Identification of iron-regulated genes of Bifidobacterium breve UCC2003 as a basis for controlled gene expression

Cronin, Michelle; Zomer, Aldert; Fitzgerald, Gerald F.; Sinderen, Douwe van

doi:10.4161/bbug.18985

Cited by 19 publications

(25 citation statements)

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“…Previous studies demonstrated that bifidobacterial strains can inhibit competing organisms in an iron concentration dependant manner [ 9 ]. However, it was also recently reported that the growth of some bifidobacterial strains was not affected by the presence of iron chelators such as 2,2-dipiridyl and 8-hydroxyquinoline [ 36 , 37 ]. Although different attempts have been done to identify iron sequestration mechanisms no study demonstrated the production of iron scavenging compounds in culture supernatant.…”

Section: Discussionmentioning

confidence: 99%

Bifidobacteria strains isolated from stools of iron deficient infants can efficiently sequester iron

et al. 2015

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BackgroundBifidobacteria is one of the major gut commensal groups found in infants. Their colonization is commonly associated with beneficial effects to the host through mechanisms like niche occupation and nutrient competition against pathogenic bacteria. Iron is an essential element necessary for most microorganisms, including bifidobacteria and efficient competition for this micronutrient is linked to proliferation and persistence. For this research we hypothesized that bifidobacteria in the gut of iron deficient infants can efficiently sequester iron. The aim of the present study was to isolate bifidobacteria in fecal samples of iron deficient Kenyan infants and to characterize siderophore production and iron internalization capacity.ResultsFifty-six bifidobacterial strains were isolated by streaking twenty-eight stool samples from Kenyan infants, in enrichment media. To target strains with high iron sequestration mechanisms, a strong iron chelator 2,2-dipyridyl was supplemented to the agar media. Bifidobacterial isolates were first identified to species level by 16S rRNA sequencing, yielding B. bifidum (19 isolates), B. longum (15), B. breve (11), B. kashiwanohense (7), B. pseudolongum (3) and B. pseudocatenulatum (1). While most isolated bifidobacterial species are commonly encountered in the infantile gut, B. kashiwanohense was not frequently reported in infant feces. Thirty strains from culture collections and 56 isolates were characterized for their siderophore production, tested by the CAS assay. Siderophore activity ranged from 3 to 89% siderophore units, with 35 strains (41%) exhibiting high siderophore activity, and 31 (36%) and 20 (23%) showing intermediate or low activity. The amount of internalized iron of 60 bifidobacteria strains selected for their siderophore activity, was in a broad range from 8 to118 μM Fe. Four strains, B. pseudolongum PV8-2, B. kashiwanohense PV20-2, B. bifidum PV28-2a and B. longum PV5-1 isolated from infant stool samples were selected for both high siderophore activity and iron internalization.ConclusionsA broad diversity of bifidobacteria were isolated in infant stools using iron limited conditions, with some strains exhibiting high iron sequestration properties. The ability of bifidobacteria to efficiently utilize iron sequestration mechanism such as siderophore production and iron internalization may confer an ecological advantage and be the basis for enhanced competition against enteropathogens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-014-0334-z) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Bifidobacteria strains isolated from stools of iron deficient infants can efficiently sequester iron

et al. 2015

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“…(). The common decrease in Bifidobacteriaceae through iron is more difficult to explain as they are known to be dependent on iron as their growth is generally impaired in response to iron limitation, created by the addition of the iron chelator dipyridyl (Bezkorovainy et al ., ; Cronin et al ., ). This growth impairment in response to dipyridyl indicates the absence of a high‐affinity siderophore‐mediated iron uptake system in most Bifidobacterium species, but it also indicates that they require iron for their growth.…”

