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Molecular and chemical dialogues in bacteria-protozoa interactions.

Song C, Mazzola M, Cheng X, Oetjen J, Alexandrov T, Dorrestein P, Watrous J, van der Voort M, Raaijmakers JM - Sci Rep (2015)

Bottom Line: Lipopeptide (LP) biosynthesis was induced in Pseudomonas upon protozoan grazing and LP accumulation transitioned from homogeneous distributions across bacterial colonies to site-specific accumulation at the bacteria-protist interface.Also putrescine biosynthesis was upregulated in P. fluorescens upon predation.This multifaceted study provides new insights in common and strain-specific responses in bacteria-protozoa interactions, including responses that contribute to bacterial survival in highly competitive soil and rhizosphere environments.

View Article: PubMed Central - PubMed

Affiliation: 1] Laboratory of Phytopathology, Wageningen University, 6708 PB Wageningen, the Netherlands [2] Microbial Ecology Department, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB Wageningen, the Netherlands.

ABSTRACT
Protozoan predation of bacteria can significantly affect soil microbial community composition and ecosystem functioning. Bacteria possess diverse defense strategies to resist or evade protozoan predation. For soil-dwelling Pseudomonas species, several secondary metabolites were proposed to provide protection against different protozoan genera. By combining whole-genome transcriptome analyses with (live) imaging mass spectrometry (IMS), we observed multiple changes in the molecular and chemical dialogues between Pseudomonas fluorescens and the protist Naegleria americana. Lipopeptide (LP) biosynthesis was induced in Pseudomonas upon protozoan grazing and LP accumulation transitioned from homogeneous distributions across bacterial colonies to site-specific accumulation at the bacteria-protist interface. Also putrescine biosynthesis was upregulated in P. fluorescens upon predation. We demonstrated that putrescine induces protozoan trophozoite encystment and adversely affects cyst viability. This multifaceted study provides new insights in common and strain-specific responses in bacteria-protozoa interactions, including responses that contribute to bacterial survival in highly competitive soil and rhizosphere environments.

No MeSH data available.


Related in: MedlinePlus

(A) Experimental setup to study Pseudomonas-protozoa interactions by MALDI imaging mass spectrometry (IMS). The green box-line indicates the protozoan predator N. americana alone; the red box-line indicates the interface of P. fluorescens SS101-N. americana; the yellow box-line indicates P. fluorescens SS101 alone. (B) MALDI-IMS analysis of the Pseudomonas-protozoa interaction, including imaging of metabolite classes, spatial segmentation and co-localization of the MALDI IMS data. (C) MS/MS network analysis and annotation of ion clusters from the P. fluorescens SS101-N. americana interaction. Ion clusters in the black squares represent the lipopeptide massetolide A and its derivatives; the black circle represents the 325-477 m/z ion cluster; the grey square represents the 766-796 m/z ion cluster. MS/MS analysis further indicated that the parent ion with 1162.70 m/z detected in the P. fluorescens SS101- N. americana interaction is most likely massetolide A. Complete lists of the ion clusters detected in the network analysis are given in Tables S4, S5 and S6.
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f3: (A) Experimental setup to study Pseudomonas-protozoa interactions by MALDI imaging mass spectrometry (IMS). The green box-line indicates the protozoan predator N. americana alone; the red box-line indicates the interface of P. fluorescens SS101-N. americana; the yellow box-line indicates P. fluorescens SS101 alone. (B) MALDI-IMS analysis of the Pseudomonas-protozoa interaction, including imaging of metabolite classes, spatial segmentation and co-localization of the MALDI IMS data. (C) MS/MS network analysis and annotation of ion clusters from the P. fluorescens SS101-N. americana interaction. Ion clusters in the black squares represent the lipopeptide massetolide A and its derivatives; the black circle represents the 325-477 m/z ion cluster; the grey square represents the 766-796 m/z ion cluster. MS/MS analysis further indicated that the parent ion with 1162.70 m/z detected in the P. fluorescens SS101- N. americana interaction is most likely massetolide A. Complete lists of the ion clusters detected in the network analysis are given in Tables S4, S5 and S6.

Mentions: In order to explore and identify specific classes of metabolites produced at the bacteria-protozoa interface, an experiment similar to that used for the transcriptional profiling was conducted. In brief, strain SS101 was streaked across the surface of solid 0.2 X NBY medium using an inoculation loop (Fig. 3A). After 3 h incubation at 25 °C, 5 μL of a suspension containing 200 N. americana cysts μL−1 was spotted at one end of the linear bacterial growth, and the plates were incubated at 25 °C for 3 days. A section of the agar containing the interaction zone was applied to MALDI-TOF to study the secreted metabolites by IMS (Fig. 3B). In addition, live colony NanoDESI mass spectrometry was performed on the protozoan colony, the interaction zone and the Pseudomonas colony to construct MS/MS metabolite networks. Nodes with a high MS/MS spectral analogy cluster together and often belong to the same chemical class49. Clusters of the different metabolite classes were then compared to the ions observed in the MALDI IMS data. We detected metabolites produced by Pseudomonas alone (yellow nodes), protozoa alone (green nodes) and produced during the Pseudomonas-protozoa interaction (red nodes). The network was constructed combing the different samples per species together (Fig. 3C).


Molecular and chemical dialogues in bacteria-protozoa interactions.

