Expressing Vitreoscilla hemoglobin in Escherichia coli Nissle 1917 enhances its probiotic potential for alleviating ulcerative colitis.

Ulcerative colitis causes chronic intestinal inflammation with a complex etiology and limited treatment options. Active probiotics are an effective way to treat gastrointestinal diseases, which often face challenges in surviving and colonizing the complex gastrointestinal environment. In this study, we investigated the potential of Escherichia coli Nissle 1917 with a cloned bacterial hemoglobin gene (EcN-VHb) in intestinal colonization and therapeutic efficacy for treating ulcerative colitis. The EcN-VHb strain demonstrated exceptional resistance to hypoxic and oxidative stress, endowing it with an advantageous edge in intestinal colonization in testing mice. EcN-VHb also modulated the gut microbiota and alleviated dextran sulfate sodium-induced colitis in mice, a model of ulcerative colitis. In comparison, the parent strain EcN relieved the colitis with reduced efficiency. This study provides a novel approach to enhance the stability and functionality of probiotics in hypoxic gut environments and offers a potentially new platform for developing other probiotic-based therapies.