Plating out & growing out colonies.

[Microscopist]

I'm going to plate out my wild yeast culture tonight - just on malt extract agar, one thing that concerns me with a mixed culture is that some of the organisms in there might be reliant on others to grow so may not fair so well on a plate - Is that a serious concern?

I figure the next step will be to pick out morphologically distinct colonies into filter sterilised malt extract broth, about 10ml each, grow them out and then have a quick sniff and taste test to see what's producing the desirable flavours. Any pitfalls I can expect? I'm a properly trained microbiologist but we don't normally go around tasting our cultures.

 

[dantheman13]

I'm going to plate out my wild yeast culture tonight - just on malt extract agar, one thing that concerns me with a mixed culture is that some of the organisms in there might be reliant on others to grow so may not fair so well on a plate - Is that a serious concern?

My understanding is that things tend to lean the other way, meaning that the environment gets too harsh for certain organisms because of other organisms (as opposed to a SCOBY). For example, too low of a pH caused by bacteria is stressful for Saccharomyces. The sugar coated plate should be a good medium, I would say.

 

[Microscopist]

Cheers, just updated my main thread with photos of the resulting plates. Surprisingly little variation in colony appearance, perhaps passing the culture through wort has already done quite a lot of selection.

 

[Microscopist]

That was totally worth the effort, just tasted and subcultured my strains. I'm amazed at the variation in flavour from colonies cultured from the same brew. Out of the ten; 9 had the fruitiness to varying degrees, half were acid, three earthy and one was utterly foul - burny peppery with a pungent stale yeast aroma ( I shall save that for my enemies.)

I'll store all the subs for a while but I've picked two to go on with - going for high fruit with acid and a little earth.

Next test ought to be a triple batch of a few litres of wort trying the two winners alone and combined.