Abstract: Ten Lactobacillus strains (L. crispatus I12, L. brevis I23, I211, I218 and C10C, L. fermentum I25, I24C and C17C and L. acidophilus I16C and I26C) which originated from the gastrointestinal tract of chickens were transformed with plasmids pSA3b3 and pSA3b6. These plasmids harbored a bglA gene, cloned in opposite orientation, which encoded for β-glucanase enzyme. Enzyme expression was only detected in pSA3b6 transformants. The plasmid stability in transformants L. crispatus I12pSA3b6, L. brevis I23pSA3b6, I211pSA3b6, I218 pSA3b6 and C10CpSA3b6 and L. fermentum I25pSA3b6, were comparatively higher than the other strains. Approximately 30-48% of the cells retained the plasmid after 21-36 generations of growth. All the strains, except for L. brevis C10CpSA3b6, produced 22.8-25.1 U mL-1 of β-glucanase during late exponential growth phase (14 h old cultures). In L. brevis C10CpSA3b6, 37.2 U mL-1 of β-glucanase was detected during early exponential phase (6 h old culture).