Abstract:
:We have developed a program that can accurately analyze the dynamic properties of tethered bacterial cells. The program works especially well with cells that tend to give rise to unstable rotations, such as polar-flagellated bacteria. The program has two novel components. The first dynamically adjusts the center of the cell's rotational trajectories. The second applies piecewise linear approximation to the accumulated rotation curve to reduce noise and separate the motion of bacteria into phases. Thus, it can separate counterclockwise (CCW) and clockwise (CW) rotations distinctly and measure rotational speed accurately. Using this program, we analyzed the properties of tethered Pseudomonas aeruginosa and Pseudomonas putida cells for the first time. We found that the Pseudomonas flagellar motor spends equal time in both CCW and CW phases and that it rotates with the same speed in both phases. In addition, we discovered that the cell body can remain stationary for short periods of time, leading to the existence of a third phase of the flagellar motor which we call "pause." In addition, P. aeruginosa cells adopt longer run lengths, fewer pause frequencies, and shorter pause durations as part of their chemotactic response. We propose that one purpose of the pause phase is to allow the cells to turn at a large angle, where we show that pause durations in free-swimming cells positively correlate with turn angle sizes. Taken together, our results suggest a new "run-reverse-turn" paradigm for polar-flagellated Pseudomonas motility that is different from the "run-and-tumble" paradigm established for peritrichous Escherichia coli.
journal_name
Appl Environ Microbioljournal_title
Applied and environmental microbiologyauthors
Qian C,Wong CC,Swarup S,Chiam KHdoi
10.1128/AEM.01027-13subject
Has Abstractpub_date
2013-08-01 00:00:00pages
4734-43issue
15eissn
0099-2240issn
1098-5336pii
AEM.01027-13journal_volume
79pub_type
杂志文章abstract::Mineralization of [U-(14)C]methyl t-butyl ether (MTBE) to (14)CO(2) without accumulation of t-butyl alcohol (TBA) was observed in surface-water sediment microcosms under denitrifying conditions. Methanogenic activity and limited transformation of MTBE to TBA were observed in the absence of denitrification. Results ind...
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journal_title:Applied and environmental microbiology
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doi:10.1128/AEM.47.4.601-606.1984
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journal_title:Applied and environmental microbiology
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更新日期:2000-05-01 00:00:00