1,3-Propanediol and its copolymers: research, development and industrialization

1,3-Propanediol (PDO), is now taking the transition from a traditional "specialty chemical" to a "commodity chemical". The market for PDO is growing rapidly as the technology develops. With the advancing PDO production technology, polytrimethylene terephthalate (PTT) as a new type of polyester has been applied in carpet and textile fibers, monofilaments, films, and nonwoven fabrics, and in the engineering thermoplastics area, because PTT has unique properties compared to other polymers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Responding to the environmental and sustainability factors, one- or two-step fermentation technology for PDO production has attracted people's attention. A novel flexible process for PDO production by using aerobic fermentation from glycerol or glucose has been developed and demonstrated with a facility capacity of 4000 t/year in a pilot plant. By using engineered Escherichia coli, 135 g/L PDO was obtained with glucose as feedstock. Since the bio-process of PDO production consumes 40% less energy and reduces greenhouse gas emissions by 20% versus petroleum-based propanediol, the bio-based PTT is more environmentally friendly and sustainable compared with the fossil fuel-based polymers, which made PTT more attractive with good prospects for the future.     

聚乙二醇丙烯酸酯的合成与表征

以聚乙二醇-400（PEG400）与丙烯酸直接缩合反应,在不加有毒带水剂的条件下合成了丙烯酸聚乙二醇酯（PEGA）。通过正交实验确定酯化反应的最佳条件：丙烯酸／PEG400的摩尔比为2．0：1．0,反应温度是110℃,阻聚剂对苯二酚为0．4％（以醇酸总质量计）,反应时间为6小时,催化剂对甲苯磺酸为0．8％（以醇酸总质量计）,产率为76．7％。产品结构经IR和1HNMR表征,证明是所需的产物。     

Hydrolysis of PET and bis-(benzoyloxyethyl) terephthalate with a new polyesterase from Penicillium citrinum

A polyethylene terephthalate (PET) model substrate, bis-(benzoyloxyethyl)terephthalate (3PET), was used to screen for micro-organisms producing enzymes hydrolyzing PET. From this screen, a strain growing on 3PET was isolated and identified as Penicillium citrinum. The polyesterase responsible for 3PET and PET hydrolysis was purified to electrophoretic homogeneity. The polyesterase had a molecular weight of 14.1 kDa, and the K_m and K_cat values on 4-nitrophenyl butyrate were 0.57 mM and 0.21 s^-1, respectively. Highest enzyme activities were obtained when P. citrinum was grown on a medium containing cutin, which was hydrolyzed by the polyesterase. Surface hydrolysis of PET with the enzyme lead to an increase in hydrophilicity based on rising height (+5.1 cm) and drop dissipation measurements (55 s). Both from PET and 3PET bis-(2-hydroxyethyl)terephthalate and mono-(2-hydroxyethyl)terephthalate were released, while only low amounts of terephthalic acid were liberated.     

Hg2+ and small-sized polyethylene glycols have inverse effects on membrane permeability, while both impair neutrophil cell motility

Toxic effects after exposure to mercury are well documented in human. Little is, however, known about how Hg(2+) affect host defense in general and neutrophil functions in particular. We show here that exposure of human neutrophils to HgCl(2) dose-dependently impairs chemoattractant-stimulated motility. Long-term exposure (5-10 min) to Hg(2+) yields a rapid influx of extracellular Ca(2+) followed by leakage of cytosolic fluorophores, as assessed using fura-2 and ratio imaging microscopy. The inhibition on motility was partly reversible, since pre-treated neutrophils placed in an Hg(2+)-free environment displayed higher migration rates. The Hg(2+)-induced fluxes were prevented by addition of small-sized polyethylene glycols (PEG 200-400), which also dose-dependently inhibited neutrophil transmigration. Localized, minute micropipette additions of Hg(2+) or PEG caused retraction of the leading edge and redirection of cell migration. Since Hg(2+) increases and PEGs decrease membrane permeability in a partially competitive manner, we suggest that the known aquaporin-inhibitor Hg(2+) alters membrane permeability by affecting the bidirectional flux through the leukocyte aquaporin-9 (AQP9) while small-sized PEGs yield decreased membrane permeability by becoming trapped in the promiscuous channel. The local additions of Hg(2+) or PEG probably force other cell regions to take over from those with blocked AQPs. Hence, the cells turn direction of motility away from the micromanipulator needle.     

Effect of Additives on the Production, Viability and Virulence of Blastospores of Metarhizium anisopliae

Studies on the blastospore production of Metarhizium anisopliae var. anisopliae were conducted in Adamek's medium used as a standard, enriched with lecithin, collagen, lactic acid or polyethylene glycol 200 (PEG 200) to increase spore yield and suppress mycelial pellet formation. The addition of 5% lecithin resulted in a significant 10-fold increase in spore yield up to 1.9 108 blastospores/ml compared with 1.9 107 spores/ml in the standard medium. Collagen (3%) increased the number of blastospores 3.7-fold, and lactic acid (1.5%) two-fold. A reduction of mycelial pellet formation in favour of spore production was noted with each additive. The viability of blastospores at 40IC from media with lecithin, collagen and lactic acid suspended in 25% Ringer's solution was comparable to that of spores produced in the standard medium. Striking differences were noticed in the viability of spores produced with 5% PEG 200 in standard medium. The half-life of blastospores produced in standard medium suspended in sunflower oil was 33.6 h and that of 5% PEG 200 spores only 25.2 h. In bioassays, the virulence of spores produced in standard medium to which 3% lecithin, 3% collagen, 1.5% lactic acid or 5% PEG 200 had been added was tested against third-instar nymphs of Locusta migratoria migratorioides (R. & F.). The median lethal time and the mortality of L. migratoria achieved with blastospores produced with 3% lecithin (5.7 days, 99%) was comparable to that of blastospores from standard medium (5.1 days, 98%). The virulence of blastospores from all other media with additives was significantly reduced.     

