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Trouble growing Microcystis

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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Trouble growing Microcystis

Postby SRR » Tue Apr 18, 2017 12:21 pm

Hello all,

I've been trying to grow the cyanobacterium Microcystis in liquid culture for years.

I once found water in a stream in the autumn which had a really strong green/blue/brown tint, in fact a bottle of it looked almost black in certain lighting. There was also a lot of white froth on the water.
This is what I'm trying to grow.

I've tried several different media, with different carbon sources, different nitrogen sources, different iron sources and different micronutrient solutions.

I have found that most of the recommended media use a fairly high N:P ratio, and that if I use that, or anything like the Redfield ratio, all I get is a load of green algae.

BG11 specifies citric acid, and if I use that, the water just goes orange after one or two days.

The only way that I can grow anything that looks like cyanobacteria is by using a lot of phosphate and a low N:P ratio
of about 3 with disodium EDTA as the only chelator per Allen & Arnon.

What happens is that the water either goes too yellow, or if it stays green, the water will suddenly go clear with all the greenness having apparently sunk to the bottom of the bottle, or the water stays slightly green but never gets any greener i.e. it has apparently stopped growing.

I am doing my culturing in rainwater.

I should mention that I have no training in biology at all. Everything that I know about the subject comes from
some books and a lot of documents that I've downloaded from the web.
I did study chemistry until I went to University to study electrical engineering though.

I have also tried growing Escherichia coli and Lactobacillus and found them both very easy to do.

Is there anyone here with experience of growing cyanobacteria who would like to offer any suggestions?


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