Could Paenibacillus xylanexedens MS58 be an Ecofriendly Antibiotic in Poultry Production? Impacts on Performance, Blood Biochemistry, Gut Microbiota and Meat Quality

The search for novel natural antibiotic alternatives is continuous and crucial to overcome the antibiotic-resistant bacteria. In this study, the isolation and identification of Paenibacillus xylanexedens MS58 (PX) on the gene level as a new probiotic, antibiotic alternative, and feed additive has been assessed. The effects of PX on growth performance, blood biochemical parameters, immune response, gut microbiota and meat quality of broilers were also evaluated. The selected isolate, Paenibacillus xylanexedens MS58, inhibited the growth of pathogenic bacteria with MIC of 5-15 %. One hundred sixty chicks were casually divided into four equal experimental groups: the control group (CON) delivered the basal diet, group 1 received a basal diet supplemented with 0.3 mg/kg PX, and groups 2 and 3 provided a basal diet fortified with PX at 0.9 and 1.5 mg/kg, respectively. Adding PX at 1.5 mg/kg to the diet of chicks significantly enhanced the highest body weight influenced all growth parameters during 35 days (2.304 kg) with a relative increase of 10 % compared to control. Additionally, the dietary PX enhanced the liver and kidney enzymes; ALT activity decreased by 25% and AST by 67% compared to control. The uric acid was lowered by dietary PX with a relative decrease of 18 %. In response to adding dietary PX, the abdominal fat reduced from 1.1 to 0.8 in the PX 1.5 treatment with a relative reduction of 25 %, and total cholesterol decreased by 33 %; however, HDL increased. Additionally, the immune response and beneficial gut microbiota of chicks significantly improved with the addition of the dietary PX compared to the control group. The chicken meat's moisture and protein content were enhanced, influenced by the juiciness and tenderness properties compared to control; also, the lightness of meat was enhanced with PX addition. Generally, adding dietary PX to broilers could enhance growth, blood biochemical properties, and immune response, modulate the gut microflora structure, and improve meat quality.