• Research in Plant Disease
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• v.27 no.2
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• pp.49-60
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• 2021

Cashew (Anacardium occidentale L.) is an important cash crop in Tanzania as a source of income to cashew growers and provides foreign exchange for the country. Despite its significance, the crop is threatened by fast spreading disease known as cashew Fusarium wilt caused by Fusarium oxysporum. Field assessment and laboratory tests were conducted to determine incidences of the disease, severity, ecological factors that influence them and explored the pathogen host specificity in six cashew growing districts. The results revealed significant (P<0.001) variation of disease incidences and severity among the studied districts. The results further revealed that there is both positive and negative correlation between the incidence and severity of the disease versus the evaluated ecological factors. The soil pH, soil temperature, air temperature, and relative humidity depicted positive correlation of disease incidence and severity versus ecological factors at ρ=0.50 and ρ=0.60, ρ=0.20 and ρ=0.94, ρ=0.11 and ρ=0.812, ρ=0.05 and ρ=0.771 respectively while nitrogen, phosphorus, and carbon depicted negative correlations at ρ=-0.22 and ρ=-0.58, ρ=-0.15 and ρ=-0.94, ρ=-0.19 and ρ=-0.12 respectively. In terms of host range, none of the weed species was found to be a carrier of Fusarium pathogen implying that it is host specific or semi selective. The results revealed that the tested ecological parameters favor the growth and development of Fusarium pathogen. Thus, management of the disease requires nutrients replenishment and soil shading as essential components in developing appropriate strategies for the control and prevention of further spread of the disease.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.27-36
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• 2022

Ever since bioplastics were globally introduced to a wide range of industries, the disposal of used products made with bioplastics has become an issue inseparable from their application. Unlike petroleum-based plastics, bioplastics can be completely decomposed into water and carbon dioxide by microorganisms in a relatively short time, which is an advantage. However, there is little information on the specific degraders and accelerating factors for biodegradation. To elucidate a new strain for biodegrading poly-3-hydroxybutyrate (PHB), we screened out one PHB-degrading bacterium, Microbulbifer sp. SOL03, which is the first reported strain from the Microbulbifer genus to show PHB degradation activity, although Microbulbifer species are known to be complex carbohydrate degraders found in high-salt environments. In this study, we evaluated its biodegradability using solid- and liquid-based methods in addition to examining the changes in physical properties throughout the biodegradation process. Furthermore, we established the optimal conditions for biodegradation with respect to temperature, salt concentration, and additional carbon and nitrogen sources; accordingly, a temperature of 37℃ with the addition of 3% NaCl without additional carbon sources, was determined to be optimal. In summary, we found that Microbulbifer sp. SOL03 showed a PHB degradation yield of almost 97% after 10 days. To the best of our knowledge, this is the first study to investigate the potent bioplastic degradation activity of Microbulbifer sp., and we believe that it can contribute to the development of bioplastics from application to disposal.

• Journal of Microbiology and Biotechnology
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• v.32 no.7
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• pp.892-901
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• 2022

The rising demand for carotenoids can be met by microbial biosynthesis as a promising alternative to chemical synthesis and plant extraction. Several species of lactic acid bacteria (LAB) specifically produce C₃₀ carotenoids and offer the added probiotic benefit of improved gut health and protection against chronic conditions. In this study, the recently characterized Lactiplantibacillus plantarum subsp. plantarum KCCP11226^T produced the rare C₃₀ carotenoid, 4,4'-diaponeurosporene, and its yield was optimized for industrial production. The one-factor-at-a-time (OFAT) method was used to screen carbon and nitrogen sources, while the abiotic stresses of temperature, pH, and salinity, were evaluated for their effects on 4,4'-diaponeurosporene production. Lactose and beef extract were ideal for optimal carotenoid production at 25℃ incubation in pH 7.0 medium with no salt. The main factors influencing 4,4'-diaponeurosporene yields, namely lactose level, beef extract concentration and initial pH, were enhanced using the Box-Behnken design under response surface methodology (RSM). Compared to commercial MRS medium, there was a 3.3-fold increase in carotenoid production in the optimized conditions of 15% lactose, 8.3% beef extract and initial pH of 6.9, producing a 4,4'-diaponeurosporene concentration of 0.033 A₄₇₀/ml. To substantiate upscaling for industrial application, the optimal aeration rate in a 5 L fermentor was 0.3 vvm. This resulted in a further 3.8-fold increase in 4,4'-diaponeurosporene production, with a concentration of 0.042 A₄₇₀/ml, compared to the flask-scale cultivation in commercial MRS medium. The present work confirms the optimization and scale-up feasibility of enhanced 4,4'-diaponeurosporene production by L. plantarum subsp. plantarum KCCP11226^T.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.62-75
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• 2022

