( They ( ( use ( ( ( fermentation ( or ( other methods ) ) ) ( of respiration ) ) ( that ( ( do n't ) ( require oxygen ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP use) (NP (NP (NN fermentation) (CC or) (JJ other) (NNS methods)) (PP (IN of) (NP (NN respiration))) (SBAR (WHNP (WDT that)) (S (VP (VBP do) (RB n't) (VP (VB require) (NP (NN oxygen)))))))) (. .)))
They use fermentation or other methods of respiration  that don't require oxygen.
(ROOT (S (NP (NNP Fermentation)) (VP (VBZ does) (RB not) (VP (VB use) (NP (NN oxygen)))) (. .)))