A decade of insight into ExlA toxin research and the biotechnological potential of non-virulent <i>Pseudomonas aeruginosa</i> strains

<i>Pseudomonas aeruginosa</i> remains a critical global health concern because of its virulence and multidrug resistance. While clades 1 and 2 are well documented for utilizing the type 3 secretion system (T3SS) as a primary pathogenic mechanism, clade 5 strains have drawn attention for their reliance on alternative virulence factors, such as Exolysin A (ExlA). Over the past decade, research has provided deeper insights into ExlA, a pore-forming toxin associated with clades 3 and 5, offering a unique perspective on the pathogenic strategies of these less-virulent strains. This review explores the regulatory pathways of ExlA expression, its effects on host cells, and its role in the broader context of the reduced virulence of clade 5. By examining the potential biotechnological applications of clade 5 strains, this review highlights therapeutic opportunities presented by leveraging their less harmful nature. The synthesis of this knowledge contributes to a broader understanding of how non-T3SS-dependent mechanisms can be harnessed to develop innovative anti-virulence therapies and alternative biotechnological applications.