Genome comparison reveals that Halobacterium salinarum 63 ‐R2 is the origin of the twin laboratory strains NRC‐1 and R1

The complete genomes of four Halobacterium salinarum strains were compared in detail. Two strains (91-R6T and 63-R2) were isolated in 1934 by Lochhead from cow and buffalo hides. From the results of these comparisons, we conclude that strain 63-R2 is the immediate ancestor of the two, widely used laboratory strains NRC-1 and R1. AbstractThe genome ofHalobacterium strain 63-R2 was recently reported and provides the opportunity to resolve long-standing issues regarding the source of two widely used model strains ofHalobacterium salinarum, NRC-1 and R1. Strain 63-R2 was isolated in 1934 from a salted buffalo hide (epithet “cutirubra”), along with another strain from a salted cow hide (91-R6T, epithet “salinaria,” the type strain ofHbt. salinarum). Both strains belong to the same species according to genome-based taxonomy analysis (TYGS), with chromosome sequences showing 99.64% identity over 1.85  Mb. The chromosome of strain 63-R2 is 99.99% identical to the two laboratory strains NRC-1 and R1, with only five indels, excluding the mobilome. The two reported plasmids of strain 63-R2 share their architecture with plasmids of strain R1 (pHcu43/pHS4, 99.89% identity; pHcu235/pHS3, 100.0% ident ity). We detected and assembled additional plasmids using PacBio reads deposited at the SRA database, further corroborating that strain differences are minimal. One plasmid, pHcu190 (190,816 bp) corresponds to pHS1 (strain R1) but is even more similar in architecture to pNRC100 (st...
Source: MicrobiologyOpen - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research