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To investigate the effects of inoculation strategy and cultivation approach on the performance of microbial fuel cell (MFC).A dual-chamber sediment fuel cell was set up fed with glucose under batch condition. At day 30, the supernatant consortium was partly transferred and used as inoculum for the evaluation of cultivation approach. Power output gradually increased to 9.9 mW m(-2) over 180 days, corresponding to coulombic efficiency (CE) of 29.6%. Separated biofilms attached anode enabled power output and CE dramatically up to 100.9 mW m(-2) and over 50%, respectively, whereas the residual sediment catalysed MFC gave a poor performance. MFC catalysed by in situ supernatant consortium demonstrated more than twice higher power than MFC catalysed by the supernatant consortium after Fe(OH)(3) cultivation. However, the re-generation of biofilms from the latter largely enhanced the cell performance.MFC exhibited a more efficient inducement of electroactive consortium than Fe(OH)(3) cultivation. MFC performance varied depending on different inoculation strategies.This is the first time to study cultivation approach affecting electricity generation. In addition, anodic limitations of mass and electron transfer were discussed through MFC catalysed by sediment-based bio-matrix.

AbstractAfter decades of research, we are starting to understand more about why the number of species varies from place to place on the planet. However, little is known about spatial variation in abundance, especially for soil‐dwelling organisms. In this study, we aimed to disentangle the relative influences of climatic factors, soil properties, and plant diversity on the abundance of soil‐dwelling invertebrates (i.e., nematodes and soil arthropods) at 48 alpine grassland sites on the Tibetan Plateau. We found that the abundance of these two groups of soil organisms was negatively correlated with soil pH and temperature seasonality, and was positively correlated with soil organic carbon (SOC), mean annual precipitation, and plant species richness; there was no effect of mean annual temperature or seasonality in precipitation on the abundance of nematodes or soil‐dwelling arthropods. When we considered only the nematodes, we found that soil pH, mean annual precipitation, temperature seasonality, and SOC were the best predictors of abundance. However, plant species richness was the best predictor of the abundance of soil‐dwelling arthropods. Different orders within the arthropods responded differently to the suite of factors we examined. Taken together, our results suggest that increases in temperature alone might not alter the abundances of soil organisms in these alpine grasslands. Instead, altered precipitation regimes and increases in intra‐annual variation in temperature, changes in plant community diversity, and the resulting changes in soil characteristics (e.g., pH and organic carbon) could reshape soil communities in the Tibetan grassland ecosystems, and likely elsewhere on the planet.

Chinese tallow (Triadica sebifera) is an important crop and ornamental tree. After it was introduced into the USA, it gradually became a noxious invasive tree in south-eastern America since the middle of the 1900s. Because only six microsatellites were reported previously in T. sebifera, to better understand the genetic diversity and population dynamics of such species, we reported here 28 new microsatellite markers. For these 28 microsatellites, the number of alleles per locus ranged from 2-16. The expected heterozygosity and the expected heterozygosity corrected for sample size varied from 0.0796 to 0.9081 and from 0.0805 to 0.9176, respectively. These microsatellites will provide additional choice to investigate the genetic diversity and structure in T. sebifera.

Unproductive enzyme adsorption is an important factor in addition to steric hindrance of lignin that limits the enzymatic hydrolysis of lignocellulosic biomass. While both are important factors, enzymatic hydrolysis of pretreated biomass is most likely conducted in the presence of certain amount of lignin residues that may not necessarily present accessibility hindrance, but can competitively absorb the enzyme. This paper presents a study with purified lignin samples to elucidate the role of unproductive enzyme adsorption. It appeared that lignin adsorbed cellulase quickly at 4 °C with adsorption equilibrium reached within 1h, similar to that observed for crystalline cellulose. Increasing temperature to 50 °C (typical hydrolytic reaction condition) facilitated the rate of cellulase adsorption on cellulose with a peak of adsorption reached at 0.25 h; however, adsorption on lignin was surprisingly slower and took over 12h to reach equilibrium, which was accompanied with a 10-fold increase in adsorption capacity. Despite the high adsorption capacity of lignin (which is comparable to that of cellulose) at 50 °C, the presence of added lignin imposed only minimal impact on the enzyme apparent activity, most likely due to the slow adsorption kinetics of lignin.

