Streptococcus mutans -derived exopolysaccharides are virulence determinants in the matrix of biofilms that cause caries. Extracellular DNA (eDNA) and lipoteichoic acid (LTA) are found in cariogenic biofilms, but their functions are unclear. Therefore, strains of S. mutans carrying single deletions that would modulate matrix components were used: eDNA – ΔlytS and ΔlytT; LTA – ΔdltA and ΔdltD; and insoluble exopolysaccharide – ΔgtfB. Single-species (parental strain S. mutans UA159 or individual mutant strains) and mixed-species (UA159 or mutant strain, Actinomyces naeslundii and Streptococcus gordonii) biofilms were evaluated. Distinct amounts of matrix components were detected, depending on the inactivated gene. eDNA was found to be cooperative with exopolysaccharide in early phases, while LTA played a larger role in the later phases of biofilm development. The architecture of mutant strains biofilms was distinct (vs UA159), demonstrating that eDNA and LTA influence exopolysaccharide distribution and microcolony organization. Thus, eDNA and LTA may shape exopolysaccharide structure, affecting strategies for controlling pathogenic biofilms.

Bacteriophage PhiV10 is a temperate phage, which specifically infects Escherichia coli O157:H7. The nucleotide sequence of the PhiV10 genome is 39 104 bp long and contains 55 predicted genes. PhiV10 is closely related to two previously sequenced phages, the Salmonella enterica serovar Anatum (Group E1) phage epsilon15 and a prophage from E. coli APEC O1. The attachment site of PhiV10, like those of its two closest relatives, overlaps the 3' end of guaA in the host chromosome. PhiV10 encodes an O-acetyltransferase, which modifies the O157 antigen. This modification is sufficient to block PhiV10 superinfection, indicating that the O157 antigen is most likely the PhiV10 receptor.

Highlights d Human gut Bacteroidetes and their relatives have diverse ribose-scavenging systems d A B. thetaiotaomicron ribose-utilization system (RUS) is needed on a plant diet d RUS ribokinases are the critical diet-specific determinants d Ribokinases yield ribose-1,5-bisphosphate from cleaved product of an unlinked gene

Scope Evidence suggests that dietary pattern may affect polyphenol absorption and/or metabolism. Further, obesity is associated with lower circulating nutrients, though the reason is unclear. We investigated the pharmacokinetic (PK) response of polyphenols in obese/overweight vs. lean individuals before and after repeated dosing with of grape polyphenols. Methods and results A pilot study was conducted in which PK challenges were administered before and after 11 days of repeated dosing with polyphenols. Volunteers (6 lean, 6 overweight/obese) consumed resveratrol, grape seed extract, and grape juice (2,125 mg total polyphenols) daily. On days 1 and 11, blood samples were collected for 6 hours after the polyphenol dose and analyzed for deconjugated catechin, epicatechin, resveratrol, and quercetin. Area under the plasma polyphenol mass by time curves (AUCs) were greater for catechin, epicatechin, and quercetin on day 11 vs. day 1 for low BMI individuals (p=0.039) but not high BMI individuals. Further, AUCs were greater for epicatechin and resveratrol for low vs. high BMI individuals (p=0.041), with a similar trend for catechin (p=0.065), on day 11 but not day 1. Conclusion These results suggest that that obesity and repeated exposure may modify polyphenol absorption and/or metabolism in humans.

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