Growth of succinate consumer Dialister hominis is supported by Bacteroides thetaiotaomicron

Succinate-mediated symbiosis between Dialister hominis and an uncharacterized Segatella-like pectinophile

OBJECTIVES

Syntrophy has been documented between pectinophiles and methanol-utilizing bacteria, along with instances of cross-feeding between pectinophiles and methanogens. However, studies on the ecology of pectinophiles in anaerobic digestion (AD) are lacking. Therefore, in this study, we aimed to elucidate the ecology of pectinophiles by isolating novel pectinophile forms and conducting a comprehensive analysis of their physiology and ecology.

METHODS

Complex microbial communities from AD systems were enriched in a pectin-containing medium; subsequently, specific strains were isolated using a pectinophile isolation method. The carbon source assimilation and growth ability of the isolates, along with their symbiotic relationships, were evaluated using batch tests.

RESULTS

Strain LPYR103-Pre exhibited 16S rRNA gene sequence similarity and average nucleotide identity values of 94.3 % and 77.9 %, respectively, compared to its closest related species, Segatella cerevisiae. Strain LPYR103-Pre demonstrated attenuated growth in the presence of eight common sugars but exhibited remarkably high growth in the presence of pectin, d-galacturonate, and d-glucuronate, with succinate being identified as a primary metabolite. Accumulation of succinate inhibited the growth of strain LPYR103-Pre. However, this growth impediment was alleviated by Dialister hominis LPYG114-Dih, whose growth required succinate.

CONCLUSIONS

Our results elucidate the specific carbon source requirements of the Segatella-like strain LPYR103-Pre and succinate-mediated symbiosis involving D. hominis. These findings provide new insights into the degradation of pectin and its degradation products during AD, contributing to the identification of unknown pectinophiles.

In vitro simulated digestion and fermentation behaviors of polysaccharides from Pleurotus cornucopiae and their impact on the gut microbiota

This study investigated the physicochemical characteristics and fermentative behavior between original polysaccharides (PCPs) and polysaccharides extracted after microwave cooking (MPCPs) from Pleurotus cornucopiae during simulated digestion and fecal fermentation. The results revealed notable physicochemical differences between of PCPs and MPCPs. MPCPs exhibited a higher total carbohydrate content, with an increased proportion of glucose. Additionally, MPCPs showed a lower molecular weight (MW) and, a blue shift in Fourier transform infrared spectroscopy (FT-IR). Digestion has a minimal effect on the physicochemical and structural characteristics of PCPs and MPCPs. Within the first 6 h of fermentation, the gut microbiota showed significantly higher utilization of MPCPs. However, PCPs were consumed faster and surpassed MPCPs later. After 24 h, both PCPs and MPCPs were degraded and utilized by the gut microbiota, showing an increased abundance of Firmicutes and Bacteroidota. PCPs excelled in promoting beneficial gut microbiota, such as Phascolarctobacterium, Megamonas, and Bacteroides. Conversely, MPCPs demonstrated a stronger ability to inhibit the growth of harmful opportunistic pathogenic gut microbiota, such as Fusobacterium and Parasutterella. In addition, the content of acetic, propionic, and butyric acids increased significantly in both PCPs and MPCPs. These findings highlight the potential of Pleurotus cornucopiae polysaccharides as prebiotics for intestinal homeostasis.

The regulation of glucose and lipid metabolism through the interaction of dietary polyphenols and polysaccharides via the gut microbiota pathway

The interaction of polyphenols-polysaccharides-gut microbiota to promote health benefits has become a hotspot and direction for precise dietary intervention strategies and foundational research in biomedicine. Both dietary polyphenols and polysaccharides possess biological activities that regulate body health. Single components, due to their inherent structure and physicochemical properties, have a low bioavailability, thus are unable to exert their optimal effects. The compound structure formed by the interaction of polyphenols and polysaccharides can enhance their functional properties, thereby more effectively promoting health benefits and preventing diseases. This review primarily focuses on the roles played by polyphenols and polysaccharides in regulating glucose and lipid metabolism, the improvement of glucose and lipid metabolism through the gut microbial pathway by polyphenols and polysaccharides, and the mechanisms by which polyphenols and polysaccharides interact to regulate glucose and lipid metabolism. A considerable amount of preliminary research has confirmed the regulatory effects of plant polyphenols and polysaccharides on glucose and lipid metabolism. However, studies on the combined effects and mechanisms of these two components are still very limited. This review aims to provide a reference for subsequent research on their interactions and changes in functional properties.

