( ( ( 3.7 ( Host strains ) ) ( ( ( The species ) ( of ( bacterium ( that ( is ( most ( commonly-used ( for ( cloning work ) ) ) ) ) ) ) ) ) ( is ( Escherichia coli ) ) ) ) ( , ( ( strain K12 ) . ) ) )
(ROOT (S (NP (NP (CD 3.7) (NNP Host) (NNS strains)) (SBAR (S (NP (NP (DT The) (NN species)) (PP (IN of) (NP (NP (NN bacterium)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (ADJP (RBS most) (JJ commonly-used) (PP (IN for) (S (VP (VBG cloning) (NP (NN work)))))))))))) (VP (VBZ is) (NP (NNP Escherichia) (NNS coli)))))) (, ,) (VP (VB strain) (NP (NNP K12))) (. .)))
3.7 Host strains The species of bacterium that is most commonly-used for cloning work is Escherichia coli , strain K12.
(ROOT (S (NP (NNS Bacteria)) (VP (VBP are) (NP (NP (DT the) (RBS most) (JJ numerous) (NNS species)) (PP (IN on) (NP (DT the) (NN planet))))) (. .)))