BONOROWO WETLANDS P-ISSN: 2088-110X Volume 7, Number 2, December 2017 E-ISSN: 2088-2475 Pages: 79-82 DOI: 10.13057/bonorowo/w070204 Short Communication: The potential of Sulfate Reducing Bacteria of ex-coal mine sediment pond as sulfate reducing agents of acid land in Samarinda, Indonesia EKO KUSUMAWATI 1, , SUDRAJAT 2 , IKA PURNAMASARI 3 , BINA CRISTYANTI PANGGABEAN 1 , MAIDA APRIYANTI 1 1 Laboratory of Microbiology and Molecular Genetics, Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Mulawarman. Samarinda 75123, East Kalimantan, Indonesia.  email: eko.kusumawati11@gmail.com 2 Laboratory of Animal Anatomy and Microtechnique, Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Mulawarman. Samarinda 75123, East Kalimantan, Indonesia 3 Laboratory of Economics and Business, Department of Mathematics, Faculty of Mathematics and Natural Sciences, Universitas Mulawarman. Samarinda 75123, East Kalimantan, Indonesia Manuscript received: 20 May 2017. Revision accepted: 9 September 2017. Abstract. 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. Keywords: pH of the medium, sulphate reducing bacteria, acid land INTRODUCTION Mining activities such as coal mining can provide economic benefits but also can cause environmental and soil ecosystems damage (Tala’ohu et al. 1995). One element of the causes of the impact is the generated waste as a byproduct or the remnant of the mining and processing which are often in large volume and in various kinds. United Nations Environmment Programme (UNEP) classifies the impacts of mining activities including the destruction of habitat and biodiversity at the mine site, the landscape change or loss of land use as well as B3 waste and chemicals (Fahruddin 2010). The most severe problems in mining activity is the occurrence of the phenomenon of acid mine drainage (AMD) or acid rock drainage (ARD) due to the oxidation of sulfur minerals. This will give a series of interrelated effects, namely decreasing pH, disturbing the availability and the balance of soil nutrients, and increasing the solubility of micronutrients which generally is a metal element (Havlin et al. 1999). One environmentally friendly method is bioremediation, namely, a process to restore the environment using microorganisms as contaminants eliminating. Group of microbes that can be used to improve the quality of post- mine land is sulfate reducing bacteria (SRB). In the metabolic activities SRB can convert sulfate to H2S. This gas will immediately bind to the metals found in many post-mining land and precipitated in the form of metal sulfides reductive (Hards and Higgins 2004). However, the main problem often encountered in the application of microorganisms for bioremediation is the decrease or the loss of potential microbial. To improve the effectiveness of the use of microorganisms in bioremediation, the following two strategies can be done. First; bio-stimulation, it is a technique to add certain nutrients with the aim of stimulating the activity of local (indigenous) microbes. Atlas and Bartha (1992) stated that bio-simulation technique has been successful in controlling the oil spills in water and the contamination of hydrocarbons (PAHs) in the soil. Lieberg and Cutright (1999) stated that nutrients which are often used in this technique are phosphorus and nitrogen. Second; bio-augmentation, it is a technique to introduce a specific microbes in the remediated area. In addition, environmental influences such as pH, temperature, and soil moisture were also very influential in determining the success of the bioremediation process. Based on the introduction, the problem in this research