Silage fermentation is an anaerobic reaction that reduces sugars to fermentation byproducts like lactic acid. Propylene glycol oxidizes to lactic acid. Ethanol increases production of uric acid by increasing production of lactic acid, hence lactic acidosis. This propagates tissue ischemia and worsens lactic acidosis. Poisoning with arsenic can raise lactate levels and lead to lactic acidosis. Lactic acid fermentation is important to muscle cell physiology. This malolactic fermentation is undertaken by lactic acid bacteria. Pyruvate from glycolysis undergoes a simple redox reaction, forming lactic acid. These processes are known as lactic acid fermentation and ethanol metabolism respectively. The conjugate base of lactic acid is called lactate. More commonly starter bacteria are employed instead which convert milk sugars into lactic acid. Lactic acid and lactaldehyde are common intermediates. Other strains of lactic acid bacteria may also be added. "Lactobacilli" metabolize the sugar into glucose and lactic acid. Two molecules of lactic acid can be dehydrated to the lactone lactide.