标题：Environmental and Intestinal Phylum Firmicutes Bacteria Metabolize the Plant Sugar Sulfoquinovose via a 6-Deoxy-6-sulfofructose Transaldolase Pathway
摘要：SummaryBacterial degradation of the sugar sulfoquinovose (SQ, 6-deoxy-6-sulfoglucose) produced by plants, algae, and cyanobacteria, is an important component of the biogeochemical carbon and sulfur cycles. Here, we reveal a third biochemical pathway for primary SQ degradation in an aerobicBacillus aryabhattaistrain. An isomerase converts SQ to 6-deoxy-6-sulfofructose (SF). A novel transaldolase enzyme cleaves the SF to 3-sulfolactaldehyde (SLA), while the non-sulfonated C3-(glycerone)-moiety is transferred to an acceptor molecule, glyceraldehyde phosphate (GAP), yielding fructose-6-phosphate (F6P). Intestinal anaerobic bacteria such asEnterococcus gilvus,Clostridium symbiosum, andEubacterium rectalestrains also express transaldolase pathway gene clusters during fermentative growth with SQ. The now three known biochemical strategies for SQ catabolism reflect adaptations to the aerobic or anaerobic lifestyle of the different bacteria. The occurrence of these pathways in intestinal (family)Enterobacteriaceaeand (phylum)Firmicutesstrains further highlights a potential importance of metabolism of green-diet SQ by gut microbial communities to, ultimately, hydrogen sulfide.Graphical AbstractDisplay OmittedHighlights•First known SQ-degradation pathway in phylumFirmicutes(Gram-positive) bacteria•New enzyme, sulfofructose:D-glyceraldehyde-3-phosphate glyceronetransferase•SQ fermentation pathway in human gutEnterococcus, Clostridium, andEubacteriumstrains•Novel degradation route for green-diet SQ to H2S by intestinal microbial communitiesMicrobiology; Microbial Metabolism
