Small Things Considered

A query on what is a bacterial species

What is a microbial - specifically bacterial -
species? I am writing a paper on this and would like some
crossbearings from a specialist.
--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: scienceblogs.com/evolvingthoughts
"Darwin's theory has no more to do with philosophy than any other
hypothesis in natural science." Tractatus 4.1122

My comments: This should get a rise.

You Should Be in Films

Scanning electron micrograph of a Staphylococcus biofilm
on the inner surface of a needleless connector. Source

I spent my career growing bacteria in liquid media. I wasn’t aware that my bacteria were planktonic, any more than the character in Moliere’s play Bourgeois Gentleman was conscious that he had been speaking in prose all his life. In my artifical planktonic universe, I was somewhat unconcerned that in the real world wherever there is a surface bathed in water, you can find an organized community of bacteria─a microbial biofilm.

For the likes of me, there is much catching up to do, as the subject of biofilms has progressed rapidly, capturing the imaginations of many researchers.

Time Lapse Stink (from the Cornell Mushroom Blog)

A most exciting blog on mushrooms is in the competent hands of Cornell biology students and their advisor, Kathie Hodge (LINK). By Kathie's permission, I present an article from that blog. Do not miss the video clip.

Everybody Is Always Talking About the Weather…

…but bacteria are actually doing something about it. For starters, we realize that bacteria play an important role in the climate of this planet. Microbes were the original source of all atmospheric oxygen; they are active in the nitrogen cycle and in producing and removing carbon dioxide. As we are painfully reminded every day, to change the atmosphere is to also change the climate. The changes due to microbes may not be as much in the news as the current man-made ones, but the microbes have been responsible for shaping this Earth and they continue to do their important work.

That much is commonly known. What is less well appreciated is that bacteria may play a role in the weather, that is in the day-to-day changes.

Could We Have Started Out as Magnetotactic Bacteria?

There are bacteria that have small magnets within them. Magnetotactic bacteria. The magnets consist of iron-containing crystals lined up in a row along the long axis of the cells, which endows the cells with the equivalent of a magnetic needle. These bacteria thus can sense the earth’s magnetic field, which tells them which way is up or down. (Over much of the globe, the magnetic field is felt as pointing downwards.) The actual merit in being magnetic has not yet been settled definitively. It has been proposed that these bacteria swim along the magnetic field lines to reach the lower strata of the marine sediment. That’s where the oxygen concentration is very low, something they may like. The story of bacterial magnetotaxis has captured the imagination of microbiologists and others alike.

Most magnetotactic bacteria are unicellular, each individual going its own way. However, it has been known for some time that some live in aggregates. This is not surprising in itself, as many bacteria live in communities and biofilms. But, for the most part, they are not stuck there and occasionally come and go. Here, however, the association is obligatory, and that is news.

Talmudic Question #7

Despite recent findings that some archaea may participate in oral disease, the question about their general absence from the Pantheon of Pathogens is still around.  Any new ideas as why they rarely if ever cause disease even though some are adapted to living in animal hosts (e.g., the cow’s rumen, the colon of humans).