Song C, Mazzola M, Cheng X, Oetjen J, Alexandrov T, Dorrestein P, Watrous J, van der Voort M, Raaijmakers JM - Sci Rep (2015)

(A) Experimental setup to study Pseudomonas-protozoa interactions by MALDI imaging mass spectrometry (IMS). The green box-line indicates the protozoan predator N. americana alone; the red box-line indicates the interface of P. fluorescens SS101-N. americana; the yellow box-line indicates P. fluorescens SS101 alone. (B) MALDI-IMS analysis of the Pseudomonas-protozoa interaction, including imaging of metabolite classes, spatial segmentation and co-localization of the MALDI IMS data. (C) MS/MS network analysis and annotation of ion clusters from the P. fluorescens SS101-N. americana interaction. Ion clusters in the black squares represent the lipopeptide massetolide A and its derivatives; the black circle represents the 325-477 m/z ion cluster; the grey square represents the 766-796 m/z ion cluster. MS/MS analysis further indicated that the parent ion with 1162.70 m/z detected in the P. fluorescens SS101- N. americana interaction is most likely massetolide A. Complete lists of the ion clusters detected in the network analysis are given in Tables S4, S5 and S6.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4542665&req=5

f3: (A) Experimental setup to study Pseudomonas-protozoa interactions by MALDI imaging mass spectrometry (IMS). The green box-line indicates the protozoan predator N. americana alone; the red box-line indicates the interface of P. fluorescens SS101-N. americana; the yellow box-line indicates P. fluorescens SS101 alone. (B) MALDI-IMS analysis of the Pseudomonas-protozoa interaction, including imaging of metabolite classes, spatial segmentation and co-localization of the MALDI IMS data. (C) MS/MS network analysis and annotation of ion clusters from the P. fluorescens SS101-N. americana interaction. Ion clusters in the black squares represent the lipopeptide massetolide A and its derivatives; the black circle represents the 325-477 m/z ion cluster; the grey square represents the 766-796 m/z ion cluster. MS/MS analysis further indicated that the parent ion with 1162.70 m/z detected in the P. fluorescens SS101- N. americana interaction is most likely massetolide A. Complete lists of the ion clusters detected in the network analysis are given in Tables S4, S5 and S6.
Mentions: In order to explore and identify specific classes of metabolites produced at the bacteria-protozoa interface, an experiment similar to that used for the transcriptional profiling was conducted. In brief, strain SS101 was streaked across the surface of solid 0.2 X NBY medium using an inoculation loop (Fig. 3A). After 3 h incubation at 25 °C, 5 μL of a suspension containing 200 N. americana cysts μL−1 was spotted at one end of the linear bacterial growth, and the plates were incubated at 25 °C for 3 days. A section of the agar containing the interaction zone was applied to MALDI-TOF to study the secreted metabolites by IMS (Fig. 3B). In addition, live colony NanoDESI mass spectrometry was performed on the protozoan colony, the interaction zone and the Pseudomonas colony to construct MS/MS metabolite networks. Nodes with a high MS/MS spectral analogy cluster together and often belong to the same chemical class49. Clusters of the different metabolite classes were then compared to the ions observed in the MALDI IMS data. We detected metabolites produced by Pseudomonas alone (yellow nodes), protozoa alone (green nodes) and produced during the Pseudomonas-protozoa interaction (red nodes). The network was constructed combing the different samples per species together (Fig. 3C).

Bottom Line: Lipopeptide (LP) biosynthesis was induced in Pseudomonas upon protozoan grazing and LP accumulation transitioned from homogeneous distributions across bacterial colonies to site-specific accumulation at the bacteria-protist interface.Also putrescine biosynthesis was upregulated in P. fluorescens upon predation.This multifaceted study provides new insights in common and strain-specific responses in bacteria-protozoa interactions, including responses that contribute to bacterial survival in highly competitive soil and rhizosphere environments.

View Article: PubMed Central - PubMed

Affiliation: 1] Laboratory of Phytopathology, Wageningen University, 6708 PB Wageningen, the Netherlands [2] Microbial Ecology Department, Netherlands Institute of Ecology (NIOO-KNAW), 6708 PB Wageningen, the Netherlands.

ABSTRACT
Protozoan predation of bacteria can significantly affect soil microbial community composition and ecosystem functioning. Bacteria possess diverse defense strategies to resist or evade protozoan predation. For soil-dwelling Pseudomonas species, several secondary metabolites were proposed to provide protection against different protozoan genera. By combining whole-genome transcriptome analyses with (live) imaging mass spectrometry (IMS), we observed multiple changes in the molecular and chemical dialogues between Pseudomonas fluorescens and the protist Naegleria americana. Lipopeptide (LP) biosynthesis was induced in Pseudomonas upon protozoan grazing and LP accumulation transitioned from homogeneous distributions across bacterial colonies to site-specific accumulation at the bacteria-protist interface. Also putrescine biosynthesis was upregulated in P. fluorescens upon predation. We demonstrated that putrescine induces protozoan trophozoite encystment and adversely affects cyst viability. This multifaceted study provides new insights in common and strain-specific responses in bacteria-protozoa interactions, including responses that contribute to bacterial survival in highly competitive soil and rhizosphere environments.

No MeSH data available.


Related in: MedlinePlus