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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.

The biosynthetic pathway of volatile phenylpropanoids, including eugenol, has been investigated in petunia (Petunia hybrida). However, the regulatory network for eugenol accumulation in strawberry (Fragaria × ananassa Duch.) fruit remains unclear. Here, a R2R3-type MYB transcription factor (FaMYB63) was isolated from strawberry by yeast one-hybrid screening using the promoter of the FaEGS1 (eugenol synthase 1) gene, which encodes the enzyme responsible for the last step in eugenol biosynthesis. FaMYB63 is phylogenetically distinct from other R2R3-MYB transcription factors, including FaEOBІІ, which also participates in regulating eugenol biosynthesis in strawberry receptacles. 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 (ABA), and was activated by auxins (IAA). Overexpression and RNAi-mediated silencing of FaMYB63 resulted in marked changes in the transcript levels of the biosynthetic genes FaEGS1, FaEGS2, and FaCAD1 and, thereby, the accumulation of eugenol. Electrophoretic mobility shift, yeast one-hybrid, 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.

One of the new trends of dairy farming in Japan is to intensify livestock production, which is always accompanied by the production of large amount of dairy manure. If not properly managed, dairy manure presents a potential source of various hazards to human life and the environment (Rico, Rico, Tejero, Muñoz, & Gómez, 2011; Yamashiro et al., 2013). Anaerobic digestion (AD) has been implemented for years for management of dairy manure, which provides several benefits, including the improvement of manure fertilizer quality and reduction of greenhouse gas emissions, odors and patho

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.

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.