• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.423-434
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• 1986

The role of macrophages in the resistance of ICR mice to Candida albicans and Salmonella typhimurium was assessed using silica, agent which selectively inactivates macrophages or poly-2-vinylpyridine-N-oxide(PVNO), a lysosomal stabilizing agent. In addition, effect of silica on humoral and cellular immune responses to sheep red blood cells(SRBC) or polyvinylpyroridone(PVP) was examind. Colonyforming units(CFU) of C. albicans or S. typhimurium in the spleen, livers and kidneys of silica-treated or diluent-treated mice were enumerated at various times after infection. Silica was given i. v. to mice at 4 days or 1 day before infection. Although there was no apparent differences in the number of CFU of C. albicans cultured from the spleens or livers of silica-treated and control mice at every assay period, significant differences in the number of CFU of C. albicans in the kidneys of silica-treated and control mice. Namely, silica given to mice 1 day before infection significantly increased the number of CFU of C. albicans in the kidneys at 2, 4 and 6 days after infection, but did not change the number of CFU at 8 days after infection. Silica given to mice at 4 days before infection significantly increased the number CFU in the kidneys at 2 and 4 days after infection, but rather decreased the number of CFU at 8 days after infection. The number of CFU of C. albians cultured from the kidneys of splenectomized which were experimentally infected mice was similar to the number recovered from sham-operated mice at 4 and 8 days postinfection irrespective of time of infection relative to operation. The pretreatment of mice with PVNO appeared to abrogate the silica-induced susceptibility of mice to C. albicans. PVNO alone showed somewhat protective effect against challenge with C. albicans. In contrast, silica treatment did not alter the number of CFU of S. typhimurium recovered from the spleens and kidneys of mice. The administration of silica to mice at 4 days or 1 day before SRBC immunization significantly suppressed delayed-type hypersensitivity(DTH) reactions to SRBC and antibody production to SRBC, a thymus-dependent antigen and PVP, a thymus-independent antigen. These results provide evidence that macrophages play an important role in susceptibility to Candida infection and strongly demonstrated that macrophages play an essential role in the induction of immune responses in mice.

• Journal of Life Science
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• v.26 no.10
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• pp.1163-1168
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• 2016

Plant growth-promoting rhizobacteria (PGPR) have gained worldwide importance and acceptance due to their agricultural benefits. These microorganisms are potential tools for sustainable agriculture, with effects on plant growth, biofertilization, induced systemic resistance, and biocontrol of plant pathogens. In this study, four different Pantoea species were isolated from field soil, and their plant growth-promoting characteristics were studied. Based on 16S rDNA gene sequencing analyses, the se were grouped into Pantoea ananatis, Pantoea citrea, Pantoea dispersa, Pantoea vagans and named as Pa1, Pc1, Pd1, Pv1, respectively. All of these strains have their ability for solubilization of insoluble phosphate depending on pH decrease at the range around pH 5 at 1days after inoculation and production of plant hormone indole acetic acid (IAA) with 85.3±16.3 μg/ml of Pa1, 183.9±16.8 μg/ml of Pc1, 28.8±17.3 μg/ml of Pd1 and 114.1±16.5 μg/ml of Pv1, respectively. Pa1, Pc1 and Pd1 also have high activity for production of gibberellin (GA₃) hormone with 331.1±19.2 μg/ml of Pa1, 288.5±16.8 μg/ml of Pc1, 309.2±18.2 μg/ml of Pd1, but Pv1 does not. Furthermore, all these species have significantly promoted the growth of the lettuce seedling plants at the range around 32~37% for fresh weight and 10~15% for shoot length enhancement, so that these microbe could be used as a potential bio-fertilizer agents.

• Research in Plant Disease
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• v.29 no.2
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• pp.188-192
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• 2023

Abiotic and biotic stresses have been a serious threat to crop growth and productivity in the agricultural system. In this study, four strains (HS1, H30-3, KJ40, and BC42), which have biological activities related to disease suppression or alleviation of salinity and drought stresses, were tested for broad-spectrum biocontrol activity against anthracnose caused by Colletotrichum orbiculare, a bacterial fruit blotch caused by Acidovorax citrulli, and Fusarium wilt caused by Fusarium oxysporum in cucumber plants. As a result of test, when the four strains were drenched into the soil, anthracnose in cucumber leaves significantly decrease; strain KJ40 suppressed disease incidence by A. citrulli; strain BC42 significantly reduced bacterial fruit blotch and Fusarium wilt compared to control. Therefore, strain KJ40 could be a biocontrol candidate for controlling anthracnose through induced systemic resistance and the disease caused by A. citrulli as well as alleviating drought stress; strain BC42 has broad-spectrum biocontrol activity against anthracnose, Fusarium wilt, and bacterial fruit blotch.