Identification of Cellulose-Degrading Bacteria and Assessment of Their Potential Value for the Production of Bioethanol from Coconut Oil Cake Waste

Bioconversion of lignocellulosic biomass is a highly promising alternative to rapidly reduce reliance on fossil fuels and greenhouse gas emissions. However, the use of lignocellulosic biomass is limited by the challenges of efficient degradation strategies. Given this need, Bacillus tropicus (B. tropicus) with cellulose degradation ability was isolated and screened from rotten dahlia. The strain efficiently utilized coconut oil cake (COC) to secrete 167.3 U/mL of cellulase activity. Electron microscopy results showed significant changes in the structure and properties of cellulose after treatment with B. tropicus, which increased the surface accessibility and the efficiency of the hydrolysis process. The functional group modification observed by Fourier transform infrared spectroscopy indicated the successful depolymerization of COC. The X-ray diffraction pattern showed that the crystallinity index increased from 44.8% to 48.2% due to the hydrolysis of the amorphous region in COC. The results of colorimetry also reveal an efficient hydrolysis process. A co-culture of B. tropicus and Saccharomyces cerevisiae was used to produce ethanol from COC waste, and the maximum ethanol yield was 4.2 g/L. The results of this work show that B. tropicus can be used to prepare biotechnology value-added products such as biofuels from lignocellulosic biomass, suggesting promising utility in biotechnology applications

Controlling Rates and Reversibilities of Elimination Reactions of Hydroxybenzylammoniums by Tuning Dearomatization Energies

Hydroxybenzylammonium compounds can undergo a reversible 1,4- or 1,6-elimination to afford quinone methide intermediates after release of the amine. These molecules are useful for the reversible conjugation of payloads to amines in proteins and peptides. We hypothesized that aromaticity could be used to alter the rate of reversibility as a distinct driving force. We describe the use of density functional theory (DFT) calculations to determine the effect of aromaticity on the rate of release of the amine from hydroxybenzylammonium compounds. Namely, altering the aromatic scaffold to lower the energy of dearomatization reduces the kinetic barrier and prevents the reversibility of the amine elimination. We consequently synthesized a small library of polycyclic hydroxybenzylammoniums, which resulted in a range of release half-lives from 18 minutes to 350 hours. The novel mechanistic insight provided in this study significantly expands the range of release rates amenable to hydroxybenzylammonium-containing compounds. This work is useful for the field of traceless, self-immolative linkers as it provides another way to affect the rate of payload release

Soil-water storage to a depth of 5 m along a 500-km transect on the Chinese Loess Plateau

Soil-water storage (SWS) is an important indicator of the sustainability of regional water resources and is the foundation for developing strategies of land-use management around the world, especially in areas with deficits of soil water. An investigation of the characteristics of SWS at large regional scales can provide valuable information. We measured SWS and available soil-water storage (ASWS) to a depth of 5 m along a 500-km transect across two climatic regions on the Chinese Loess Plateau (CLP). SWS5 m tended to decrease from southeast to northwest and was 320 mm higher in the subhumid than the semiarid zone. SWS5 m and ASWS(5 m) were lower in the dry than the rainy season, but SWS1 m and ASWS(1 m) did not differ significantly between the two seasons except in the 0-100 cm layer. SWS1 m and ASWS(1 m) tended to increase with depth in the semiarid zone and did not change substantially with depth in the subhumid zone. SWS5 m and ASWS(5 m) varied with land use, in the orders cropland > orchard > forest in the subhumid zone and grassland > shrubland > forest in the semiarid zone. Climatic conditions and soil textures were predominant factors affecting SWS at the transect scale. SWS5 m and ASWS(5 m) in the subhumid zone were dependent on clay content, elevation, latitude and the interaction of latitude and temperature, while clay content played a dominant role in the semiarid Zone. Understanding this information is helpful for assessing regional water resources, optimizing the rational use of land and modeling eco-hydrological processes on the CLP and possibly in other water-limited regions around the world. (C) 2016 Elsevier B.V. All rights reserved

Response of deep soil drought to precipitation, land use and topography across a semiarid watershed

