Microalgae are a group of photosynthetic microorganisms living in the water. They are in the spotlight as biostimulators and biofertilizers in modern renewable and sustainable agriculture system, attributed to characteristics such as photosynthetic, and metabolism of various industrial wastes and to increase production when treating crops. Scenedesmus sp. CHK0059 is also one of the microalgae with these characteristics, and it has been reported to suppress various diseases in crops and promote the health of vegetables. However, the mode of action that has a positive effect on plants is not yet well understood. This study was designed to focus on the modulation in diversity change of plant microbiota community, which was the result of the preliminary study, and to determine the direct changes in microbial members that trigger the diversity change in the Arabidopsis model system. As a result, there was no change in the phenotype of Arabidopsis and the microbiota community structure in the rhizosphere during the treatment period, but two bacteria genera, Brevibacterium and Pseudomonas, dominance in the rhizosphere was positively correlated with the CHK0059 treatments. And the bacteria had a positive network correlative relationship with 24 other bacteria. Our findings suggest that the application of microalgae was correlated with several microbiota members in the rhizosphere and was expected to affect the microbiota community structure modification in long-term treatment.

Strawberry is one of the major economic crops in the modern agriculture industry worldwide. Fusarium wilt disease, caused by the Fusarium oxysporum f. sp. fragariae (FOF), is known as the most problematic factor in strawberry production. In a previous study, Streptomyces griseus S4-7 was isolated from the strawberry rhizosphere, exhibited an exceptional antifungal activity against the Fusarium wilt pathogen. However, sensitivity variation to S4-7 in the pathogen population was not evaluated. Therefore, we collected the pathogen nationwide and screened the sensitivity of FOF to the biological agent. A total of 96 FOF isolates was tested their sensitivity to the S4-7 and less-sensitive FOF isolates had lower cell wall degradation than the standard FOF strain. However, gene expression level of the cell wall organization (pkc1, gcn5) was not different between the less sensitive and the standard FOF strains. The results suggested that among the FOF population, some isolates may develop tolerance against a biocontrol agent through complex tolerance mechanisms.

Kiwifruit (Actinidia chinensis Planch.) is an economically important horticultural crop. This study reports a new pathogen of brown leaf spot disease in kiwifruit. Brown leaf spot symptoms were observed on the leaves of cv. Redvita in Jeju, South Korea. The leaf spot diseases appeared as extensive, angular, brown, yellow, white or fused color spots on the leaves. Fungi were isolated and identified as Fusarium tricinctum (Corda) Sacc. based on their morphological and molecular characteristics. Pathogenicity tests were conducted with mycelium and the conidia inoculation. The pathogen was re-isolated from the artificially developed symptoms, and identified as F. tricinctum as Koch’s postulates were confirmed. To our knowledge, this is the first report of the brown leaf spot caused by F. tricinctum on kiwifruit.

농축산미생물배양실은 농축산미생물을 지자체에서 안전하게 관리하고 지원하기 위해 설립되었으며, 현재 전국에 130개소 이상 분포하고 있다. 주로 배양되는 미생물은 고초균, 광합성균, 유산균, 효모균, 질소고정균 등이다. 농축산미생물배양실의 종균관리, 오염등 품질관리에 대한 조사 연구가 수행되지 않아, 본 연구에서 농축산미생물배양실의 질적, 양적 오염 현황을 조사하였다. 조사결과 배양실에서는 공기 중에서 높은 농도의 세균(104CFU/m3)과 진균(104CFU/m3)이 검출되어 오염에 취약하였으며, 또한 배양실에서 보유 중인 종균이 다른 균주로 규명되는 경우도 조사 되었다. 효모 종균이 식중독균으로 동정되는 결과도 관찰되었다. 대부분의 농축산미생물배양실에서 미생물의 특성을 고려하지 않고 혼합하여 배양하였으며, 기업으로부터 납품받은 일부 배지에서는 미생물이 생육하지 못하는 현상도 조사 되었다. 또한, 인체병원균으로 분류되는 황색포도상구균, Bacillus cereus 병원성대장균등이 농민들에게 나누어 주는 미생물배양액에서 검출되었다. 이러한 문제점들은 배양 업무 담당자와 농민, 나아가 국민의 건강 을 해치고, 농업 경제에 악영향을 줄 수 있다.

The Cypripedium japonicum is a species of orchid, distributed mainly in the temperate regions of the Northern Hemisphere. In Korea, C. japonicum is an extremely rare species and class I endangered plant. However, little is known about the plant-microbe interaction and its ecology, especially rhizosphere bacterial communities in terms of structure and diversity in C. japonicum. In this study, the diversity of bacterial communities was investigated in C. japonicum rhizosphere and bulk soil. Proteobacteria, Acidobacteria and Actinobacteria were the most abundant groups in both rhizosphere and bulk soil. Significantly Proteobacteria and Actinobacteria abundantly inhabited in the rhizosphere when compared with the bulk soil. Conversely, significantly more unclassified bacteria were detected in the rhizosphere soil than in the bulk soil. This work increases our understanding of the rhizosphere bacterial diversity on class I endangered plant, C. japonicum.

