Let's start with the basics. Firstly, three months is too vague! Since I started Friendly Bacteria 94 days have passed. That's 2256 hours, which is much more precise! (I say 'precise veeeeery loosely here as I'm doing lots of estimating, plus my maths is awful)

*E. coli*divide once every 0.35 hours (according to this table, anyway 1 ) so in 2256 hours 6445 divisions would have occurred. So there would be a total of 2^6445 cells at the end (assuming perfect conditions and no deaths, which is unrealistic but much easier to work out) which is a ridiculously big number (1.37*10^1940). If 1 cell weighs 1 picogram (2 ) then that mass of cells would weigh about 1.37*10^162 grams, which is nearly 18 tonnes. That's the weight of like three fully grown African Elephants! Woah. Probably enough to shut down a significant amount of restaurants come inspection day!

How about something a bit more nasty? TB infects 1/3 of the world. How many people could be infected by three months worth of

*Mycobacterium tuberculosis*? Using the same resources, they replicate once every twelve hours in optimum conditions. That's 188 divisions in the time allowed, giving 2^188 cells, or 3.92*10^56. That would weigh just over 1.5kg, a much less scary number than 18 tonnes! But how bad would 1.5kg of

*M. tuberculosis*be? Ummm, pretty bad. It's really, really infectious, with an infectious dose of less than ten (3) so our kilo and a half could infect like 3.92*10^55 people. That's waaaaaay more than the population of the world. In fact, it's roughly 5*10^45 times the population of Earth... All with TB, all with three months' work. Woah.

I think that's pretty scary, but don't worry too much because that makes a whole load of assumptions and things so it's very unlikely.

Let's do a friendly bacteria!

*Bacillus thuringiensis*is an endophytic bacteria that protects plants from herbivorous insects. Time for maths: 3 months of growth would give 2.10*10^1789, weighing in at 16.5 tonnes, or six Asian Elephants put together (still less than the

*E. coli*though). To protect plants from insect pests,

*B. thuringiensis*is inoculated onto them. This inoculum has a final concentration of 1.17*10^13 CFU/kg (4) so our six-elephants-sized blob of bacteria could be used to make 1.79*10^592

*tonnes*of inoculum, which makes

**look absolutely tiny. Pretty sure that could be used to keep the bugs off all our crops for quite a while!**

*the weight of the known universe*This was way more number-y than I originally planned but it's still pretty cool! If my maths is right, anyway, which I'm almost certain it isn't, but there we go. I'm not a mathematician by any means! It was fun, scary, and involved numbers so big they make my brain hurt, but there we go.

It sort of demonstrates how awesome bacteria are; in three months they could infect everyone who could possibly ever live, protect more plants than could ever grow, and shut down every restaurant in the world. Hardcore.

That reminds me, did I leave those plates in the incubator? I should probably take them out before they're able to be weighed in elephants...

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