Vcx 750 vibra cell sonicator

Uncoated CeO₂ NPs were purchased from Sigma Aldrich (St Louis, MO, USA; batch number MKCB0040V) in powder form with a primary particle size of 16 nm, verified by the manufacturer using X-ray diffraction and Brunauer–Emmett–Teller analysis. For soil amendment working stocks, CeO₂ NPs were suspended in deionized (DI) water at either 125 mg L⁻¹ (for low concentration soils) or 12,500 mg L⁻¹ (for high concentration soils). Then, the suspensions were sonicated for 5 min at 100% intensity with a VCX 750 Vibra-Cell sonicator (Sonics and Materials Inc., Newton, CT, USA) with a cup-horn style high intensity probe in a recirculating bath.

Strain B-14859 was procured from the Agricultural Research Service Culture Collection (Peoria, Illinois, USA), which is the only known official source of the bacterium. This bacterium was cultured using LB medium at 30 °C with aeration (shaking at 200 r.p.m.). Solid LB medium was prepared using 2 % agar for culturing bacteria from glycerol stocks or plating broth cultures to test purity. Biochemical tests were performed based on the descriptions in the VetBact online resource (www.vetbact.org/) of the Faculty of Veterinary Medicine and Animal Science of the Swedish University of Agricultural Sciences. Liquid bacterial cultures were pelletted in sterile Oak Ridge tubes using a fixed angle rotor (JA20, ~12000 g for 10 min at 4 °C) in an Avanti J-25 centrifuge (Beckman Coulter, USA). Wet biomass (80 or 160 mg) was obtained from the pellets and resuspended in 1 ml acetone by gentle vortexing. The suspension was lysed using a VCX 750 Vibra-Cell sonicator (Sonics and Materials, USA) for 10 min (30 % amplitude with 5 s on/off pulse). The yellow-coloured supernatant was collected by centrifugation and scanned using a Cary 100 UV-Vis spectrophotometer (Agilent Technologies). Spectra in the 200–800 nm wavelength range were recorded.