Sunday, May 27, 2012

Filamentous bacteria under the microscope

Filamentous bacteria from soil, seen with phase contrast microscopy.
It's pretty easy to isolate soil bacteria: take a scoop of soil, mix it with some water, then plate the liquid on a Petri dish and incubate it overnight at 25-30 °C. Voilà. 

The isolated bacterial species will vary with the conditions (type of medium, temperature); here I found many filamentous bacteria on the plate. They look a little bit like filamentous fungi (since they also form a mycelium), but usually you can easily tell them apart (with a microscope) because of their smaller diameter. 

Saturday, May 19, 2012

The Human Zoo by Desmond Morris

Back in the days when I was a biology student in Lausanne I had a great time reading Desmond Morris' best seller The Naked Ape (1967), in which the British zoologist discusses what sort of curious social animals we are—and he does so with a lot of wit and humor.  

The Human Zoo (1969) is his follow-up book, thus when I found a copy of it in a second-hand bookshop I happily bought it (probably equally motivated by the lovely vintage yellow cover!). Newer editions are available, as you can see in the author's bibliography.

The Human Zoo still deals with the human animal, but this time the focus is on the social ties that we develop between each other and the sort of society in which we live. The underlying question is: How beings used to living in tribes of at most hundreds of individuals can cope with our modern society and its super-tribes of millions? The city, writes Morris, is not a concrete jungle, it is a human zoo. In the modern life and its crowded places, we tend to behave as animals in captivity.

Tuesday, May 08, 2012

Mother of vinegar

Mother of vinegar from a wine vinegar pot
I'm currently visiting my parents in Switzerland, in a lovely region located between the lake Léman (lake Geneva) and the mountains of Jura (see Nyon région tourisme). On that occasion my father gave me a tour of his vinegar pots, and even fished out the mother of vinegar from inside the pot so that I could take a picture. Have a look at this biofilm of acetic acid bacteria: it's a large and thick disc with the color of a liver!

As their name implies, these bacteria transform alcohol, for instance from wine, into acetic acid. From what I read during a quick overview of the literature, common acetic acid bacteria include species of the genera Acetobacter and Gluconobacter