The extraordinary thing with Marmite, as Tighty pointed out, it's that it's, as he put it "beer yeast crap".
When they use yeast to make beer, the yeast does it's (rather clever)fermenting trick, & the residue sinks to the bottom of the (large, stainless steel) vat.
They used to pay companies to dispose of this glutinous sludge. Now it's bottled and sold as Marmite.
in that case, I make tons of the stuff....in fact I've got 20 gallons of bitter brewing at the moment. Who wants to buy a big tub of the crappy sludge from the bottom?