L. buchneri CD034 (Heinl et al., 2012 (link)), L. buchneri NRRL B-30929 (Liu et al., 2011 (link)), L. rhamnosus GG (Claes et al., 2012 (link)) and L. plantarum CD033 (Spath et al., 2012 (link)) were grown in De Man–Rogosa–Sharpe (MRS) broth (BD Difco) (De Man et al., 1960 ) at 37 °C without shaking. Escherichia coli DH5α cells (Life Technologies) and E. coli BL21 Star BL21(DE3) cells (Life Technologies) were cultivated at 37 °C and 200 r.p.m. in Luria–Bertani (LB) medium supplemented with 50 μg kanamycin ml−1.