The R2R3-MYB transcription factor FaMYB63 participates in regulation of eugenol production in strawberry.

The biosynthetic pathway of volatile phenylpropanoids, including 4-allyl-2-methoxyphenol (eugenol), has been investigated in petunia (Petunia hybrida). However, the regulatory network for eugenol accumulation in strawberry (Fragaria × ananassa Duch.) fruit remains unclear. Here, an R2R3-type MYB transcription factor (TF; FaMYB63) was isolated from strawberry by yeast one-hybrid (Y1H) screening using the promoter of the FaEGS1 (eugenol synthase 1 [EGS 1]) gene, which encodes the enzyme responsible for the last step in eugenol biosynthesis. FaMYB63 is phylogenetically distinct from other R2R3-MYB TFs, including FaEOBІІ (EMISSION OF BENZENOID II [EOBII]), which also participates in regulating eugenol biosynthesis in strawberry receptacles. Reverse transcription quantitative PCR (RT-qPCR) assays showed that the expression of FaMYB63 was tissue-specific and consistent with eugenol content through strawberry fruit development, was repressed by abscisic acid, and was activated by auxins (indole-3-acetic acid). Overexpression and RNA interference-mediated silencing of FaMYB63 resulted in marked changes in the transcript levels of the biosynthetic genes FaEGS1, FaEGS2, and FaCAD1 (cinnamyl alcohol dehydrogenase 1 [CAD1]) and, thereby, the accumulation of eugenol. Electrophoretic mobility shift, Y1H, GUS activity, and dual-luciferase activity assays demonstrated that the transcript levels of FaEOBІІ and FaMYB10 were regulated by FaMYB63, but not the other way around. Together, these results demonstrate that FaMYB63 directly activates FaEGS1, FaEGS2, FaCAD1, FaEOBІІ, and FaMYB10 to induce eugenol biosynthesis during strawberry fruit development. These findings deepen the understanding of the regulatory network that influences eugenol metabolism in an edible fruit crop.

Microwave biochar produced with activated carbon catalyst: Characterization and adsorption of heavy metals.

Novel microwave biochar derived from wheat straw (WS) using a range of power levels, with activated carbon catalyst as microwave absorber, was produced, characterized and tested as adsorbent of three heavy metals (Pb2+, Cd2+, and Cu2+). The microwave biochar with the greatest specific surface area (156.09 m2 g-1) and total pore volume (0.0790 cm3 g-1) were produced at 600 W (WS600) and 500 W (WS500) power level, respectively. Maximum adsorption capacities of WS500 to Pb2+, Cd2+ and Cu2+ were 139.44 mg g-1, 52.92 mg g-1, and 31.25 mg g-1, respectively. Optimal pH value for heavy metal removal was at range of 5-6, and Pb2+ showed the strongest affinity in competitive adsorption experiments. The adsorption data were fitted better by pseudo-second-order model and Langmuir isotherm, indicating that adsorption process was mainly explained by monolayer adsorption, and chemical adsorption occupied important role. The predominant adsorption mechanisms of heavy metals on microwave pyrolysis biochar included complexation with oxygen-containing functional groups (i.e., carboxylic acid CO and -OH) and precipitation with carbonate. In addition, reused WS600 maintained 76.17% and 96.07% of their initial adsorption capacity for Cu2+ and Cd2+, respectively. These results suggest that microwave biochar produced with activated carbon catalyst has excellent potential for efficient use in the removal of heavy metals from waste water.

Novel pretreatment with hydrogen peroxide enhanced microwave biochar for heavy metals adsorption: Characterization and adsorption performance.

Hydrogen peroxide (HP) was used to pretreat wheat straw (WS) for microwave biochar production at 100-600 W, the physicochemical properties of pretreated WS and biochar products as well as heavy metals adsorption performance were investigated. Results showed that HP enhanced specific surface area (SSA) and pore volume (PV) of WS, and the largest SSA (190.35 m2 g-1) and PV (0.1493 cm3 g-1) of biochar were obtained at microwave powers of 600 W (HPWS600) and 500 W (HPWS500), respectively. HPWS500 showed maximum adsorption capacities, which were 57.56, 190.21, and 65.16 mg g-1 for Cd2+, Pb2+, and Cu2+, respectively. Solution pH values and cation concentrations exhibited significant effects on adsorption capacities of biochar. The pseudo-second-order kinetic and Langmuir isotherm models fitted better for metal adsorption process. The FTIR results suggested that chemisorption mechanisms including precipitation with carbonate and complexation with oxygen-containing functional groups might be predominant adsorption mechanisms. These results suggest that HP pretreatment has excellent potential for biochar production.

Anaerobic co-digestion of dairy manure and Japanese knotweed (Fallopia japonica) under thermophilic condition: Optimal ratio for biochemical methane production.

