Analysis of the Genome of Vibrio costicola: Pulsed-Field Gel Electrophoretic Analysis of Genome Size and Plasmid Content

Abstract

Summary The genome organization of the moderate halophile Vibrio costicola has been investigated. To estimate its genome size, large restriction fragments of genomic DNA were separated by pulsed-field gel electrophoresis (PFGE) after digestion with restriction endonucleases. Enzymes SfiI and MboI generated 25 and 6 restriction fragments, respectively. The genome size of V. costicola E-367 was estimated to be 2,505 kb (SfiI) or 2,259 kb (MboI). Genomic DNA digested with SfiI also permitted the calculation of the genome sizes of five additional V. costicola strains, which ranged from 2,100 to 2,600 kb. Besides, three plasmids, designated pVC1, pVC2 and pVC3 (of 2.95 kb, 19 kb and 21 kb, respectively), as well as a megaplasmid, were detected in V. costicola E-367. The restriction map of pVC1 was determined following the use of 14 restriction enzymes, showing cleavage sites for BamHI, BglII, HindII and SalI. Plasmid pVC1 is a candidate for use in the development of cloning vectors suitable for genetic manipulation of V. costicola. An interesting finding is that the DNA of V. costicola is likely to be highly methylated because digestion with MboI yields few cleavage sites. Additionally, different MboI restriction patterns were observed when this moderate halophile was grown at different salinities. This suggests that the methylation system of this halophile may be affected by the salinity of the growth medium.