Clonality and protein diversity of Bacillus pumilus isolates from different sources and geographic regions

The constant increase of multi-drug resistant pathogens stimulates research to identify and develop new antibacterial compounds. Nature and its huge biodiversity harbors an endless source of compounds containing unique chemical structures, being several medicines originated from various natural sources including terrestrial microorganisms. Recent advances in genome sequencing have highlighted Bacillus genus as an unexpected source of antibiotic-like compounds'. Nevertheless, descriptions of compounds with antibacterial activity from Bacillus pumilus are scarce and with chemical/biochemical/microbiological features insufficiently described. B.pumilus is associated with a wide range of biotechnological activities, however, its diversity is also scarce characterized and few studies compared the genomic content derived from PFGE (Pulsed Field Gel Electrophoresis) with proteomic analysis by SDS-PAGE (Sodium Dodecyl Sulfate Polycrylamide Gel Electrophoresis).

In this study, using PFGE and SDS-PAGE, we assessed genomic and protein diversity of B. pumilus isolates (n=24) from a variety of sources and geographic regions, which includes food medicines and cosmetics' contaminants; cucumber roots and gastropods' normal flora.

Clonal relationship evaluated by ApaI-PFGE, defined 18 PFGE-types, being particular pulsotypes associated with isolates'origin. An ability to produce a large variety of proteins was also observed, suggesting its important role in the maintenance and adaptation of B.pumilus to different niches as well as that the toxigenic and biotechnological potential of this species is insufficiently explored. Moreover, clonal host specificity from gastropods isolates highlights the plasticity of B.pumilus and stresses the relevance of studying symbiotic associations, as a source of unrecognized strains able to produce new compounds of pharmaceutical and/or biotechnological interest.