Production of biodiesel from oleaginous fungal lipid using highly catalytic bimetallic gold-silver core-shell nanoparticle.

AIMS: This study aims to synthesize, characterize and apply gold-silver core-shell nanoparticles (Au@Ag NPs), a nanocatalyst, to maximize biodiesel production from fungal isolate Fusarium solani (FS12) via a transesterification one-step reaction. METHODS AND RESULTS: The Au@Ag NPs structure was examined by UV-vis spectrophotometer, transmission electron microscopy, X-ray diffraction and Fourier transform infrared (FTIR). All devices were used to characterize Au@Ag NPs and confirmed successful synthesis of nanoparticles. Fungal lipid was quantitatively determined by sulfo-phospho-vanillin colorimetric method. Among 15 F. solani isolates obtained from rhizospheric soils of the date palm, F. solani (AF12) was chosen as the highly significant producer that accumulates above 20% lipid. The maximum biodiesel yield was 91.28 ± 0.19%, obtained under the optimum reaction conditions of 3% Au@Ag NPs as nanocatalyst concentration, and 1:20 oil to methanol molar ratio at 70℃ for 30 min. HPLC method was applied for monitoring in situ transesterification reaction. FTIR spectroscopy was used in qualitative analysis of biodiesel by verifying the presence of unique characteristic peaks of diagnostic significance. The quality of the biodiesel produced was confirmed by the high purity of fatty acid methyl esters analysis content up to >99%. CONCLUSIONS: These findings propose the applicability of F. solani (FS12) as a promising isolate to accumulate lipids and biodiesel production as a feedstock. SIGNIFICANCE AND IMPACT OF THE STUDY: The link between nanotechnology and fungi. Au@Ag NPs were synthesized at room temperature, which displayed high catalytic activity for in situ transesterification reaction. Catalytic activity appeared at low temperature, mole ratio and short reaction time. Oleaginous fungi are described as easily grown, have short life cycle, are cost-effective, and they utilized various sources of carbon up to waste and a simplified process to develop scale-up production as well, economic value, opposite the usage of vegetable oils which need for large agricultural areas.

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 °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.