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Figure 4 | Biotechnology for Biofuels

Figure 4

From: Saccharomyces cerevisiae expressing bacteriophage endolysins reduce Lactobacillus contamination during fermentation

Figure 4

Reduction of L. fermentum during fermentation of corn mash composed of 20% solids. Fermentations were prepared with untransformed yeast (circles) or transformed yeast harboring LysA (triangles) or LysA2 (squares). The top panels (a, c, e) represent early time points (0 h to 1.5 h) and the bottom panels (b, d, f) represent long-term (72 h) fermentations. (a-d) Induced fermentations were induced with 6.8 mL of 25% galactose (final conc. of 10%) and (e,f) non-induced fermentations were treated with 6.8 mL of DI water rather than galactose. Samples of corn mash were taken at 0, 0.5, 1.0, 1.5, 24, 48, and 72 h to enumerate bacterial CFUs. (c,d) To prepare a yeast lysate containing LysA or LysA2, 10% of the fermentation volume (2 mL) was removed at 0 h and 0.5 h and mechanically lysed (bead beating; BB) for five rounds of 30 s followed by 30 s on ice and returned to the fermentation. Control samples included untransformed yeast under induced conditions, untransformed yeast under induced conditions and BB, and untransformed yeast under non-induced conditions.

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