Nanoparticle-assisted structural tailoring of trehalose lipid biosynthesis by Rhodococcus erythropolis WJ-2
Achieving sustainable and cost-effective production and modulating the structure of biosurfactants is increasingly obtaining attention due to carbon neutrality and eco-safety. Nanotechnology-assisted approaches have been emerging as a promising strategy for this purpose. Here, we investigated the effect of metal oxide nanoparticles on the yield and molecular structure of trehalose lipids produced by Rhodococcus erythropolis WJ-2. Sunflower oil was identified as the optimal carbon source against other oils, yielding 12.60 g L−1. Subsequent optimization of four key medium components (sunflower oil, ZnSO4, (NH4)2SO4, and yeast extract) using a Box–Behnken design elevated the baseline yield to 24.75 g L−1. Interestingly, the trehalose lipid yield was further enhanced to 28.12 g L−1 compared to the optimized medium without NPs when supplemented with 0.5 g per L Fe2O3 NPs (≈20 nm). Furthermore, structural diversity analyzed by FTIR and HPLC-MS showed the obvious m/z value shifts of trehalose lipids with NPs comprising longer hydrophobic fatty acid chains and more unsaturated fatty acid derivatives. In the absence of Fe2O3 NPs, the main m/z peaks were detected at m/z 496, 694, 877, and 1044 (relative abundances: 14.19%, 27.08%, 44.18%, 14.55%), corresponding to short-to-medium-chain fatty acid derivatives (e.g., methyl hexanoate, methyl octanoate). In contrast, the dominant peaks shifted to m/z 673, 807, 874, and 1043 (relative abundances: 22.21%, 18.39%, 47.64%, 11.76%) with Fe2O3 NP supplementation. These findings suggest that the unique redox properties and high surface area of Fe2O3 nanoparticles could enhance the yield and modulate the structures to enable the tailored biosynthesis of glycolipids by influencing key-enzyme activity and metabolic flux. This nanoparticle-assisted fermentation strategy offers a promising route for the scalable production of designer biosurfactants for diverse industrial applications.
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