Probiotic Potential of Clostridium spp.—Advantages and Doubts

Clostridium spp. is a large genus of obligate anaerobes and is an extremely heterogeneous group of bacteria that can be classified into 19 clusters. Genetic analyses based on the next-generation sequencing of 16S rRNA genes and metagenome analyses conducted on human feces, mucosal biopsies, and luminal content have shown that the three main groups of strict extremophile anaerobes present in the intestines are Clostridium cluster IV (also known as the Clostridium leptum group), Clostridium cluster XIVa (also known as the Clostridium coccoides group) and Bacteroides. In addition to the mentioned clusters, some C. butyricum strains are also considered beneficial for human health. Moreover, this bacterium has been widely used as a probiotic in Asia (particularly in Japan, Korea, and China). The mentioned commensal Clostridia are involved in the regulation and maintenance of all intestinal functions. In the literature, the development processes of new therapies are described based on commensal Clostridia activity. In addition, some Clostridia are associated with pathogenic processes. Some C. butyricum strains detected in stool samples are involved in botulism cases and have also been implicated in severe diseases such as infant botulism and necrotizing enterocolitis in preterm neonates. The aim of this study is to review reports on the possibility of using Clostridium strains as probiotics, consider their positive impact on human health, and identify the risks associated with the expression of their pathogenic properties.