Unconventional yeast in the degradation of hydrocarbons in contaminated soil

Abstract

The influence of Yarrowia lipolytica inoculum on biodegradation of hydrocarbons, and changes in microbiota composition in the soil contaminated with petroleum have been investigated. The material under study was contaminated clay soil, containing petroleum-derived substances at approximately 17 000 [mg/kg d. m.]. Microbiological analysis was carried out by the cultivation method and the content of individual hydrocarbons (n-aliphatic, BTEX and PAHs) was determined by the GC/MS method. The largest decrease of oil-derived substances, versus the control sample, was recorded at the beginning of the process. During the first 30 days, the yeast inoculation caused most effectively removal of n-aliphatic hydrocarbons and PAHs (approximately 80% reduction), however, the content of BTEX increased nearly three times. After 60 days of the process, PAHs concentration further decreased (by 40%), concentration of n-aliphatic hydrocarbons decreased a little, however the content of BTEX increased by 10%, compared to the initial concentration. Stimulating the biodegradation process with the yeast inoculum influenced the increase of the bacteria count, mainly Gram-positive, with simultaneous decrease of fungi number.

The Influence of Stimulation Techniques on the Microbiological Changes and n-Alkane Transitions in the Soil Contaminated of Petroleum-Derived Substances

“…Independently on the bioremediation method applied, the toxic substances decay takes place with the participation of enzymes produced by microorganisms. The level of soil bioremediation depends on the catalytic efficiency of the enzymes present in the microorganisms' cells or in the induced ones, developed towards particular substrates (Csutak et al 2010;Lal et al 2010;Krzyśko-Łupicka and Robak 2011;Krzyśko-Łupicka and Kręcidło 2018). Organic compounds degradation in the environments contaminated by hydrocarbons has been conducted by three groups of microorganisms, isolated from crude oil and liquids extracted out of mining processes: fermentative bacteria, bacteria responsible for sulfates (BRS) reduction, which completely oxygenate organic compounds to carbon dioxide or incompletely to acetate and metanotrophic archeons, which produce CH 4 (Wolicka 2010;Jankowska and Swędrzyńska 2016).…”