Incubated refrigerated orbital shaker

The SLs were isolated according to a modified method of [5 (link)], whereas 100 ml of methanol was added to the cultures, then the mixture was shaken at 160 rpm for 2 h at 30 ℃ with a reciprocal shaker (Incubated/Refrigerated Orbital Shaker, Thermo SCIENTIFIC- USA). Then through Whatman No. 2 filter paper, the extract was filtered. The methanol was evaporated at 40 ℃ by a rotary evaporator (heidolph cooling analog vacuum controller G1-Germany) to obtain the methanol SL extract.

Initially, each yeast isolate was pre-activated by cultivation on Potato Dextrose Broth (PDB) for 24 h at 28 °C in a shaking environment (Incubated/Refrigerated Orbital Shaker, Thermo SCIENTIFIC- USA). Screening of different yeast isolates for their ability to produce biosurfactant was investigated using a low-cost culture medium that based on PPW and FOW. For this purpose, PPW (5 g/l) and FOW (5 g/l) that had been prepared and moistened (60%) with the Czapek Dox medium (g/l): NaNO₃, 2; K₂HPO₄,1.0; MgSO₄.7H₂O, 0.5; KCl, 0.5; and FeSO₄, 0.001, along with adjustment of pH at 7.2. Under SSF conditions, PPW and FOW were used as carbon and inducer sources for SL synthesis. The sterilized PPW-FOW was inoculated with 1.0 × 10⁷ cfu/ml of yeast cells and incubated for 5 days at 28 °C under a static condition.