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Best general purpose media?

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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Best general purpose media?

Postby stopherlogic » Sun Nov 09, 2008 10:25 pm

What is the best general purpose media for both bacteria and fungi, I have had a read around and found that nutrient agar will support the growth of most bacterial species. I also think that it may be malt agar as far as fungi is concerned.

Could someone please tell me whether I am right?
(Or a point in the right direction would be appreciated)
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Postby MrMistery » Mon Nov 10, 2008 7:50 pm

agar is not a nutrient. Agar is the stuff you grow your cultures on - the physical support if you wish. It is preferred precisely because there are very few bacterial species that can break it down, and no yeasts as far as I know. Malt agar will probably be ok to grow both bacteria and yeast as long as they are wild-types. That means that your bugs need to synthesize everything they need (amino acids, nucleotides etc) by themselves. It also very prone to contamination, as it has no antibiotic and anything can grow there.
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Re:

Postby canalon » Mon Nov 10, 2008 8:04 pm

MrMistery wrote:agar is not a nutrient. Agar is the stuff you grow your cultures on - the physical support if you wish.


Andrew Nutrient Agar is a culture medium. Relatively rich, it is used for general purpose, just as LB could be. BHI Agar which is very rich could also be used, and will allow the growth of some more fastidious organisms. But it will not cover the needs of all cultivable bacteria, and conditions (aerobic, microaerophylic, anaerobic, temperature) are also important.
But whatever agar is used only a tiny fraction of the diversity of bacteria can be successfuly cultured.
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Postby stopherlogic » Mon Nov 10, 2008 8:24 pm

Thanks, much indebted, any idea about fungi general purpose media? Like I said I think Malt agar is a good general purpose I was just wondering if anyone knows of better?
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Postby MrMistery » Wed Nov 12, 2008 12:17 am

Ups, sorry about that. "Nutrient agar" is kind of a weird name for a medium. But anyway, sorry for the sidetracking.
For yeast the richest medium I use is YPD(I think it stands for yeast peptone dextrose) medium. But don't really know much about it, I only use it to recover yeast after transformations, don't actually grow anything in it.
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Postby victor » Fri Nov 14, 2008 2:03 pm

Yup, I also grew my little tiny red bacteria on nutrient agar slant. In my country, culture of bacteria usually uses Nutrient Agar (NA) or Nutrient Broth (NB). And for culture of mold, we usually use potato dextrose agar (PDA)
Some people prefer to use branded PDA, but my lecturer prefer to make a potato extract by herself and then mixed with dextrose (or table sugar) and agar powder :lol:
The result shows that self-make PDA is better than branded PDA :lol:
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Postby MrMistery » Sat Nov 15, 2008 5:52 am

the point with ready-made stuff is that you don't waste a whole bunch of time doing it yourself. For example, ready-cast gels save me 3-4 hours for every gel I run, ready-made media saves me god knows how much, ready-poured plates save me half an hour, ready-cut blotting paper saves me an extra 3 minutes and the pain of cutting it wrongly etc.
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Postby JorgeLobo » Mon Nov 17, 2008 12:17 am

It;s hard to imagine that anyone wgo had worked in microbiology would not be familiar with nutrient agar.

Malt agar is not a good general purpose medium. I recommend trypticase soy agar as recommended for general recovery by FDA.
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