Correction to: Microb Cell Fact (2020) 19:186 https://doi.org/10.1186/s12934-020-01449-3

Unfortunately, in the original publication [1] of the article, an error was found in Fig. 1b and Fig. 4b. In Fig. 1b, the background noises of images in panel anti-E2 and panel anti-ctxB were modified. Although the modification does not change the conclusions of the Western blotting experiment (anti-E2 and anti-ctxB), the authors had reperformed the experiment again and reassembled Fig. 1b with the new results. In Fig. 4b, the image of the panel pPG-E2-ctxB/Lc W 56 was one of the results of the pPG-E2/Lc W 56 group, which was mistaken by the students and should be corrected.

The corrected Figs. 1 and 4 are provided in this correction.

Fig. 1
figure 1

Construction of the recombinant Lactobacillus strains and identification of the proteins of interest expressed by the recombinant Lactobacillus strains. a Schematic illustration of the construction of the recombinant pPG-E2 and pPG-E2-ctxB plasmids. b Identification of the proteins of interest expressed by the recombinant strains pPG-E2/Lc W56 and pPG-E2-ctxB/Lc W56 using Western blot with mouse anti-E2 or anti-ctxB mAb, respectively. c Identification of the E2 protein expressed by pPG-E2/Lc W56 by IFA. d Identification of the fusion protein E2-ctxB expressed by pPG-E2-ctxB/Lc W56 by IFA

Fig. 4
figure 4

Detection of T lymphocytes expressing Bcl-6 in the PPs of the mice in each group on day 7 after oral vaccination by IHC assay (a) and fluorescence IHC assay (b)