The best studied mechanisms of bacterial plant growth promotion include
providing plants with resources/nutrients (Glick 2012). Some of the above-tested EDB stains were able to produce
IAA, which may play a major role, as does plant growthpromoting
phytohormone. The production may depend on species, but also depends on culture conditions, growth stage,
and availability of substrate (Chaiharn and Lumyong 2011).