Background: Pollinators help plants to reproduce and support economically valuable food for humans and entire ecosystems. However, declines of pollinators along with population growth and increasing agricultural activities hamper this mutual interaction. Nectar and pollen are the major reward for pollinators and flower morphology and volatiles mediate the specialized plant-pollinator interactions. Limited information is available on the volatile profiles attractive to honey bees and bumblebees. In this study we analyzed the volatile organic compounds of the flowers of 9 different plant species that are predominantly visited by honey bees and bumblebees. The chemical compositions of the volatiles were determined using a head space gas chromatography-mass spectrometry (GC-MS) method, designed to understand the plant-pollinator chemical interaction. Results: Results showed the monoterpene 1,3,6-octatriene, 3,7-dimethyl-, (E) (E-𝞫-ocimene) was the dominating compound in most flowers analyzed, e.g., in proportion of 60.3% in Lonicera japonica, 48.8% in Diospyros lotus, 38.4% Amorpha fruticosa and 23.7% in Robinia pseudoacacia. Ailanthus altissima exhibited other monoterpenes such as 3,7-dimethyl-1,6-octadien-3-ol (𝞫-linalool) (39.1%) and (5E)-3,5-dimethylocta-1,5,7-trien-3-ol (hotrienol) (32.1%) as predominant compounds. Nitrogen containing volatile organic compounds (VOCs) were occurring principally in Corydalis speciosa; 1H-pyrrole, 2,3-dimethyl- (50.0%) and pyrimidine, 2-methyl- (40.2%), and in Diospyros kaki; 1-triazene, 3,3-dimethyl-1-phenyl (40.5%). Ligustrum obtusifolium flower scent contains isopropoxycarbamic acid, ethyl ester (21.1%) and n-octane (13.4%) as major compounds. In Castanea crenata the preeminent compound is 1-phenylethanone (acetophenone) (46.7%). Conclusions: Olfactory cues are important for pollinators to locate their floral resources. Based on our results we conclude monoterpenes might be used as major chemical mediators attractive to both honey bees and bumblebees to their host flowers. However, the mode of action of these chemicals and possible synergistic effects for olfaction need further investigation.

• ALGAE
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• v.38 no.4
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• pp.283-294
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• 2023

Previous research indicated that free-living sporangial filament keep hollow morph under high-culture density and form bipartite cells under low-culture density, while the following conchospore release was inhibited by high light. Here, we further explored the molecular bases of these affects caused by light and culture density using a transcriptome analysis. Many differentially expressed genes (DEGs) related to carbon dioxide concentration and fixation, photosynthesis, chlorophyll synthesis and nitrogen absorption were upregulated under high-light conditions compared with low-light conditions, indicating the molecular basis of rapid vegetative growth under the former. The stress response- and ion transport-related DEGs, as well as the gene encoding the vacuole formation-brefeldin A-inhibited guanine nucleotide exchange protein (BIG, py05721), were highly expressed under high-density conditions, indicating the molecular basis of the hollow morph of free-living sporangial filaments under high-culture density conditions. Additionally, the brefeldin A treatment indicated that the hollow morph was directly influenced by vacuole formation-related vesicle traffic. Others DEGs related to cell wall components, zinc-finger proteins, ASPO1527, cell cycle and cytoskeleton were highly expressed in the low density with low-light group, which might be related to the formation and release of conchospores. These results provide a deeper understanding of sporangial filaments in Neopyropia yezoensis and related species.

• Animal Bioscience
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• v.36 no.12
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• pp.1842-1852
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• 2023

Objective: Hairy vetch is considered to improve the nutritional value of corn because of its high protein and mineral levels. To better understand the mechanism underlying hairy vetch regulated whole-plant corn silage fermentation, this experiment investigated the fermentation quality and bacterial community of whole-plant corn and hairy vetch mixture. Methods: Whole-plant corn and hairy vetch were mixed at ratios of 10:0 (Mix 10:0), 8:2 (Mix 8:2), 6:4 (Mix 6:4), 4:6 (Mix 4:6), 2:8 (Mix 2:8), and 0:10 (Mix 0:10) on a fresh weight basis. After ensiling 60 days, samples were collected to examine the fermentation dynamics, ensiling characteristics, and bacterial communities. Results: Mix 0:10, Mix 2:8, and Mix 4:6 showed poor fermentation characteristics. Mix 8:2 and Mix 6:4 silages showed high quality, based on the low pH, acetic acid, and ammonia nitrogen levels and the high lactic acid, crude protein, and crude fat contents. The bacterial diversity was affected by the mixing ratio of the two forage species. The genus Lactobacillus dominated the bacterial community in Mix 10:0 silage, whereas with the addition of hairy vetch, the relative abundance of unclassified-Enterobacter increased from 7.67% to 41.84%, and the abundance of Lactobacillus decreased from 50.66% to 13.76%. Conclusion: The silage quality of whole-plant corn can be improved with inclusion levels of hairy vetch from 20% to 40%.

