An improved temperature-sensitive shuttle vector system for scarless gene deletion in human-gut-associated species.

is a prevalent bacterial taxon in the human gut that comprises over 10 (sub)species. Previous studies suggest that these species use evolutionarily distinct strategies for symbiosis with their hosts. However, the underlying species-specific mechanisms remain unclear due to the lack of efficient gene knockout systems applicable across different species.

Human gut-associated species salvage exogenous indole, a uremic toxin precursor, to synthesize indole-3-lactic acid via tryptophan.

Indole in the gut is formed from dietary tryptophan by a bacterial tryptophan-indole lyase. Indole not only triggers biofilm formation and antibiotic resistance in gut microbes but also contributes to the progression of kidney dysfunction after absorption by the intestine and sulfation in the liver. As tryptophan is an essential amino acid for humans, these events seem inevitable.

Substrate recognition mode of a glycoside hydrolase family 42 β-galactosidase from subspecies (Bga42A) revealed by crystallographic and mutational analyses.

subsp. uses a glycoside hydrolase (GH) family 42 β-galactosidase (Bga42A) for hydrolyzing lacto--tetraose (LNT), which is the most abundant core structure of human milk oligosaccharides (HMOs). As such, Bga42A represents one of the pivotal enzymes underpinning the symbiosis between bifidobacteria and breastfed infants.

Preferential sugar utilization by bifidobacterial species.

Bifidobacteria benefit host health and homeostasis by breaking down diet- and host-derived carbohydrates to produce organic acids in the intestine. However, the sugar utilization preference of bifidobacterial species is poorly understood. Thus, this study aimed to investigate the sugar utilization preference (i.