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Hello since a couple of monthes I have a huge problem with bacteria, 90 % of my jars (rye) get contaminated with wet spot at various stages, sometimes it doesn't appear before I shake them the first time and then the mycelium dies... Apparently my cultures in petri dishes are free of contam so it seems to happen in the rye. I tried to leave the jars longer in the pressure cooker to sterilize (from 1 hour to 1 hour and 20 minutes now) but it doesn't change anything. I tried to change the type of rye (from organic to non-organic). I also tried to soak the rye 24 hours before in water but then when I sterilize the jars they get all mashed, the kernels explode in some kind of paste. What else could I try to get rid of this problem ? thanks for any help
Ok Magnum, I will try this today (in fact I already tried this tek of PCing them two times, with a mashed rye result too...) Another question : is it possible that the bacillus goes from one jar to another in my incubator ? (the lids have a 1/2 inch hole with polyfill and covered with aluminium foil) or are we talking of endospores for sure ?
Wet spot/Bacillus is [fortunately] an easy problem to overcome. It's encouraged by a few factors:
1. Incomplete PC cycle I doubt that's the problem. 1 hour should really be enough. I don't work with rye, but I'd never go over an hour with WBS. You're going to 15 PSI, right?
2. High endospore-ridden grain You've changed sources, which would have been a suggestion. Another option is to change the type of grain; I always failed with rye, but never tried to figure out the problem because [cheaper] WBS worked like a charm. Another step that can help, regardless of grain type, is to thoroughly rinse it before soaking/steeping.
3. Too much moisture Some folks will tell you that steeping is better than soaking. What I'll tell you is that if you're having this big of a problem, you need to experiment to find what works for you. Run an entire load of jars as a 'test batch' with varying amounts of added water/steeping times from jar to jar. Label the jars and keep notes. This is going to require measuring the amount of water added [if any] so the best recipe can be reproduced easily. The details are up to you, but this is a very powerful way to get the water content right. . .you will likely have to pitch most of the test batch, but you will end up with a valuable 'recipe' that works *for you*, and can immediately run a full optimized load.
4. [rarely] jar to jar contamination Often overlooked, but rarely the actual problem. If you have a wet/humid incubator, this is worth looking at. When a jar is PC'ing, it's possible that some of the liquid can boil over, essentially coating the outsides of the jar [or soaking the polyfill] with dilute grain water. After PC'ing, it's sterile, but is prime breeding grounds for bacteria [esp. in a wet incubator]. Bacillus is a motile bacterium, meaning it can swim up moist surfaces and possibly through filters/threads. If you think this is a possibility, replace the polyfill [a good idea anyway] and make sure to give the jars/lids a soapy scrub before re-use. Bleach/re-PC'ing will kill the organisms, but only scrubbing will remove the bacteria food source. Dry incubators/no incubators can also help.
One last thing; any time you're having problems of this type, it's a good idea to leave an uninoculated negative control jar [or two]. This is after you've figured out an optimal moisture content, of course. You seem confident that the inoculum is clean, but it's still a good idea. If the control ends up clean, it can be inoculated later.