We have extracted DNA from tissue stored for a month in 70% ethanol in the tropics with no trouble. We did not refrigerate these samples until back at the lab. Not sure how you'd go over a year though. My understanding is water is the enemy. Ethanol evaporates and causes condensation over time if not kept cold. Make sure your samples are kept in airtight containers. Top up the ethanol if you see condensation forming in the lids. Don't put your samples through freeze-thaw cycles.

Dear Chris De Ruyck

This response may be a little late. However there are faecal preservation buffers that can protect nucleic acids for 2 years at room temperature and prevent microbial growth.

Depending on your sample amount, there are smaller or larger tubes available. The smaller tubes will also come with glass beads and are compatible with any isolation workflows requiring homogenization.

Small tubes for preservation: https://norgenbiotek.com/product/fecal-dna-collection-preservation-mini-tubes

Larger tubes for preservation: https://norgenbiotek.com/product/stool-nucleic-acid-collection-and-preservation-tubes

Attached is more information on preservation of the gut microbiome diversity with fresh, frozen, TE-buffer, or Norgen preserved samples.

Hope that helps.

JP