Isolation and characterization of bacterial community in root of chili plant as potential plant growth-promoting bacteria / Nur `Azamiyah Ab Rani and Aslizah Mohd-Aris

Agricultural sector is a significant contribution to the growth of Malaysia's economic sector, and its sustainability should be maintained. Dependency on the application of synthetic chemical fertilizers and pesticides required special attention due to their negative effect on extensive usage. Attention to the search for alternative strategies is urgently needed. The plant growth-promoting bacteria (PGPB) showed great potential as biofertilizers and biocontrol of pathogens. This research aims to isolate and identify the potential PGPB from the local chili plant's roots. Isolation and characterization of the potential isolates of PGPB were performed using standard microbiology procedures. A total of 10 isolates were successfully obtained during the isolation stage. The isolates were designated as strain A1 to strain A10. Based on Gram staining, strains A1, A5, A6, A8, A9, and A10 were found to be Gram- positive. Strains A2, A3, and A4 were found to be Gram-negative. However, strain A7 was not able to be retrieved after a series of restreaking procedures, perhaps due to symbiosis factors. Besides, strains A5 and A10 were found to be unmatched by any PGPB strains. Further biochemical analysis proposed that strains A1, A3, A6, and A8 belong to Bacillus sp., strains A2 and A4 belong to Pseudomonas sp., and strain A9 proposed to be Brevibacillus sp. In conclusion, it was strongly suggested that these nine isolates belong to PGPB due to the strain identification resembling a common PGPB strain. In the future, studies on the ability of the isolates to act as bioprotectants and biofertilizers are recommended.