This study was conducted to develop a bacterial glucan as an animal feed additive. A novel glucan-producing bacterium, Paenibacillus polymyxa JB115, was isolated from Korean soil. The glucan, JB115-BG, produced by P. polymyxa JB115, was confirmed by TLC to be composed of glucose only. By examining FT-IR, $^1H;NMR$, and $^{13}C;NMR$ spectra, it was proven that JB115-BG has ${eta}-(1{ ightarrow}3)-and;{eta}-(1{ ightarrow}6)-linked$ glucan structure. The particle size of JB115-BG was distributed in the range of $4{sim}800{mu}m$, with a mean value of $149.1{mu}m$, and its molecular distribution ranged from $6.9{sim}3$, 103.7kDa. It was also observed that 80% of the purified JB115-BG had a molecular distribution above 100kDa. The obtained results suggest that the glucan JB115-BG can be used as an animal feed additive for the purpose of enhancing immunity.