上游充通大￥ Shanghai Jiao Tong University Figure 12-1.Agrobacterium ra- diobacter grown on two different media.Left:Mucoid colonies on sucrose-salts medium:right:non- mucoid colonies on trypticase-soy agar medium. Figure 12-2.Morphological modi- fications (phenotypic changes)re- sulting from changes in media composition.(A)and (B)are phase-contrast micrographs of No- cardia sp.in (A)tryptone agar culture:(B)brain-heart infusion agar;both cultures 12 h at 30C. (Courtesy of B.L.Beaman and D. M.Shankel,and J.Bacteriol, 99:876,1969.)(C)and(D)are electron micrographs of thin sec- tions of Arthrobacter globiformis 425 grown in(C)nutritionally complete medium and(D)biotin- deficient medium resulting in ab- normal forms of the bacterium (several protoplasts embedded in an amorphous matrix).Note that the aberrant cells are devoid of cell walls and no longer exhibit the typical shape of the species as shown in (C).Incubation was at 25C for 36 h.(Courtesy of Mar- garet Gomersall and E.C.S. m Chan.) No.5 上海交大生命学院陈峰Shanghai Jiao Tong University No. 5 上海交大生命学院陈峰