Efficient production and characterization of homopolymeric poly(3-hydroxyvalerate) produced by Bacillus strain PJC48.

Aliphatic polyester, poly(3-hydroxyvalerate) (PHV), is commonly produced as a granular component in bacterial cells of various species. Based on 16S rDNA gene sequence analysis, strain PJC48 was identified as a Bacillus species. The current study is aimed to screen for a high-yield strain that can produce PHV efficiently and to increase PHV product yield by optimizing the fermentative process. We identified a high-producer strain based on Nile red staining. Characterization of the PHV produced by PJC48 by nuclear magnetic resonance spectroscopy revealed that it consisted of (R)-3-hydroxyvalerate monomers. The suggested model was validated by response surface methodology. Optimization of the PHV yield resulted in an increase of 32.75% compared to control, with a maximum production of 1.64 g/L after 48 H.

Adhesive polydopamine coated avermectin microcapsules for prolonging foliar pesticide retention.

In this work, we report a conceptual strategy for prolonging foliar pesticide retention by using an adhesive polydopamine (PDA) microcapsule to encapsulate avermectin, thereby minimizing its volatilization and improving its residence time on crop surfaces. Polydopamine coated avermectin (Av@PDA) microcapsules were prepared by emulsion interfacial-polymerization and characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, field-emission scanning electron microscope, and transmission electron microscopy. The in situ synthesis route confers Av@PDA microcapsules with remarkable avermectin loading ability of up to 66.5% (w/w). Kinetic study of avermectin release demonstrated that Av@PDA microcapsules exhibit sustained- and controlled-release properties. The adhesive property of Av@PDA microcapsules on different surfaces was verified by a comparative study between Av@PDA and passivated Av@SiO2 and Av@PDA@SiO2 capsules with silica shell. Moreover, PDA shell could effectively shield UV irradiation and so protect avermectin from photodegradation, making it more applicable for foliar spraying. Meanwhile, it is determinated that Av@PDA microcapsules have good mechanical stability property.