Bioremediation of diesel-contaminated seawater by a novel yeast Candida sp. AC06 capable of synchronously degrading hydrocarbon and producing biosurfactant: Performance and genomic mechanism

Zhang N. Lin X. Yan Z. Chen C. Li Y. Yang X. Ren X. Wei X. Zhang C. Bu K. Zhou H.
October 2025 Elsevier Ltd

Journal of Environmental Chemical Engineering
2025 #13 Issue 5

Marine oil pollution is a global issue due to its potential to affect human health and cause severe damage to ecosystems. Microorganisms with biosurfactant (BS) producing capacity plays an active role in the bioremediation of petroleum hydrocarbon pollution. However, the research on the exploration and role of strains with both petroleum hydrocarbon degradation and BS production functions is relatively limited. Herein, a yeast Candida sp. AC06 was isolated and proved excellent BS-producing and oil-degrading capacity. The optimal carbon and nitrogen sources together with other fermentation conditions (temperature, pH, salinity, and inoculum amount) were evaluated based on single factor and orthogonal experiment. For the bacterial growth dynamics and alkane degradation performance, strain AC06 preferentially used n -hexadecane and NH₄Cl for growth in the initial stage, then synthesized BS and degraded n -hexadecane after the biomass increased to a certain amount. Response surface methodology (RSM) revealed significant interactions between fermentation factors, identifying pH and inoculum as the most critical for growth, while salinity, pH, and inoculum were key for minimizing surface tension. The BS generated by strain AC06 exhibited exceptional surface activity across a broad temperature and salinity spectrum, with a critical micelle concentration of 125 mg/L. The analysis of thin-layer chromatography, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry revealed that the BS was a lipopeptide. Inoculation of Candida sp. AC06 significantly enhanced the remediation of diesel-contaminated seawater, with a 60-day long-term experiment confirming its stable activity, sustained metabolite accumulation, and effective removal of n-alkanes and polycyclic aromatic hydrocarbons (PAHs). Integrated genomic, transcriptomic, and metabolomic analyses uncovered the genetic foundation and transcriptional regulation of alkane metabolism and lipopeptide synthesis, illustrating the coordinated roles of fatty acid degradation, fatty acid biosynthesis, and the TCA cycle in facilitating diesel degradation and biosurfactant production. This study presents Candida sp. AC06 as a promising candidate for both BS production and marine diesel pollution bioremediation, contributing novel insights into the use of dual-functional microorganisms for environmental cleanup.

Bioremediation , Biosurfactants , Fermentation conditions , Multi-omics analyses , Yeast strain

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Department of Environmental Engineering, School of Chemistry and Chemical Engineering, Henan University of Science and Technology, Henan, Luoyang, 471000, China
Institute of Marine Biology, Ocean College, Zhejiang University, Zhejiang, Zhoushan, 316021, China
Zhejiang Provincial Zhoushan Marine Ecological Environmental Monitoring Station, Zhejiang, Zhoushan, 316021, China
Eurasian Geochemical Engineering Technical Service Co., LTD., Aktobe city, 030000, Kazakhstan
Key Laboratory of Tropical Marine Ecosystem and Bioresource, Fourth Institute of Oceanography, MNR, Guangxi, Beihai, 536000, China
Xinjiang Keli New Technology Development Co., Ltd., Xinjiang, Karamay, 834000, China
State Key Laboratory for Quality and Safety of Agro – Products, Zhejiang Provincial Key Laboratory of Agricultural Microbiomics, Institute of Environment, Resource, Soil and Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou, China

Department of Environmental Engineering
Institute of Marine Biology
Zhejiang Provincial Zhoushan Marine Ecological Environmental Monitoring Station
Eurasian Geochemical Engineering Technical Service Co.
Key Laboratory of Tropical Marine Ecosystem and Bioresource
Xinjiang Keli New Technology Development Co.
State Key Laboratory for Quality and Safety of Agro – Products

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