The soil-borne oomycete pathogen Phytophthora capsici poses a serious threat to plant growth and results in substantial economic impact on the pepper industry. Therefore, the isolation of multifunctional biocontrol agents has become a major research priority. In this study, we isolated a biocontrol strain, Bacillus subtilis Z-294, which demonstrated strong inhibition of P. capsici in both plate and greenhouse experiments. This strain Z-294 exhibited broad-spectrum antagonistic activities as well as plant growth-promoting ability. Phylogenetic analysis based on core-genome and average nucleotide identity (ANI) further identified Z-294 as B. subtilis. Importantly, we found that the strain Z-294 alleviates the P. capsici disease through mechanisms associated with changes in the plant microbiome. Plants treated with Z-294 showed higher alpha-diversity. The application of B. subtilis Z-294 showed that the relative abundance of Alphaproteobacteria, Bacilli, Bacteroidia, Agaricomycetes, and Eurotiomycetes increased, while the relative abundance of Gammaproteobacteria and Sordariomycetes declined. Strain Z-294 holds great promise as a multifunctional biocontrol agent for the sustainable management of diseases and the enhancement of plant health, laying a solid foundation for its future agricultural applications.
Yanan Zhao, Qingchao Zeng, Kunzhi Long et al.· Agronomy· 0 citations
Poly(ethylene terephthalate) (PET) is a widely used plastic whose persistence and improper disposal pose serious environmental and health risks. In this study, three novel PET hydrolases TbPETase, AbPETase, and AfPETase were identified from Thermoanaerobacterales, Acidimicrobiales, and Actinokineospora fastidiosa, respectively. Among these, TbPETase exhibited the highest enzymatic activity and thermostability. Based on structural analysis, we performed semirational truncations targeting the intrinsically disordered N- and C-terminal regions of TbPETase, generating two improved variants ΔN36 and ΔC4. The double mutant, TbPETaseΔN36/ΔC4, demonstrated a 2.3-fold increase in overall enzymatic activity and a 2.6-fold improvement in catalytic efficiency (kcat/Km) compared to the wild-type enzyme, along with significantly enhanced thermal stability. Molecular dynamics simulations revealed that the removal of flexible terminal regions increased the overall structural rigidity of TbPETaseΔN36/ΔC4. This structural stabilization was associated with the formation of a hydrogen bond at T215 and a π–π stacking interaction at W193. In a 100 mL one-pot reaction system, the combination of TbPETaseΔN36/ΔC4 with an engineered BMHETase variant, BMHETase6M, achieved 81.2% degradation of semicrystalline PET powder at 60 °C over 60 h, yielding terephthalic acid as the major product. These findings demonstrate the potential of TbPETaseΔN36/ΔC4 as a highly efficient and industrially applicable biocatalyst for PET degradation.
Lin Zhang, Keyan Chen, Zhiwen Xi et al.· ACS Synthetic Biology· 0 citations
