Project description:In this paper, two predicted lac I type transcription factors (TFs) were characterised and shown to be involved in the regulation of the central metabolic pathways of B. breve UCC2003. Although, genetically different, these TF were functionally very similar. When first identified these TFs were named AraQ and MalR1, due to their predicted associations with arabinose and maltose metabolism, respectively. Now, however they have been renamed as BifR1 and BifR2 respectively, due to their control of the central metabolic pathways including the bifid shunt.
Project description:The transcription of the cldEFGC gene cluster of Bifidobacterium breve UCC2003 was shown to be induced upon growth on cellodextrins, implicating these genes in the metabolism of these sugars. Phenotypic analysis of a B. breve UCC2003::cldE insertion mutant confirmed that the cld gene cluster is exclusively required for cellodextrin utilization by this bacterium. HPAEC-PAD analysis of medium samples obtained during growth of B. breve UCC2003 on a mixture of cellodextrins revealed its ability to utilize cellobiose, cellotriose, cellotetraose and cellopentaose, with cellotriose representing the preferred substrate. The cldC gene of the cld operon of B. breve UCC2003 was shown to be the first described bifidobacterial β-glucosidase exhibiting hydrolytic activity towards various cellodextrins.
Project description:The transcription of the cldEFGC gene cluster of Bifidobacterium breve UCC2003 was shown to be induced upon growth on cellodextrins, implicating these genes in the metabolism of these sugars. Phenotypic analysis of a B. breve UCC2003::cldE insertion mutant confirmed that the cld gene cluster is exclusively required for cellodextrin utilization by this bacterium. HPAEC-PAD analysis of medium samples obtained during growth of B. breve UCC2003 on a mixture of cellodextrins revealed its ability to utilize cellobiose, cellotriose, cellotetraose and cellopentaose, with cellotriose representing the preferred substrate. The cldC gene of the cld operon of B. breve UCC2003 was shown to be the first described bifidobacterial β-glucosidase exhibiting hydrolytic activity towards various cellodextrins. In order to investigate differences in gene expression patterns of B. breve UCC2003 when grown on cellobiose or cellodextrins as compared to growth on glucose, DNA microarray experiments were performed. Total RNA was isolated from B. breve UCC2003 cultures grown on cellobiose, cellodextrins, or glucose (see Materials and Methods). The cultures were harvested at the time points that ensured that B. breve UCC2003 was metabolizing cellobiose or cellodextrins as opposed to the residual glucose present in the cellodextrin preparation. Analysis of the DNA microarray data was obtained from two independent biological replicates.
Project description:Bifidobacteria constitute a specific group of commensal bacteria which inhabit the gastrointestinal tract of humans and other mammals. Bifidobacterium breve UCC2003 has previously been shown to utilise several plant-derived carbohydrates that include cellodextrins, starch and galactan. In the current study, we investigate the ability of this strain to utilise the mucin- and human milk oligosaccharide (HMO)-derived carbohydrate, sialic acid. Using a combination of transcriptomic and functional genomic approaches, we identified a gene cluster dedicated to the uptake and metabolism of sialic acid. Furthermore, we demonstrate that B. breve UCC2003 can cross feed on sialic acid derived from the metabolism of 3’ sialyllactose, a HMO, by Bifidobacterium bifidum PRL2010.
Project description:Bifidobacteria constitute commensal bacteria that commonly inhabit the mammalian gastro intestinal tract. The gut commensal Bifidobacterium breve UCC2003 was previously shown to utilise a variety of plant/diet-derived carbohydrates, including cellodextrin, starch and galactan. In the current study, we investigated the ability of this strain to utilize (parts of) a host-derived source of carbohydrate, namely the mucin glycoprotein. Here, we demonstrate that B. breve UCC2003 exhibits growth properties in a mucin-based medium, but only when in the presence of Bifidobacterium bifidum PRL2010, which is known to metabolize mucin. Based on HPAEC analysis, transcriptome data and insertion mutagenesis, it appears that B. breve UCC2003 sustains this improved survival in co-culture by cross-feeding on a combination of fucose, sialic acid and galactose-containing oligosaccharides.
Project description:Phenotypic screening of a random mutant library combined with microarray analysis of the transcriptional response of B. breve UCC2003 to iron limitation, allowed the identification of a number of genes implicated in the survival of Bifidbacterium breve UCC2003 under iron-limiting conditions. Of the identified genes, two putative iron-uptake systems, were further characterised: (i) a presumed ferrous iron uptake system, designated here as bfeUO, and (ii) a predicted ferric iron/siderophore uptake system, designated sifABCDE. In silico analysis also illustrated that these two clusters are highly conserved across members of the genus Bifidobacterium and are invariably co-located. Murine colonization studies demonstrated that B. breve UCC2003-bfeU and B. breve UCC2003-sifA insertion mutants are able to colonize a healthy murine gut as efficiently as the wild type B. breve strain, indicating that these genes are not crucial for gut survival or colonization in a healthy host.
