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Growth and Survival of Mesorhizobium loti Inside Acanthamoeba Enhanced Its Ability to Develop More Nodules on Lotus corniculatus.

Karaś MA, Turska-Szewczuk A, Trapska D, Urbanik-Sypniewska T - Microb. Ecol. (2015)

Bottom Line: Although the association ability and the initial uptake rate of both strains were similar, recovery of viable M. huakuii MAFF303099 after 4 h postinfection decreased markedly and that of M. loti NZP2213 increased.The internalization of mesorhizobia was mediated by the mannose-dependent receptor.M. loti NZP2213 bacteria released from amoebae developed 1.5 times more nodules on Lotus corniculatus than bacteria cultivated in an amoebae-free medium.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics and Microbiology, Maria Curie-Sklodowska University, Akademicka 19, 20-033, Lublin, Poland, magdalena.karas@poczta.umcs.lublin.pl.

ABSTRACT
The importance of protozoa as environmental reservoirs of pathogens is well recognized, while their impact on survival and symbiotic properties of rhizobia has not been explored. The possible survival of free-living rhizobia inside amoebae could influence bacterial abundance in the rhizosphere of legume plants and the nodulation competitiveness of microsymbionts. Two well-characterized strains of Mesorhizobium: Mesorhizobium loti NZP2213 and Mesorhizobium huakuii symbiovar loti MAFF303099 were assayed for their growth ability within the Neff strain of Acanthamoeba castellanii. Although the association ability and the initial uptake rate of both strains were similar, recovery of viable M. huakuii MAFF303099 after 4 h postinfection decreased markedly and that of M. loti NZP2213 increased. The latter strain was also able to survive prolonged co-incubation within amoebae and to self-release from the amoeba cell. The temperature 28 °C and PBS were established as optimal for the uptake of Mesorhizobium by amoebae. The internalization of mesorhizobia was mediated by the mannose-dependent receptor. M. loti NZP2213 bacteria released from amoebae developed 1.5 times more nodules on Lotus corniculatus than bacteria cultivated in an amoebae-free medium.

No MeSH data available.


Related in: MedlinePlus

Uptake rates of A. castellanii Neff for Mesorhizobium spp. presented as a percentage of bacterial inocula (CFU = 6 × 106). Experiment carried out a in PBS at 28 °C, b in PYG at 28 °C, c in PBS at 18 °C and d in PYG at 18 °C. Results are the mean of three independent experiments performed in duplicate. Error bars represent standard deviation (n = 3)
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Fig2: Uptake rates of A. castellanii Neff for Mesorhizobium spp. presented as a percentage of bacterial inocula (CFU = 6 × 106). Experiment carried out a in PBS at 28 °C, b in PYG at 28 °C, c in PBS at 18 °C and d in PYG at 18 °C. Results are the mean of three independent experiments performed in duplicate. Error bars represent standard deviation (n = 3)

Mentions: The fate of the bacteria inside amoeba cells was tested using the antibiotic protection assay. The results are presented in Fig. 2. The bacterial uptake at 28 °C after 2- and 3-h co-incubation was almost constant (Fig. 2a, b). However, the amount of the NZP2213 bacteria residing inside the amoebae increased significantly after 4-h co-incubation, while the number of MAFF303099 cells was reduced. The percentage of the initial inoculum of these strains in PBS and in PYG reached 24.94 % ± 1.67 and 6.28 % ± 1.25 (Fig. 2a) and 20.86 % ± 1.5 and 4.94 % ± 0.47 (Fig. 2b), respectively. The rate of bacterial uptake measured at 18 °C in PBS was similar, indicating that the uptake rate of strain NZP2213 increased and that of strain MAFF303099 considerably decreased along with the co-incubation time (Fig. 2c). On the basis of the results obtained, it can be deduced that the increase in the number of NZP2213 bacteria residing in the amoebas was due to both their active uptake and multiplication in the course of incubation (Fig. 3). The decline in the number of viable MAFF303099 cells inside Acanthamoeba may indicate that with time amoebae utilize these bacteria as a source of nutrients. The intracellular survival assays were performed in order to confirm this suggestion. In that experiment, NZP2213 bacteria that were not taken up after 2-h co-incubation with amoebae were killed with antibiotics, while those inside the protists were left for 24 h. Extended residence time of the bacteria inside the amoebae was applied to show whether they are digested by amoebae or can survive inside. After the incubation, the bacteria were seeded on TY agar plates without prior dilution. The abundance of strain NZP2213 colonies was high, whereas that of strain MAFF303099 was negligible.Fig. 2


Growth and Survival of Mesorhizobium loti Inside Acanthamoeba Enhanced Its Ability to Develop More Nodules on Lotus corniculatus.

