Fig. 3

Characterization of a transposon mutant with attenuated inhibitory activity of E. faecalis YM0831 against glucose uptake by Caco-2 cells. a Experimental scheme of the screening to obtain a transposon mutant with attenuated inhibitory activity of E. faecalis YM0831 against glucose uptake by Caco-2 cells. b Decrease in inhibitory activity of E. faecalis YM0831 transposon mutant (Tp10-72) against glucose uptake by Caco-2 cells. E. faecalis YM0831DR (parent, 62.5 mg wet weight cells/ml) or Tp10-72 (Tp10-72, 62.5 mg wet weight cells/ml) was added in the uptake system of 2-NBDG in Caco-2 cells and fluorescence uptake by the Caco-2 cells was measured. n = 3–6/group. c Decrease in inhibitory activity of Tp10-72 against sucrose-induced hyperglycemia in silkworms. Silkworms were fed a diet containing 10% (w/w) sucrose with or without E. faecalis parent (YM0831DR, 12.5% [w/w] in diet) or Tp10-72 (Tp10-72, 12.5% [w/w] in the diet) for 1 h. Glucose levels in the silkworm hemolymph were measured (n = 12–14/group). d Decrease in inhibitory activity of Tp10-72 against glucose-induced hyperglycemia in silkworms. Silkworms were fed a diet containing 10% (w/w) glucose with or without E. faecalis YM0831DR (parent, 12.5% [w/w] in diet) or Tp10-72 (Tp10-72, 12.5% [w/w] in the diet) for 1 h. Glucose levels in the silkworm hemolymph were measured (n = 7/group). e Inserted region of transposon Tn916 in Tp10-72 genome determined by whole genome sequencing analysis. f Functions of ManX, ManY, and ManZ coded by the man operon. g Decreases in mRNA amounts of genes in the man operon in TP10-72 revealed by RT-PCR analysis. h Complementation of decreased inhibitory activity of TP10-72 on glucose uptake by Caco-2 cells. E. faecalis YM0831DR/pND50 (parent/vector, 70 mg wet weight cells/ml), Tp10-72/pND50 (Tp10-72/vector, 70 mg wet weight cells/ml), or Tp10-72/pMan operon (Tp10-72/pMan operon, 70 mg wet weight cells/ml) were added in the uptake system of 2-NBDG in Caco-2 cells and fluorescence uptake by the Caco-2 cells was measured. n = 3–15/group. Data represent mean ± SEM. Statistically significant differences between groups were evaluated using Student’s t-test. *P < 0.05; **P < 0.01; ***P < 0.001