Bioremediation of Crude Oil by Rhizosphere Fungal Isolates in the Presence of Silver Nanoparticles

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 degrees C, pH value of 7, crude oil concentration of 4 g/L, a 1:1 ratio betweenA. flavusAF15 andT. harzianumTH07, 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.