N60 nano spectrophotometer

Twenty-four, 48 and 72 h WT and mutant strain cultures were centrifuged (1 min at 13 200 r.p.m.), after which the supernatant was discarded. Cell pellets were then resuspended in 1.5 M NaCl, as described previously [22 (link)]. The resuspended cells were then centrifuged once more, and the supernatant was collected to measure the concentration of DNA, proteins and saccharides. To quantify DNA in the isolated ECM, DNA was purified with the Promega SV Wizard DNA purification system (Promega, USA) according to the manufacturer’s instructions. The concentration of the purified DNA was measured using an Implen N60 nano-spectrophotometer (Implen, USA). Proteins in the isolated ECM fractions were quantified via the Bradford assay based on a bovine serum albumin standard curve. Protein concentration was measured at 590 nm on a UV/Vis spectrophotometer (Eppendorf, Germany). The total saccharide concentration in the ECMs was measured using the phenol–sulfuric acid method [22 (link)]. Briefly, 20 µl of 5 % phenol was added to 20 µl of the ECM fraction and mixed in the 96-well plate. Afterward, 100 µl of sulfuric acid was added, and the mixture was incubated for 10 min at room temperature. Saccharide concentration measurements were performed at 492 nm using a Spark (Tecan, Switzerland) instrument with glucose as a standard.