A container, vessel, or organism that ferments or in which fermentation takes place.
From ferment (to cause fermentation) plus the suffix -er (one who does or something that does), creating a noun for the agent of fermentation.
Modern biofuel companies use massive industrial fermenters the size of buildings to grow bacteria and algae that turn plant waste into ethanol—the same basic principle as a jar of kombucha, but scaled up millions of times.
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