Genomic insights from Monoglobus pectinilyticus: a pectin-degrading specialist bacterium in the human colon

Abstract

Pectin is abundant in modern day diets, as it comprises the middle lamellae and one-third of the dry carbohydrate weight of fruit and vegetable cell walls. Currently there is no specialized model organism for studying pectin fermentation in the human colon, as our collective understanding is informed by versatile glycan-degrading bacteria rather than by specialist pectin degraders. Here we show that the genome of Monoglobus pectinilyticus possesses a highly specialized glycobiome for pectin degradation, unique amongst Firmicutes known to be in the human gut. Its genome encodes a simple set of metabolic pathways relevant to pectin sugar utilization, and its predicted glycobiome comprises an unusual distribution of carbohydrate-active enzymes (CAZymes) with numerous extracellular methyl/acetyl esterases and pectate lyases. We predict the M. pectinilyticus degradative process is facilitated by cell-surface S-layer homology (SLH) domain-containing proteins, which proteomics analysis shows are differentially expressed in response to pectin. Some of these abundant cell surface proteins of M. pectinilyticus share unique modular organizations rarely observed in human gut bacteria, featuring pectin-specific CAZyme domains and the cell wall-anchoring SLH motifs. We observed M. pectinilyticus degrades various pectins, RG-I, and galactan to produce polysaccharide degradation products (PDPs) which are presumably shared with other inhabitants of the human gut microbiome (HGM). This strain occupies a new ecological niche for a primary degrader specialized in foraging a habitually consumed plant glycan, thereby enriching our understanding of the diverse community profile of the HGM.

Ruminant fat intake improves gut microbiota, serum inflammatory parameter and fatty acid profile in tissues of Wistar rats

“…These results warrant further investigations on functional approaches addressing the effects of Blautia and Lachnospiraceae organisms on the systemic metabolism. The reduction of fibrolytic bacteria such as Monoglobus and Prevotella caused by the HFD intake corroborate previous findings 70 , 71 and suggest that long-term use of HFD may pose undesirable changes in the gut microbiota composition of rats.…”

Flavonoid-Modifying Capabilities of the Human Gut Microbiome—An In Silico Study

“…With a lower abundance (about 50 appearances), metagenome-derived rhamnosidase 2 orthologs were detected in MAGs of the genus CAG-170 (family Oscillospiraceae ). Orthologs (PID of about 98) of the metagenome-derived rhamnosidase 1 were detected in only five MAGs from the family Monoglobaceae , which could not yet be assigned to a genus and differ from the only described member of this genus, the pectin-degrading intestinal Monoglobus pectinilyticus [ 65 , 66 ], which does not encode the corresponding rhamnosidase. Below a 65 PID cutoff, mainly species from the genera Parabacteroides and Bacteroides and the species Alistipes onderdonkii (approximately 45 to 50 PID to MGR2) were found to be highly abundant ( Supplementary Figure S4 ).…”

Captivity Shifts Gut Microbiota Communities in White-Lipped Deer (Cervus albirostris)

“…Among these species, CW had significantly higher relative abundance of Monoglobus and Alistipes . Monoglobus is a highly specialized bacteria for pectin degradation that might be caused by excess exposure to human environments [ 55 ]. Opportunistic pathogens in the host gut microbiota, such as Alistipes and Lachnospiraceae unclassified were increased in both groups [ 56 , 57 ].…”