Genesys 10 uv vis spectrophotometer

The chlorophyll a, b, and carotenoid contents were determined using the Lichtenthaler method [42 (link)]. The samples were triturated with 80% acetone in the dark. The absorbance of the samples was measured with a Genesys 10 UV–Vis spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) at wavelengths of 470, 646, and 663 nm. The content of the photosynthetic pigments was calculated as described in [42 (link)].

Spores of C. botulinum Beluga WT and Beluga Ei were used to inoculate CMM-TPGY in three biological replicates. Culture OD₆₀₀ was measured at a wavelength of 600 nm using a Thermo Spectronic Genesys 10 UV/Vis Spectrophotometer. Heat-resistant spore and viable cell concentrations were determined as described^{42 (link)} applying the most probable number technique^{57 (link)}. One-way ANOVA was used to compare the total viable cell and spore counts.

The chlorophyll a (Chl a), b (Chl b) and carotenoid (Car) contents were determined using the Lichtenthaler method [26 ]. The samples were triturated with 80% acetone in the dark. The absorbance of the centrifuged samples was measured with a Genesys 10 UV–Vis spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) at wavelengths of 470, 646, and 663 nm. The content of the photosynthetic pigments was determined using the Lichtenthaler formulas [26 ]:

The HEX activity was determined by using 50 µL of hemolysate in a reaction medium containing a buffer (0.1 M Tris-HCl and 0.5 mM EDTA, at pH = 8.0), 0.01 M MgCl₂, 0.2 mM NADP, 2 mM glucose, 2 mM of ATP, and 0.1 of a unit of glucose-6-phosphate dehydrogenase enzyme. The absorbance was measured in a GENESYS™ 10 UV/Vis spectrophotometer (Thermo Scientific^®, Waltham, MA, USA) at 340 nm, and its variation per minute was evaluated, with and without ATP. The enzyme activity was quantified by the reduction of NADP⁺ to NADPH. The enzymatic activity was calculated at Ul·gHb⁻¹·min⁻¹, where U was equal to 1 µmol of NADP⁺·min⁻¹·mL⁻¹ [28 ].

For the ultraviolet-visible (UV-vis) analysis, the resultant AgNPs/GG hydrogel sample was dispersed in deionized water by agitation to get a diluted suspension. Then, about 2.5 mL of upper solution was taken for the UV-vis analysis, and the data were collected on a GENESYS 10 UV-Vis spectrophotometer from 200 to 800 nm wavelength (Thermo Fisher Scientific Inc.) using deionized water as the background. The samples for transmission electron microscopy (TEM) observation were also prepared by disintegrating the hydrogel in water. A drop of the aforementioned suspension was cast on a carbon-coated copper grid for TEM observation. The TEM study was carried out on a JEOL 2011 with a 200 kV acceleration voltage. The size and size distribution of AgNPs were measured and analyzed using an ImageJ software. The elemental analysis of the hydrogel samples was carried out with an energy dispersive X-ray system (EDX) attached to the TEM. For the scanning electron microscopy (SEM) observation, the resultant hydrogels were dried based on the solvent exchange technique using ethanol. The samples were treated/fractured in liquid nitrogen for the cross-section observation. SEM images were taken using a JEOL 6400 microscopy with a 15 kV acceleration voltage.