446
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