, Volume 60, Issue 2, pp 91-99

First online:

Symbiotic influence of endophytic Bacillus pumilus on growth promotion and probiotic potential of the medicinal plant Ocimum sanctum

  • RM. MurugappanAffiliated withDepartment of Zoology and Microbiology, Thiagarajar College Email author 
  • , S. Benazir BegumAffiliated withDepartment of Zoology and Microbiology, Thiagarajar College
  • , R. Raja RoobiaAffiliated withDepartment of Zoology and Microbiology, Thiagarajar College

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


Bacillus pumilus was isolated from surface-sterilized tissues of the medicinal plant Ocimum sanctum. Scanning electron microscopic (SEM) imaging confirmed the presence of a rod shaped bacterium within the plant tissues. The bacterium was identified as B. pumilus by biochemical analyses and 16S rRNA gene sequencing. In vitro analyses indicate that the isolated strain of B. pumilus was endowed with multiple plant growth promotion (PGP) traits such as phosphate solubilization and the production of indole acetic acid (IAA), siderophore and hydrogen cyanide (HCN). Phosphate solubilization (37.3 μg ml−1) and IAA production (36.7 μg ml−1) by the isolate was found to reach a maximum after 60 h of incubation. Siderophore mediated iron sequestration by B. pumilus may confer a competitive advantage to the host with respect to pathogen inhibition. Siderophore produced by the isolate was found to be of a trihydroxamate type with hexadentate nature. The B. pumilus isolate also exhibited cellulolytic, proteolytic and chitinolytic activity. Cell free supernatant, culture filtrates of the isolate were found to suppress the growth of fungal phytopathogens. The culture filtrate retained its antifungal activity even after exposure to heat. In addition to PGP, the isolate exhibited probiotic properties such as acid tolerance (pH2), bile salt tolerance (2 %), auto-aggregation, antibiotic resistance and the absence of haemolytic activity. These finding suggest the possibility of utilizing this endophytic strain of B. pumilus as a bioinoculant to enhance plant growth and also as a probiotic.


Ocimum sanctum Bacillus pumilus Plant growth promotion Siderophore Probiotics