Abstract
Background: This research work focuses on the utilization of indigenous fungi for in situ bioremediation of crude oil in the presence of silver nanoparticles. Methods: Two fungi belonging to two different genera showed promising crude oil-degrading abilities. Fungal isolates were identified based on internal transcribed spacer rDNA sequence analysis. Gas chromatography-mass spectrometry analysis of the crude oil remaining in the culture medium after seven days was performed. The response surface method (RSM) designed by Box-Behnken was used to establish a mathematical model. Inter-simple sequence repeat (ISSR) primers were used to examine the genetic variation of fungal isolates. Results: Gas chromatography-mass spectrometry (GC-MS) analysis after seven days showed that the optimum biodegradation of crude oil was 57.8%. The crude oil degradation rate was significantly affected by a temperature of 30 °C, pH value of 7, crude oil concentration of 4 g/L, a 1:1 ratio between A. flavus AF15 and T. harzianum TH07, and an silver nanoparticle (AgNP) concentration of 0.05 g. Molecular characterization in fungal isolates is extremely valuable when using ISSR markers. Conclusions: Two fungal isolates showed promising crude oil-degrading abilities with positive effect of low concentrations of AgNPs on biodegradation. RSM is an efficient mathematical method to optimize the microbial biodegradation of crude oil.
Highlights
Saudi Arabia, which has almost a quarter of the world’s oil reserves, is the largest producer and exporter of oil
The morphological and microscopic fungal isolate characteristics and molecular tools used for isolate identification were compared with those of reference isolates in the NCBI GenBank
In the BLAST-based analysis, the internal transcribed spacer (ITS) region sequence of each identified fungal isolate showed that isolate A. terreus KC462061 was 99% similar to A. terreus GU 966497 (Figure S1)
Summary
Saudi Arabia, which has almost a quarter of the world’s oil reserves, is the largest producer and exporter of oil. Crude oil is an extremely toxic carcinogenic, is strongly mutagenic, and consists of teratogenic complex compounds It is recognized as a serious threat to ecosystems and it takes several years or decades to recover from many environmental problems after the event of a spill [1]. The presence of crude oil in the natural environment is a critical problem because it causes gradual soil degradation and occasionally leads to the permanent destruction of soil and loss of fertility [2] This necessitates the utilization of methods that are environmentally friendly for cleaning up oil spills. Conclusions: Two fungal isolates showed promising crude oil-degrading abilities with positive effect of low concentrations of AgNPs on biodegradation. RSM is an efficient mathematical method to optimize the microbial biodegradation of crude oil
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