Streptomyces blastmyceticus strain 12-6 was isolated from a forest soil sample of Cheonan area on the basis of strong antifungal activities against plant pathogenic fungi. Butanol extracts of the cultural filtrates were active against C. acutatum, C. coccodes, C. gloeosporioides, F. oxysporum, and T. roseum. Active fractions were prepared by thin layer chromatography using silica gel plate; 12-6-2 (Rf 0.36), 12-6-3 (Rf 0.44). Scanning electron microscopy showed that the active fractions caused a change in surface texture of fungal spores from smooth surface to wrinkled surface. The lethal effect on the spores of the active fractions varied from 56% to 100%. It was shown that the spores of C. acutatum were more sensitive to the antifungal fractions than the spores of F. oxysporum. Fluorescence staining using TOTO-1 indicated that the antifungal fractions could make the spores more sensitive to the fluorescence dye. Thus, it was suggested that antifungal agents prepared in this study exhibited the antifungal activity by damaging the plasma membrane of both fungal spores and hyphae. Identification of antifungal agents in the active fraction using GC-MS analysis revealed the presence of cyclo-(Leu-Pro) and 9-octadecenamide as major components that have already been known as antifungal substances.

Iris yellow spot virus (IYSV) is a plant pathogenic virus which has been reported to continuously occur in onion bulbs, allium field crops, seed crops, lisianthus, and irises. In South Korea, IYSV is a “controlled” virus that has not been reported, and inspection is performed when crops of the genus Iris are imported into South Korea. In this study, reverse-transcription polymerase chain reaction (RT-PCR) and nested PCR inspection methods, which can detect IYSV, from imported crops of the genus Iris at quarantine sites, were developed. In addition, a modified positive plasmid, which can be used as a positive control during inspection, was developed. This modified plasmid can facilitate a more accurate inspection by enabling the examination of a laboratory contamination in an inspection system. The inspection methods that were developed in this study are expected to contribute, through the prompt and accurate inspection of IYSV at quarantine sites to the plant quarantine in South Korea.

Tobacco ringspot virus (TRSV) is a plant quarantine virus in Korea. As such, a TRSV examination is conducted when importing various crops. In this study, RT-PCR and nested PCR systems for TRSV detection in quarantine sites, and the modified-positive control plasmid for proving laboratory contamination and false positive reactions were developed. The developed diagnostic system was used to detect TRSV in the quarantine site. It revealed that from 2012 to August 2014, a total of 12 cases were detected in imported various crops. The system is expected to continue contributing to TRSV detection in plant quarantine.

No abstract

A lead binding protein was purified from the culture filtrate of Streptomyces subrutilus P5. The subunit and native molecular weights were estimated to be 28 and 55 kDa, respectively, indicating that the protein was composed of two identical subunits. The inhibition pattern, the metal content analysis and the EPR spectrum confirmed that the protein was a superoxide dismutase containing Fe and Zn (FeZnSOD). The protein precipitated immediately upon mixing with lead ions and the saturation number of lead ions was about 1100 lead atoms per subunit. Using this property, lead ions could be effectively removed from solutions.