Plant Growth Promoting Rhizobacteria (PGPR) involves the use of large array of soil bacteria to improve yield, plant growth and sustainable food production. As free living and symbiotic rhizobacteria, PGPR exert its role by colonizing extracellular and/or intracellular rhizoenvironment in the quest for carbon source. In the past decades, focus has been on developing a biosafety agro base approach void of continuous burden on soil micro flora as a result of agrochemicals application. However, with clear understanding of PGPR mechanisms of action "biocontrol, biofertilization and biostimulation", more hope on the possibility of curbing food insecurity amidst rising population has been strengthened. Seeds or soil application of PGPR inoculants enhances phosphates solubilization, biological nitrogen fixation and secretion of plant hormones (indole acetic acid, gibberellins, cytokinins and ethylene) needed for growth and adaptation in stressed environment. As soil pathogen constantly rival the roles of these organisms, PGPR has developed over time wide spectrum of strategies in the form of systemic resistance, iron, space and nutrient competition, antibiotics synthesis, lytic acid production and hydrogen cyanide for efficient food production. In view of this, the review broadens our scope on the use of PGPR as an efficient microbial consortium for enhanced agrobiology and sustenance especially in the tropics were paucity of data on its use, implementation and application of genetically modified organisms has long prevailed.

Aim:To evaluate the antimicrobial activities of Pleurotus squarrosulus mushroom extracts on bacterial and fungal isolates. Methodology: Pleurotus squarrosulus was extracted using ethanol, methanol and aqueous. Antimicrobial susceptibility tests were carried out by agar disc diffusion technique using National Committee of Clinical Laboratory Standard. Qualilative phytochemical analysis was carried out using standard methods. Results: Methanol, ethanol and aqueous extracts of Pleurotus squarrosulus were tested against E. coli, B. cereus, S. aureus, P. aeruginosa, C. albicans and C. glabrata. The different test microorganisms showed varied susceptibility to the test extracts. All the test organisms were Kalu and Kenneth; JAMB, 4(3): 1-9, 2017; Article no.JAMB.34644 2 inhibited by methanol, ethanol and aqueous extract at varied concentrations ranging between 500 mg/ml and 125 mg/ml. Statistically, inhibition of the antibacterial and antifungal control for the test organisms were significantly higher (P < 0.05) than that of the extracts. The phytochemical analysis revealed the presence of saponin, carbohydrates, tannins, flavonoids and proteins in all the extracts while glycoside and alkaloids, were found in some. Conclusion: The finding of this result suggest that Pleurotus squarrosulus possess broad-spectrum antimicrobial activity. The potential of developing antimicrobials from plants appear rewarding. Original Research Article