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Mutualistic interaction between Salmonella enterica and Aspergillus niger and its effects on Zea mays colonization.

Balbontín R, Vlamakis H, Kolter R - Microb Biotechnol (2014)

Bottom Line: Aspergillus niger is a ubiquitous fungus that can often be found in soil or associated to plants and microbial consortia.In this work, we have found that this interaction is stable for weeks without a noticeable negative effect on either organism.Strikingly, co-colonization also causes a reduction in plant invasion by S. Typhimurium.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, HIM building, Room #1042, Boston, MA, 02115, USA.

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Ratios of attached bacteria normalized to input ratios. Mixtures of mutant : wild-type S. Typhimurium strains or wild type with an antibiotic resistance gene : wild type with no resistance marker (WT : WT, as a control) at 1:1 proportion were incubated with A. niger mycelia for 1 h. Mycelia were then rinsed and attached bacteria were detached and plated onto selective media. The ratio of attached bacteria was calculated for each mutant and a control wild type, and subsequently normalized to the corresponding ratios of the input mixtures. Error bars represent standard deviation of the values obtained in three independent biological replicates (n = 3).
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fig02: Ratios of attached bacteria normalized to input ratios. Mixtures of mutant : wild-type S. Typhimurium strains or wild type with an antibiotic resistance gene : wild type with no resistance marker (WT : WT, as a control) at 1:1 proportion were incubated with A. niger mycelia for 1 h. Mycelia were then rinsed and attached bacteria were detached and plated onto selective media. The ratio of attached bacteria was calculated for each mutant and a control wild type, and subsequently normalized to the corresponding ratios of the input mixtures. Error bars represent standard deviation of the values obtained in three independent biological replicates (n = 3).

Mentions: Because S. Typhimurium is found associated with the fungal hyphae within minutes of co-inoculation, we hypothesized that the bacteria might be using directed motility and chemotaxis (Krell et al., 2011) to move towards the fungus. To test if motility and chemotaxis were involved in the initial attraction of bacteria to the fungus, we performed competition experiments where we analysed attachment of wild-type bacteria compared with either a motility mutant that completely lacks flagella (fliGHI) or a mutant that can swim, but is defective in chemotaxis (cheY). Competition between two differentially labelled wild-type strains was used as a control. When wild-type cells were challenged against each other the competition index was 1, which is what would be expected if equivalent numbers of each strain attached to the fungi (Fig. 2). The ability to swim was essential for fungal colonization by S. Typhimurium as the mutant without flagella was decreased to only 5% of the attached population when competed with the wild type. The chemotaxis mutant also showed a defect, although not as pronounced; the cheY mutant showed a 40% reduction in the attachment to the fungus with respect to the wild type (Fig. 2). These results indicate that S. Typhimurium must be able to swim directionally towards the fungus in order for colonization to occur and the bacterial cells are able to sense the fungus in order to actively move towards it. All in all these results suggest that the interaction is specific.


Mutualistic interaction between Salmonella enterica and Aspergillus niger and its effects on Zea mays colonization.

Balbontín R, Vlamakis H, Kolter R - Microb Biotechnol (2014)

Ratios of attached bacteria normalized to input ratios. Mixtures of mutant : wild-type S. Typhimurium strains or wild type with an antibiotic resistance gene : wild type with no resistance marker (WT : WT, as a control) at 1:1 proportion were incubated with A. niger mycelia for 1 h. Mycelia were then rinsed and attached bacteria were detached and plated onto selective media. The ratio of attached bacteria was calculated for each mutant and a control wild type, and subsequently normalized to the corresponding ratios of the input mixtures. Error bars represent standard deviation of the values obtained in three independent biological replicates (n = 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4265077&req=5

fig02: Ratios of attached bacteria normalized to input ratios. Mixtures of mutant : wild-type S. Typhimurium strains or wild type with an antibiotic resistance gene : wild type with no resistance marker (WT : WT, as a control) at 1:1 proportion were incubated with A. niger mycelia for 1 h. Mycelia were then rinsed and attached bacteria were detached and plated onto selective media. The ratio of attached bacteria was calculated for each mutant and a control wild type, and subsequently normalized to the corresponding ratios of the input mixtures. Error bars represent standard deviation of the values obtained in three independent biological replicates (n = 3).
Mentions: Because S. Typhimurium is found associated with the fungal hyphae within minutes of co-inoculation, we hypothesized that the bacteria might be using directed motility and chemotaxis (Krell et al., 2011) to move towards the fungus. To test if motility and chemotaxis were involved in the initial attraction of bacteria to the fungus, we performed competition experiments where we analysed attachment of wild-type bacteria compared with either a motility mutant that completely lacks flagella (fliGHI) or a mutant that can swim, but is defective in chemotaxis (cheY). Competition between two differentially labelled wild-type strains was used as a control. When wild-type cells were challenged against each other the competition index was 1, which is what would be expected if equivalent numbers of each strain attached to the fungi (Fig. 2). The ability to swim was essential for fungal colonization by S. Typhimurium as the mutant without flagella was decreased to only 5% of the attached population when competed with the wild type. The chemotaxis mutant also showed a defect, although not as pronounced; the cheY mutant showed a 40% reduction in the attachment to the fungus with respect to the wild type (Fig. 2). These results indicate that S. Typhimurium must be able to swim directionally towards the fungus in order for colonization to occur and the bacterial cells are able to sense the fungus in order to actively move towards it. All in all these results suggest that the interaction is specific.

Bottom Line: Aspergillus niger is a ubiquitous fungus that can often be found in soil or associated to plants and microbial consortia.In this work, we have found that this interaction is stable for weeks without a noticeable negative effect on either organism.Strikingly, co-colonization also causes a reduction in plant invasion by S. Typhimurium.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, HIM building, Room #1042, Boston, MA, 02115, USA.

Show MeSH
Related in: MedlinePlus