Palmitoleic acid (C16:1) and stearic acid (C18:0) are precursors of polyunsaturated fatty acids, which are the focus of intensive global research due to their nutritional value, medicinal applications, and potential use as biofuel. Acyl-acyl carrier protein (ACP) thioesterases are intraplastidial enzymes that determine the types and amounts of fatty acids produced in plants and release fatty acids into the cytosol to be incorporated into glycerolipids. Based on amino acid sequence identity and substrate specificity, these enzymes are classified into two families, FatA and FatB. In this study, we cloned FatA and FatB thioesterases from Arachis hypogaea L. seeds and functionally expressed these genes, both individually and in tandem, in a blue-green alga Synechocystis sp. PCC6803. The heterologous expression of these genes in Synechocystis altered the fatty acid composition of lipids, resulting in a 29.5–31.6% increase in palmitoleic acid production and a 22.5–35.5% increase in stearic acid production. Moreover, the transgenic Synechocystis cells also showed significant increases in levels of oleic acid (C18:1, OA), linoleic acid (C18:2, LA), and α-linolenic acid (C18:3n3, ALA). These results suggest that the fatty acid profile of algae can be significantly improved by the heterologous expression of exogenous genes. This study not only provides insight into fatty acid biosynthesis, but also lays the foundation for manipulating the fatty acid content of cyanobacteria.

The influence of detergent and its components (sodium tripolyphosphate and ethoxylated cetyl oleyl alcohol) at 0.1 % concentration on the enzymatic and metabolic activity of Fusarium oxysporum during exponential growth was investigated in this paper. The fungus Fusarium oxysporum was isolated from wastewater originating from households which contain detergent. The following biochemical parameters were analyzed: pH, redox potential, proteolytic activity, production of carbohydrates, free and total organic acids, proteins and total dry weight biomass. The detergent had influence on the significant decreasing of redox potential, slight increasing of pH and quantity of glucose and total organic acids, while the proteolytic activity was triple insensive in relation to control. The sodium tripolyphosphate had influence on the slight decreasing of pH, significant increasing of redox potential and quantity of glucose and free and total organic acids, whereas the proteolytic activity was intsensive only 5th and 6th day. The total dry weight biomass of the fungus F. oxysporum was slightly inhibited by ethoxylated alcohol but significantly inhibited by detergent and sodium tripolyphosphate.

The inhibitory effect of Al3+on photosystem II (PSII) electron transport was investigated using several biophysical and biochemical techniques such as oxygen evolution, chlorophyll fluorescence induction and emission, SDS-polyacrylamide and native green gel electrophoresis, and FTIR spectroscopy. In order to understand the mechanism of its inhibitory action, we have analyzed the interaction of this toxic cation with proteins subunits of PSII submembrane fractions isolated from spinach. Our results show that Al 3+, especially above 3 mM, strongly inhibits oxygen evolution and affects the advancement of the S states of the Mn4O5Ca cluster. This inhibition was due to the release of the extrinsic polypeptides and the disorganization of the Mn4O5Ca cluster associated with the oxygen evolving complex (OEC) of PSII. This fact was accompanied by a significant decline of maximum quantum yield of PSII (Fv/Fm) together with a strong damping of the chlorophyll a fluorescence induction. The energy transfer from light harvesting antenna to reaction centers of PSII was impaired following the alteration of the light harvesting complex of photosystem II (LHCII). The latter result was revealed by the drop of chlorophyll fluorescence emission spectra at low temperature (77 K), increase of F0 and confirmed by the native green gel electrophoresis. FTIR measurements indicated that the interaction of Al 3+ with the intrinsic and extrinsic polypeptides of PSII induces major alterations of the protein secondary structure leading to conformational changes. This was reflected by a major reduction of α-helix with an increase of β-sheet and random coil structures in Al 3+-PSII complexes. These structural changes are closely related with the functional alteration of PSII activity revealed by the inhibition of the electron transport chain of PSII.