Project description:Bbr_0838 from Bifidobacterium breve UCC2003 encodes a 683 residue membrane protein, that contains a permease domain displaying similarity to transporters belonging to the major facilitator superfamily, as well as a CBS (cystathionine beta synthase) domain. The high level of similarity to bile-efflux pumps from other bifidobacteria, suggests a significant role for Bbr_0838 in bile tolerance of B. breve UCC2003. Bbr_0838 transcription was shown to be monocistronic and strongly induced upon exposure to bile. Further analysis delineated the transcriptional start site and the minimal region required for promoter activity and bile regulation. Insertional inactivation of Bbr_0838 in B. breve UCC2003 resulted in a strain that exhibited reduced survival upon cholate exposure as compared to the parent strain, a phenotype that was reversed when a functional Bbr_0838 gene was introduced into UCC2003::838800. Transcriptome analysis of UCC2003::838800 grown in the presence or absence of bile demonstrated that transcription of Bbr_0832, which is predicted to encode a macrolide-efflux transporter gene, was significantly increased in the presence of bile, representing a likely compensatory mechanism for bile removal in the absence of Bbr_0838. This study represents the first in depth analysis of a bile-inducible locus in bifidobacteria, identifying a key gene relevant for bifidobacterial bile tolerance. In order to investigate differences in global gene expression upon growth or exposure of B. breve UCC2003-delta0838 to cholic acid compared to normal growing cells, DNA microarray experiments were performed. Total RNA was isolated from B. breve UCC2003-delta0838 cultures under normal conditions and cultures grown on or exposed to cholic acid. All experiments were performed in duplo and targets where confirmed with QRT-PCR. In addition transcriptome analyse was performed of B. breve UCC2003 compared to that of B. breve UCC2003-delta0838 both exposed to 0.1 % cholic acid. This was performed as a single experiment and targets were confirmed by QRT-PCR
Project description:Bifidobacteria constitute a specific group of commensal bacteria which inhabit the gastrointestinal tract of humans and other mammals. Bifidobacterium breve UCC2003 has previously been shown to utilise several plant-derived carbohydrates that include cellodextrins, starch and galactan. In the current study, we investigate the ability of this strain to utilise the mucin- and human milk oligosaccharide (HMO)-derived carbohydrate, sialic acid. Using a combination of transcriptomic and functional genomic approaches, we identified a gene cluster dedicated to the uptake and metabolism of sialic acid. Furthermore, we demonstrate that B. breve UCC2003 can cross feed on sialic acid derived from the metabolism of 3’ sialyllactose, a HMO, by Bifidobacterium bifidum PRL2010. DNA-microarrays containing oligonucleotide primers representing each of the 1864 annotated genes on the genome of B. breve UCC2003 (O'Connell Motherway et al., 2011) were designed by and obtained from Agilent Technologies (Palo Alto, Ca., USA). Methods for cell disruption, RNA isolation, RNA quality control, complementary DNA synthesis and labeling were performed as described previously (Pokusaeva et al., 2009). Labeled cDNA was hybridized using the Agilent Gene Expression hybridization kit (part number 5188-5242) as described in the Agilent Two-Color Microarray-Based Gene Expression Analysis v4.0 manual (G4140-90050). Following hybridization, microarrays were washed in accordance with Agilent’s standard procedures and scanned using an Agilent DNA microarray scanner (model G2565A). Generated scans were converted to data files with Agilent's Feature Extraction software (Version 9.5). DNA-microarray data were processed as previously described (Garcia De La Nava et al., 2003). Differential expression tests were performed with the Cyber-T implementation of a variant of the t-test (Long et al., 2001). A gene was considered differentially expressed when p < 0.001 and an expression ratio of >3 or <0.33 relative to the control.
Project description:A bacterial nursling stool isolate, Bifidobacterium breve UCC2003, encodes two putative sulfatases. The sulfated monosaccharide N-acetylglucosamine-6-sulfate (GlcNAc-6-S) was shown to support growth of B. breve UCC2003, while three other tested sulfated monosaccharides, N-acetylglucosamine-3-sulfate, N-acetylgalactosamine-3-sulfate and N-acetylgalactosamine-6-sulfate, did not. Using a combination of transcriptomic and functional genomic approaches, a gene cluster, designated ats2, was shown to be specifically required for GlcNAc-6-S metabolism. Transcription of the ats2 cluster is shown to be regulated by a ROK-family transcriptional repressor. Expression profiling by array