Chiral coating-mediated interactions of bacteria with diverse biointerfaces

Bacteria,as living agents,have been widely used for microbial therapy due to their inherent ability to colonize different in vivo microenvironments,particularly in the gut and tumor.The interaction with diverse biointerfaces plays a critical role in bacterial colonization,and thereby determine the ultimate efficacy of microbial therapy.Although surface modification of bacteria with exogenous functional motifs can vary their interaction with surroundings,the effects of surface chirality of modified bacteria on mucous adhesion,tumor cell binding,and bacterial competition remain unknown.Here,we describe surface chirality-dependent selective interactions of bacteria to mucins,tumor cells,and pathogens.By coating bacteria with cationic polyethyleneimine modified with different chiral amino acids through electrostatic interaction,we find that bacteria coated with a D-chiral surface structure exhibit greatly increased adhesion to both mucins and tumor cells compared with those of L-and DL-structures.In addition,by adjusting the chirality of the coating,wrapped probiotic bacteria can selectively resist pathogenic bacteria,showing great potential to enhance colonization and positively modulate the gut and tumor microbiota.This work discloses surface chirality-dependent interaction of bacteria with different biointerfaces,showing a potential to tune the colonization and therapeutic effect of living bacterial agents for disease treatment.

Deciphering non-steady landscape evolution by in-situ cosmogenic nuclide depth profile

In-situ cosmogenic nuclide s are receiving growing attention in surface Earth system science in which the steady-state denudation is an important assumption for estimating the surface denudation of long-lived(103-106 years)surfaces.However,distinguishing steady-state denudation and deciphering a reliable denudation rate from non-steady state denudation region are difficult.Recent depth profile models for investigating the denudation rate,exposure age and inheritance are widely used for sediment and regolith of steady-state denudation region.Here we present in-situ co smogenic nuclides^(10)Be and^(26)Al from two typical granite regolithes from Jixian in Tianjin and Tengchong in Yunnan to model non-steady landscape evolution process by using steady state(Model 1)and non-steady state(Model 2,continuous exposure;Model 3 a,changed denudation rate;Model 3 b,abrupt denudation event)models.The results of steady state model show that both regolithes are in non-steady state.^(10)Be non-steady state models of Jixian regolith reveal that the surface has likely experienced a denudation rate change or an abrupt denudation event during the past several millennia,resulting in a non-steady state.The similar Model 3 a and 3 b denudation rates of 14.6-12.9^(+9.4)and 14.7-14.7^(+9.0)mmkyr^(-1),respectively,might demonstrate the long-term denudation rate rather than the exaggerated rate s of 39.0-2.3^(+2.6)and 39.0-2.4+^(2.5)mm kyr^(-1)calculated by assuming steady-state denudation and ignoring inheritance.The non-steady state model results of Tengchong regolith suggest that the surface has likely experienced a strong denudation about 157 ka(^(10)Be)or 127 ka(^(26)Al)ago.This timing is basically consistent with the termination of the MIS 6(TII:130 ka)and the climate change events in the Tibetan Plateau,suggesting a strong surface landscape denudation during the transition from glacial to interglacial.The compiling of basin-wide denudation rates in the Tibetan Plateau shows a good positive correlation with the regional tectonic activity,indicating that the denudation rate derived from non-steady state region with strong tectonic activity is likely to be overestimated by assuming steady state.We suggest that a combination of steady state and non-steady state depth profile models should be used to quantify denudation rate and exposure age more accurately and effectively in strong tectonic activity or climate change regions.