An efficient method of Yarrowia lipolytica immobilization using oil- and emulsion-modified bacterial cellulose carriers

BackgroundYarrowia lipolytica is a nonconventional, dimorphic yeast with multiple biotechnological applications. Considering the size of Y. lipolytica cells and a plethora of its morphological forms (spherical cells or hyphae and pseudohyphae), it is highly difficult to select a suitable carrier for this useful microorganism. Bacterial cellulose (BC) is currently considered one of the most promising immobilization carriers. In the current study, the usefulness of oil- and emulsion-modified BCs as a carrier for Y. lipolytica immobilization was investigated. Static and agitated cultures were conducted in media supplemented with oil or emulsion to improve carrier porosity.ResultsIt was found that the application of oil- and emulsion-modified BCs correlated with significantly higher efficiency of Y. lipolytica immobilization and hence higher yield than the yield achieved with an unmodified carrier. Increased efficiency of immobilization correlated with BC porosity-related parameters, which, in turn, depended on the size of oil droplets introduced into the culture medium. Moreover, changes in porosity-related parameters caused by the addition of oil or emulsion to the medium were observed when the cultures were conducted only under static conditions and not under agitated conditions.ConclusionThe application of oil- and emulsion-modified BCs as carriers significantly increased the efficiency of Y. lipolytica immobilization as compared to unmodified BC. The addition of oil or emulsion to the culture medium can be a simple but effective method to modify the porosity of BC-based carriers.How to cite: Żywicka A, Wenelska K, Junka A, et al. An efficient method of Yarrowia lipolytica immobilization using oil- and emulsion-modified bacterial cellulose carrier. Electron J Biotechnol 2019;41. https://doi.org/10.1016/j.ejbt.2019.06.004.     

Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot device

We utilize a recently developed microfluidic device, the Optimized Shape Cross-slot Extensional Rheometer (OSCER), to study the elongational flow behavior and rheological properties of hyaluronic acid (HA) solutions representative of the synovial fluid (SF) found in the knee joint. The OSCER geometry is a stagnation point device that imposes a planar extensional flow with a homogenous extension rate over a significant length of the inlet and outlet channel axes. Due to the compressive nature of the flow generated along the inlet channels, and the planar elongational flow along the outlet channels, the flow field in the OSCER device can also be considered as representative of the flow field that arises between compressing articular cartilage layers of the knee joints during running or jumping movements. Full-field birefringence microscopy measurements demonstrate a high degree of localized macromolecular orientation along streamlines passing close to the stagnation point of the OSCER device, while micro-particle image velocimetry is used to quantify the flow kinematics. The stress-optical rule is used to assess the local extensional viscosity in the elongating fluid elements as a function of the measured deformation rate. The large limiting values of the dimensionless Trouton ratio, Tr ∼ O(50), demonstrate that these fluids are highly extensional-thickening, providing a clear mechanism for the load-dampening properties of SF. The results also indicate the potential for utilizing the OSCER in screening of physiological SF samples, which will lead to improved understanding of, and therapies for, disease progression in arthritis sufferers.     

Enhanced expression of HMG-Y proteins in proliferating tissues

The high mobility group (HMG) proteins I and Y are well characterised non-histone chromosomal proteins which bind to A-T rich regions of DNA and regulate gene expression and/or DNA replication. A correlation has been demonstrated between the increased expression of HMG-Y proteins and malignancy. However, it is not known whether the expression of HMGs particularly, the Y group, is a function of proliferation rate. In the present study, we have used normal tissues of calf testes, thymus and liver. The results show distinctly high expression of HMG-Y proteins in testes than in thymus and the expression was practically undetectable in liver. The results suggest that even in normal tissues there is a direct correlation between the proliferation rate and the expression of the HMG-Y proteins, which can partly explain its increased expression in cancer.     

Enhanced efficiency in vector control of a Surface-mounted PMSM drive

In this paper, emphasis has been put on providing the result of a detailed simulation study on the dynamics and efficiency of a vector-controlled voltage source inverter (VSI)-fed surface-mounted permanent magnet synchronous motor (SPMSM) drive; which employs firstly a model-based loss-minimization algorithm (MLMA) and secondly a binary search-based online loss-minimization algorithm (BSOLMA), so as to reduce the total controllable electrical losses without much affecting the dynamic performance of the drive. The steady-state SPMSM model taking into account the core loss has been considered. The dynamic performances of the SPMSM drive employing individually the abovementioned loss minimization algorithms (LMAs) have been compared with that employing conventional zero d-axis current control (ZDCC) through extensive digital computer simulations. The simulation results show that efficiency of the drive enhances with the employment of the LMA.     

