SCRIPTA BIOLOGICA | VOLUME 5 | NUMBER 2 | JUNE 2018 | 79–82 | HTTPS://DOI.ORG/10.20884/1.SB.2018.5.2.812 | http://scri.bio.unsoed.ac.id 79 BIODEGRADATION OF DIESEL OIL BY YEAST ISOLATED FROM MANGROVE’S RHIZOSPHERE RYAN FIRMAN SYAH 1 , AGUS IRIANTO 2 , NUNIEK INA RATNANINGTYAS 2 1 Faculty of Health, Universitas MH Thamrin, Jalan Raya Pondok Gede 23–25 Kramat Jati, East Jakarta 13550 2 Faculty of Biology, Jenderal Soedirman University, Jalan dr. Soeparno 63, Purwokerto 53122 ABSTRACT Diesel oil-degrading yeast strains isolated from mangrove rhizosphere at Tritih Kulon, Cilacap had been screened with SMSS medium. Four culturable yeast were isolated. Qualitative test was conducted by culturing and incubating the yeasts for one month in a medium added with 1mL diesel oil. By measuring the reduction of diesel oil, two best yeasts were selected. The quantitative test, GC-MS analysis, was conducted to determine the detailed degradation process of diesel oil. Candida lusitaniae and Cryptococcus laurentii performed the degradative ability. Three highest percent area of hydrocarbon compounds were compared for assessment. The results showed that C. lusitanie had better degradative capability than C. laurentii, in which hexadecane and methyl hexadecanoate decreased by 90–95%, and 9- octadecenoic acid, methyl ester declined by 30–40%. The increasing pH medium during incubation suggested that fermentation process occurred. KEY WORDS: yeast, diesel oil-degrading, hydrocarbon compound Corresponding author: RYAN FIRMAN SYAH | email: ryansuparman@gmail.com Submitted: 27-03-2018 | Accepted: 23-06-2018 INTRODUCTION The mangrove forest is a forest located between land and sea. Its ecosystem has a vital role in the ecological and economic cycles since it consists of elements such as nitrogen, accumulated dissolved phosphor, the primary, and secondary productions. The ecosystem services provided include protection of shoreline, prevention of seawater intrusion, regulation of microclimate, germplasm provision of mangrove biota, source of bioenergy, site of animal shelter, site of animal feed and breed (Soedradjad, 2003; Setyawan & Winarno, 2006; Pribadi et al., 2009). The Segara Anakan mangrove, Cilacap covered 24,000 ha area in 1980, then declined to approximately 12.343 ha (Caraka, 2012). The ecosystem is increasingly threatened by sedimentation, industrialization, and overexploitation (Soedradjad, 2003), which was demonstrated by the shrinking reproduction area up to nearly 500 ha, and a shrimp (Metapenaeus elegans) production decrease. Both are caused partly by pollution in water bodies in the region (Suradi et al., 2005). Oil contaminant is a common problem of pollutant compounds brought by River Donan waters. The river had an oil content of 6.6 ppm (Soedradjad, 2000), while the maximum limit of oil according to the water quality standards based on Kepmen KLH No. 02/1988 is less than 5.0 ppm. Oil pollution in the River Donan comes from the liquid waste of oil refineries (average activities of 167.136 kg/h with the debit of 10.502 m 3 /sec) (Soedradjad, 2003). An effort to reduce the water pollution is by using microbes that are capable of breaking down the oil pollutants to particular molecules (Irianto et al., 2003). Yeast is a microbe capable of degrading the oil. Nurhayati et al. (2001) reported that yeast could degrade hydrocarbons. They managed to obtain nine isolates from areas contaminated with oil port at Tanjung Perak comprising eight genera consisting of two isolates of Candida and one isolate from each genus of Rhodotorula, Geotrichum, Torulopsis, Trichosporon, Cryptococcus, and Saccharomyces. Miranda et al. (2007) isolated yeast from the diesel oil filling station at the Port of Suape Pernambuco, Brazil and cultured two isolates of Candida ernobii UFPEDA, i.e., 862 and 845 UFPEDA. Candida utilizes oil hydrocarbons as its nutrient source for growth by breaking down Carbon to aliphatic and aromatic hydrocarbon. Chandran and Das (2010) isolated Trichosporon asahii yeast which became a powerful biosurfactant on mineral salt medium contaminated with diesel fuel in India. T. asahii uses the diesel fuel as its carbon source and efficiently degrade (95%) diesel fuel in 10 days. The ability of yeast to decompose the hydrocarbons, the aliphatic and aromatic compounds, can be enhanced by adding a nitrogen source to the degradation medium. A nitrogen source which has a high nitrogen content at a low price and easily obtained is urea (carbamide). According to Leahy and Colwell (1990), nitrogen fertilizers can stimulate hydrocarbon biodegradation. Therefore, it is necessary to examine the biodegradation of diesel oil by yeast isolates from mangrove Cilacap. This research was conducted to explore indigenous yeast isolates from the oil-contaminated area. The isolated yeasts were then cultivated on nitrogen enhancing medium and tested for their ability to degrade diesel oil. METHODS The yeasts were isolated from Mangrove Forest Area at Tritih Kulon, Cilacap, Central Java. The microbiological analysis was done at the Laboratory of Microbiology, Universitas Jenderal Soedirman. Tests for yeast ability to degrade hydrocarbons was carried out experimentally. Analysis of hydrocarbon compounds using Gas Chromatography-Mass Spektro was conducted at the