Soil drought caused by climatic change and/or poor land management in arid and semi-arid regions are seldom recognised due to a lack of comparative data on soil moisture (SM) in soil profiles. This lack of information endangers the sustainability of these fragile ecosystems. The current study assessed spatial-temporal variations of soil drought, as indicated by dried soil layers (DSL), at a watershed scale, and tested the hypothesis that soil drought in deep profiles is controlled by the combined effects of meteorological processes, land use, and topography. We measured SM to a depth of 500 cm on 20 occasions at 73 locations from 2013 to 2016 at a small watershed on the Chinese Loess Plateau (CLP). We also collected data on possible environmental factors including meteorological variables, land use, topographical elements, and soil properties. The DSLs occurred at > 90% of the sampling sites within the watershed, and the spatially and temporally averaged DSL formation depth (DSLFD), DSL thickness (DSLT) and soil water content within the DSL (DSL-SWC) were 125 cm, 257 cm, and 10.4%, respectively. This suggests that 51.4% of the 500-cm-profile is drying out below 125 cm. The DSLFD, DSLT and DSL-SWC demonstrated a moderate degree of variability (20% < CV < 84%) in space, and showed a moderate, moderate and weak temporal variability, in time, respectively. The temporal series of the mean spatial DSLT and DSLFD were significantly correlated with climatic variables. The spatial variation of the mean temporal DSL-SWC differed significantly among the land uses and between shaded and sunlit aspects. We found that plan curvature, slope gradient, clay and silt content regulated DSLs in both space and time. This result verified our hypothesis that meteorological processes, land use, and topography play an essential role in shaping DSL variation and distribution pattern. Taking DSL reclamation into account in the study area, grassland would be the optimum land use type. Understanding this information is helpful for watershed soil and water conservation, and soil drought meditation via the best management practices in the CLP and other water-limited regions with deep soils

Spatial and temporal variability of 0‐ to 5‐m soil–water storageat the watershed scale

Dynamic relationships among rainfall patterns, soil water distribution, and plant growth are crucial for sustainable conservation of soil and water resources in water-limited ecosystems. Spatial and temporal variation in deep soil water content at a watershed scale have not yet been characterized adequately due to the lack of deep soil water data. Deep soil-water storage (SWS) up to a depth of 5m (n=73) was measured at 19 sampling occasions at the LaoYeManQu watershed on the Chinese Loess Plateau (CLP). At a depth of 0-1.5m, the annual mean SWS was highly correlated with rain intensity, and the correlation decreased with depth, but within the layers at 1.5-5.0m, the changes in SWS indicated a lag between precipitation and the replenishment of soil water. Geostatistical parameters of SWS were also highly dependent on depth, and the mean SWS presented similar spatial structures in two adjacent layers. Temporal stability of SWS as indicated by mean relative difference, standard deviation of the relative difference (SDRD), and mean absolute bias error (MABE) was significantly weaker at the shallow than at deeper layers. Soil separates and organic carbon content controlled the spatial pattern of SWS at the watershed scale. One representative location (Site 57) was identified to estimate the mean SWS in the 1- to 5-m layer of the watershed. Semivariograms of the SDRD and MABE were best fitted by an isotropic spherical model, and their spatial distributions were depth-dependent. Both temporal stability and spatial variability of SWS increased over depth. This study is helpful for deep SWS estimation and sustainable management of soil and water on the CLP, and for other similar regions around the world

Soil-water storage to a depth of 5 m along a 500-km transect on the Chinese Loess Plateau

Soil-water storage (SWS) is an important indicator of the sustainability of regional water resources and is the foundation for developing strategies of land-use management around the world, especially in areas with deficits of soil water. An investigation of the characteristics of SWS at large regional scales can provide valuable information. We measured SWS and available soil-water storage (ASWS) to a depth of 5 m along a 500-km transect across two climatic regions on the Chinese Loess Plateau (CLP). SWS5 m tended to decrease from southeast to northwest and was 320 mm higher in the subhumid than the semiarid zone. SWS5 m and ASWS(5 m) were lower in the dry than the rainy season, but SWS1 m and ASWS(1 m) did not differ significantly between the two seasons except in the 0-100 cm layer. SWS1 m and ASWS(1 m) tended to increase with depth in the semiarid zone and did not change substantially with depth in the subhumid zone. SWS5 m and ASWS(5 m) varied with land use, in the orders cropland > orchard > forest in the subhumid zone and grassland > shrubland > forest in the semiarid zone. Climatic conditions and soil textures were predominant factors affecting SWS at the transect scale. SWS5 m and ASWS(5 m) in the subhumid zone were dependent on clay content, elevation, latitude and the interaction of latitude and temperature, while clay content played a dominant role in the semiarid Zone. Understanding this information is helpful for assessing regional water resources, optimizing the rational use of land and modeling eco-hydrological processes on the CLP and possibly in other water-limited regions around the world. (C) 2016 Elsevier B.V. All rights reserved