Jong-Hui Lim

Induction of Drought Stress Resistance by Multi-Functional PGPR Bacillus licheniformis K11 in Pepper

Drought stress is one of the major yield affecting factor for pepper plant. The effects of PGPRs were analyzed in relation with drought resistance. The PGPRs inoculated pepper plants tolerate the drought stress and survived as compared to non-inoculated pepper plants that died after 15 days of drought stress. Variations in protein and RNA accumulation patterns of inoculated and non-inoculated pepper plants subjected to drought conditions for 10 days were confirmed by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and differential display PCR (DD-PCR), respectively. A total of six differentially expressed stress proteins were identified in the treated pepper plants by 2D-PAGE. Among the stress proteins, specific genes of Cadhn, VA, sHSP and CaPR-10 showed more than a 1.5-fold expressed in amount in B. licheniformis K11-treated drought pepper compared to untreated drought pepper. The changes in proteins and gene expression patterns were attributed to the B. licheniformis K11. Accordingly, auxin and ACC deaminase producing PGPR B. licheniformis K11 could reduce drought stress in drought affected regions without the need for overusing agrochemicals and chemical fertilizer. These results will contribute to the development of a microbial agent for organic farming by PGPR.

Effects on the Soil Microbial Diversity and Growth of Red Pepper by Treated Microbial Agent in the Red Pepper Field

We investigated the effects on soil microbial diversity and the growth promotion of red pepper resulting from inoculation with a microbial agent composed of Bacillus subtilis AH18, B. licheniformis K11 and Pseudomonas fluorescens 2112 in a red pepper farming field. Photosynthetic bacteria, Trichoderma spp., Azotobacter spp., Actinomycetes, nitrate oxidizing bacteria, nitrite oxidizing bacteria, nitrogen fixing bacteria, denitrifying bacteria, phosphate solubilizing bacteria, cellulase producing bacteria, and urease producing bacteria are all indicator microbes of healthy soil microbial diversity. The microbial diversity of the consortium microbial agent treated soil was seen to be 1.1 to 14 times greater than soils where other commercial agent treatments were used, the latter being the commercial agent AC-1, and chemical fertilizer. The yield of red pepper in the field with the treated consortium microbial agent was increased by more than 15% when compared to the other treatments. Overall, the microbial diversity of the red pepper farming field soil was improved by the consortium microbial agent, and the promotion of growth and subsequent yield of red pepper was higher than soils where the other treatments were utilized.

Selection and Identification of Phytohormones and Antifungal Substances Simultaneously Producing Plant Growth Promoting Rhizobacteria from Microbial Agent Treated Red-pepper Fields

In this study, a total of more than 1,000 bacteria, including 739 species of aerobic bacteria, 80 species of urease producing bacteria and 303 species of photosynthetic bacteria, were isolated from red-pepper field soils located in the Gyeongsan Province of the Republic of Korea. Amongst these, 158 species of aerobic bacteria, 70 species of urease producing bacteria and 228 species of photosynthetic bacteria were found to be auxin producing soil bacteria through quantification analysis with the Salkowski test. The latter groupings were then tested for antifungal activities to -Glucanase and siderophore using CMC congo red agar and CAS blue agar media. In addition, the selected strains were examined for antifungal activity against various phytopathogenic fungi on PDN agar media. Six strains; BCB14, BCB17, C10, HA46, HA143, and HJ5, were noted for their ability to both produce auxin and act as antifungal substances. 16S rDNA sequence comparison analyses of these six strains identified them as Bacillus subtilis BCB14, B. methylotrophicus BCB17, B. methylotrophicus C10, B. sonorensis HA46, B. subtilis HA143, and B. safensis HJ5.