( ( Over ( ( 100 strains ) ( of ( the bacterium ) ) ) ) ( ( that ( cause ( Lyme disease ) ) ) ( ( have ( been ( identified ( in ( the ( United States ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN Over) (NP (NP (CD 100) (NNS strains)) (PP (IN of) (NP (DT the) (NN bacterium))))) (NP (DT that) (NN cause) (NN Lyme) (NN disease)) (VP (VBP have) (VP (VBN been) (VP (VBN identified) (PP (IN in) (NP (DT the) (NNP United) (NNPS States)))))) (. .)))
Over 100 strains of the bacterium that cause Lyme disease have been identified in the United States.
(ROOT (S (NP (JJ Lyme) (NN disease)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NNS bacteria))))) (. .)))
Lyme disease is caused by bacteria.