Kusumawati E, Sudrajat, Purnamasari I, Panggabean BC, Apriyanti M. 2017. Short Communication: The potential of Sulfate Reducing Bacteria of ex-coal mine sediment pond as sulfate reducing agents of acid land in Samarinda, Indonesia. Bonorowo Wetlands 1: 79-82. The study aims to determine the effect of pH medium on the growth of sulfate reducing bacteria taken from the e-coal mine sediment pond and to determine its potential as a reducing sulphate agent of acid ex-coal mine land in Samarinda, East Kalimantan, Indonesia. Six SRB isolated from ex-coal mine sediment pond in Samarinda were used in this study. The SRB potency test in reducing sulfate was conducted by growing the SRB on Postgate liquid medium at different pH of 2, 4 and 6 by the addition of acid soils on each treatment. The results showed that sulfate reducing bacteria isolated from ex-coal mine sediment pond in Samarinda,, i.e., sp.1 (Desulfococcus sp.), sp.2 (Desulfotomaculum sp.), sp.3 (Desulfobacter sp.), sp.4 (Desulfobulbus sp. ), sp.5 (Desulfobacterium sp.) and sp.6 (Desulfotomaculum sp.) had potential as sulfate reducing agent of acid land. The efficiency of sulfate reduction was 89%, 91% and 91% in the pH of 2, 4 and 6, respectively. This indicated that the highest number of sulfate reduction is in the medium with pH 4 and pH 6. In addition, sp.5 (Desulfobacterium sp.) growing on medium at pH 4 had the best sulfate reduction efficiency (93%) compared with other SRB isolates.