Functional constipation (FC) is a gastrointestinal disorder with high incidence, and it seriously affects patients’ physical and mental health. Several studies have shown that the gut microbiome is associated with FC, but these studies have produced inconsistent findings, with few reflecting the relationship between the gut microbiome and metabolites. This study used 16S rRNA microbial genomics and non-target metabolome based on liquid chromatography–mass spectrometry to analyze the gut microbiota composition and serum metabolic profiles of 30 FC patients and 28 healthy individuals. We found that patients with FC and healthy individuals have different gut microbiota structures and serum metabolic profiles. FC patients had more Bacteroides and butyrate-producing bacteria (Roseburia, Faecaliberium, Butyriccoccus). The upstream products of host arginine biosynthesis (2-oxoglutaric acid, L-glutamic acid, N-acetylornithine, and L-ornithine) were significantly reduced in FC patients’ serum metabolites. In summary, our study describes the gut microbiome and serum metabolome of patients with functional constipation. It reveals that functional constipation may be associated with increased Bacteroidetes and downregulation of upstream products of host arginine biosynthesis, which may be potential markers for diagnosing functional constipation.

Cathartic colon (CC), a type of slow-transit constipation caused by the long-term use of stimulant laxatives, does not have a precise and effective treatment. This study aimed to evaluate the ability of Bifidobacterium bifidum CCFM1163 to relieve CC and to investigate its underlying mechanism. Male C57BL/6J mice were treated with senna extract for 8 weeks, followed by a 2-week treatment with B. bifidum CCFM1163. The results revealed that B. bifidum CCFM1163 effectively alleviated CC symptoms. The possible mechanism of B. bifidum CCFM1163 in relieving CC was analyzed by measuring the intestinal barrier and enteric nervous system (ENS)-related indices and establishing a correlation between each index and gut microbiota. The results indicated that B. bifidum CCFM1163 changed the gut microbiota by significantly increasing the relative abundance of Bifidobacterium, Faecalibaculum, Romboutsia, and Turicibacter as well as the content of short-chain fatty acids, especially propionic acid, in the feces. This increased the expression of tight junction proteins and aquaporin 8, decreased intestinal transit time, increased fecal water content, and relieved CC. In addition, B. bifidum CCFM1163 also increased the relative abundance of Faecalibaculum in feces and the expression of enteric nerve marker proteins to repair the ENS, promote intestinal motility, and relieve constipation.