What does the published scientific research say about Bacillus circulans?

Eight PubMed-indexed studies reference Bacillus circulans — now formally reclassified as Niallia circulans — in plant-input and agricultural contexts. The peer-reviewed record spans growth promotion, pathogen suppression, and heavy-metal tolerance across multiple crop types and geographies.

For Bacillus circulans plant growth promotion, published research reports scalable IAA production by strain E9 (Niallia circulans), with that IAA shown to induce root development in Arabidopsis thaliana at levels comparable to synthetic auxin. Isolates have also been cited in the literature for phosphate and zinc solubilization and ACC deaminase (ACCD) activity. The literature additionally identifies B. circulans as a potassium-solubilizing microorganism (KSM), and one study reported that strain TC7 improved spinach shoot and root growth in cadmium- and nickel-contaminated soil while limiting metal bioaccumulation in plant tissue.