Uv 1600pc

The T. maritimum strain (ACC13.1) used in this study was isolated from Senegalese sole and belongs to the serotype O3 (24 ). The strain was kindly provided by Professor Alicia E. Toranzo (Departamento de Microbiología y Parasitología, Facultad de Biología, University of Santiago de Compostela, Spain) and stocks were kept frozen at −80°C until use. Recovery from frozen stocks was achieved using marine agar (MA; Laboratories CONDA, Spain) at 25°C for 48 h.
For inoculum preparation, bacteria were inoculated in 50 mL of marine broth (MB; Laboratories CONDA, Spain) in a 500 mL Erlenmeyer and grown at 25°C, with continuous shaking (180 rpm) for 48 h. Turbidity was measured at 600 nm (Spectrophotometer, UV-1600PC, VWR) and exponentially growing bacteria (OD=0.886) were collected by centrifugation at 3,000 x g for 10 min and resuspended in MB at a concentration of 5 x 10⁵ CFU mL^-1. The bacterial concentration was adjusted with the predetermined growth curve for this specific strain: y = 2 x 10⁸x + 4 x 10⁷ (25 (link)).

TPC was determined according to the spectrophotometric method Folin–Ciocalteu, described by Marques et al., (2017). Briefly, 1.25 mL of Folin–Ciocalteu reagent (0.2 M) was added to 250 µL of degassed beer sample or gallic acid GA (standard solution) and allowed to stand for 5 min. Then, 2 mL of sodium carbonate (Na₂CO₃) solution (75 g/L) was added. Distilled water was added until 5 mL. The solution was incubated for 1 h at room temperature in the dark and then the absorbance was read at 760 nm using a UV-Vis spectrophotometer (Model VWR UV-1600PC). Absorbance values were converted to gallic acid equivalents (GAE) mg/L craft beer through a calibration curve obtained with standard GA in water [41 (link)].

The optical density of honey samples at 50% (w/v) was measured at 450, 635, and 720 nm using a UV/Vis spectrophotometer (UV-1600PC; VWR International, Radnor, PA, USA) with sterile water as a blank. Colour intensity was calculated using the equation $(A_{720}-A_{450})\times 1000$ and expressed in milli-absorbance units (mAU). Pfund value was calculated using the equation $-38.70+371.39\left(A_{635}\right)$ and expressed in mm. For pH measurements, 1 g of honey was diluted in 7.5 mL of sterile water and pH was determined using a pH meter (Seven Compact S220; Mettler Toledo, Greifensee, Switzerland). Brix value and moisture content were measured at 20 °C using a refractometer (HI96801; Hanna Instruments, Smithfield, RI, USA) according to the AOAC Official Method 969.38 (AOAC, 2023 ). Water activity (a_w) was assessed using a water activity analyser (PRE; Aqualab Scientific, Pullman, WA, USA) at 25 °C with a correction of ±0.005 a_w made per 0.1 °C deviation (Stoloff, 1978 (link)). Raw data is presented in Table S1.

Reduction in optical density at 620 nm was used as a measure of cell lysis after exposure to antibacterial agents. The optical density determined using a spectrophotometer (UV1600PC, VWR, Leuven, Belgium). Lysed cells suspensions were made by sonication (Qsonica, LLC, USA).

Hydrophobicity was determined according to the method described by Salaheen et al. [25 (link)]. L. monocytogenes was grown in Luria–Bertani (LB) broth in the absence and presence of predetermined sub-inhibitory concentrations (½ MIC and ¼ MIC) of ohelo berry juice at 37 °C for 24 h. Each culture was centrifuged at 3000 g for 20 min. The cells were thoroughly suspended in 5 mL of phosphate buffer saline (PBS, pH 7.2). The absorption of suspension was measured at 570 nm using a spectrophotometer (UV-1600PC, VWR) and adjusted to approximately 0.5 (Ht0) with PBS. After that, 2 mL of each adjusted solution was transferred to a new tube and mixed with 1 mL of n-hexadecane, followed by incubation at room temperature for 5 min. The hexadecane phase was removed, and the absorption of the aqueous phase was measured at 570 nm (Ht5). Hydrophobicity was calculated using the equation as follows:

The electronic absorption spectrum was recorded using a UV-Vis (UV-1600PC) double-beam spectrophotometer (VWR) from 190 to 700 nm at 0.5 nm spectral resolution.
Density measurements were performed using a temperature-controlled Anton Paar DMA cell with accuracy of ±0.0001 g/cm³. Dynamic (shear) viscosity was determined using the density and the kinematic viscosity values. The latter was measured by means of a Ubbelohde-type glass capillary viscosity meter (Schott, Mainz, Germany) at the desired temperature with accuracy of ±1%.

Overnight cultures of Escherichia coli BL21(DE3) cells transformed with appropriate plasmids were diluted to OD₆₀₀ = 0.05 in LB medium containing 50 μg/ml kanamycin and grown in shaking flasks at 37°C. The OD₆₀₀ values were measured using the UV/Vis spectrophotometer, UV-1600PC (VWR, Vienna, Austria) and determined at the indicated times. If necessary, the cultures were diluted prior to measurement so that the maximum optical density measured was below 1.0. When OD₆₀₀ reached values between 0.4 and 0.6, protein expression was induced by the addition of isopropyl 1-thio-β-d-galactopyranoside (IPTG) to 1 mM final concentration. The cultures were grown on an orbital shaker at 37°C and OD₆₀₀ was followed at 1-h intervals up to 8 h after induction.