Biotransformation of naproxen by an atoxigenic <i>Bacillus cereus</i> group strain closely related to <i>Bacillus anthracis</i> : linking genomic features to biodegradative activity

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen (Nap), are among the most widely consumed medications worldwide. However, wastewater treatments are inefficient at removing them, leading to their persistence in the environment. In this study, bacteria isolated from the contaminated lagoon "La Escondida", Reynosa, Mexico, were initially screened for tolerance to pharmaceutical drugs, including Nap. Ten bacterial isolates showed growth in the presence of both Amp (ampicillin) and Nap (100 mg l-1). Isolate P43-LBF was identified as a Bacillus group, showing high genomic similarity (ANI 98.26 %) to Bacillus anthracis but lacking the pOX1 and pOX2 virulence plasmids. It caused a degradation of 67.43 % and 43.78 % (5 and 25 mg l-1, respectively) of Nap in glucose-supplemented minimal medium in seven days. Degradation products, such as 6-O-desmethylnaproxen, were detected by Ultra Performance Liquid Chromatography Mass Spectrometry (UPLC-MS), indicating active biotransformation. Genomic analysis revealed genes associated with xenobiotic degradation, including catE, encoding catechol-2,3-dioxygenase. Additionally, genes associated with virulence and resistance were also identified, which support stress tolerance. Phylogenetic analysis of Bacillus species known for their ability to degrade aromatic compounds supports their potential application in pharmaceutical bioremediation. These findings highlight strain P43-LBF as a promising candidate for pharmaceutical bioremediation.