Phenotypic Characterization of P. ganghwense

Phenotype Microarrays (Biolog, Hayward, CA, USA) were used for the characterization of P. ganghwense C2.2 (DSM 109767) with regard to the usage pf carbon (PM1 plates) and nitrogen (PM3 plates) sources, osmolyte requirements (PM9 plates), and pH tolerance (PM10 plates). Synthetic seawater minimal medium (ASW) [44 (link)] without NH₄Cl was the basal medium for the microarrays, supplemented with: 0.2% (w/v) urea for PM1; 2% (w/v) glycerol for PM3; 0.2% (w/v) urea, 2% (w/v) glycerol, and no NaCl for PM9; and 0.2% (w/v) urea, 2% (w/v) glycerol, 2% (w/v) NaCl, and pH adjusted to 7 before inoculation for PM10. For the PM array inoculation, the strain was grown on ASW supplemented with 1 g/L yeast extract and 5 g/L peptone (designated as “marine peptone”—MP) agar [7 (link)] for 24 h at 20 °C. Transmittance values were adjusted to 65%, and Biolog Redox Dye Mix A (#74221) was added, with a dilution factor of 100. A working volume of 100 µL was used in each well. Plates were incubated at 20 °C, and the optical density at 590 nm (OD₅₉₀) was measured at 24 h intervals using the Biolog Microstation Reader (Biolog, Hayward, CA, USA). For data analysis, the OD₅₉₀ values measured at the time of inoculation were subtracted from each of the following readings. Heat maps were generated using a custom python script.