Probiotics colonize the intestine of animals and birds and provide useful effects on their performance and immune status. This study describes a high throughput screening and characterization of spore-forming bacteria from Iranian poultry farms with the aim to identify potential probiotic native Bacillus spp. and determine its effects on growth performance, hemato-biochemical parameters, immunity, intestinal microflora, morphology and MUC2 gene expression of broiler chickens. A total of 300 one-day-old female Ross 308 broilers (42.6 ± 0.6 g) were used in a 6-wk study. Broilers were randomly allotted to 1 of 3 dietary treatments consisting of 4 replicate cages with 25 broilers each: 1-Control (Corn-soy-based diet: C), 2-C + 200 g/ton of the GalliPro® (Bacillus subtilis DSM 17299, 4×10 9 CFU/g, as positive control group: PC), 3-C + 200 g/ton of the native probiotic (B. tequilensis K03, 4×10 9 CFU/g: NP) identified in this study. During the experiment parameters were measured weekly. The results revealed that birds of the NP and PC groups exhibited improved feed conversion ratio (FCR) and increased body weight (BW), carcass and breast meat yield compared with the birds of the C group (P<0.05). Also, lymphocytes level, antibody titers against Newcastle diseases virus (NDV) and infectious bronchitis virus (IBV) of vaccinated birds were increased, while serum triglycerides, total cholesterol levels and abdominal fat of birds fed NP and PC were decreased compared to birds of the C group (P<0.05). The villus height, the relative expression of MUC2 gene and Bacillus spp. populations were increased, while E. coli was significantly decreased in the ileum content of treated groups (P<0.05). These results indicate that the identified native B.tequilensis K03 strain can improve immunity and broiler performance by modifying intestinal microflora and morphology. Studied native probiotic Bacillus tequilensis K03 has useful effects on health status and it can be used as poultry feed supplement.

Probiotic strains of Bacillus Species are used in industrial poultry production because of their ability to produce enzymes enhancing the absorption of food, and their ability to reduce the risk of Salmonella spp. infection. The aim of this study was to isolate native potential probiotic Bacillus spp. with the ability to produce enzymes and attachment to intestinal epithelial cells in order to prevent Salmonella typhimurium infection. First, 25 samples of chicken feces were collected from 7 industrial poultry in Golestan province located in north of Iran. Bacillus species from samples were isolated on nutrient agar. These strains were evaluated for the ability of producing amyalse and phytase and their probiotic characteristics such as bile salt, acid and antibiotic resistance, the ability to attach to intestinal epithelial cells and inhibit Salmonella typhimurium invasion. Then selected isolates were identified based on 16S rDNA.  Results showed that from 86 isolated, 4 Bacillus strains‌ had desirable characteristics such as the ability to produce phytase and amylase and having suitable probiotics features. We identified K03, K02, and K20 isolates as Bacillus tequilensis and K20 as Bacillus subtilis. Bacillus tequilensis K03 showed the highest attachment ability to intestinal epithelium cells and could inhibited Salmonella typhimurium attachment.