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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) Time to encystment of amoeboid and flagellate forms of N. americana exposed to increasing concentrations of putrescine. For each putrescine concentration, the average of three replicates is shown. Error bars refer to the standard error of the mean. (B) Representative images of trophozoite viability at 0, 7, 20 and 30 seconds after exposure to 250 mM putrescine. A replicate consisted of an individual sample containing the protist incubated in the indicated putrescine concentration from which a 6 μl sample was extracted and all cysts or trophozoites in that sample were enumerated.
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f2: (A) Time to encystment of amoeboid and flagellate forms of N. americana exposed to increasing concentrations of putrescine. For each putrescine concentration, the average of three replicates is shown. Error bars refer to the standard error of the mean. (B) Representative images of trophozoite viability at 0, 7, 20 and 30 seconds after exposure to 250 mM putrescine. A replicate consisted of an individual sample containing the protist incubated in the indicated putrescine concentration from which a 6 μl sample was extracted and all cysts or trophozoites in that sample were enumerated.

Mentions: In vitro assays were conducted to examine the effect of putrescine on trophozoites of N. americana. The results of dose-dependent experiments showed that putrescine induced trophozoite encystment (Fig. 2A). The time required for induction of trophozoite encystment decreased with increasing putrescine concentrations. At a putrescine concentration of 50 mM, all trophozoites encysted within approximately 10 min whereas at a concentration of 250 mM or higher, the time to encystment was approximately 1 min. From a concentration of 350 mM onward, there were no observable cysts. This was likely due to trophozoite lysis, which in some instances left visible remnants of deflated trophozoites. Already after 7 seconds exposure to 250 mM putrescine, trophozoites started to deflate (Fig. 2B). Subsequently, cyst viability was assessed by determining the average number of trophozoites obtained from putrescine-treated cysts transferred to the surface of water agar plates amended with heat-killed E. coli. Cyst viability decreased with prior exposure to increasing concentrations of putrescine (Table 1). Whether the putrescine concentrations used here are representative of the concentrations produced by the bacterium in situ remains to be determined.


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) Time to encystment of amoeboid and flagellate forms of N. americana exposed to increasing concentrations of putrescine. For each putrescine concentration, the average of three replicates is shown. Error bars refer to the standard error of the mean. (B) Representative images of trophozoite viability at 0, 7, 20 and 30 seconds after exposure to 250 mM putrescine. A replicate consisted of an individual sample containing the protist incubated in the indicated putrescine concentration from which a 6 μl sample was extracted and all cysts or trophozoites in that sample were enumerated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: (A) Time to encystment of amoeboid and flagellate forms of N. americana exposed to increasing concentrations of putrescine. For each putrescine concentration, the average of three replicates is shown. Error bars refer to the standard error of the mean. (B) Representative images of trophozoite viability at 0, 7, 20 and 30 seconds after exposure to 250 mM putrescine. A replicate consisted of an individual sample containing the protist incubated in the indicated putrescine concentration from which a 6 μl sample was extracted and all cysts or trophozoites in that sample were enumerated.
Mentions: In vitro assays were conducted to examine the effect of putrescine on trophozoites of N. americana. The results of dose-dependent experiments showed that putrescine induced trophozoite encystment (Fig. 2A). The time required for induction of trophozoite encystment decreased with increasing putrescine concentrations. At a putrescine concentration of 50 mM, all trophozoites encysted within approximately 10 min whereas at a concentration of 250 mM or higher, the time to encystment was approximately 1 min. From a concentration of 350 mM onward, there were no observable cysts. This was likely due to trophozoite lysis, which in some instances left visible remnants of deflated trophozoites. Already after 7 seconds exposure to 250 mM putrescine, trophozoites started to deflate (Fig. 2B). Subsequently, cyst viability was assessed by determining the average number of trophozoites obtained from putrescine-treated cysts transferred to the surface of water agar plates amended with heat-killed E. coli. Cyst viability decreased with prior exposure to increasing concentrations of putrescine (Table 1). Whether the putrescine concentrations used here are representative of the concentrations produced by the bacterium in situ remains to be determined.

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