Anaerobic co-digestion of animal manure and lignocellulosic biomass is a potent approach for sustainable biomethane production. Co-digestion of dairy manure (DM) and Japanese knotweed (JK), which was collected from a riverbank, was investigated at five different DM-to-JK mixing ratios (100:0, 90:10, 80:20, 60:40, and 0:100; wet weight basis) under thermophilic condition. The results showed that the methane yields obtain from the co-digestion of DM and JK were much higher than that obtained from JK alone (104 ml/gVS), which indicates the synergistic effect and the benefits of co-digesting JK with DM. The highest methane yield (232 ml/gVS) was obtained from the DM-to-JK ratio of 90:10, which was 14.9% and 123.1% higher than that from DM and JK alone, respectively. It also showed the highest synergistic effect (61 ml/gVS). However, further increase in JK ratios led to the decrease in methane yield and synergistic effect. Therefore, applying the co-digestion of DM and JK at a ratio of 90:10 is recommended for biomethane production.

Morphology control and interface characteristics of well-dispersed nanomaterials in K-ion batteries.

Potassium ion batteries (KIBs), the working mechanism of which is similar to that of lithium-ion batteries (LIBs), have drawn much interest as power sources for large-scale grid energy storage because of their low cost and abundant resources. In this paper, the feasibility of KMnF3 as a cathode material for KIBs, the optimization of synthesis conditions and the interface characteristics of the charge and discharge process have been studied in detail. The study of interface characteristics is mainly done through the non-destructive test of electrochemical impedance spectroscopy (EIS).

Effect of solid-liquid separation on anaerobic digestion of dairy manure in semi-continuous stirred tank reactors: Process performance and digestate characteristics.

The objective of this study was to investigate the effect of solid-liquid separation on anaerobic digestion of dairy manure in semi-continuous stirred tank reactors. Reactors fed with liquid fraction of dairy manure (screened liquid manure) were kept in water baths at mesophilic (Run 1) and thermophilic (Run 3) temperatures, respectively, while reactors fed with water diluted manure and kept at mesophilic (Run 2) and thermophilic (Run 4) temperatures as control reactors. The performances of reactors were compared in terms of biogas and methane production, and digestate characteristics. The methane yields obtained from screened manure were higher than those from diluted manure at both mesophilic and thermophilic temperatures, while the highest methane yield was 185 L/kg VSadded under thermophilic temperature. Solid-liquid separation also had improved the effect on digestate fertilizer characteristics. Among four digestates from reactors, the highest contents of nutrients, N (4.12 g/kg) and P (2.36 g/kg) were found in Run 3, while the highest content of K (3.42 g/kg) was found in Run 1. These results showed the benefits of solid-liquid separation of dairy manure on process performance and digestate characteristics.

The survival of pathogenic bacteria and plant growth promoting bacteria during mesophilic anaerobic digestion in full-scale biogas plants.

The introduction of biogas plants is a promising way to recycle organic wastes with renewable energy production and reducing greenhouse gas. Application of anaerobic digestate as a fertilizer reduces the consumption of chemical fertilizers. In this study, the survival of pathogenic bacteria and plant growth promoting bacteria (PGPB) in two full-scale biogas plants operated at mesophilic condition were investigated. Feedstock and anaerobic digestate samples were collected from biogas plants and bacteria load in samples were detected using standard dilution plate method. Pathogenic bacteria were reduced to not detected level through mesophilic digestion tank except for Campylobacter. However, it could be reduced by 98.7% through a sterilization tank. Bacillus was detected at 8.00 and 7.81 log10  CFU/g dry matter in anaerobic digestates, and it was also resistant to sterilization tank. Bacillus spp. is considered to be the safe bacteria that hold remarkable abilities for promoting plant growth. The results showed that treatment at biogas plants is effective to reduce pathogenic bacteria in dairy manure, and sterilization could further reduce the sanitary risks of pathogenic bacteria relating to anaerobic digestate application. Anaerobic digestates could also be utilized as bio-fertilizer as the high load of plant growth promoting bacteria.

Potential of anaerobic digestate of dairy manure in suppressing soil-borne plant disease.

Frequent use of pesticides to control soil-borne plant disease leads to environmental pollution and the development of pesticide resistance in phytopathogens. Soil amendment is considered to have the potential of suppressing plant disease because of its biological properties. However, information on anaerobic digestate is limited. In this study, potential of antagonistic activities of anaerobic digestate against phytopathogens were investigated by detecting the amounts of antagonistic bacteria (Bacillus and Pseudomonas) in anaerobic digestates of dairy manure. The results showed that anaerobic digestion increased the total amounts of Bacillus and Pseudomonas in digestate. Bacillus suppressed growth of phytopathogens, while Pseudomonas did not show any antagonistic activities. These results indicated that Bacillus was an effective antagonistic bacterium in digestate against phytopathogens. Furthermore, two selected isolates, B11 (Bacillus subtilis) and B59 (Bacillus licheniformis), were applied in field experiments and showed significant reduction in percent infection of potato late blight (Phytophthora infestans). These results demonstrate the benefits of digestate in suppressing soil-borne plant diseases caused by antagonistic bacteria.