细菌或许是解决可持续能源问题的关键

研究人员对大肠杆菌的脂肪酸路径进行操纵，并用该生物自身反应机制以一种可再生的方式生成丙烷。虽然最初产率低，但能够通过识别和添加必要的生物化学成分以助推该生物合成反应，从而使得特定的大肠杆菌菌种能够合成相当大数量的丙烷。重要的是，这一丙烷生成路径能在有氧存在的情况下操作，这为该系统应用于蓝细菌(以太阳光能为主要能量来源、低营养需求的细菌)开辟了道路。

论文链接:Kallio P，Pásztor A，Thiel K，et al..An engineered pathway for the biosynthesis of renewable propane.

The deployment of next-generation renewable biofuels can be enhanced by improving their compatibility with the current infrastructure for transportation，storage and utilization.Propane，the bulk component of liquid petroleum gas，is an appealing target as it already has a global market.In addition，it is a gas under standard conditions，but can easily be liquefied.This allows the fuel to immediately separate from the biocatalytic process after synthesis，yet does not preclude energy-dense storage as a liquid.Here we report，for the first time，a synthetic metabolic pathway for producing renewable propane.The pathway is based on a thioesterase specific for butyryl-acyl carrier protein(ACP)，which allows native fatty acid biosynthesis of the Escherichia coli host to be redirected towards a synthetic alkane pathway.Propane biosynthesis is markedly stimulated by the introduction of an electron-donating module，optimizing the balance of O2supply and removal of native aldehyde reductases.

提高植物细胞油脂含量的新途径

小球藻可作为生产生物柴油的原料，但含油量相对较低，研究人员将大豆的转录因子GmDof4基因转入椭圆小球藻，在异养条件下GmDof4过表达的藻株含油量比对照提高46.4% ～52.9%，而藻株的生长率并没有受到影响。转录组分析表明，转基因藻株含油量的提高归因于大量相关基因的表达被GmDof4所调控，特别是乙酰辅酶A羧化酶的表达和酶活性被显著上调。

论文链接:Zhang J H，Hao Q，Bai L，et al..Overexpression of the soybean transcription factor GmDof4 significantly enhances the lipid content of Chlorella ellipsoidea.

Biotechnology for Biofuels，2014，7:128.doi:10.1186/s13068 －014 －0128 －4.

Abstract:The lipid content of microalgae is regarded as an important indicator for biodiesel.Many attempts have been made to increase the lipid content of microalgae through biochemical and genetic engineering.Significant lipid accumulation in microalgae has been achieved using biochemical engineering，such as nitrogen starvation，but the cell growth was severely limited.However，enrichment of lipid content in microalgae by genetic engineering is anticipated.In this study，GmDof4 from soybean(Glycine max)，a transcription factor affecting the lipid content in Arabidopsis，was transferred into Chlorella ellipsoidea.We then investigated the molecular mechanism underlying the enhancement of the lipid content of transformed C.ellipsoidea.We constructed a plant expression vector，pGmDof4，and transformed GmDof4 into C.ellipsoidea by electroporation.The resulting expression of GmDof4 significantly enhanced the lipid content by 46.4 to 52.9% ，but did not affect the growth rate of the host cells under mixotrophic culture conditions.The increase in lipid content could be attributed to the large number of genes with regulated expression.In particular，the acetyl-coenzyme A carboxylase gene expression and enzyme activity were significantly upregulated in the transgenic cells.Our research provides a new way to increase the lipid content of microalgae by introducing a specific transcription factor to microalgae strains that can be used for the biofuel and food industries.

基于细菌表面展示酶的生物燃料电池

研究人员利用生物模板法在氟掺杂二氧化锡(FTO)导电玻璃上制备出具有三维多孔结构的金膜，并以此作为电极共价固定漆酶，制成生物阴极。该三维多孔金膜可显著地提高酶的固定效率，并实现直接电子传递。生物阳极则采用细菌表面展示的葡萄糖脱氢酶突变体(bacteria-GDH)。电池在连续工作55 h后仍可保持84%的最大功率密度，表现出较高的稳定性。

论文链接: Chuantao H，Dapeng Y，Bo L，et al..Enhanced performance of a glucose/O2biofuel cell assembled with laccase-covalently immobilized three-dimensional macroporous gold film-based biocathode and bacterial surface displayed glucose dehydrogenase-based bioanode.

Bioanode.Anal.Chem.，2014，86(12):6057 －6063.doi:10.1021/ac501203n.

Abstract:The power output and stability of enzyme-based biofuel cells(BFCs)is greatly dependent on the properties of both the biocathode and bioanode，which may be adapted for portable power production.In this paper，a novel highly uniform three-dimensional(3D)macroporous gold(MP-Au)film was prepared by heating the gold"supraspheres"，which were synthesized by a bottom-up protein templating approach，and followed by modification of laccase on the MP-Au film by covalent immobilization.The as-prepared laccase/MP-Au biocathode exihibited an onset potential of 0.62 V versus saturated calomel electrode(SCE，or 0.86 V vs NHE，normal hydrogen electrode)toward O2reduction and a high catalytic current of 0.61 mAcm－2.On the other hand，mutated glucose dehydrogenase(GDH)surface displayed bacteria(GDH-bacteria)were used to improve the stability of the glucose oxidation at the bioanode.The as-assembled membraneless glucose/O2fuel cell showed a high power output of 55.8 ± 2.0 μW cm－2and open circuit potential of 0.80 V，contributing to the improved electrocatalysis toward O2reduction at the laccase/MP-Au biocathode.Moreover，the BFC retained 84%of its maximal power density even after continuous operation for 55 h because of the high stability of the bacterial surface displayed GDH mutant toward glucose oxidation.Our findings may be promising for the development of more efficient glucose BFC for portable bat tery or self-powered device applications.