Hyang Burm Lee

Improved production of teicoplanin using adsorbent resin in fermentations

Aims: To use adsorbent resins in fermentations to eliminate toxic effects on growth, reduce feedback repression of production and assist in recovery of teicoplanin.

A bleaching herbicidal activity of methoxyhygromycin (MHM) produced by an actinomycete strain Streptomyces sp. 8E-12.

Aims: To screen bioherbicidal isolates and evaluate herbicidal activity of methoxyhygromycin (MHM) produced by Streptomyces sp. 8E‐12.

Cochlioquinone A1, a new anti-angiogenic agent from Bipolaris zeicola.

Cochlioquinone A1 (CoA1) was newly isolated from the culture extract of Bipolaris zeicola as a potent anti-angiogenic agent. CoA1 inhibited in vitro angiogenesis of bovine aortic endothelial cells (BAECs) such as bFGF-induced tube formation and invasion at the concentration (1 microg/mL) without cytotoxicity. Notably, CoA1 exhibited more potent inhibition activity for the growth of BAECs than that of normal and cancer cell lines investigated in this study. These results demonstrate that CoA1 is a new anti-angiogenic agent and can be developed as a new therapeutic agent for angiogenesis-related diseases.

Nematicidal Activity of Kojic Acid Produced by Aspergillus oryzae against Meloidogyne incognita

The fungal strain EML-DML3PNa1 isolated from leaf of white dogwood (Cornus alba L.) showed strong nematicidal activity with juvenile mortality of 87.6% at a concentration of 20% fermentation broth filtrate at 3 days after treatment. The active fungal strain was identified as Aspergillus oryzae, which belongs to section Flavi, based on the morphological characteristics and sequence analysis of the ITS rDNA, calmodulin (CaM), and β-tubulin (BenA) genes. The strain reduced the pH value to 5.62 after 7 days of incubation. Organic acid analysis revealed the presence of citric acid (515.0 mg/kg), malic acid (506.6 mg/kg), and fumaric acid (21.7 mg/kg). The three organic acids showed moderate nematicidal activities, but the mixture of citric acid, malic acid, and fumaric acid did not exhibit the full nematicidal activity of the culture filtrate of EML- DML3PNa1. Bioassay-guided fractionation coupled with (1)H- and (13)C-NMR and EI-MS analyses led to identification of kojic acid as the major nematicidal metabolite. Kojic acid exhibited dose-dependent mortality and inhibited the hatchability of M. incognita, showing EC50 values of 195.2 µg/ml and 238.3 µg/ml, respectively, at 72 h postexposure. These results suggest that A. oryzae EML-DML3PNa1 and kojic acid have potential as a biological control agent against M. incognita.

First report of leaf spot on Japanese plum caused by an Alternaria sp. in Korea.

Japanese plum (Prunus salicina Lindley) is a deciduous tree in the family Rosaceae. In Korea, this plant is widely distributed in orchards as an important stone fruit as well as in gardens as an ornamental tree because of their abundant white blossoms. Every September to November since 2001, leaf spots were observed on Japanese plum in a garden in Cheongyang, Chungnam District, Korea. Early symptoms consisted of small, brown spots that were 2 to 5 mm in diameter. Later, the leaf lesions became circular or irregular, dark brown, expanded to 15 mm in diameter, and resulted in discoloration with necrosis on twisted leaves that was followed by defoliation. In November, older lesions sometimes appeared blackish brown as sporulation occurred on the lesions. The causal fungus was isolated from diseased leaves and cultured on potato dextrose agar. A culture has been placed in the CABI Herbarium (IMI Accession No. 387139). Conidial dimension averaged 34 × 12 μm. On the basis of morphological characteristics of conidia and conidiophores, the causal fungus was identified as a small-spored species of Alternaria as described by E. G. Simmons (1). Pathogenicity tests were conducted by inoculating slightly wounded and nonwounded leaves with a conidial suspension adjusted to 1 × 106 conidia/ml. Four leaves per each experiment were either wounded or not and inoculated with a spore suspension. The eight leaves were placed in a moist chamber at 25°C. After 6 to 10 days, small brown spots appeared on 87% of the wounded and nonwounded leaves. Control leaves sprayed with distilled water did not develop any symptoms. The causal fungus was consistently reisolated from the leaf spots. Results from pathogenicity tests were similar in a repeated test. It is possible that small-spored Alternaria spp. isolates are host specific (2). Eight Alternaria spp., including A. alternata, A. tenuis, A. tenuissima, and A. citri, have been found to cause black spot on fifteen Prunus spp. in China, Japan, Hong Kong, Libya, Mexico, Australia, and the United States (2). Further studies on the host-specific toxin production, geographical distribution, and host ranges for the species of Alternaria isolated from Japanese plum are in progress. To our knowledge, this is the first report of leaf spot on Japanese plum (P. salicina) caused by a small-spored Alternaria sp. in Korea. References: (1) E. G. Simmons. Mycotaxon 55:79, 1995. (2) K. Inoue and H. Nasu. J. Gen. Plant Pathol. 66:18, 2002.

First Report of Post-Harvest Fruit Rot of Aronia melanocarpa Caused by Fusarium tricinctum in Korea

Black chokeberry, Aronia melanocarpa (Michx.) Elliott, is commonly used as a source of jam and jelly in Korea and worldwide. A fungal isolate EML-CCB6 was isolated from the decaying fruit of black chokeberry. Based on the morphological characteristics and rDNA internal transcribed spacer sequence analysis, the isolate was identified as Fusarium tricinctum (Corda) Sacc. This is the first report of post-harvest fruit rot of black chokeberry caused by F. tricinctum in Korea.

Characterization of Nivalenol-Producing Fusarium culmorum Isolates Obtained from the Air at a Rice Paddy Field in Korea

Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2) of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multi-locus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea

In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus) leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

A New Record of Penicillium raphiae Isolated from Agricultural Soil of Ulleung Island, Korea.

Abstract A fungal isolate EML-NCP01 was recovered from agricultural soil in Ulleung Island, Korea. Phylogenetic analysis of internal transcribed spacer and β-tubulin genes identified the isolate as the Penicillium species P. raphiae. Morphologically, the EML-NCP01 isolate was identical to the previous description of P. raphiae. The species presented here has not been reported in Korea.

First Report of Bulb Canker of Garlic Caused by Embellisia allii in Korea

Abstract Embellisia allii causing bulb canker of white garlic (Allium sativum) has been observed on harvested or stored garlic bulbs. Identification of the fungus was determined based on the symptoms and morphological characteristics on in vitro potato dextrose agar (PDA) and malt extract agar (MEA). Colonies were effuse, blackish brown to black, velvety or powdery. Conidia were solitary, almost straight, most commonly ellipsoidal (or subcylindrical) to ovoid, mid to dark brown, smooth, with very dark 1 to 6 transverse (commonly 3~4) and occasionally 1 or 2 oblique or longitudinal septa, and 30.4×13.4 μm (av.). Conidiophores were simple or branched, straight or flexuous, up to 80 μm long and 5.1~10.2 μm thick. Chlamydospores were developed through enlargement and repeated cellular division of several adjacent hyphal cells to form a complex of thickwalled cells. The conidial measurements of garlic isolates closely matched the previous description of E. allii.