Investigating the plant growth promoting ability of Pseudomonas and Bacillus species as candidates for bio-fertilizer production

The world population is expected to increase by up to 70% by 2050, and the global community is faced with the constraint of providing safe and secure food supplies to an increasing number of people. Also, the problems of excessive use of chemical fertilizers include the fact that most of the fertilizers are relatively non-affordable and that they also contaminate underground and surface water, which can increase the risk of blue baby syndrome in infants and stomach cancer in adults. There is therefore a need to harness more cost-effective, eco-friendly, and beneficial biological agents to improve crop productivity. Thus, this research was carried out to investigate the use of rhizobacteria that encourage plant growth to increase maize growth. Soil samples were obtained from the rhizosphere of 23 maize plants cultivated on the research farm at the University of Benin, Nigeria's Faculty of Agriculture. It was then sealed in a plastic bag and brought to the laboratory for examination, where bacteria were isolated. Cultural characterization of the isolates was done, followed by Gram staining and total heterotrophic count. Then, biochemical characterization, such as citrate, catalase, and oxidase tests, were carried out. Isolates were then screened for their plant growth-promoting tests, like hydrogen cyanide, indole-acetic acid, phosphate solubilization, and ammonium production tests. Isolates (0.5 ml) were inoculated into Petri dishes containing sterile Whatman filter papers, and 30 sterile seeds of white maize, new yellow maize, and old yellow maize were added to the Petri dishes. Control experiments were also set up and incubated for 8 days. Test bacteria identified as Pseudomonas sp. and Bacillus sp. were used to inoculate three varieties (old yellow, new yellow, white maize) of maize seeds. From the results, the treatments increased the root length in the old yellow maize, and this was significantly different from the control (p