germs and stuff

[Daave]

whats the fasted growing bacteria?

i know a few that are supposed to double in a few minutes, but even after a week, there still wont be many as they are microscopic

is there anything that multiplies so fast that you can see it?

[dawkins]

yes

blooms of cyanobacteria:

http://www-cyanosite.bio.purdue.edu/images/lgi mages/bloom10.jpg

[theprof]

Of what are popularly known as "germs", the species Escherichia coli (E.coli) is one of the fastest at reproducing. Some strains of the bacteria, such as the infamous 0157, divide every twenty minutes or so.

Your second question is not easy to answer for a number of reasons.

Firstly, most bacteria, being invisible to the naked eye, will not seem to reproduce much if you watch them for hours. Yet, if you look at a certain bacterial colonies on a petri-dishes under a correctly set-up microscope, you may well see binary fission (division) taking place over a minimum time period of around twenty minutes. This time period is known as the generation time or doubling time

Secondly, some bacteria, such as certain Beggiatoa species, are amongst the "big boys" of the bacterial world insofar as although the individual bacteria are invisible to the naked eye, colonies of bacteria are visible as a film in their living environment as the bacteria resemble filaments. The only problem here is that Beggiatoa species are not the fastest reproducing bacteria and the majority live in unusual environments such as polluted water, sewage and even volcanoes.

(Continued)

[theprof]

Thirdly, the environment they live in has a huge influence on their growth rate. Adequate nutrient must be present at all times for optimum growth, toxic waste products must be kept under control, temperature is crucial, overpopulation and the avoidance of a vacant microbial niche are also important factors along with many others. If these conditions are not met, bacterial fission is hindered or made impossible. Death of the bacterial colony is a real possibility in this scenario.

So all in all, a lot of conditions have to be met for optimum bacterial growth to occur for you to "see" that growth taking place. Some human pathogenic bacteria divide every twenty to twenty-five days and you would obviously stand no chance of seeing such growth under normal circumstances.

If you really want to see something growing, obtain a fungal organism called a slime-mould. These are composed of an ameboid, multinucleate mass of cytoplasm called a plasmodium. The plasmodium, which reaches macroscopic size, will visibly creep along the walls of a glass tank at a rate which you can see fairly easily. It reproduces via spores that form swarm spores and ultimately, new plasmodia. They are simple and undemanding to keep and the two main parent organisms I've got in one of the uni labs are over twenty years old and are a lurid green in colour.

The look on the faces of the department undergraduates who have never seen a slime mould is a joy to behold each year!