Tibicos or Water Kefir grains are a symbiotic culture of bacteria and yeasts entrapped within in a polysaccharide biofilm matrix created by the bacteria. The polysaccharide produced is called Kefiran which has been shown to be produced by Lactobacillus kefiranofaciens and Lactobacillus delbrueckii subsp.
These preliminary experiments investigate the potential use of Kefiran as a hard bioplastic. The next steps will be to purify and culture the lactic acid bacteria…. Continue reading →
I’ve been obsessed with crystals ever since reading Ballard’s Crystal World and Vonnegut’s Cat’s Cradle as a teenager. Here’s a type of “ice” that crystallises at room temperature. An early test for ice-nine.
Experiments or art, from our BMS1035 Practical and Biomedical Bacteriology students, who recently did experiments to isolate bacteria from soil taken from the University grounds. Their experiments reveal that vast complexity of soil’s most imporant denizens, its bacteria !
” This investigation has yielded an unanticipated result that reaction of cyanic acid with ammonia gives urea, a noteworthy result in as much as it provides an example of the artificial production of an organic, indeed a so-called animal, substance from inorganic substances. ” Friedrich Wöhler, 1828
Until the early 19th century most people, and indeed many scientists, believed in a theory called vitalism that held that living organisms were fundamentally different from non-living entities, in that they contained some unique non-physical element called the vital or life spark. In this context, believers of vitalism predicted that organic materials could not be synthesised from simple inorganic components. However, when Friedrich Wöhler synthesised urea, a compound present in the body, from simple chemicals, it spelled the end for the concept of vitalism. Wöhler, however, was troubled by his discovery and wrote “The great tragedy of science, the slaying of a beautiful hypothesis by an ugly fact.” because he saw vitalism to be a beautiful concept, and his crystals of urea suggested that the theory was false. Nevertheless, he eventually shed his faith in vitalism, and accepted the simple scientific facts before him. These videos document the formation of crystals of urea and the creation of order from disorder. This is what would have been what Wöhler would have observed had he had access to 21st microscopic techniques, that is, self-assembling shards, that penetrate, and emerge from the random dance of urea molecules. Today, there is no need invoke vitalism’s life spark when considering biological systems, and I believe that Nature’s mechanisms are far more beautiful than Wöhler could have ever envisaged.
In the late nineteenth century, the German microbiologist Robert Koch established a set of procedures to identify, and confirm the causative agent of a particular infectious disease. The following four steps, which are still very much used today, are known as Koch’s Postulates.
1. A specific organism must be always be observed in association with the disease.
2, The same organism must be isolated from an infected host and grown in pure culture
3. When the organism from the pure culture is inoculated into a susceptible host organism, it must cause the same disease.
4. The infectious organism must be re-isolated from the diseased organism and then grown again in pure culture.
I came across this bag of infected oranges this morning, (Penicillium digitatum I think), and its very clear to see how the infection has spread. With some General Kitchen Agar, this could be used as a lovely little DIY/Kitchen demonstration of a very important microbiological concept.
Here’s a nice little kitchen microbiology experiment. Kombucha is a natural and symbiotic fermentation that involves yeast and nanocellulose producing Gluconoacetobacter. It can be eaten and is safe to culture at home, but produces bacterial cellulose, natural biomaterial with unique properties that make it suitable for tissue engineering applications. For example, it might be used to prepare nerve conduits to repair peripheral nerve injuries or as scaffold to grow new tissue. Here is some home grown Kombucha, stained with the Ehrlich stain (a simple of the shelf DIY staining method that I developed), and viewed down a microscope. The larger cells are the yeasts, and the much smaller rod shape ones, the cellulose producing Gluconoacetobacter.