Effects of lime amendment on the organic substances changes, antibiotics removal, and heavy metals speciation transformation during swine manure composting.

Aerobic composting has been used for a long time for bioconversion of manure wastes, however, its application has been limited due to slow transition of organic matters and influence of heavy metals and antibiotics residues. Compost with lime addition can speed up the composting process, while its effects on the evolution of organic matters, heavy metals and antibiotics need to be further investigated. In this research, the effects of lime amendment on organic substances changes was assessed by the spectroscopic characteristics. Besides, chlortetracycline (CTC) removal and Cu, Zn chemical speciation transformation were also evaluated. Results showed that the humic acid-like substances region of fluorescence regional integration (FRI-EEM) increased from 20.5% to 40.9% and 20.6%-32.6%, respectively, in lime addition treatment and control after 15 days of composting, indicating that the addition of lime remarkably improved the transition of organic matter and accelerated the maturity process. Besides, 94.04% of CTC in the manure was removed when lime was added, higher than 86.10% in the control group. The transformation of zinc from exchangeable and reducible into oxidizable and residual fractions was improved while the transformation of copper was affected slightly. Therefore, lime is a suitable amendment material for manure composting, which can accelerate the transition of organic matters due to the regulation of composting pH, as well as eliminate harmful CTC and bioavailable heavy metal, thus promoting the further utilizing of organic substance.

Control of Plant Viruses by CRISPR/Cas System-Mediated Adaptive Immunity.

Plant diseases caused by invading plant viruses pose serious threats to agricultural production in the world, and the antiviral engineering initiated by molecular biotechnology has been an effective strategy to prevent and control plant viruses. Recent advances in clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) system-mediated DNA or RNA editing/interference in plants make them very attractive tools applicable to the plant protection field. Here, we review the development of CRISPR/Cas systems and summarize their applications in controlling different plant viruses by targeting viral sequences or host susceptibility genes. We list some potential recessive resistance genes that can be utilized in antiviral breeding and emphasize the importance and promise of recessive resistance gene-based antiviral breeding to generate transgene-free plants without developmental defects. Finally, we discuss the challenges and opportunities for the application of CRISPR/Cas techniques in the prevention and control of plant viruses in the field.

[Removal of Chlortetracycline and Morphological Changes in Heavy Metals in Swine Manure Using the Composting Process].

The widespread use of antibiotics and heavy metals in livestock farms results in large residues of antibiotics and heavy metals in the livestock manure. Composting technology can biodegrade residual antibiotics and solidify heavy metals. A pilot composting reactor was used to analyze the characteristics of chlortetracycline (CTC) removal at different antibiotic concentrations[0 mg·kg-1 (CK), 10 mg·kg-1 (T1), and 50 mg·kg-1 (T2)]. Moreover, the morphological changes in heavy metals during the composting process were analyzed. After composting, no chlortetracycline was detected in the CK group and the antibiotics degradation rates of T1 and T2 groups reached 96.31% and 97.32%, respectively. The chlortetracycline degradation fits the pseudo-first-order kinetics model. Heavy metals can be solidified during the composting; thus, the bioavailable state of Cu and Zn (exchangeable state, reducible state) changed into the oxidation state and residues with apparent passivation formed. The correlation analysis showed that the removal of CTC showed strong positive correlations with the biological available Cu and Zn.