Growth and Cell Properties of Modified Lactobacillus plantarum CICC21001 with Supplementing C18-FFAs to Growth Medium in vitro.

Fatty acids (FAs) are one of the important factors that can influence cell growth and membrane composition. The aim of this study was to investigate the influence of supplementing MLM+ growth medium with C18 free fatty acids (C18-FFAs), including stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acid, on the growth of Lactobacillus plantarum CICC21001 by forming ion pairs with lysine to increase the solubility of FAs in liquid medium. The utilization of C18-FFAs was further confirmed by GC-FID. The investigation of cell properties, including cell surface hydrophobicity and zeta potential, was carried out for the modified L. plantarum and control group (non-supplementation). Furthermore, cell survival was measured in real time under heat (at 55 and 62 °C for 5 min), acid (pH 2.2), and bile salt stress. Our results indicated that the action of L. plantarum was modulated by assimilating C18-FFAs. This study suggested that C18-FFAs altered the life cycles and physiochemical properties of L. plantarum, which provided a guideline for probiotics production and their medical application.

Improving the performance of immobilized ß-glucosidase using a microreactor.

Here, we have presented a technically simple and efficient method for preparing a continuous flow microreactor by employing immobilized ß-glucosidase in a silica quartz capillary tube. Developing an immobilized enzyme layer on the inner wall of the capillary tube involved the modification of the inner wall using bifunctional crosslinking agents 3-aminopropyltriethoxysilane and glutaraldehyde before attaching ß-glucosidase. The microreactor afforded unique reaction capacities compared with conventional batch operational configurations. These included enhanced pH and thermal stability during storage tests, increased conversion rates of cellobiose, and reduced product inhibition. The maximum conversion rate of soluble substrate cellobiose digestion in the microreactor was 76% at 50°C and pH 4.8 when the microreactor was operated continually over 10 h at a flow rate of 7 µL/min. This was markedly contrasting to the observed conversion rate of 56% when cellobiose was digested in a conventional batch mode under the same pH and temperature conditions. Reaction inhibition by glucose was significantly reduced in the microreactor. We postulate that the increased capacity of glucose to diffuse into the continual flowing media above the immobilized enzyme layer prevents glucose from reaching inhibitory concentrations at the substrate-enzyme interface.

Effect of metformin on angiotensin Ⅱ-induced abdominal aortic aneurysm in ApoE-/-mice / 中国现代普通外科进展

Objective:To investigate the role of metformin (MET) in inflammatory response in abdominal aortic aneurysm(AAA) formation induced by angiotensin Ⅱ.Methods:AAA models were established by Ang Ⅱ infusion in ApoE-/-mice.Thirty male ApoE-/-mice (8-10-week-old) were randomly and equally divided into four groups:Control group,AAA group and AAA+MET group.HE staining and immunohistochemical staining were used to analyze the inflammatory response.Real-time quantitative polymerase chain reaction (qPCR) was used to analyze the mRNA expression of intercellular cell adhesion molecule-1 (ICAM-1).Western blotting was used to analyze the activation of nuclear factor κB signaling (NF-κB).Results:The AAA incidence and mean maximum suprarenal aortic diameter of AAA group is larger than the AAA+MET group.Compared with the AAA grouP,the expression of ICAM-1 and activity of NF-κB is lower in AAA+MET group.Conclusion:Metformin can attenuate AAA formation partially by regulating macrophage infiltration through regulating the mRNA expression of ICAM-1 regulated by the activation of NF-κB signaling pathway.

Axial multi-image phase retrieval under tilt illumination.

As a coherent diffractive imaging technique, axial multi-image phase retrieval utilizes a series of diffraction patterns on the basis of axial movement diversity to reconstruct full object wave field. Theoretically, fast convergence and high-accuracy of axial multi-image phase retrieval are demonstrated. In experiment, its retrieval suffers from the tilt illumination, in which diffraction patterns will shift in the lateral direction as the receiver traverses along the axis. In this case, the reconstructed result will be blurry or even mistaken. To solve this problem, we introduce cross-correlation calibration to derive the oblique angle and employ tilt diffraction into axial phase retrieval to recover a target, which is successfully demonstrated in simulation and experiment. Also, our method could provide a useful guidance for measuring how obliquely the incident light illuminates in an optical system.

