Ol om software version 3.0

The metabolism of the wild strain and mutants was examined with GP2 MicroPlate™ using phenotype microarrays system (Biolog, California, USA). Sample preparation and assays were conducted according to the manufacturer’s instructions. In brief, Lactococcus cells on the surface of solid medium were collected using cotton swab and suspended in inoculating fluid (0.40% NaCl, 0.03% Pluronics F-68, and 0.02% Gellan Gum) (Biolog, California, USA). The cell density was equalized, and 150 µL of the cells suspension were pipetted into GP2 plates with various substrates, respectively. Then, the plates were incubated in OmniLog^® instrument (Biolog, California, USA) at 30 °C for 24 h. The data were automatically recorded every 30 min, and were analyzed by OL-OM software (version 3.0) (Biolog, California, USA).

The metabolism of wild and mutant strains was identified with GP2 MicroPlate™ by the phenotype microarray system (Biolog, California, USA). Sample preparation and assays were conducted in accordance with the manufacturer’s instructions. Briefly, the fresh cultured cells of lactococcal strains on the surface of the solid medium were collected by cotton swab and then dissolved into inoculating fluid (0.40% sodium chloride, 0.03% Pluronic F-68, and 0.02% Gellan Gum) (Biolog, California, USA). Cell density of different strains was equalized to maintain the same number of incubated bacteria. One hundred and fifty microliter tested samples were then pipetted into GP2 plate with various substrates. The plates with the sealing were incubated in the OmniLog® instrument (Biolog, California, USA) at 30 °C for 24 h. The machine automatically recorded the test data once per 30 min. The plates were shaken for 15 s before the data were recorded. Up to two strains can be tested and compared per experiment. Data were analyzed using OL-OM software (version 3.0) (Biolog, California, USA).