Impact analysis of hydraulic residence time and dissolved oxygen on performance efficiency and microbial community in N, N-dimethylformamide wastewater treated by an AnSBR-ASBR

Suitable operating parameters are one of the key factors to efficient and stable biological wastewater treatment of N, N-dimethylformamide (DMF) wastewater. In this study, an improved AnSBR-ASBR reactor (anaerobic sequencing batch reactor, AnSBR, and aerobic SBR, ASBR, run in series) was used to investigated the effects of operating conditions such as hydraulic residence time (HRT), AnSBR stirring speed and ASBR dissolved oxygen (DO) for DMF wastewater treatment. When HRT decreased from 24 h to 12 h, the average removal rates of COD by the AnSBR were 34.59% and 39.54%, respectively. Meanwhile, the removal rate of NH4+-N by ASBR decreased from 88.38% to 62.81%. The DMF removal rate reached the best at 18 h and the expression of dehydrogenase was the highest in the AnSBR. The abundance of Megasphaera, the dominant sugar-degrading bacteria in the AnSBR, continued to decline due to the decrease of HRT. The relative abundance of Methanobacterium gradually increased to 80.2% with the decrease of HRT and that hydrotrophic methanogenesis dominated the methanogenic process. The HRT decrease promoted butyrate and pyruvate metabolism in anaerobic sludge, but the proportion of glycolysis and methane metabolism decreased. The AnSBR-ASBR reactor had the best operation performance when HRT was 18 h, AnSBR speed was 220 r/min, and ASBR DO content was 3-4 mg/L. This study provided an effective reference for the reasonable selection of operating parameters in the treatment of DMF-containing wastewater by the AnSBR-ASBR.

Association of gut microbiota and SCFAs with finishing weight of Diannan small ear pigs

Finishing weight is a key economic trait in the domestic pig industry. Evidence has linked the gut microbiota and SCFAs to health and production performance in pigs. Nevertheless, for Diannan small ear (DSE) pigs, a specific pig breed in China, the potential effect of gut microbiota and SCFAs on their finishing weight remains unclear. Herein, based on the data of the 16S ribosomal RNA gene and metagenomic sequencing analysis, we found that 13 OTUs could be potential biomarkers and 19 microbial species were associated with finishing weight. Among these, carbohydrate-decomposing bacteria of the families Streptococcaceae, Lactobacillaceae, and Prevotellaceae were positively related to finishing weight, whereas the microbial taxa associated with intestinal inflammation and damage exhibited opposite effects. In addition, interactions of these microbial species were found to be linked with finishing weight for the first time. Gut microbial functional annotation analysis indicated that CAZymes, such as glucosidase and glucanase could significantly affect finishing weight, given their roles in increasing nutrient absorption efficiency. Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthologies (KOs) and KEGG pathways analysis indicated that glycolysis/gluconeogenesis, phosphotransferase system (PTS), secondary bile acid biosynthesis, ABC transporters, sulfur metabolism, and one carbon pool by folate could act as key factors in regulating finishing weight. Additionally, SCFA levels, especially acetate and butyrate, had pivotal impacts on finishing weight. Finishing weight-associated species Prevotella sp. RS2, Ruminococcus sp. AF31-14BH and Lactobacillus pontis showed positive associations with butyrate concentration, and Paraprevotella xylaniphila and Bacteroides sp. OF04-15BH were positively related to acetate level. Taken together, our study provides essential knowledge for manipulating gut microbiomes to improve finishing weight. The underlying mechanisms of how gut microbiome and SCFAs modulate pigs' finishing weight required further elucidation.