Vol.:(0123456789) 1 3 Current Microbiology https://doi.org/10.1007/s00284-019-01641-8 Biosurfactant-Producing Capability and Prediction of Functional Genes Potentially Benefcial to Microbial Enhanced Oil Recovery in Indigenous Bacterial Communities of an Onshore Oil Reservoir Thanachai Phetcharat 1  · Pinan Dawkrajai 2  · Thararat Chitov 3,5  · Wuttichai Mhuantong 4  · Verawat Champreda 4  · Sakunnee Bovonsombut 3,5,6 Received: 20 April 2018 / Accepted: 28 January 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Microbial enhanced oil recovery (MEOR) is a bio-based technology with economic and environmental benefts. The success of MEOR depends greatly on the types and characteristics of indigenous microbes. The aim of this study was to evaluate the feasibility of applying MEOR at Mae Soon Reservoir, an onshore oil reservoir experiencing a decline in its production rate. We investigated the capability of the reservoir’s bacteria to produce biosurfactants, and evaluated the potentials of uncul- tured indigenous bacteria to support MEOR by means of prediction of MEOR-related functional genes, based on a set of metagenomic 16s rRNA gene data. The biosurfactant-producing bacteria isolated from the oil-bearing sandstones from the reservoir belonged to one species: Bacillus licheniformis, with one having the ability to decrease surface tension from 72 to 32 mN/m. Gene sequences responsible for biosurfactant (licA3), lipase (lipP1) and catechol 2,3-dioxygenase (C23O) were detected in these isolates. The latter two, and other genes encoding MEOR-related functional proteins such as enoyl-CoA hydratase and alkane 1-monooxygenase, were predicted in the bacterial communities residing the reservoir’s sandstones. Exposure of these sandstones to nutrients, consisting of KNO 3 and NaH 2 PO 4 , resulted in an increase in the proportions of some predicted functional genes. These results indicated the potentials of MEOR application at Mae Soon site. Using the approaches demonstrated in this study would also assist evaluation of the feasibility of applying MEOR in oil reservoirs, which may be enhanced by an appropriate nutrient treatment. Introduction Many non-renewable energy resources have become criti- cally limited. Crude oil, one of the limited resources, remains the main fuel that plays a signifcant role in eco- nomic development [26]. With the decreasing rates of oil reservoir discoveries, attempts have been made to meet the energy demands by exploiting renewable or alternative energy resources and developing technologies to recover petroleum products. The petroleum industry has paid much attention to the latter since two-thirds of original oil in place (OOIP) is still in oil reservoirs even after conventional (pri- mary and secondary) recovery processes [16, 52]. It is esti- mated that over two trillion barrels of crude oil and fve trillion barrels of heavy oil remain in the worldwide oil res- ervoirs [58]. Microbial enhanced oil recovery (MEOR) is one of the tertiary recovery methods used to increase the efciency of oil production [3]. This method employs microorgan- isms and their metabolic products to recover residual oil Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00284-019-01641-8) contains supplementary material, which is available to authorized users. * Sakunnee Bovonsombut sakunnee.b@cmu.ac.th 1 Interdisciplinary Program in Biotechnology, Graduate School, Chiang Mai University, Chiang Mai 50200, Thailand 2 Defence Energy Department, Northern Petroleum Development Center, Fang, Chiang Mai 50110, Thailand 3 Division of Microbiology, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand 4 Enzyme Technology Laboratory, The National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Pathum Thani 12120, Thailand 5 Environmental Science Research Center (ESRC), Chiang Mai University, Chiang Mai 50200, Thailand 6 Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand