What does the published scientific research say about Bacillus polymyxa?

Bacillus polymyxa — reclassified in the scientific literature as Paenibacillus polymyxa — is a gram-positive, spore-forming rhizobacterium studied extensively for plant growth promotion. Published research documents atmospheric nitrogen fixation, phosphorus solubilization, siderophore production, IAA synthesis, and ACC deaminase activity. Microbiome analyses cited in the literature find Paenibacillus enriched in rhizospheres of several agriculturally important crops.

Multiple studies report antifungal biocontrol potential against significant plant pathogens. A strain (SK1) isolated from Lilium lancifolium bulbs inhibited Fusarium oxysporum, Botrytis cinerea, Fusarium fujikuroi, and Botryosphaeria dothidea in vitro. Wheat-rhizosphere strain 7F1 produced lipopeptides — including iturin A and surfactin — with broad-spectrum activity, and strains from Amazonian dark earths also showed antagonism toward Fusarium oxysporum in published genome characterizations.

A published consortium trial reported up to a 17% wheat yield increase and measurable gains in grain zinc and iron content when Paenibacillus polymyxa ZM27 was co-applied with two Bacillus strains. Reviewers also note that phytotoxicity cases have been described in the literature, with growth conditions appearing to influence outcomes — a caveat for anyone evaluating Paenibacillus polymyxa as a biofertilizer or PGPR inoculant.