![]() pylori have two genetic mechanisms that cause the helical shape. It turns out that if you knock out this gene from the non-twisty mutants the bacteria loose all traces of curve or twistyness and movement through viscous solutions that mimic the stomach lining is a lot harder. In reference 2, the found a new gene (csd4) involved in the curved shape of the bacteria, which the original non-twisty mutants still maintained. The less-twisty bacteria did still show a difference in colonisation - the twisted wildtype bacteria were much more likely to colonise the stomach lining than the straighter mutants. ![]() pylori live in the mucus lining of the stomach, and it was thought that the helical shape would it to push through this viscous material more easily. Previous research in bacteria which had lost their helical twist (although they still maintained a slightly curved shape, hold that thought) showed no difference in movement or swimming motility. jejuni seems to be controlled by one major gene (probably with the help of a few others) and is important for pathogenicity. jejuni and expressed at the correct levels, which is a pity because spiral shaped E. The corkscrew-effect the pgp1 produces is only present when the gene is in C. When they took the pgp1 gene and put it into a normally rod-shaped bacteria ( E. The researchers also made mutants that overexpressed the pgp1 and found that this too had a straightening effect on the cells (again, lovely bacteria pictures in figure 3). jejuni and pgp1 mutants when it came to growth, stress survival or general living on nutrient agar the spiral shape only seems to have an effect on factors important for virulence and survival inside a body. There were no differences between normal c. Figure 1 in the reference has some excellent pictures of the spiral bacteria and the sad rod-shaped mutants. jejuni is also a major causes of diseases in chickens) and are also bad at forming biofilms and generally moving around. When deleted, the resultant rod-shaped bacteria are three times worse at colonising chicks ( C. As its name suggests pgp1 acts on peptidoglycan, which is a major component of the bacterial cell wall. Researchers in reference 1 found one gene, which they called pgp1 (peptidoglycan peptidase 1), which when deleted turns the bacteria from a neat little spiral into a boring rod shape. So first of all, how to remove the spiral shape from the bacteria. jejuni, which I have a soft spot for because I worked with it back when I was studying bacteriophages. In both cases the helical shape can be destroyed by fairly simple gene knockouts, and in both bacteria the loss of the helical shape resulted in a decrease in virulence and the ability of the bacteria to function within a body. One concerned the bacteria campylobacter jejuni (which causes bacterial-induced diarrhoea) and one was on helicobacter pylori (the bacteria that causes stomach ulcers, which I've written about previously). ![]() I was quite excited therefore, to see two recent articles in PLoS Pathogens that both addressed this issue. Likewise a rod is a good shape for bacteria that move around a lot, giving them more propulsion through crowded spaces (and when you're small enough to be on the same scale as large molecules, every space is crowded).īut why spirals? What benefits do bacteria gain from being shaped like a corkscrew? Spherical bacteria make sense as a sphere is a fairly simple shape to grow into and chains or colonies of bacteria allow them to spread into their environment. Not a huge range of shapes admittedly, but the main shapes are spherical, rod-shaped, or spiral. ![]() One of the first things you learn in bacteriology is that bacteria come in different shapes. ![]()
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