The preference priority of Bacillus subtilis in uptaking free DNA during the natural transformation

Abstract

Although genetic material is vertically transferred between the generations via sexual or asexual reproduction, the huge similarities in some chromosome and gene parts of unrelated organisms provide important clues to another way of transfer. The mobility of genetic information among different organisms, known as HGT has immediate or delayed effects on the recipient host. One of the most notable mechanisms of HGT is NT, a process in which cells take free DNA from the extracellular environment and incorporate it into their chromosomes by homologous recombination. NT is widely conserved in many bacterial species as it can promote to spread of resistance genes. Although it is known that many organisms carry out HGT, there is limited information about how organisms decide to a particular genetic material horizontally transferred. Here, we have investigated the preference priority among different gene sources presented under certain stress conditions for B. subtilis possessing NT ability. To test this, two DNA specimens (E and C) with different sequence contents of the same length were presented to B. subtilis under different stress environments (BK, BC, BE and BCE). The hypothesis was evaluated according to the analysis results of the colonies formed on the selective plates (pE, pC and pCE). All the data have presented a strong positive correlation that the bacteria have preference priority during NT depending on a stimulator. The tendency of the bacteria to uptake useful DNA fragments in a specific environment can be suggested, for example, the majority of colonies grow on pE plates rather than the pC and pCE when the transformation media includes Eryt as an inducer. Although the data significantly overlaps with the idea claiming that the bacteria have a preference priority to uptake free DNAs during the NT, further investigations are needed to support the data strongly and understand the phenomenon properly.