1. Cell density and secreted enzymes contribute to aggregate invasive growth.
Cell density and secreted enzymes contribute to aggregate invasive growth. (A) One microliter of cells at an A600 OD of 10 was spotted onto YEP-Gal medium. Cells were incubated for 24 h at 30°C. The invasive pattern was photographed at 5×, and a composite image is shown. The line marks the colony perimeter at 24 h, prewash. White lines indicate aggregate and regular invasive growth. Bar, 1 mm. (B) Scatter plot of Agg (%), as a function of starting cell concentration. Asterisk, P value of <0.01, in reference to A600 of 20 on the x axis. Line shows the best fit, which resembles a nonlinear, cubic polynomial relationship (y = 0.0008x x2 − x, R2 = 1). The equation was generated in Microsoft Excel. (C) Wild isolate NSA from a vineyard in Spain (181) grown on SALG (synthetic ammonium low-glucose medium [55]) with or without 2% ethanol as indicated. (D) Examples of aggregates formed on synthetic media for wild-type cells and the rtg1Δ mutant. Bar, 100 μm. (E) Average size of aggregates formed by the indicated mutants on S-Gal medium. Error bars represent standard error. Asterisk, P < 0.05. (Inset) Invasive pattern of wild-type cells and the rtg3Δ mutant. (F) Quantitative PCR analysis showing relative fold changes of SUC2 in the indicated strains. Error bars represent standard deviation. (G) Aggregation [Agg (%)] of wild-type, suc2Δ, and flo11Δ cells. Asterisk, P value of <0.05. (H) PWA. Indicated strains were examined under standard aggregate-producing conditions. Far right, typical bright-field images are shown (5×). Bar, 500 μm.
Jacky Chow et al. mSphere 2019; doi: /mSphere