Improvement of hydrogen yield of ethanol-producing Escherichia coli recombinants in acidic conditions

BackgroundAn effective single culture with high glycerol consumption and hydrogen and ethanol coproduction yield is still in demand. A locally isolated glycerol-consuming Escherichia coli SS1 was found to produce lower hydrogen levels under optimized ethanol production conditions. Molecular approach was proposed to improve the hydrogen yield of E. coli SS1 while maintaining the ethanol yield, particularly in acidic conditions. Therefore, the effect of an additional copy of the native hydrogenase gene hycE and recombinant clostridial hydrogenase gene hydA on hydrogen production by E. coli SS1 at low pH was investigated.ResultsRecombinant E. coli with an additional copy of hycE or clostridial hydA was used for fermentation using 10 g/L (108.7 mmol/L) of glycerol with an initial pH of 5.8. The recombinant E. coli with hycE and recombinant E. coli with hydA showed 41% and 20% higher hydrogen yield than wild-type SS1 (0.46 ± 0.01 mol/mol glycerol), respectively. The ethanol yield of recombinant E. coli with hycE (0.50 ± 0.02 mol/mol glycerol) was approximately 30% lower than that of wild-type SS1, whereas the ethanol yield of recombinant E. coli with hydA (0.68 ± 0.09 mol/mol glycerol) was comparable to that of wild-type SS1.ConclusionsInsertion of either hycE or hydA can improve the hydrogen yield with an initial pH of 5.8. The recombinant E. coli with hydA could retain ethanol yield despite high hydrogen production, suggesting that clostridial hydA has an advantage over the hycE gene in hydrogen and ethanol coproduction under acidic conditions. This study could serve as a useful guidance for the future development of an effective strain coproducing hydrogen and ethanol.     

启发式与探究式结合下的提高采收率原理教学实践

受课程内容繁杂、教学模式局限等影响,提高采收率原理教学效果不佳。本文在对启发式教学与探究式教学优劣势进行分析的基础上,提出结合提高采收率原理课程特点,借助多元化教学手段,将两种教学模式充分结合,通过巧妙启发,激发学生对课程的兴趣,引导学生进行深层思维;通过合理定向探究,加深学生对课程的认识深度与广度,锻炼学生的思辨能力;并利用现代教学网络平台与学生建立学习共同体,最终提升提高采收率原理课程的教学质量与石油工程专业人才的培养层次。     

藏东南春青稞高产栽培示范推广效益

察雅县在吉塘镇、卡贡乡实施春青稞万亩400公斤高产栽培项目，通过“两改”(坡改梯、低产田改造)、推广良种、机播、种子包衣、增施化肥等综合增产技术示范推广，春青稞平均亩产达409．5kg，增产增收效果显著。     

增强型绿色荧光蛋白在莱茵衣藻中的高效表达

莱茵衣藻素有"光合酵母"之称,是目前少数三套基因组均能进行遗传转化的生物.但由于莱茵衣藻细胞中存在复杂的表达调控体系、密码子偏爱等原因,莱茵衣藻的外源基因表达体系目前还处于探索阶段.通过构建两个莱茵衣藻外源基因表达载体,即以RBCS2序列为启动子的p105和以HSP70A RBCS2序列为启动子的pH105,分别将增强型绿色荧光蛋白基因(egfp)插入两个表达载体中,得到p105G124和pH105G124转化载体.然后通过"珠磨法"转化细胞壁缺陷的莱茵衣藻cc-849,并得到两种类别的转基因藻Tran-Ⅰ和Tran-Ⅱ.在光诱导和热激诱导条件下,两种类型的转基因藻均能稳定表达绿色荧光蛋白.通过实验比较二者的转化效率和蛋白表达水平,结果显示pH105可使egfp基因的转化效率提高8倍;HSP70A-RBCS2启动子至少使绿色荧光蛋白的表达水平提高了2倍,40℃热激后绿色荧光蛋白的表达量再提高约3倍.以上结果表明获得的pH105是一个高效、可诱导的莱茵衣藻外源基因表达载体,这为利用莱茵衣藻高效表达外源基因和开发生物反应器奠定基础.     

Enhanced bilirubin binding to different mammalian erythrocytes in the presence of magnesium ions

Effect of magnesium ions on the binding of bilirubin to erythrocytes of different mammalian species, namely, human, buffalo, goat and sheep was studied. Increase in the concentration of magnesium ions led to a gradual increase in the erythrocyte-bound bilirubin in both human and buffalo erythrocytes whereas in sheep and goat erythrocytes, the pronounced increase was found beyond 2.0 and 2.7 mM MgCl₂ concentrations respectively. Percentage increase in erythrocyte-bound bilirubin was found highest in human erythrocytes followed by buffalo and sheep erythrocytes and minimum in goat erythrocytes. These differences in the binding of bilirubin to different mammalian erythrocytes can be attributed to the differential shielding effect of metal ions which involves the masking of negatively charged phosphate of phospholipids found on the erythrocyte surface.     

Enhanced secondary pollution offset reduction of primary emissions during COVID-19 lockdown in China

To control the spread of the 2019 novel coronavirus(COVID-19),China imposed nationwide restrictions on the movement of its population(lockdown)after the Chinese...     

