Fig. 2. Bacteria promote C. albicans hyphal growth and the activity is significantly enhanced by β-lactam antibiotics in liquid cultures.

a, c Sa or Ec seed cultures were inoculated into fresh LB to OD₅₉₅ = 0.01 and grown at 37 °C with 200 rpm shaking till the cell density reached 10¹⁰ cells/mL. The culture was split into two parts, and to one was an antibiotic added to a final concentration of 30 µg/mL, which is at least two times the MIC of all antibiotics used on both Sa and Ec (Supplementary Fig 1a). The cultures were grown for 16 more hours before harvesting the culture supernatant by centrifugation. To test the hypha-inducing activity of the supernatant, C. albicans yeast cells were inoculated at 5 × 10⁵ cells/mL into Hank’s Balanced Salt Solution (HBSS) supplemented with 5% of 100-fold diluted bacterial supernatants and incubated at 37 °C for 3 h. Scale bar, 5 µm. The experiment was repeated independently at least three times with similar results. b, d Percentage and length of hyphae. Results were from three independent experiments. n > 50. Scale bar, 250 µm. P values were calculated using two-tailed unpaired t test. Error bars are means ± SD. Source data are provided as a Source Data file.