Abstract:A commensal microbial community is established in the mammalian gut during its development, and these organisms protect the host against pathogenic invaders. The hallmark of noninvasive Salmonella gut infection is the induction of inflammation via effector proteins secreted by the type III secretion system, which modulate host responses to create a new niche in which the pathogen can overcome the colonization resistance imposed by the microbiota. Several studies have shown that endogenous microbes are importan… Show more
“…Considering that bacteria from the Enterobacteriaceae family are the major groups present in the gut and have similar metabolic traits, it is possible that these bacteria use the same antibacterial antagonistic mechanisms, such as colicins, microcins, T6SS specialized protein secretion systems, and contact-dependent growth inhibition to counteract Salmonella in the gut. These bacterial interactions take place in a highly complex chemical environment, composed of chemical substances [ 109 , 110 ]. Additionally, the characterization of the interactions between the gut microbiota and host plasma metabolites could provide crucial insights into the effects of the gut microbiota on human health.…”
The effect of putative probiotic fermented milk (FM) with buriti pulp (FMB) or passion fruit pulp (FMPF) or without fruit pulp (FMC) on the microbiota of healthy humans was evaluated. FM formulations were administered into a simulator of the human intestinal microbial ecosystem (SHIME®) to evaluate the viability of lactic acid bacteria (LAB), microbiota composition, presence of short-chain fatty acids (SCFA), and ammonium ions. The probiotic LAB viability in FM was affected by the addition of the fruit pulp. Phocaeicola was dominant in the FMPF and FMB samples; Bifidobacterium was related to FM formulations, while Alistipes was associated with FMPF and FMB, and Lactobacillus and Lacticaseibacillus were predominant in FMC. Trabulsiella was the central element in the FMC, while Mediterraneibacter was the central one in the FMPF and FMB networks. The FM formulations increased the acetic acid, and a remarkably high amount of propionic and butyric acids were detected in the FMB treatment. All FM formulations decreased the ammonium ions compared to the control; FMPF samples stood out for having lower amounts of ammonia. The probiotic FM with fruit pulp boosted the beneficial effects on the intestinal microbiota of healthy humans in addition to increasing SCFA in SHIME® and decreasing ammonium ions, which could be related to the presence of bioactive compounds.
“…Considering that bacteria from the Enterobacteriaceae family are the major groups present in the gut and have similar metabolic traits, it is possible that these bacteria use the same antibacterial antagonistic mechanisms, such as colicins, microcins, T6SS specialized protein secretion systems, and contact-dependent growth inhibition to counteract Salmonella in the gut. These bacterial interactions take place in a highly complex chemical environment, composed of chemical substances [ 109 , 110 ]. Additionally, the characterization of the interactions between the gut microbiota and host plasma metabolites could provide crucial insights into the effects of the gut microbiota on human health.…”
The effect of putative probiotic fermented milk (FM) with buriti pulp (FMB) or passion fruit pulp (FMPF) or without fruit pulp (FMC) on the microbiota of healthy humans was evaluated. FM formulations were administered into a simulator of the human intestinal microbial ecosystem (SHIME®) to evaluate the viability of lactic acid bacteria (LAB), microbiota composition, presence of short-chain fatty acids (SCFA), and ammonium ions. The probiotic LAB viability in FM was affected by the addition of the fruit pulp. Phocaeicola was dominant in the FMPF and FMB samples; Bifidobacterium was related to FM formulations, while Alistipes was associated with FMPF and FMB, and Lactobacillus and Lacticaseibacillus were predominant in FMC. Trabulsiella was the central element in the FMC, while Mediterraneibacter was the central one in the FMPF and FMB networks. The FM formulations increased the acetic acid, and a remarkably high amount of propionic and butyric acids were detected in the FMB treatment. All FM formulations decreased the ammonium ions compared to the control; FMPF samples stood out for having lower amounts of ammonia. The probiotic FM with fruit pulp boosted the beneficial effects on the intestinal microbiota of healthy humans in addition to increasing SCFA in SHIME® and decreasing ammonium ions, which could be related to the presence of bioactive compounds.
