Figure 3.

Transformation of Methanosarcina species by pWM307. Total DNA was isolated from each strain and from Pur^R clones obtained from each after transformation with pWM307. EcoRI-digested (A) or undigested (B) DNA was electrophoresed, blotted, and hybridized to labeled pXS2 as described. Plasmid pXS2 hybridizes to both the chromosomal serC gene and the pWM307 bla gene. A band corresponding to the chromosomal serC locus is seen in both transformed and untransformed strains, whereas a band corresponding to pWM307 is seen only in the transformed strains. The pWM307 band migrates with a mobility much higher than the chromosomal serC band in undigested DNA, indicating that pWM307 is replicating as a plasmid in these transformants. The strains examined were Methanosarcina spp. WH1 (WH1), Methanosarcina spp. WH2 (WH2), Methanosarcina barkeri MS (MS), Methanosarcina barkeri Fusaro (Fusaro), Methanosarcina barkeri W (W), Methanosarcina thermophila TM1 (TM1), Methanosarcina siciliae C2J (C2J), Methanosarcina mazei S-6 (S-6), and Methanosarcina acetivorans C2A (C2A). +, Pur^R clones; −, untransformed parental strains. The 1.6-kbp band of the molecular weight markers (M_r) hybridizes to pXS2 vector sequences.