Section: Effect Of Nutritional Iron On the Gut Microbiota Compositionmentioning

confidence: 97%

“…We note that in older studies, Enterobacteriaceae as a family were often not assessed, but an increase in coliforms and/or E. coli may consequently favour the growth and colonisation of closely related (pathogenic) Enterobacteriaceae, a phenomenon known as the like-will-to-like concept postulated by Stecher et al (2010). The common decrease in Bifidobacteriaceae through iron is more difficult to explain as they are known to be dependent on iron as their growth is generally impaired in response to iron limitation, created by the addition of the iron chelator dipyridyl (Bezkorovainy et al, 1996;Cronin et al, 2012). This growth impairment in response to dipyridyl indicates the absence of a highaffinity siderophore-mediated iron uptake system in most Bifidobacterium species, but it also indicates that they require iron for their growth.…”

Section: Summary Of the Effects Of Nutritional Iron On The Gut Microbmentioning

confidence: 99%

Nutritional iron turned inside out: intestinal stress from a gut microbial perspective

et al. 2014

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Iron is abundantly present on earth, essential for most microorganisms and crucial for human health. Human iron deficiency that is nevertheless highly prevalent in developing regions of the world can be effectively treated by oral iron administration. Accumulating evidence indicates that excess of unabsorbed iron that enters the colonic lumen causes unwanted side effects at the intestinal host-microbiota interface. The chemical properties of iron, the luminal environment and host iron withdrawal mechanisms, especially during inflammation, can turn the intestine in a rather stressful milieu. Certain pathogenic enteric bacteria can, however, deal with this stress at the expense of other members of the gut microbiota, while their virulence also seems to be stimulated in an iron-rich intestinal environment. This review covers the multifaceted aspects of nutritional iron stress with respect to growth, composition, metabolism and pathogenicity of the gut microbiota in relation to human health. We aim to present an unpreceded view on the dynamic effects and impact of oral iron administration on intestinal host-microbiota interactions to provide leads for future research and other applications.

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“…Further studies of the transcriptional activity of promoters relative to other promoters, for example by transcriptional analysis on a genomewide level, might help to identify highly active constitutive or tightly regulated promoters leading to the development of better genetic tools. One such example is the recently published study by Cronin et al, who used microarray analysis to identify ironregulated genes and used the results to create an iron-inducible expression system (13). However, while the recently published bile-and iron-inducible promoters will prove valuable tools to study the role of individual proteins on bifidobacterial physiology in vitro and in vivo, they are probably of limited use for the generation of recombinant strains expressing tumor therapeutics or vaccine antigens.…”

Section: Discussionmentioning

confidence: 99%

Accessing the Inaccessible: Molecular Tools for Bifidobacteria

Sun

Baur

Zhurina

et al. 2012

Appl Environ Microbiol

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ABSTRACTBifidobacteria are an important group of the human intestinal microbiota that have been shown to exert a number of beneficial probiotic effects on the health status of their host. Due to these effects, bifidobacteria have attracted strong interest in health care and food industries for probiotic applications and several species are listed as so-called “generally recognized as safe” (GRAS) microorganisms. Moreover, recent studies have pointed out their potential as an alternative or supplementary strategy in tumor therapy or as live vaccines. In order to study the mechanisms by which these organisms exert their beneficial effects and to generate recombinant strains that can be used as drug delivery vectors or live vaccines, appropriate molecular tools are indispensable. This review provides an overview of the currently available methods and tools to generate recombinant strains of bifidobacteria. The currently used protocols for transformation of bifidobacteria, as well as replicons, selection markers, and determinants of expression, will be summarized. We will further discuss promoters, terminators, and localization signals that have been used for successful generation of expression vectors.

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Identification of iron-regulated genes of Bifidobacterium breve UCC2003 as a basis for controlled gene expression

Cited by 19 publications

References 58 publications

Bifidobacteria strains isolated from stools of iron deficient infants can efficiently sequester iron

Bifidobacteria strains isolated from stools of iron deficient infants can efficiently sequester iron

Nutritional iron turned inside out: intestinal stress from a gut microbial perspective

Accessing the Inaccessible: Molecular Tools for Bifidobacteria

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