“…The infestation success of Salmonella infection is highly dependent on the colonization resistance imposed by the microbiota, and Sibinelli‐Sousa et al. [20] give a fascinating insight into the antagonistic strategies of interbacterial interactions between Salmonella enterica and gut commensals during the pathogen's race to induce inflammation. “The flash of light you saw in the sky was not a UFO. Swamp gas from a weather balloon was trapped in a thermal pocket and reflected the light from Venus.” …”
Section: Figmentioning
confidence: 99%
“…Help from within is provided by beneficial microbial communities that are colonizing the host, and the mammalian gut is a good example of how those commensals protect the host and support immune responses against invaders. The infestation success of Salmonella infection is highly dependent on the colonization resistance imposed by the microbiota, and Sibinelli-Sousa et al [20] give a fascinating insight into the antagonistic strategies of interbacterial interactions between Salmonella enterica and gut commensals during the pathogen's race to induce inflammation.…”
This Special Issue of The FEBS Journal consists of 20 reviews covering various aspects and new developments in ‘Infection and Immunity’. The issue includes expert views on the role of different immune cell populations, on the regulation of innate and adaptive immune responses, and novel concepts in host defence and inflammatory signalling. Many reviews in this issue also highlight potential targets for future therapeutic interventions that aim to tackle inflammatory and immune responses in health and disease
“…Type six secretion systems (T6SSs) are dynamic nanomachines that Gram-negative bacteria use for numerous biological functions. These diverse functions include killing competing bacteria (1)(2)(3)(4)(5), self-recognition (6,7), pathogenesis (8,9), micronutrient acquisition (10-13), and direct communication by the microbiota with a eukaryotic host (14,15). Although the core proteins of the T6SS ejection apparatus are conserved across Gram-negative bacteria (16,17), the T6SSs of individual species typically harbor a unique set of protein effectors.…”
Section: Introductionmentioning
confidence: 99%
“…Although the core proteins of the T6SS ejection apparatus are conserved across Gram-negative bacteria (16,17), the T6SSs of individual species typically harbor a unique set of protein effectors. These species unique effectors can aid in host adaptation (18,19) and are reflective of a toxin arms race between Gram-negative bacteria that compete for the same niche and resources (2,9).…”
The type VI secretion system (T6SS) is a molecular machine that Gram-negative bacteria have adapted for multiple functions, including interbacterial competition. Bacteria use the T6SS to deliver protein effectors into adjacent cells to kill rivals and establish niche dominance. Central to T6SS mediated bacterial competition is an arms race to acquire diverse effectors to attack and neutralize target cells. The peptidoglycan has a central role in bacterial cell physiology, and effectors that biochemically modify peptidoglycan structure effectively induce cell death. One such T6SS effector is Tlde1a from Salmonella Typhimurium. Tlde1a functions as an LD-carboxypeptidase to cleave tetrapeptide stems and as an LD-transpeptidase to exchange the terminal D-alanine of a tetrapeptide stem with a noncanonical D-amino acid. To understand how Tlde1a exhibits toxicity at the molecular level, we determined the X-ray crystal structure of Tlde1a alone and in complex with D-amino acids. Our structural data revealed that Tlde1a possesses a unique LD-transpeptidase fold consisting of a dual pocket active site with a capping subdomain. This includes an exchange pocket to bind a D-amino acid for exchange and a catalytic pocket to position the D-alanine of a tetrapeptide stem for cleavage. Toxicity assays in Escherichia coli and in vitro peptidoglycan biochemical assays with Tlde1a variants, correlate Tlde1a molecular features directly to its biochemical functions. We observe that the LD-carboxypeptidase and LD-transpeptidase activities of Tlde1a are both structural and functionally linked. Overall, our data highlights how an LD-transpeptidase fold has been structurally altered to create a toxic effector in the T6SS arms race.
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