Isolation and characterization of plant growth-promoting rhizobacteria (PGPR) from the soils of begonia sp. in Panay Island, Philippines

Abstract

The effects of plant growth-promoting rhizobacteria (PGPR) on the rooting and root growth of Plectranthus scutellarioides stem cuttings Zea mays seeds were investigated in this study. The two PGPR isolated from the soils of Begonia sp. in Panay Island used in the study were identified as both Bacillus cereus after subjecting to biochemical characterization and identification by University of the Philippines-Manila Philippine General Hospital Department of Laboratories and Macrogen Korea. The isolates were also found to have the capacity to produce indole-3-acetic acid amounting to 29.07 µg/ml and 27.88 µg/ml respectively. Inoculation of the PGPR to P. scutellarioides stem cuttings was found to significantly affect the growth of stem cuttings such that the treatment caused the highest root length averaging 136.67 cm. On the other hand, the PGPR did not affect the rooting of the seeds of Zea mays. The antimicrobial potential of B. cereus was also tested against Bacillus subtilis, Escherichia coli, and Candida albicans. The results showed no evidence of antimicrobial property of B. cereus against the three test organisms as there was the absence of the zone of inhibition; however, bacterial growth was observed in the presence of C. albicans. The negative result may be attributed to the difference in the source of PGPR and the strain. Further studies should be made in order to investigate the role of PGPR in plant growth in general.