본 연구는 수입에 의존하고 있는 꽃가루의 안전성을 검토하기 위하여 수행되었다. 수입된 사과 꽃가루에서 동정된 세균은 6종류로 나타났으며, 복숭아 꽃가루에서는 4종 배 꽃가루에서는 5종 키위 꽃가루에서는 5종의 세균이 검출되었다. 이 중 사과와 복숭아에서 분리된 Pantoea ananatis와 Pantoea agglomera는 2007년 검역대상 병으로 고시되었다가 현재는 국내에서 발견되어 보고되어있는 세균이다. 꽃가루에서 분리된 세균 20종을 담배에 접종하여 과민성반응을 조사한 결과 총 9종의 세균이 과민성반응을 일으키는 것으로 나타났다. 아세톤 처리에 따른 세균의 밀도는 대조구와 비교하여 감소하는것으로 나타났다. 아세톤을 처리한 후 발아율을 검정한 결과 사과 꽃가루는 37%에서 13%로 발아율이 떨어졌으며, 복숭아는 39%에서 22%로 떨어졌다. 배 꽃가루 역시 32%에서 19%로 발아율이 떨어졌으며키위의 38%에서 3%로 가장 많이 떨어지는 것으로 나타났다.

In year of 2013, anthracnose disease symptoms were observed on stem of stonecrop in a plant resource field, Southern Forest Resource Research Center, Jinju, South Korea. The disease symptoms were appeared 2-5 cm smudged irregular black spot color on the plant stems. Suspected pathogen was isolated from the lesion with surface sterilization method and identified it as Colletotrichum gloeosporioides by morphological characteristics and phylogenetic analyses. Artificially inoculated the isolated pathogen led to the similar disease symptom as originally observed in the field. The fungal pathogen was re-isolated from the inoculated lesion and it exhibited the same characteristics compared to the original isolate. This is the first report of anthracnose of stonecrop grown in open fields, caused by Colletotrichum gloeosporioides in Korea.

Soybean sprouts have been a considered a nutrient-rich vegetable for hundreds of years. To evaluate the seedlot quality of soybean sprouts grown, and to evaluate a method for reducing the presence of improper seeds in soybean seedlots, microbes associated with soybean sprout rot were isolated from samples collected. Morphological characteristics and gas chromatography profiles of the cultured fungal and bacterial strains were identified. Eight types of improper seeds were identified: purple stain(Ps), black rot(Br), seed coat black spot(Cb), wrinkled seed(Ws), brown hilum(Bh), seed coat fracture(Cf), unripe seed(Us), and brown seed coat(Bc). The improper seeds were also dipped into 15%, 20%, and 25% NaCl solutions, as well as a saturated solution of NaCl, for 1min. As the NaCl concentration increased, the number of floating improper seeds increased as well. The highest floating rates were observed for the Cf seeds.

Rhizopus fruit rot was observed on strawberry fruit (Fragaria x ananassa Duchesne) grown in a glass greenhouse at the Gyeongsangnam-do Agricultural Research and Extension Services, Jinju, South Korea, from 2011 to 2013. Symptoms included water-soaking, rapid softening, and rotting. When these symptoms were left untreated, vigorous fungal growth was observed on the surface of infected fruits. Colonies on potato dextrose agar (PDA) at 30°C were white-cottony to brownish-black. Sporangia were globose, black, and 40–210 ㎛ in diameter. Sporangiophores were light-brown and 6–22 ㎛ in diameter. Sporangiospores were globose to oval, brownish, streaked, and 4–12 ㎛ in length. Columellae were light brownish gray, hemispherical, and 80– 120 ㎛ in diameter. To confirm the identity of the causal fungal pathogen, the complete internal transcribed spacer (ITS) ribosomal RNA gene region was amplified and sequenced. Based on these symptoms, mycological characteristics, pathogenicity tests on host plants, and molecular identification, the fungus was identified as Rhizopus oryzae Went & Prinsen Geerligs. This is the first report of Rhizopus fruit rot on strawberry caused by R. oryzae in Korea.