角质酶在生物可降解聚酯聚己二酸/对苯二甲酸丁二醇酯降解中的应用

随着废弃塑料带来的环境污染越来越严重,生物可降解聚酯已成为大众关注的焦点。聚己二酸/对苯二甲酸丁二醇酯[poly(butylene adipate-co-terephthalate),PBAT]是脂肪族和芳香族共聚形成的生物可降解聚酯,兼具两者的优异性能。针对PBAT在自然条件下对降解环境要求严格且降解周期长的不足之处,本研究探究了角质酶在PBAT降解中的应用和对苯二甲酸-丁二醇酯(butylene terephthalate,BT)含量对PBAT生物降解性的影响,以实现对PBAT降解速率的提升。选取5种不同来源的聚酯降解酶对PBAT进行降解应用并比较出降解效果最优的酶,并测定了含有不同BT含量的PBAT聚酯的降解效率。结果表明,角质酶ICCG为降解效果最好的酶,且BT含量越高PBAT的降解率越低。此外,还确定了角质酶ICCG对高BT含量的PBAT(H)降解的最适温度、最适缓冲液类型、最适pH、最适E/S(enzyme to substrate)和最适底物浓度比分别为75℃、Tris-HCl、9.0、0.4%和1.0%。本研究结果可为角质酶在PBAT降解中的应用提供一定的理论依据和实验...     

Chemical modification of Vibrio vulnificus metalloprotease with activated polyethylene glycol

Abstract Vibrio vulnificus , an opportunistic human pathogen causing septicemia, produces a metalloprotease which is suspected to be a virulence determinant, but which is labile in vivo due to inactivation by α -macroglobulin. To obtain a derivative which is stable in vivo, the metalloprotease was modified with activated monomethoxy polyethylene glycol. The modified protease retained full activity to a peptide substrate and 10–20% activity to protein substrates, and was resistant to entrapment by α -macroglobulin because of the increased molecular size (approx. 90 kDa). These findings suggest that the modified protease is stable in vivo and may be used to investigate the pathological actions of the protease in the bloodstream.     

紫云英细胞转化条件的研究

研究了紫云英（ＡｓｔｒａｇａｌｕｓｓｉｎｉｃｕｓＬ．）细胞遗传转化的条件。根癌农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍｔｕｍ ｅｆａｃｉｅｎｓ）经含乙酰丁香酮的低ｐＨ／ＰＯ３－４ 诱导培养后,用来感染紫云英下胚轴原生质体,随后的细胞ＧＵＳ瞬间表达活性显著提高,间接证明了上述预培养诱导活化了细菌ｖｉｒ基因,促进了Ｔ－ＤＮＡ 向植物细胞转移。在ＰＥＧ介导的ＤＮＡ 转移中,较高的ｐＨ 和Ｃａ２＋ 浓度能够提高细胞ＧＵＳ活性。质粒ＤＮＡ 浓度及启动子类型对外源基因在植物细胞内表达也有一定影响。采用外植体－农杆菌共培养法,获得ＧＵＳ和ＮＰＴ Ⅱ基因稳定表达的紫云英转化植株     

豇豆原生质体遗传转化的研究(简报)

豆科植物中有重要的粮食,油料及蔬菜作物,一直是国内外学者热衷研究的对象。豆科作物遗传转化的研究,虽已取得一些进展,但有关籽粒型豆科重要作物细胞转化的报道仍不多。我们以豇豆下胚轴为材料,探讨了农杆菌介导的和PEG介导的外源DNA转移到豇豆细胞的条件,并获得外源基因稳定表达的转化愈伤组织。豇豆原生质体分离与培养:豇豆种子用0.1%HgCl_2灭菌20min,无菌水冲洗数次后,置1/2MS_0培养基上萌发3—4天(25℃),在超净工作台上切取子叶。参照我们以前所采用的方法分离和培养豇豆原生质体(MS培养基)。     

Protocols for production of selenomethionine-labeled proteins in 2-L polyethylene terephthalate bottles using auto-induction medium

Protocols have been developed and applied in the high-throughput production of selenomethionine labeled fusion proteins using the conditional Met auxotroph Escherichia coli B834. The large-scale growth and expression uses a chemically defined auto-induction medium containing 125 mg L(-1) selenomethionine, salts and trace metals, other amino acids including 10 mg L(-1) of methionine, vitamins except vitamin B12, and glucose, glycerol, and alpha-lactose. A schematic for a shaker rack that can hold up to twenty-four 2-L polyethylene terephthalate beverage bottles in a standard laboratory refrigerated floor shaker is provided. The growth cycle from inoculation of the culture bottle through the growth, induction, and expression was timed to take approximately 24 h. Culture growth in the auto-induction medium gave an average final optical density at 600 nm of approximately 6 and an average wet cell mass yield of approximately 14 g from 2 L of culture in greater than 150 expression trials. A simple method for visual scoring of denaturing electrophoresis gels for total protein expression, solubility, and effectiveness of fusion protein proteolysis was developed and applied. For the favorably scored expression trials, the average yield of purified, selenomethionine-labeled target protein obtained after proteolysis of the fusion protein was approximately 30 mg. Analysis by mass spectrometry showed greater than 90% incorporation of selenomethionine over a approximately 8-fold range of selenomethionine concentrations in the growth medium, with higher growth rates observed at the lower selenomethionine concentrations. These protein preparations have been utilized to solve X-ray crystal structures by multiwavelength anomalous diffraction phasing.