The gastrointestinal tract (GIT) of chickens is massively occupied by pathogens and lactobacillus where lactobacillus may basically be used as symbiotic member. Particular species of lactobacillus such as Lactobacillus casei (Lc393) and Lactobacillus saerimneri (M11) regulating the function of immune system, as a probiotics and therapeutic agent produce protein against pathogens. In this study, we constructed a series of recombinant lactobacillus ppG-T7g10-ppT-ompC₁-fimA₁/Lc393 (POF₁/Lc393), ppG-T7g10-ppT-ompC₁-fimA₁/M11 (POF₁/M11), ppG-T7g10-ppT-ompC₇₈-fimA₇₈/Lc393 (POF₇₈/Lc393) and ppG-T7g10-ppT-omp C₇₈-fimA₇₈/M11 (POF₇₈/M11). For Examination, 70 day one old (SPF) chicks were divided into 5 batches (1Lc,78Lc,1M11,78M11 and PBS control) comprising 14 chicks in each batch. At day one, all batches were drenched orally with recombinants of 1.5x10⁹ CFU/ ml, 1.5x10¹⁰ CFU/ ml, 1.5x10¹¹ CFU/ ml and also drenched control with100ul of PBS respectively. After vaccination, all batches were challenged orally with 0.5ml of E.coli. The colonization and adherence ability were then examined in ileum, cecum and colon of chickens at different intervals. Results of recombinant lactobacillus POF₁/Lc393 and POF₇₈/Lc393 demonstrated that 1.5x10⁹ml, 1.5x10¹⁰ ml and 1.5x10¹¹ ml concentration of recombinants drenched respectively had no mortality while POF₁/M11, POF₇₈/M11 showed 20% mortality in all batches. Vaccine treated groups POF₁/Lc393 and POF₇₈/Lc393 showed significantly higher chicken growth performance (P<0.05) as compared with POF₁/M11, POF₇₈/M11 and control (PBS). The results determined that possibility to construction and colonization of these recombinants to be used as therapeutic agent and growth performance modulator in chickens.

Key words: Chickens, Colonization, Gastrointestinal tract, Probiotics, Recombinant lactobacillus