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. Author manuscript; available in PMC: 2019 Sep 12.
Published in final edited form as: Parasitology. 2018 Sep 24;146(3):380–388. doi: 10.1017/S0031182018001555

Figure 1. Spent medium from Lactobacillus bombicola inhibited growth of Crithidia bombi (Strain VT1); acidity of the spent medium was necessary and sufficient for inhibition.

Figure 1.

Spent medium (“Spent”, red solid line) completely inhibited parasite growth. However, spent medium neutralized to pH 6.2 with NaOH (“Neutralized spent”, green dotted line) resulted in no inhibition relative to the fresh medium control (“Fresh”, light green dashed line), demonstrating that acidity was necessary for inhibition. Fresh medium acidified to pH 4.8 with lactic acid (“Acidified fresh”, blue dashed line) showed that acidity was sufficient for complete growth inhibition. Final pH of both spent medium and acidified fresh medium was 5.0 after combination with equal volume of fresh Crithidia medium (pH 5.9). Y-axis represents approximate number of parasite cell divisions, as measured by optical density (630 nm). Points and error bars show means and 95% confidence intervals (n = 36 wells per treatment).