Uv visible spectrophotometer

The total phenolics content was determined by using the Folin-Ciocalteu reagent based on colourimetric reduction [33 ]. Folin-Ciocalteau (10%, w/v,) of 1 mL is added to 0.2 mL of prepared Cornelian cherry juice, followed by the addition of 1.2 mL of aqueous Na₂CO₃ (7.5%, w/v). The mixture was left in the dark for 90 min. The absorbance of the blue colour solution was monitored at 760 nm on a UV visible spectrophotometer (Shimadzu, Kyoto, Japan) against a blank (distilled water). Total phenolics concentration (mg/100 mL) of the samples were analyzed in triplicates and extrapolated from a standard curve constructed by using Gallic acid as a standard. Results were expressed as mg Gallic acid equivalents (GAE)/100 mL juice. All measurements were repeated three times.

The stock solution of ibuprofen was prepared by dissolving 20 mg drug into 100 ml phosphate buffer (pH 6.8), which was used to plot a standard curve of ibuprofen. The four different concentrations (0.1, 0.05, 0.025, and 0.0125 mg/ml) were prepared from the stock solution. UV-visible spectrophotometer (Shimadzu, Japan) was used to analyze the absorbance of these dilutions. The standard curve was prepared by plotting different concentrations of ibuprofen against absorption as shown in Figure 3.

The effect of NaCl concentration on growth of haloarchaea was studied by monitoring its growth in SG medium containing 5%, 8%, 10%, 15%, 20%, 25%, 30% & 35% (w/v) NaCl at 40 °C for 7 days. The growth was measured in terms of absorbance at 600 nm using UV-Visible Spectrophotometer (Shimadzu, Japan). The isolate RR12 (Hal. marismortui) that demonstrated growth and stable pigment production over a wide range on sodium chloride concentration (8% to 20% NaCl) was selected for further studies.

Total phenolic content was determined by using the Folin-Ciocalteu reagent (Sigma, St. Louis, MO, USA) based on colorimetric reduction [32 ]. The phenolic compounds are oxidized to phenolates by the reagent at alkaline pH in a saturated solution of sodium carbonate resulting in a blue complex. About 1mL of Folin–Ciocalteau (10%, w/v,) is added to 0.2 mL of prepared pomegranate juice, followed by the addition of 1.2 mL of aqueous Na₂CO₃ (7.5%, w/v). The mixture was left in the dark for 90 min. The absorbance of the blue color solution was monitored at 760 nm on a UV visible spectrophotometer (Shimadzu, Kyoto, Japan), against blank (distilled water). The total phenolics content (TPC) was assessed by plotting the gallic acid calibration curve and expressed as mg of gallic acid equivalents (GAE)/100 ml juice. The antioxidant activity (AA) of pomegranate juices was evaluated applying the ABTS radical cation decolorization assay [33 (link)]. ABTS⁺ was prepared by reacting of ABTS with potassium persulfate. Samples were analyzed at five different dilutions, within the linearity range of the assay, as previously described by Gentile, et al. [34 (link)]. TAA was expressed as mg of Trolox equivalent (TE)/100 mL juice. All measurements were repeated three times. All measurements were repeated three times.

In 50 ml deionized water, 2.7 mmol of DBT and 200 μl dimethylformamide (DMF) were mixed. Then, 0.125 g of NR1 (bacterial strain) was added, and a sample was agitated at 37°C and 200 rpm in an incubator. The oil (n-octane) phase of the solvent was extracted using a separatory funnel after 25 h. A UV–Visible spectrophotometer (Shimadzu, Japan) was used to measure the remaining DBT in the oil phase at 325 nm (Shah et al., 2016 (link)).

The modified method of microbial adhesion of hydrocarbon (Górna et al. 2011 (link)) was used to determine the cell surface hydrophobicity. In bacterial cultures, as the carbon and energy sources were used: fructose, diesel oil, heptane, toluene, Lutensol GD 70 (in different concentrations 6, 60, 120, 240, and 360 mg L⁻¹). Moreover, the strains grown on diesel oil and Lutensol GD 70 were also investigated. The bacterial cells from the 7-day cultures were centrifuged (8000 rpm, 5 min, 10 °C) and washed twice with PUM buffer (19.7 g L⁻¹ K₂HPO₄, 7.26 g L⁻¹ KH₂PO₄, 1.8 g L⁻¹ H₂NCONH₂, 0.2 g L⁻¹ MgSO₄ · 7H₂O) in order to remove residual surfactant and carbon sources. Then, the cells were resuspended in the PUM buffer, an optical density was fitted to ca. 1.0. The optical density was measured at 600 nm (OD₆₀₀) on a Shimadzu UV–Visible Spectrophotometer. Afterwards, 0.5 mL of heptane was added to 5 mL of cell suspension and vortexed for 2 min. After 60 min, the OD₆₀₀ of the aqueous phase was measured. The microbial adhesion to hydrocarbons was calculated as follows: $H=\left(1-\left(A_1/A_0\right)\right)\times 100\%$
H—hydrophobicity [%]; A₀—OD₆₀₀ of initial aqueous phase [−]; A₁—OD₆₀₀ of aqueous phase after mixing with hexadecane [−].