Contamination of lithium heparin blood by K2-ethylenediaminetetraacetic acid (EDTA): an experimental evaluation

Introduction:

The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K₂EDTA.

Materials and methods:

Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K₂EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K₂EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K₂EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium.

Results:

A significant variation starting from 5% K₂EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K₂EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K₂EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K₂EDTA contamination), sodium, phosphate and iron (from 29% K₂EDTA contamination).

Conclusions:

The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K₂EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K₂EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K₂EDTA contamination.     

Enhanced production of prodigiosin by Serratia marcescens FZSF02 in the form of pigment pellets

BackgroundProdigiosin has been demonstrated to be an important candidate in investigating anticancer drugs and in many other applications in recent years. However, industrial production of prodigiosin has not been achieved. In this study, we found a prodigiosin-producing strain, Serratia marcescens FZSF02, and its fermentation strategies were studied to achieve the maximum yield of prodigiosin.ResultsWhen the culture medium consisted of 16.97 g/L of peanut powder, 16.02 g/L of beef extract, and 11.29 mL/L of olive oil, prodigiosin reached a yield of 13.622 ± 236 mg/L after culturing at 26 °C for 72 h. Furthermore, when 10 mL/L olive oil was added to the fermentation broth at the 24th hour of fermentation, the maximum prodigiosin production of 15,420.9 mg/L was obtained, which was 9.3-fold higher than the initial level before medium optimization. More than 60% of the prodigiosin produced with this optimized fermentation strategy was in the form of pigment pellets. To the best of our knowledge, this is the first report on this phenomenon of pigment pellet formation, which made it much easier to extract prodigiosin at low cost. Prodigiosin was then purified and identified by absorption spectroscopy, HPLC, and LCMS. Purified prodigiosin obtained in this study showed anticancer activity in separate experiments on several human cell cultures: A549, K562, HL60, HepG2, and HCT116.ConclusionsThis is a promising strain for producing prodigiosin. The prodigiosin has potential in anticancer medicine studies.How to cite: Lin C, Jia X, Fang Y, et al. Enhanced production of prodigiosin by Serratia marcescens FZSF02 in the form of pigment pellets. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.007     

我国油田开发中后期提高采收率技术成熟度评估研究

我国陆上油田大多已经进入高、特高含水期,开采难度越来越大,选择适合油藏特征的提高采收率技术对于油田稳产增产日趋重要。本研究梳理了我国油田已应用和将要采用的提高采收率技术清单,提出油田中后期提高采收率技术成熟度评估方法,将技术成熟度等级和技术生命周期对应起来,绘制了技术成熟度曲线,并讨论了各类提高采收率技术的未来发展路线。研究结果表明,蒸汽吞吐、蒸汽驱、聚合物驱等技术目前已基本成熟,在适宜油藏类型和地质特征的油田得到了较为广泛地推广应用；稠油开采技术需拓展矿场实验规模和类型；水驱技术需加强对地质油藏的认识程度和表征精度；化学驱技术需进攻关经济、环保、稳定的体系配方；注气技术需突破气源低成本供应瓶颈；微生物驱技术需扩大试验规模,增强实验效果；超前储备颠覆性技术需做大量基础研究、先导试验、技术攻关试验和矿场试验。     

Improving the yield of Anoectochilus roxburghii by Bacillus licheniformis cultured in Agaricus bisporus industrial wastewater

BackgroundThere is a large amount of industrial wastewater produced by the mushroom industry during the canning processing each year, which could provide abundant carbon, nitrogen and inorganic salts for microbial growth. The aim of this study was to optimize the culture conditions for Bacillus licheniformis cultured in the Agaricus bisporus industrial wastewater to produce the agricultural microbial fertilizer.ResultsIn this work, the maximal biomass of B. licheniformis could be obtained under the following culture conditions: 33.7°C, pH 7.0, 221 rpm shaking speed, 0.5% wastewater, 2 (v:v, %) inoculum dose, loading liquid of 60 mL/250 mL and a culture time of 24 h, and the average experimental value obtained was 1.35 ± 0.04 × 10⁹ Obj/mL, which was within the 95% confidence interval of the predicted model (1.29–1.38 × 10⁹ Obj/mL), and met the national microbial fertilizers' standard in China. Furthermore, the field experiment results showed that the fermentation broth of B. licheniformis could significantly improve the yield of Anoectochilus roxburghii.ConclusionsAgaricus bisporus industrial wastewater can be used to produce agricultural microbial fertilizer.How to cite: Huang J, Huang A, Lu L, et al. Improving the yield of Anoectochilus roxburghii by Bacillus licheniformis cultured in Agaricus bisporus industrial wastewater. Electron J Biotechnol 2020;48. https://doi.org/10.1016/j.ejbt.2020.08.002.