BIODIVERSITAS ISSN: 1412-033X Volume 24, Number 10, October 2023 E-ISSN: 2085-4722 Pages: 5391-5398 DOI: 10.13057/biodiv/d241021 Amplicon-based sequencing revealed potential microbiologically influenced corrosion in the interim storage for spent fuel of RSG-GAS, Serpong, Indonesia IRAWAN SUGORO 1,♥ , DIANNISA SYAHWA RAHMA FADILA 2 , MEGGA RATNASARI PIKOLI 2 , FERI EKO HERMANTO 3,4 , FIRDAUS RAMADHAN 5 , SYALWA ERSADIWI SHALSABILLA 2 , ADE CICI 2 , MOHAMMAD SYAMSUL RIJAL 2 , DYAH SULISTYANI RAHAYU 1 , MARHAENI JOKO PUSPITO 1 , DINDA RAMA HARIBOWO 2 , DEVITA TETRIANA 1 1 Research Center for Radiation Process Technology, National Research and Innovation Agency. Jl. Lebak Bulus Raya No. 49, Jakarta Selatan 12440, Jakarta, Indonesia. ♥ email: iraw004@brin.go.id 2 Department of Biology, Faculty of Science and Technology, Universitas Islam Negeri Syarif Hidayatullah. Jl. Ir H. Juanda No.95, Ciputat Timur, Tangerang Selatan 15412, Banten, Indonesia 3 Biomolecular and Bioinformatics Research Center, Indonesia Institute of Bioinformatics. Perum Sarimadu II B3 No. 09, Pakisaji, Malang 65162, East Java, Indonesia 4 Faculty of Animal Sciences, Universitas Brawijaya. Jl. Veteran, Ketawanggede, Lowokwaru, Malang 65145, East Java, Indonesia 5 Institut Sains dan Teknologi Nasional. Jl. Moch. Kahfi II, Srengseng Sawah, Jakarta Selatan 12630, Jakarta, Indonesia Manuscript received: 13 June 2023. Revision accepted: 18 October 2023. Abstract. Sugoro I, Fadila DSR, Pikoli MR, Hermanto FE, Ramadhan F, Shalsabilla SE, Cici A, Rijal MS, Rahayu DS, Puspito MJ, Haribowo DR, Tetriana D. 2023. Amplicon-based sequencing revealed potential microbiologically influenced corrosion in the interim storage for spent fuel of RSG-GAS, Serpong, Indonesia. Biodiversitas 24: 5391-5398. Interim storage of spent fuel (ISSF) corrosion can negatively impact nuclear power plant maintenance, specifically concerning safety, financial costs, and regulatory compliance. Besides chemical reactions, microbiologically influenced corrosion (MIC) also primarily occurred. Sulfate-reducing bacteria (SRB) plays a significant role in the development of MIC. The quantitative of MIC research has never been conducted in the ISSF - Multipurpose nuclear reactor of G.A. Siwabessy (RSG-GAS). So, this study aims to monitor the potential MIC development in the ISSF of RSG-GAS pool and canal through bacterial diversity analysis using total plate count (TPC) and metagenomic approach. TPC results showed that SRB was identified in the canal of ISSF but not in the pool site. However, metagenomics analysis revealed higher diversity measures in the pool than in the canal sites. Staphylococcus sp. was the most abundant species in both sites, with a relative abundance greater than 85%. The number of SRB and MIC-related bacteria was higher in the canal than in the pool, both from TPC and metagenomic analysis. Several SRB taxa were identified, such as Desulfobulbus mediterraneus, Desulfobulbus sp., Desulfofustis sp., Desulfovibrio sp., and Truepera sp. The potential MIC development also strengthens by diversity-based metabolic pathway prediction, which mainly displayed sulfur oxidation and sulfate reduction pathways in the canal system. Keywords: Bacterial diversity, biocorrosion, ISSF, MIC, SRB INTRODUCTION The spent nuclear fuel (SNF) will be stored in the interim storage of spent fuel (ISSF) upon being used in a reactor or power plant. The ISSF mainly builds as a water basin (Ojovan and Lee 2014). Wet storage lets the fuel securely disperse heat while allowing dangerous radionuclides to decay naturally (Bagwell et al. 2018). The ISSF facility for Multipurpose Reactor-G. A. Siwabessy (RSG-GAS) was built as pool and canal (Sugoro et al. 2022). Long-term storing of SNF from nuclear research reactors in pool and canal creates the potential for corrosion (Karley et al. 2022). These conditions may be caused by several microbes that highly adapt to oligotrophic environment at ISSF (Karley et al. 2022). This microbes-associated corrosion is known as microbiologically influenced corrosion (MIC) (Diler et al. 2023), highly adaptive microbes, involve in MIC progression mainly classified as sulfate-reducing bacteria (SRB) (Lavanya 2022). The growth inhibition of SRB is essential step as a part of maintenance of the ISSF facility. Spent fuel has fission products bordered with stainless steel coatings. The quality of the water in the spent fuel storage pond, according to the International Atomic Energy Agency (IAEA) in 2011, has a pH value of 6-8, a conductivity value of <10 μS/cm, a TDS value of <1350 mg/L, a temperature of <45°C, and has a maximum bacterial density of 1000 CFU/mL. Water in ISSF pools must be free from microorganisms such as microalgae and bacteria that live in a radioactive environment. Moreover, microalgae can cause corrosion to stainless steel, an ISSF component. Microalgae at ISSF facility of RSG-GAS are dominated by the genus Chlorella sp. (Chlorophyceae). Bacteria associated with algae can induce corrosion- affected MIC (Sugoro et al. 2022), and bacteria that has an essential role in corrosion is SRB. SRB is a type of bacteria that can live in an environment with little or no oxygen; this bacterium can convert sulfates into sulfites so they can