Mycobiota of Oil-Contaminated Soil Samples and Their Abilities for Dibenzothiophene Desulfurization

High sulfur content of crude oil leads to poor quality of oil products and many other negative consequences such as corrosion, catalyst poisoning and environmental pollution. Saudi Arabia is seeking to reduce sulfur content in diesel and gasoline to 10 ppm and to lower benzene content in gasoline to 1%. Biotechnological processes such as biodesulfurization can be considered an alternative or complement to conventional oil refining technologies. So, the objective of the present project is to isolate and identify endogenous fungal isolates capable of oil biodesulfurization. From 60 oil-contaminated soil samples collected from Saudi Arabia, 15 species belonged to 9 fungal genera were collected and identified morphologically and with ITS sequencing. Members of Aspergillus, Penicillium and Fusarium were the most prevalent in the investigated samples. Among the collected fungal species, only Stachybotrys bisbyiisolates were able to utilize dibenzothiophene (DBT) as the sole sulfur source. Stachybotrys bisbyi TUSb1 could desulfurize 99% of the DBT (0.3 mM) as the sulfur source by a co-metabolism reaction with other carbon sources through the same pathway as 4S (involves sequential oxidation of the sulfur part and cleaving of the C–S bonds), and produced 2-hydroxy biphenyl (2-HBP) during 7 days of incubation at 30°C and 180 rpm. Stachybotrys bisbyi TUSb1 showed broad specificity for removing sulfur in different sulfur-containing compounds.