Next-generation probiotics: beyond lactic acid bacteria to untapped taxa and engineered strains for better health.

In this perspective, we discuss the evolving landscape of next-generation probiotics (NGPs), challenging the ambiguity of the term and proposing a framework for unifying the concepts associated with the field. We highlight the potential of novel candidates, including lactic acid bacteria and other commensal microorganisms from untapped taxa and genetically engineered strains, while examining their applications for human health. Rather than defining NGPs as a distinct category, we propose using the term to describe microbial-based health-promoting products in development, particularly where novelty relates to the organism, mechanism, engineering strategy, formulation, or targeted function. We address their safety concerns and regulatory challenges, while clarifying the divergence between therapeutic and dietary supplement pathways. We argue that as these products become more fully characterized and their safety, efficacy, intended use, and regulatory pathway are established, more specific terminology may take precedence, including the long-accepted probiotic category once efficacy and safety are established, or the live biotherapeutic products category if they are specifically developed for therapeutic applications. We suggest that the future of the 'beneficial microbes for health' field depends on striking a balance between the benefits of innovation and the necessity of rigorous safety and efficacy considerations.