mtlA, a novel typing gene offering enhanced resolution for pandemic Vibrio species

The gene mtlA, encoding the mannitol transporter subunit IICBA of the phosphotransferase system, was the core gene with the greatest variability in Vibrio parahaemolyticus and could be used as a new typing marker in Vibrio parahaemolyticus. To expand its application, we performed an evolutionary analysis and found that the mtlA gene was present in nine phyla, 371 genera, and 1,662 species of bacteria. It is commonly found in pathogenic species of Vibrio, followed by Paenibacillus, Mycolicibacterium, etc. To investigate whether the mtlA gene could serve as a novel typing gene for whole Vibrio species, we compared the typing effect of the mtlA gene with multilocus sequence type (MLST) in 13 common pathogenic Vibrio species. The results revealed that the mtlA gene was present in all common pathogenic species, providing comparable or even higher typing resolution than MLST, especially in Vibrio cholerae, Vibrio alginolyticus, Vibrio harveyi, and Vibrio anguillarum, enabling accurate typing and traceability; however, many species lacked allelic profiles of MLST genes, making it impossible to obtain accurate STs. In summary, these findings validated the potential typing application of the mtlA gene in Vibrio species.IMPORTANCEVibrio is a collection of gram-negative bacteria characterized by possessing two chromosomes, which exhibit numerous shared biological and genomic traits. Around 13 species of Vibrio are known to cause infections in humans. Without appropriate medical interventions, the consequences of these infections can escalate to become life-threatening. Therefore, based on the prevalent characteristics of pathogenic Vibrio, it is imperative for us to classify and trace various Vibrio species that cause human illness and prescribe medication rationally to control the spread of diseases. In our investigation, we explored the prevalence and typing accuracy of the mtlA gene in Vibrio. Our findings revealed its ubiquitous presence across typical pathogenic Vibrio species, offering superior typing efficacy compared with MLST and more extensive implications.