Optimizing Laccase Production From Halotolerant <i>Enterobacter</i> sp. <i>GR18</i> for Hydrocarbon Bioremediation

ABSTRACT Hydrocarbon contamination, primarily from oil spills and their derivatives, poses significant environmental challenges and has profound impacts on public health and ecosystems. Innovative bioremediation strategies, especially those utilizing laccase enzymes, have emerged as robust and sustainable solutions to degrade these persistent pollutants. This study focused on optimizing laccase production from Enterobacter sp. GR18 , isolated from the Grawan mineral spring near Sardasht, West Azerbaijan Province, Iran. The bacterium was identified through comprehensive biochemical tests and 16S rRNA sequencing. Advanced methodologies were used to optimize laccase production conditions. The purified laccase enzyme was characterized using SDS‐PAGE. The effects of various carbon and nitrogen sources, metal ions, and inducers on enzymatic activity were thoroughly investigated. Structural changes in crude oil samples treated with laccase were analyzed using nuclear magnetic resonance (NMR) spectroscopy. Enterobacter sp. GR18 showed exceptional laccase activity among 33 isolated strains. Glucose and yeast extract were the most effective carbon and nitrogen sources, respectively. Copper and iron ions significantly enhanced enzyme activity. NMR spectroscopy indicated substantial breakdown of complex hydrocarbons in crude oil samples posttreatment, demonstrating the enzyme's effectiveness in hydrocarbon degradation. This study reveals the potential of Enterobacter sp. GR18 for high laccase production and efficient hydrocarbon degradation under extreme environmental conditions. These findings can catalyze the development of robust and sustainable bioremediation technologies to address hydrocarbon contamination.