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991.
Objectives
To investigate the contribution of direct electron transfer mechanisms to electricity production in microbial fuel cells by physically retaining Shewanella oneidensis cells close to or away from the anode electrode.Results
A maximum power output of 114 ± 6 mWm?2 was obtained when cells were retained close to the anode using a dialysis membrane. This was 3.5 times more than when the cells were separated away from the anode. Without the membrane the maximum power output was 129 ± 6 mWm?2. The direct mechanisms of electron transfer contributed significantly to overall electron transfer from S. oneidensis to electrodes, a result that was corroborated by another experiment where S. oneidensis cells were entrapped in alginate gels.Conclusion
S. oneidensis transfers electrons primarily by direct electron transfer as opposed to mediated electron transfer.992.
Jiandong Zhang Zhimei Cui Honghong Chang Xiaojun Fan Qiuyong Zhao Wenlong Wei 《Biotechnology letters》2016,38(9):1559-1564
Objectives
To investigate the efficiency of a cofactor regeneration enzyme co-expressed with a glycerol dehydrogenase for the production of 1,3-dihydroxyacetone (DHA).Results
In vitro biotransformation of glycerol was achieved with the cell-free extracts containing recombinant GlyDH (glycerol dehydrogenase from Escherichia coli), LDH (lactate dehydrogenase form Bacillus subtilis) or LpNox1 (NADH oxidase from Lactobacillus pentosus), giving DHA at 1.3 g l?1 (GlyDH/LDH) and 2.2 g l?1 (GlyDH/LpNox1) with total turnover number (TTN) of NAD+ recycling of 6039 and 11100, respectively. Whole cells of E. coli (GlyDH–LpNox1) co-expressing both GlyDH and LpNox1 were constructed and converted 10 g glycerol l?1 to DHA at 0.2–0.5 g l?1 in the presence of zero to 2 mM exogenous NAD+. The cell free extract of E. coli (GlyDH–LpNox) converted glycerol (2–50 g l?1) to DHA from 0.5 to 4.0 g l?1 (8–25 % conversion) without exogenous NAD+.Conclusions
The disadvantage of the expensive consumption of NAD+ for the production of DHA has been overcome.993.
Objectives
To improve the production and activity of an alkaline zinc metalloprotease from Salinivibrio proteolyticus in response to ZnSO4 (ionic and nanoparticle forms) and low intensity direct electric current (LIDC).Results
A DC of 50 µA for 10 min increased enzyme production from 35 to 53 U ml?1 when applied to the stationary phase bacterial cells. Zn2+ improved enzyme production better than zinc nanoparticles (52 vs. 43.5 U ml?1). Zinc nanoparticles (0.5 mM) added to an enzyme reaction mixture containing casein (0.65 %) and 20 mM Tris/HCl buffer (pH 8) improved enzyme activity more than Zn2+ (42 vs. 36 U ml?1).Conclusion
LIDC exposure (50 µA, 10 min) to the stationary phase bacterial cells increases metalloprotease production in Salinivibrio. A low concentration of zinc nanoparticles (0.5 mM) increases maximum enzyme activity.994.
995.
Pegah Amiri Azar Shahpiri Mohammad Ali Asadollahi Fariborz Momenbeik Siavash Partow 《Biotechnology letters》2016,38(3):503-508
Objectives
To engineer the yeast Saccharomyces cerevisiae for the heterologous production of linalool.Results
Expression of linalool synthase gene from Lavandula angustifolia enabled heterologous production of linalool in S. cerevisiae. Downregulation of ERG9 gene, that encodes squalene synthase, by replacing its native promoter with the repressible MET3 promoter in the presence of methionine resulted in accumulation of 78 µg linalool l?1 in the culture medium. This was more than twice that produced by the control strain. The highest linalool titer was obtained by combined repression of ERG9 and overexpression of tHMG1. The yeast strain harboring both modifications produced 95 μg linalool l?1.Conclusions
Although overexpression of tHMG1 and downregulation of ERG9 enhanced linalool titers threefold in the engineered yeast strain, alleviating linalool toxicity is necessary for further improvement of linalool biosynthesis in yeast.996.
