A Keystone Gut Bacterium Christensenella minuta-A Potential Biotherapeutic Agent for Obesity and Associated Metabolic Diseases

A new next-generation probiotic, Christensenella minuta was first discovered in 2012 from healthy human stool and described under the phylum Firmicutes. C. minuta is a subdominant commensal bacterium with highly heritable properties that exhibits mutual interactions with other heritable microbiomes, and its relative abundance is positively correlated with the lean host phenotype associated with a low BMI index. It has been the subject of numerous studies, owing to its potential health benefits. This article reviews the evidence from various studies of C. minuta interventions using animal models for managing metabolic diseases, such as obesity, inflammatory bowel disease, and type 2 diabetes, characterized by gut microbiota dysbiosis and disruption of host metabolism. Notably, more studies have presented the complex interaction between C. minuta and host metabolism when it comes to metabolic health. Therefore, C. minuta could be a potential candidate for innovative microbiome-based biotherapy via fecal microbiota transplantation or oral administration. However, the detailed underlying mechanism of action requires further investigation.

Biocatalytic Synthesis of D-Allulose Using Novel D-Tagatose 3-Epimerase From Christensenella minuta

D-allulose, which is one of the important rare sugars, has gained significant attention in the food and pharmaceutical industries as a potential alternative to sucrose and fructose. Enzymes belonging to the D-tagatose 3-epimerase (DTEase) family can reversibly catalyze the epimerization of D-fructose at the C3 position and convert it into D-allulose by a good number of naturally occurring microorganisms. However, microbial synthesis of D-allulose is still at its immature stage in the industrial arena, mostly due to the preference of slightly acidic conditions for Izumoring reactions. Discovery of novel DTEase that works at acidic conditions is highly preferred for industrial applications. In this study, a novel DTEase, DTE-CM, capable of catalyzing D-fructose into D-allulose was applications. In this study, a novel DTEase, DTE-CM, capable of catalyzing D-fructose into D-allulose was DTE-CM on D-fructose was found to be remarkably influenced and modulated by the type of metal ions (co-factors). The DTE-CM on D-fructose was found to be remarkably influenced and modulated by the type of metal ions (co-factors). The 50°C from 0.5 to 3.5 h at a concentration of 0.1 mM. The enzyme exhibited its maximum catalytic activity on D-fructose at pH 6.0 and 50°C from 0.5 to 3.5 h at a concentration of 0.1 mM. The enzyme exhibited its maximum catalytic activity on -fructose at pH 6.0 and 50°C with a K cat /K m value of 45 mM-1min-1. The 500 g/L D-fructose, which corresponded to 30% conversion rate. With these interesting catalytic properties, this enzyme could be a promising candidate for industrial biocatalytic applications.

Draft Genome Analysis of Christensenella minuta DSM 22607, exhibiting an unusual expansion of transporter homologs of unknown function

Christensenella minuta was first formally described in 2012 as a member of a novel species, genus, and proposed family of Christensenellaceae. C. minuta was later shown in one study to be part of the most heritable taxonomic group in the human gut microbiome and to be enriched in people with low body mass index (BMI). Mouse work demonstrated that injection of cultured C. minuta into germ-free mice prevented the onset of obesity after a fecal transplant to the mice from high BMI individuals. Here we describe the genome sequence of C. minuta DSM 22607. Examination and analysis of the annotation revealed an unusually high number of genes predicted to be involved in carbohydrate metabolism, many of which were multiple homologs of RbsA, RbsB and RbsC, which together make up the Ribose ABC Transport System. These genes may be also involved in quorum sensing which could potentially relate to the importance of C. minuta in the gut microbiome.

High rejection rate of polysaccharides by microfiltration benefits Christensenella minuta and acetic acid production in an anaerobic membrane bioreactor for sludge fermentation

Substrates, the microbial community, and volatile fatty acids (VFAs) are interacting factors in anaerobic fermentation. In this paper, a microfiltration membrane was installed in a conventional reactor for sludge anaerobic fermentation, and changes in the VFA composition and the microbial community structure after the application were monitored. The membrane rejected much more polysaccharide than protein. VFA production, mainly acetic acid, was greatly enhanced by the membrane separation. The glycolytic species Christensenella minuta was significantly enriched. The explanation was inferred to be the higher retention rate of polysaccharide compared with proteins by the microfiltration. However, surprisingly, another polysaccharide using genus, Parabacteroides, did not benefit from the application of the membrane separation, suggesting more complicated mechanisms might be involved.

Effects of Christensenella minuta lipopolysaccharide on RAW 264.7 macrophages activation

Christensenella minuta (C. minuta) is a gram-negative gastrointestinal bacterium associated with weight loss. However, recent studies have shown that C. minuta might be a potential pathogen and thus limited its application in the control of obesity. Research into the genetic characteristics and pathogenicity of C. minuta remain elusive. As a major virulence factor of gram-negative bacteria, lipopolysaccharide (LPS) can induce various diseases. In this study, we report the complete genome sequence of C. minuta and have also identified some genes related to LPS biosynthesis. The structure of C. minuta LPS, detected by SDS-PAGE, was different from that of Escherichia coli (E. coli) LPS. The incubation of RAW 264.7 macrophages with C. minuta LPS resulted in lower levels of cellular proliferation, phagocytosis and nuclear factor-kappa B (NF-κB) activation as compared to incubation with E. coli LPS. Furthermore, the expression of pro-inflammatory cytokines, as well as nitric oxide and reactive oxygen species production, was induced in C. minuta LPS-treated cells but to a much lower extent than that by E. coli LPS. These findings show that C. minuta LPS acts as a weak agonist for RAW 264.7 macrophages and can only trigger a weak inflammatory response through the NF-κB signalling pathway. In conclusion, these results suggest that the toxicity of C. minuta LPS is significantly attenuated due to its atypical structure and weak agonist activity for RAW 264.7 macrophages.

First report of human infection by Christensenella minuta, a gram-negative, strickly anaerobic rod that inhabits the human intestine

Christensenella minuta is a Gram-negative strictly anaerobic short rod that inhabits the human gut. This bacterium was isolated in a mixed infection with Desulfovibrio desulfuricansfrom the blood of a patient with a diagnosis of acute appendicitis. The strain was identified by 16S rRNA sequence analysis. As far as we know, this is the first time C.minuta has been isolated from a human clinical specimen.