Homology among nearly all plasmids infecting three Bacillus species

Abstract

We have surveyed naturally occurring plasmids in strains of Bacillus subtilis and the closely related species B. mojavensis and B. licheniformis. Previous studies have failed to find host-benefitting functions for plasmids of these species, suggesting that these plasmids are nonmutualistic. Only one type of plasmid was found in each plasmid-bearing strain, suggesting that most of the plasmids infecting these Bacillus species are in the same incompatibility group. A sample of 18 plasmids from these species ranged in size from 6.9 to 16 kb, with all but 6 plasmids falling into three size groups. These groups differed in the sizes of their host ranges and geographical ranges. All but 1 of the 18 plasmids from these three host species are homologous with one another. The cryptic plasmids from these three species are far less diverse than are plasmids (from other species) that are known to benefit their bacterial hosts. The low-level diversity among these cryptic plasmids is consistent with the hypothesis that host-benefitting adaptations play an important role in fostering the coexistence of plasmid populations, but other explanations for the low-level plasmid diversity are possible. Comparison of the phylogenies of the plasmids with those of their hosts suggests that Bacillus plasmids are horizontally transferred in nature at a low rate similar to that found for the colicin plasmids of Escherichia coli.

Differentiation of plasmids in marine diazotroph assemblages determined by randomly amplified polymorphic DNA analysis

“…Attempts to assign particular phenotypic traits to plasmids from aquatic and terrestrial habitats (Zawadzki et al, 1996 ;Sobecky et al, 1997 ;van Elsas et al, 1998), as well as results from this study, suggest that many naturally occurring plasmids are cryptic. Some of these plasmids may in fact be advantageous to hosts occurring in either ' localized ' niches or specific environmental conditions that vary temporally and spatially (Eberhard, 1990).…”

The Bacillus thuringiensis Linear Double-Stranded DNA Phage Bam35, Which Is Highly Similar to the Bacillus cereus Linear Plasmid pBClin15, Has a Prophage State

“…Bacilli harbor a large variety of plasmids, which include a linear species of Ϸ15 kb (2,13,15,31,34). Recently, the genome sequencing of Bacillus cereus ATCC 14579 revealed the sequence of a linear plasmid (pBClin15) of 15,100 bp (19).…”

Analysis of Dna Plasmid Composition of Salt Tolerant Strains of Rh Izosphere Microorganisms

“…Аналогичные данные встречаются в работах Zowadzki [13] при изучении плазмидных ДНК трех видов бактерий рода Bacillus (B. subtilis, B. mojavensis, B. licheniformis), где были выявлены 18 плазмид из пустынных почв разных географических регионов. Размер выделенных плазмид варьировал от 6,9 до 16 т.п.н и две из них размером 8,5 до 7,5 т.п.н имели доминантные сайты генов солеустойчивости, которые возможно находятся в пределах 4470 и 4870 н.т.…”