Karaś MA, Turska-Szewczuk A, Trapska D, Urbanik-Sypniewska T - Microb. Ecol. (2015)

Uptake rates of A. castellanii Neff for Mesorhizobium spp. presented as a percentage of bacterial inocula (CFU = 6 × 106). Experiment carried out a in PBS at 28 °C, b in PYG at 28 °C, c in PBS at 18 °C and d in PYG at 18 °C. Results are the mean of three independent experiments performed in duplicate. Error bars represent standard deviation (n = 3)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4494150&req=5

Fig2: Uptake rates of A. castellanii Neff for Mesorhizobium spp. presented as a percentage of bacterial inocula (CFU = 6 × 106). Experiment carried out a in PBS at 28 °C, b in PYG at 28 °C, c in PBS at 18 °C and d in PYG at 18 °C. Results are the mean of three independent experiments performed in duplicate. Error bars represent standard deviation (n = 3)
Mentions: The fate of the bacteria inside amoeba cells was tested using the antibiotic protection assay. The results are presented in Fig. 2. The bacterial uptake at 28 °C after 2- and 3-h co-incubation was almost constant (Fig. 2a, b). However, the amount of the NZP2213 bacteria residing inside the amoebae increased significantly after 4-h co-incubation, while the number of MAFF303099 cells was reduced. The percentage of the initial inoculum of these strains in PBS and in PYG reached 24.94 % ± 1.67 and 6.28 % ± 1.25 (Fig. 2a) and 20.86 % ± 1.5 and 4.94 % ± 0.47 (Fig. 2b), respectively. The rate of bacterial uptake measured at 18 °C in PBS was similar, indicating that the uptake rate of strain NZP2213 increased and that of strain MAFF303099 considerably decreased along with the co-incubation time (Fig. 2c). On the basis of the results obtained, it can be deduced that the increase in the number of NZP2213 bacteria residing in the amoebas was due to both their active uptake and multiplication in the course of incubation (Fig. 3). The decline in the number of viable MAFF303099 cells inside Acanthamoeba may indicate that with time amoebae utilize these bacteria as a source of nutrients. The intracellular survival assays were performed in order to confirm this suggestion. In that experiment, NZP2213 bacteria that were not taken up after 2-h co-incubation with amoebae were killed with antibiotics, while those inside the protists were left for 24 h. Extended residence time of the bacteria inside the amoebae was applied to show whether they are digested by amoebae or can survive inside. After the incubation, the bacteria were seeded on TY agar plates without prior dilution. The abundance of strain NZP2213 colonies was high, whereas that of strain MAFF303099 was negligible.Fig. 2

Bottom Line: Although the association ability and the initial uptake rate of both strains were similar, recovery of viable M. huakuii MAFF303099 after 4 h postinfection decreased markedly and that of M. loti NZP2213 increased.The internalization of mesorhizobia was mediated by the mannose-dependent receptor.M. loti NZP2213 bacteria released from amoebae developed 1.5 times more nodules on Lotus corniculatus than bacteria cultivated in an amoebae-free medium.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics and Microbiology, Maria Curie-Sklodowska University, Akademicka 19, 20-033, Lublin, Poland, magdalena.karas@poczta.umcs.lublin.pl.

ABSTRACT
The importance of protozoa as environmental reservoirs of pathogens is well recognized, while their impact on survival and symbiotic properties of rhizobia has not been explored. The possible survival of free-living rhizobia inside amoebae could influence bacterial abundance in the rhizosphere of legume plants and the nodulation competitiveness of microsymbionts. Two well-characterized strains of Mesorhizobium: Mesorhizobium loti NZP2213 and Mesorhizobium huakuii symbiovar loti MAFF303099 were assayed for their growth ability within the Neff strain of Acanthamoeba castellanii. Although the association ability and the initial uptake rate of both strains were similar, recovery of viable M. huakuii MAFF303099 after 4 h postinfection decreased markedly and that of M. loti NZP2213 increased. The latter strain was also able to survive prolonged co-incubation within amoebae and to self-release from the amoeba cell. The temperature 28 °C and PBS were established as optimal for the uptake of Mesorhizobium by amoebae. The internalization of mesorhizobia was mediated by the mannose-dependent receptor. M. loti NZP2213 bacteria released from amoebae developed 1.5 times more nodules on Lotus corniculatus than bacteria cultivated in an amoebae-free medium.

No MeSH data available.


Related in: MedlinePlus