Biochemical characterization of extended-spectrum β-lactamases from Akkermansia genus

Akkermansia muciniphila, a member of the Verrucomicrobiota phylum, is recognized as a key gut microbe and has emerged as a potential next-generation probiotic. Assessment of antibiotic resistance in probiotics is a prerequisite for their therapeutic application, while very few is known in Akkermansia species. Firstly, we screened eight representative class A {beta}-lactamases (36.90%-41.30% identity with known {beta}-lactamases) from the Akkermansia species, which could increase the minimum inhibitory concentration (MIC) of Escherichia coli to{beta}-lactams. Secondly, four{beta}-lactamases were purified and identified as extended-spectrum {beta}-lactamase because they exhibited hydrolase activity against 19 {beta}-lactam antibiotics from penicillin, cephalosporins, and monobactam classes. Based on sequence alignment, three-dimensional structure, and binding pocket information, we hypothesized and validated that serine at 51 position was catalytic amino acid. Thirdly, the genomic context analysis revealed the absence of mobile genetic elements or other antibiotic resistance genes surrounding {beta}-lactamase genes, suggesting that the {beta}-lactamases from Akkermansia species may not be transferable. The finding and biochemical characterization of {beta}-lactamase from Akkermansia species provide a foundational basis for the safety evaluation of Akkermansia species as probiotics.