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Factors affecting daughter cells' arrangement during the early bacterial divisions.

Su PT, Yen PW, Wang SH, Lin CH, Chiou A, Syu WJ - PLoS ONE (2010)

Bottom Line: Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population.Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings.Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China.

ABSTRACT
On agar plates, daughter cells of Escherichia coli mutually slide and align side-by-side in parallel during the first round of binary fission. This phenomenon has been previously attributed to an elastic material that restricts apparently separated bacteria from being in string. We hypothesize that the interaction between bacteria and the underneath substratum may affect the arrangement of the daughter bacteria. To test this hypothesis, bacterial division on hyaluronic acid (HA) gel, as an alternative substratum, was examined. Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population. Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings. Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors. With oscillatory optical tweezers, we further demonstrated that the interaction force decreased in bacteria without Lpp, a result substantiating our notion that the side-by-side sliding phenomenon directly reflects the strength of in-situ interaction between bacteria and substratum.

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Related in: MedlinePlus

Bacterial motility detected on agar plates.Appropriately diluted bacteria were grown overnight at 37°C on LB plates containing 0.6% or 0.27% agar. No differences of bacterial colonies are seen in panel (A) (0.6% agar) whereas panel B (0.27% agar) shows that the parental BW25113 gave strong swarming activity that is not seen with the ΔfliG mutant.
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pone-0009147-g006: Bacterial motility detected on agar plates.Appropriately diluted bacteria were grown overnight at 37°C on LB plates containing 0.6% or 0.27% agar. No differences of bacterial colonies are seen in panel (A) (0.6% agar) whereas panel B (0.27% agar) shows that the parental BW25113 gave strong swarming activity that is not seen with the ΔfliG mutant.

Mentions: To demonstrate that an interaction does exist between the bacterium and the substratum, the interaction force (represented by a force constant Kbio) between a single bacterium and the surrounding agar gel (0.2%) in LB was measured by oscillatory optical tweezers (Figure 3); similar techniques have been applied successfully to measure the interaction between biomolecules and mammalian cells [14], [15]. The mean value of Kbio for strain BW25113 was 34.2±7.0 dyne/cm. The corresponding value for the fliG-deleted mutant JW1923 under the same condition was 46.9±12.7 dyne/cm. The increase in the interaction force constant in the absence of flagella implies that the interaction (between bacterium and 0.2% agar) is weakened probably by the rotary motion of the flagella. To confirm whether the mutation at fliG readily dampens the bacterial motility, strain BW25113 and the fliG-deleted mutant were trapped by optical tweezers, and the flagellar rotation frequencies were measured and compared. Besides, the motilities of these bacteria were analyzed by microscopic tracking. In the flagellar rotation frequency analysis, the power spectrum of BW25113 had a distinct peak at 185 Hz, which is absent in the spectrum of flagellum- JW1923 (Figure 4). Consistent with this result, the moving speed of BW25113 in motility medium was significantly faster than that of JW1923 when analyzed in the travel-tracking experiments (Figure 5). In the agar motility assays, JW1923 apparently lost the ability of swarming in 0.27% agar that is inherited with the parental BW25113 strain (Figure 6).


Factors affecting daughter cells' arrangement during the early bacterial divisions.

Su PT, Yen PW, Wang SH, Lin CH, Chiou A, Syu WJ - PLoS ONE (2010)

Bacterial motility detected on agar plates.Appropriately diluted bacteria were grown overnight at 37°C on LB plates containing 0.6% or 0.27% agar. No differences of bacterial colonies are seen in panel (A) (0.6% agar) whereas panel B (0.27% agar) shows that the parental BW25113 gave strong swarming activity that is not seen with the ΔfliG mutant.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2818839&req=5

pone-0009147-g006: Bacterial motility detected on agar plates.Appropriately diluted bacteria were grown overnight at 37°C on LB plates containing 0.6% or 0.27% agar. No differences of bacterial colonies are seen in panel (A) (0.6% agar) whereas panel B (0.27% agar) shows that the parental BW25113 gave strong swarming activity that is not seen with the ΔfliG mutant.
Mentions: To demonstrate that an interaction does exist between the bacterium and the substratum, the interaction force (represented by a force constant Kbio) between a single bacterium and the surrounding agar gel (0.2%) in LB was measured by oscillatory optical tweezers (Figure 3); similar techniques have been applied successfully to measure the interaction between biomolecules and mammalian cells [14], [15]. The mean value of Kbio for strain BW25113 was 34.2±7.0 dyne/cm. The corresponding value for the fliG-deleted mutant JW1923 under the same condition was 46.9±12.7 dyne/cm. The increase in the interaction force constant in the absence of flagella implies that the interaction (between bacterium and 0.2% agar) is weakened probably by the rotary motion of the flagella. To confirm whether the mutation at fliG readily dampens the bacterial motility, strain BW25113 and the fliG-deleted mutant were trapped by optical tweezers, and the flagellar rotation frequencies were measured and compared. Besides, the motilities of these bacteria were analyzed by microscopic tracking. In the flagellar rotation frequency analysis, the power spectrum of BW25113 had a distinct peak at 185 Hz, which is absent in the spectrum of flagellum- JW1923 (Figure 4). Consistent with this result, the moving speed of BW25113 in motility medium was significantly faster than that of JW1923 when analyzed in the travel-tracking experiments (Figure 5). In the agar motility assays, JW1923 apparently lost the ability of swarming in 0.27% agar that is inherited with the parental BW25113 strain (Figure 6).

Bottom Line: Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population.Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings.Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China.

ABSTRACT
On agar plates, daughter cells of Escherichia coli mutually slide and align side-by-side in parallel during the first round of binary fission. This phenomenon has been previously attributed to an elastic material that restricts apparently separated bacteria from being in string. We hypothesize that the interaction between bacteria and the underneath substratum may affect the arrangement of the daughter bacteria. To test this hypothesis, bacterial division on hyaluronic acid (HA) gel, as an alternative substratum, was examined. Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population. Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings. Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors. With oscillatory optical tweezers, we further demonstrated that the interaction force decreased in bacteria without Lpp, a result substantiating our notion that the side-by-side sliding phenomenon directly reflects the strength of in-situ interaction between bacteria and substratum.

Show MeSH
Related in: MedlinePlus