[colarris (OP)]

Im hoping to grow some cultures in petrie dishes as a home experiment and will be using vegetarian alternative to gelatine. I've picked up a tin of 'Grass Jelly' and wondered if this could be used? It contains Grass Jelly, Corn starch. Is this ok to use?

[RD]

agar does not include gelatine ... https://en.wikipedia.org/wiki/Nutrient_agar

BTW
Cultivating micro-organisms is potentially hazardous to your health as you could be growing something pathogenic.

[colarris (OP)]

Thanks, but I don't think you can buy agar in the high street, may be wrong(?)

[CliffordK]

Thanks, but I don't think you can buy agar in the high street, may be wrong(?)

For better or worse, just about anything is available on E-Bay, often in small quantities.  One may be able to buy petri dishes with agar already in them, but I believe most labs make the agar and fill the dishes.

Keep in mind that there may be different types of agar or growth media depending on the organism that is being grown.  For example, one may choose Blood Agar to culture certain organisms, and different agars for yeasts and molds vs that for bacteria.

[colarris (OP)]

agar does not include gelatine ... https://en.wikipedia.org/wiki/Nutrient_agar

BTW
Cultivating micro-organisms is potentially hazardous to your health as you could be growing something pathogenic.

Good point RD. I think I'd better not play around with it just in case. :s

[CliffordK]

It would depend on what your goals are, and what your access is.

Some estimates are that there are more non human cells in humans than human cells, so you can think of your body as a petri dish.

I would think it would be reasonably safe to culture some bugs collected from your own body.  Skin, nose, excrement, etc.

Not that you would necessarily want to eat the agar after you've grown something on it. 

Some bugs such as staph aureus will build up toxins, but then it just gives you a mild upset stomach when you eat them. 

Yeasts and molds can form spores, and could potentially be more hazardous.  Likewise, there are some spore forming bacteria.  But, if you already have it, it is probably not going to get you that sick. 

Oh, also pick up some Latex or Nitrile gloves while you are at it.

[RD]

... if you already have it, it is probably not going to get you that sick.

It is estimated that 20% of the human population are long-term carriers of S. aureus  which can be found as part of the normal skin flora and in anterior nares of the nasal passages.

https://en.wikipedia.org/wiki/Staphylococcus_aureus

Staphylococcus aureus is a major cause of bacteremia, and S. aureus bacteremia is associated with higher morbidity and mortality, compared with bacteremia caused by other pathogens.

http://cid.oxfordjournals.org/content/48/Supplement_4/S231.full

https://en.wikipedia.org/wiki/Methicillin-resistant_Staphylococcus_aureus#Signs_and_symptoms

[CliffordK]

I didn't suggest growing it then injecting it.   [xx(]

The Staph aureus is supposed to create a yellowish colony (thus the name aureus) on various media, and would be interesting to culture and see if you carry it.

How big of a difference is there between smearing some of your own bacteria on agar in a petri dish, and leaving some dirty dishes in your sink overnight?

[RD]

My point was that it is not uncommon for people to carry bacteria which can cause illness if the bacteria are transferred to another location on the body , or their concentration is increased say by deliberately growing them.

For example, Staphylococcus or Streptococcus are also part of the normal human flora and usually exist on the skin or in the nose without causing disease, but can potentially cause skin infections, pneumonia, meningitis, and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation and death

https://en.wikipedia.org/wiki/Pathogenic_bacteria#Conditionally_pathogenic