Yoshihisa Shimizu Chiaki Yoshikawa Junji Suzuki Jun Qiu Edith van den Bosch 《Biotechnology letters》2016,38(3):403-408
Objective
When polymer brushes are applied as the inner coating for artificial blood vessels, they may induce unwanted responses in vascular endothelial cells continuously exposed to the polymer surface. Accordingly, we have examined the in vitro effect of non-biofouling concentrated polymer brushes (CPBs) on pro-inflammatory and angiogenic responses of human umbilical vein endothelial cells (HUVECs).Results
Micro-patterned CPBs were prepared on silicon wafers using biocompatible polymers, poly(poly(ethylene glycol)methyl ether methacrylate) (PPEGMA) and poly(2-hydroxyethyl methacrylate) (PHEMA). HUVECs were cultured on PPEGMA-CPBs and PHEMA-CPBs with different channel widths (20, 50, and 80 µm) and analyzed for mRNA expression of the pro-inflammatory cytokines IL-6 and IL-8 and angiogeneic vascular endothelial growth factor (VEGF). Irrespective of channel width, PHEMA-CPBs reduced the expression of all target genes, whereas PPEGMA-CPBs reduced VEGF and did not affect IL-6 and IL-8 levels.Conclusion
Micro-patterned CPBs, irrespective of chemical structure or adhesion area, do not induce the expression of important pro-inflammatory and angiogenic mediators in endothelial cells.997.
Ramdhan Yadav Dharmesh Kumar Avnesh Kumari Sudesh Kumar Yadav 《Biotechnology letters》2016,38(2):259-269
Objectives
Betulin (BT) is an abundant triterpene found predominantly in the bark of Himalayan birch. It is difficult to deliver it in vivo because of its low aqueous solubility. We have therefore developed novel formulations of BT for improving its solubility, bioavailability and therapeutic efficacy.Results
Poly-d,l-lactide nanovectors (PLA NVs) were synthesized using poly(vinyl alcohol) and Lonicera japonica leaf extract (LE) as a stabiliser and named as PLA-1 NVs and PLA-2 NVs. PLA-1 NVs and PLA-2 NVs were used for the encapsulation of betulin (BT) and named as BT-En-1 and BT-En-2 NVs. The encapsulation efficiency of BT-En-1 and BT-En-2 NVs were 99.3 and 100 % respectively. Prepared nanoformulations were physically stable. An in vitro study revealed 45 % BT was released over 24 h. BT had a prolonged release from BT-En-2 NVs as compared to BT-En-1 NVs. BT-En-2 NVs had better anticancerous activity against SiHa cells than BT-En-1 NVs.Conclusions
Developed BT-EN-2 NVs had better biocompatibility, excellent stability and enhanced release characteristics than BT-En-1 NVs.998.
Wei Li Yi Xue Jingjing Li Jing Yuan Xiaotang Wang Wei Fang Zemin Fang Yazhong Xiao 《Biotechnology letters》2016,38(2):345-349
Objectives
To express and characterize a putative α-glucosidase, Pagl, from Pseudoalteromonas sp. K8 obtained via genome mining approach.Results
Pagl was expressed and purified to homogeneity, with a molecular mass of 60 kDa. It was optimally active at pH 8.5 and 30 °C, and showed cold-adapted activity. Pagl exhibited specific activity towards substrates with α-1,4-linkage, with the highest specific activity of 19.4 U/mg for maltose, followed by pNPαG and maltodextrins, suggesting that Pagl belongs to the type II α-glucosidase. Interestingly, the activity of Pagl is significantly enhanced (2.7 times) in the presence of 200 mM glucose.Conclusion
The unique catalytic properties of Pagl make it an attractive candidate for several industrial applications.999.
Xuechang Wu Lijie Zhang Xinna Jin Yahong Fang Ke Zhang Lei Qi Daoqiong Zheng 《Biotechnology letters》2016,38(7):1097-1106
1000.