The growth process of bacteria produced lots of trace elements, enzyme and hormone which one of it is identified to promote plant growth.
As in our biofertilizer biome, studies by KRIBB state that these intended functional bacteria develop in Malaysia emitted volatile chemical compound, 2,3 butanediol. 2, 3 butanediol is airbone chemical signalling that triggered the plant growth. As we can see from the diagram, the plant growth better in size inside water with bacteria than by using water only.