Fat,oil,and grease as new feedstock towards bioelectrogenesis in microbial fuel cells:Microbial diversity,metabolic pathways,and key enzymes

Microbial fuel cells(MFCs)are a well-known technology used for bioelectricity production from the decomposition of organic waste via electroactive microbes.Fat,oil,and grease(FOG)as a new substrate in the anode and microalgae in the cathode were added to accelerate the electrogenesis.The effect of FOG concentrations(0.1%,0.5%,1%,and 1.5%)on the anode chamber was investigated.The FOG degradation,volatile fatty acid(VFAs)production,and soluble chemical oxygen demand along with voltage output kinetics were analyzed.Moreover,the microbial community analysis and active functional enzymes were also evaluated.The maximum power and current density were observed at 0.5%FOG which accounts for 96 mW m^(-2)(8-folds enhancement)and 560 mA m^(-2)(3.7-folds enhancement),respectively.The daily voltage output enhanced upto 2.3-folds with 77.08%coulombic efficiency under 0.5%FOG,which was the highest among all the reactors.The 0.5%FOG was degraded>85%,followed by a 1%FOG-loaded reactor.The chief enzymes inβ-oxidation and electrogenesis were acetyl-CoA C-acetyltransferase,riboflavin synthase,and riboflavin kinase.The identified enzymes symbolize the presence of Clostridium sp.(>15%)and Pseudomonas(>10%)which served as electrochemical active bacteria(EAB).The major metabolic pathways involved in electrogenesis and FOG degradation were fatty acid biosynthesis and glycerophospholipid metabolism.Utilization of lipidic-waste(such as FOG)in MFCs could be a potential approach for simultaneous biowaste utilization and bioenergy generation.

Effect of mutations on acetohydroxyacid synthase(AHAS)function in Cyperus difformis L.

Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primary cause for the resistance of Cyperus difformis.However,the effect of different mutations on AHAS function is not clear in Cyperus difformis.To confirm the effect of mutations on AHAS function,six biotypes were collected,including Pro197Arg,Pro197Ser,Pro197Leu,Asp376Glu,Trp574Leu and wild type,from Hunan,Anhui,Jiangxi and Jiangsu provinces,China and the function of AHAS was characterized.The AHAS in vitro inhibition assay results indicated that the mutations decreased the sensitivity of AHAS to pyrazosulfuron-ethyl,in which the I_(50)(the half maximal inhibitory concentration)of wild type AHAS was 0.04μmol L^(-1)and Asp376Glu,Pro197Leu,Pro197Arg,Pro197Ser and Trp574Leu mutations were 3.98,11.50,40.38,38.19 and 311.43μmol L^(-1),respectively.In the determination of enzyme kinetics parameters,the Km and the maximum reaction velocity(Vmax)of the wild type were 5.18 mmol L^(-1)and 0.12 nmol mg^(-1)min^(-1),respectively,and the Km values of AHAS with Asp376Glu,Trp574Leu,Pro197Leu and Pro197Ser mutations were 0.38-0.93 times of the wild type.The Km value of the Pro197Arg mutation was 1.14times of the wild type,and the Vmax values of the five mutations were 1.17-3.33-fold compared to the wild type.It was found that the mutations increased the affinity of AHAS to the substrate,except for the Pro197Arg mutation.At a concentration of 0.0032-100 mmol L^(-1)branched-chain amino acids(BCAAs),the sensitivity of the other four mutant AHAS biotypes to feedback inhibition decreased,except for the Pro197Arg mutation.This study elucidated the effect of different mutations on AHAS function in Cyperus difformis and provided ideas for further study of resistance development.

Study on Synthesis and Deplete Harmful Radical of Cobalt Porphyrins as the Mimic of Enzyme

The four cobalt porphyrins [Co (3, 4, 5 MeO TPP) (1) ; Co (TTP) (2) ; Co (4 CI TPP) (3);Co (4 HSO 3 TPP) (4)] were synthesized and considered as two mimic of superoxide dismutaes (SOD) and catalase (CAT). The catalytic efficiency of them on deplete the harmful radical have been proved using riboflavin methionine photoreduction method in the concentration range of 10 6 ～10 5 mol/L. The catalytic efficiency of them at decomposing H 2O 2 has been performed by spectrophotometer. The percentage of decomposing H 2O 2 while the increasing the concentration of the imitating compounds. The lipid peroxidationproduced in liver homogenatcd of mice was determined by spectrophotometer detecting the content of MDA.

Design and construction of microbial cell factories based on systems biology

Environmental sustainability is an increasingly important issue in industry.As an environmentally friendly and sustainable way,constructing microbial cell factories to produce all kinds of valuable products has attracted more and more attention.In the process of constructing microbial cell factories,systems biology plays a crucial role.This review summarizes the recent applications of systems biology in the design and construction of microbial cell factories from four perspectives,including functional genes/enzymes discovery,bottleneck pathways identification,strains tolerance improvement and design and construction of synthetic microbial consortia.Systems biology tools can be employed to identify functional genes/enzymes involved in the biosynthetic pathways of products.These discovered genes are introduced into appropriate chassis strains to build engineering microorganisms capable of producing products.Subsequently,systems biology tools are used to identify bottleneck pathways,improve strains tolerance and guide design and construction of synthetic microbial consortia,resulting in increasing the yield of engineered strains and constructing microbial cell factories successfully.