본 연구는 친환경제제인 미강제제를 처리하였을 때 고추 생육기간에 따른 토양의 이화학적 특성과 밭토양의 미생물 군집을 조사하였으며, 시들음병과 수확량에 미치는 영향을 조사하기 위하여 수행되었다. 제조된 미강제제의 이화학적 특성과 유해성분을 조사한 결과 농촌진흥청에서 제시한 기준인 비료공정규격보다 질소, 인산, 칼륨의 최소함량이 높은 것으로 나타났다. 또한 유해성분 함량도 기준치 이하로 나타났다. 미강제제 처리 후 밭토양의 이화학적 특성은 고추생육이 끝난 시점에도 유효인산의 함량이 대조구에 비하여 높게 유지되는 것으로 나타났다. Phospholipid fatty acid (PLFA) 분석에 의한 토양내의 미생물 군집을 조사한 결과 토양내 미생물 군집변화는 큰 차이가 없었으나 전체적인 미생물 생체량이 높게 나타났다. 미강제제 시용은 고추시들음병 방제에 효과가 있었으며 이로 인해 고추수확량이 약 2.7배 높게 증수되었다.

본 연구에서는 파프리카 재배포장과 저온저장 후 미생물상을 조사하였으며, 동정된 미생물의 병원성을 검정하여 전염원 유입과 저장병 발생의 관련성을 조사하였다. 재배포장에서는 세균의 경우 과일표면에서 Bacillus spp., Clavibacter sp.와 Pseudomonas spp. 등 7종류의 세균이 분리되었으며 저온저장 후에는 인체에 유해한 균을 포함하여 Erwinia sp., Salmonella spp., Streptococcus spp. 등 8종류의 세균이 분리되었다. 재배포장과 저온저장 후 분리된 주요 진균은 Alternaria sp,, Botrytis sp,, Cladosporium sp,, Fusarium sp,와 Penicillium sp.가 분리되었으며, Geotrichum sp.은 저온저장 후 과일에서 분리되었다. 진균의 경우 분리된 균 모두 파프리카의 부패에 관여하는 것으로 나타났으나 분리된 세균을 단독으로 접종하였을 때 파프리카의 부패에 관여하지 않는 것으로 조사되었다. 이 결과로 진균에 의해 1차적으로 저장병이 발생한 후 세균에 의해 2차적 부패가 발생하는 것으로 판단된다.

Streptomyces padanus IA70-5 has been shown to be a promising biological control agent for the suppression of pepper anthracnose. In this study, we assessed the potential use of strain IA70-5 as a biological control agent for Phytophthora blight caused by Phytophthora capsici. Strain S. padanus IA70-5 was found to inhibit the mycelial growth and zoosporangium formation of P. capsici causing Phytophthora blight on pepper plants. In experiments with hot pepper fruit, IA70-5 suppressed the progression of Phytophthora rot by over 90% in pre-inoculated treatments with culture suspension. In experiments with 60-day-old pepper plants, IA70-5 suppressed Phytophthora blight by over 90%. These results demonstrated the potential for S. padanus IA70-5 to provide a practical biological agent for the control of Phytophthora blight in the field.

Pseudomonas fluorescens B16 has been shown to be a promising biological control agent for the promotion of plant growth, root colonization, and suppression of bacterial wilt. This study investigated the dispersion of B16 from seed to radicle, and to the whole root system, and illustrated population changes within cucumber seeds and radicles using scanning electron microscopy (SEM), fluorescence microscopy (FM) and immunofluorescence microscopy (IFM). When cucumber seeds were soaked in a bacterial suspension of B16, bacterial cells entered the seeds through the pore at the base, colonized the inner plane, and proliferated germination advanced. Population densities of B16 were gradually increased, and increased initial populations within newly growing roots. The root surface was covered by cylindrical rod-shaped bacterial cells, and junctions between epidermal cells were covered preferentially. Previous studies exploring root colonization of rhizobacteria have not focused on colonized populations inside seeds. Our microscopic observations confirmed the importance of bacterial cells colonized inside seed coats. Population densities of B16 were then naturally sustained up to harvesting time. The results obtained in this study provide about a novel insight into the commercial application of biological control agents within seeds.

고추에 큰 피해를 일으키는 탄저병에 대한 강한 길항력이 있는 세균을 선발하기 위해 선행연구에서 식물뿌리 시료로부터 분리하여 보관중인 세균들을 대상으로 검정에 사용하였다. 총 457균주로부터 IA70-5균주를 최종 선발하였고, 16S rDNA 염기서열 분석을 통해 Streptomyces padanus로 동정하였다. S. padanus IA70-5는 색소를 분비하지 않고 운동성이 없으며 전형적인 Streptomyces속에 속하는 세균들처럼 나선형의 형태를 이루고 있었다. S. padanus IA70-5 균주는 in vitro에서 Colletotrichum acutaum의 균사생장, 포자발아, 그리고 부착기 형성을 효과적으로 억제하였다. 실내 고추 과실에 대하여 병원균 접종 전 IA70-5 배양액 처리 시 약 90%의 탄저병 억제효과를 나타내었다. 본 연구결과를 통하여 길항방선균 S. padanus IA70-5는 고추 탄저병을 억제하는 효과가 있음을 확인하였다.