A new series for 1999
'Dance of the Spirochaetes'
video clips taken by Edward Cowen, UK
(Text by Dave Walker)
Videos in 'avi' format. Click
here for animated gif version
if your computer doesn't support
'avi'.
In the second of this Video Gallery series we show two video clips taken by Edward Cowen, UK. The video clips show the intriguing movements of Spirochaetes which are bacteria (phylum Spirochaetae) characterised by their corkscrew shape.
Obtaining video sequences of bacteria is quite a challenge as many bacteria are only a few micrometres long and demand the highest power objectives. The sequences shown are aquatic bacteria and use Edward's home adapted phase contrast outfit at high magnification (100x, NA1.3 oil immersion objective).
As an aside not all bacteria are very small i.e a few microns, there are some species that are fractions of a millimetre in diameter. The largest found to date, a bacterium 0.75mm across, was recently reported in the press and is thus just visible to the naked eye. The full illustrated paper on this bacterium is in the April 16th 1999 edition of the magazine 'Science' (use Search routine with 'bacteria' and 'Schulz' together as keywords, a small fee is charged for non-subscribers).The web video clips have to be compressed to keep the files small so losses cf. the original video are inevitable.To view this video clip an 'avi' plugin must be installed in your web browser.
| Video clip left 211kB, avi format. Six
seconds at 5 frames/second, continuous loop.
This first video clip shows an intriguing dance between two Spirochaete bacteria taken using darkfield illumination. |
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| Video clip left 145kB, avi format. Four
seconds at 5 frames/second, continuous loop.
This second video clip using phase contrast lighting gives an indication of the teeming mass of bacteria that can occur in many habitats. Although some bacteria are harmful to man, many aren't and we could not live without their vital role eg. in breaking down organic matter and cycling various elements essential to man such as nitrogen. |
Comments to Edward Cowen welcomed.
Further information
A well illustrated book showing the various types of bacteria is 'Five Kingdoms' by L. Margulis and K. V. Schwartz, publisher W H Freeman (third edition 1998). Multimedia encyclopaedias should also give a good overview. There are also many web sites describing and illustrating bacteria, a web search engine with appropriate keywords should list them.
Please report any Web problems or offer general comments
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Micscape is the on-line monthly magazine of the Microscopy
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