Characterization of a ß-glucosidase from Paenibacillus species and its application for succinic acid production from sugarcane bagasse hydrolysate.

In this study, a ß-glucosidase from Paenibacillus sp. M1 was expressed in E. coli BL21(DE3), purified and characterized. The specific activity of purified BglA was 137.64U·mg-1 protein with optimal temperature and pH of 50°C and 6.0. Furthermore, BglA shows excellent adaption to various environmental factors such as temperature, pH and metal ions. Engineered E. coli Suc260 was further reconstructed by overexpressing the ß-glucosidase for achieving direct cellobiose utilization, which could efficiently utilize the pretreated sugarcane bagasses hydrolysate (SBH) consisting of 25.30g·L-1 cellobiose, 9.70g·L-1 glucose, 5.90g·L-1 arabinose and 7.10g·L-1 xylose. As a result, 26.50g·L-1 and 24.30g·L-1 succinic acid were produced by strain Suc260(pTbglA) from cellobiose and SBH with corresponding yields of 88.30% and 89.20% using dual-phase fermentation, respectively. This study indicated that incomplete enzymatic hydrolysate of SCB will be a potential feedstock for succinic acid production.

Coherent diffraction imaging by moving a lens.

A moveable lens is used for determining amplitude and phase on the object plane. The extended fractional Fourier transform is introduced to address the single lens imaging. We put forward a fast algorithm for the transform by convolution. Combined with parallel iterative phase retrieval algorithm, it is applied to reconstruct the complex amplitude of the object. Compared with inline holography, the implementation of our method is simple and easy. Without the oversampling operation, the computational load is less. Also the proposed method has a superiority of accuracy over the direct focusing measurement for the imaging of small size objects.

Enhanced chitinase production by Chitinolyticbacter meiyuanensis SYBC-H1 using staged pH control.

The pH of a microbiological culture is important for both cell growth and chitinase accumulation, but the optimal pH is not normally the same for both. The objective of this study was to investigate the effect of pH on chitinase production by Chitinolyticbacter meiyuanensis strain SYBC-H1 (ATCC BAA-2140) in a mineral medium. The results of batch culture at different pH values showed that the optimum pH for cell growth and chitinase production varied with time, although KOH produced the best results for cell growth and chitinase production, NaOH was chosen because of cost considerations. We designed a three-stage pH control strategy using NaOH as the neutralizing agent. Maximum cell growth (1.07 g dry cell weight/l) and maximum chitinase activity (13.6 U/ml) were observed after culture at 26°C for 72 h in a mineral medium. These values were greater by 129% and 162%, respectively, and the length of time to attain maximum chitinase activity was decreased by 12 h, compared with results from an earlier study (Hao et al., 2011b).

Comparison of the hydrodynamics and mass transfer characteristics in internal-loop airlift bioreactors utilizing either a novel membrane-tube sparger or perforated plate sparger.

Two gas spargers, a novel membrane-tube sparger and a perforated plate sparger, were compared in terms of hydrodynamics and mass transfer (or oxygen transfer) performance in an internal-loop airlift bioreactor. The overall gas holdup ε T, downcomer liquid velocity V d, and volumetric mass transfer coefficient K L a were examined depending on superficial gas velocity U G increased in Newtonian and non-Newtonian fluids for the both spargers. Compared with the perforated plate sparger, the bioreactor with the membrane-tube sparger increased the values of ε T by 4.9-48.8% in air-water system when the U G was from 0.004 to 0.04 m/s, and by 65.1-512.6% in air-CMC solution system. The V d value for the membrane-tube sparger was improved by 40.0-86.3%. The value of K L a was increased by 52.8-84.4% in air-water system, and by 63.3-836.3% in air-CMC solution system. Empirical correlations of ε T, V d, and K L a were proposed, and well corresponding with the experimental data with the deviation of 10%.