Disclosed herein is an isolated Pediococcus acidilactici 05B0111 capable of producing an exopolysaccharide. The Pediococcus acidilactici 05B0111 is deposited in Biosource Collection and Research Center (BCRC) of Food Industry Research and Development Institute (FIRDI) under an accession number BCRC 910420 and deposited in Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ) under an accession number DSM 22345. A method of producing an exopolysaccharide is also disclosed. The method involves cultivating an isolated Pediococcus acidilactici in a suitable medium under condition such that the exopolysaccharide is formed. A pharmaceutical composition including the aforementioned Pediococcus acidilactici 05B0111 and a food product including the aforementioned Pediococcus acidilactici 05B0111 are disclosed as well.