• Journal of Korean Society on Water Environment
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• v.40 no.1
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• pp.1-10
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• 2024

Algal blooms occur seasonally in the eutrophicated rivers or reservoirs, and some harmful cyanobacteria species produce toxic substances, which are directly or indirectly harmful to the ecosystem and terrestrial animals. So, the monitoring and control of harmful cyanobacteria occurrence and toxins residual in the aquasystem are important to preserve the water environment and secure public health. In this study, the four harmful cyanobacteria occurrences and toxic substance concentrations of two agricultural reservoirs in the southern part of Gyeonggi Province were investigated from August to October 2022. Among four harmful cyanobacteria (Microcystis sp., Anabaena sp., Oscillatoria sp., Aphanizomenon sp.), three kinds of cyanobacteria except Oscillatoria sp. were observed, and Microcystis sp. was the dominant cyanobacteria except for Anabaena sp. dominant result of a sample collected on October at reservoir B. The cell density of cyanobacteria was influenced by season and weather due to the length of daytime and concentrations of organic carbon and nitrogen. Three kinds of microcystin and anatoxin-a were quantitatively analyzed as total (in the cell body and water) and extracellular (in water) concentrations. The maximum total concentrations of anatoxin-a, microcystin-LR, microcystin-RR, and microcystin-YR were 0.1291 ㎍/L, 0.2776 ㎍/L, 0.3721 ㎍/L, and 0.0306 ㎍/L, respectively, in reservoir A and 0.3274 ㎍/L, 0.1495 ㎍/L, 0.2037 ㎍/L, and 0.0153 ㎍/L, respectively, in reservoir B.

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.710-724
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• 2024

Flavobacterium can synthesize xanthophyll, particularly the pigment zeaxanthin, which has significant economic value in nutrition and pharmaceuticals. Recently, the use of carotenoid biosynthesis by bacteria and yeast fermentation technology has shown to be very efficient and offers significant advantages in large-scale production, cost-effectiveness, and safety. In the present study, JSWR-1 strain capable of producing xanthophyll pigment was isolated from a freshwater reservoir in Wanju-gun, Republic of Korea. Based on the morphological, physiological, and molecular characteristics, JSWR-1 classified as belonging to the Flavobacterium species. The bacterium is strictly aerobic, Gram-negative, rod-shaped, and psychrophilic. The completed genome sequence of the strain Flavobacterium sp. JSWR-1 is predicted to be a single circular 3,425,829-bp chromosome with a G+C content of 35.2% and 2,941 protein-coding genes. The optimization of carotenoid production was achieved by small-scale cultivation, resulting in zeaxanthin being identified as the predominant carotenoid pigment. The enhancement of zeaxanthin biosynthesis by applying different light-irradiation, variations in pH and temperature, and adding carbon and nitrogen supplies to the growth medium. A significant increase in intracellular zeaxanthin concentrations was also recorded during fed-batch fermentation achieving a maximum of 16.69 ± 0.71 mg/l, corresponding to a product yield of 4.05 ± 0.15 mg zeaxanthin per gram cell dry weight. Batch and fed-batch culture extracts exhibit significant antioxidant activity. The results demonstrated that the JSWR-1 strain can potentially serve as a source for zeaxanthin biosynthesis.

• Journal of Environmental Science International
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• v.33 no.7
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• pp.477-487
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• 2024

This study aimed to identify the growth environment of Cudrania tricuspidata by analyzing the site environment, soil characteristics, and vegetation structure of the species habitats and to provide basic data for identifying suitable cultivation sites for mass production. The study was conducted on 17 sites in five cities/counties of Gyeongnam and Jeonnam province. It was found that C. tricuspidata habitats were mainly distributed on gentle slopes in the southeast and southwest, with an average altitude of approximately 290 m. The soil of the C. tricuspidata habitats was sandy loam with a high proportion of sand, averaging 73.9%, 4.6%, and 21.5% sand, silt, and clay, respectively. The soil had a pH value of 5.41 (5.20-5.79), organic matter content of 8.2% (3.6-12.6%), total nitrogen content of 0.36% (0.19-0.54%), available phosphorus content of 3.50 ppm (0.95-7.61 ppm), and cation exchange capacity of 15.9 cmol⁺/kg (10.0-20.7 cmol⁺/kg) on average. The vegetation structure analysis showed that C. tricuspidata appeared in the tree layers of regions A (Jinju) and E (Yeosu), but the importance of C. tricuspidata was found to be high in the subtree and shrub layers in all regions. The ecological niche breadth was widest (0.874) in region B (Hadong) and narrowest (0.480) in region E (Yeosu).

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.54-62
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• 1990

The recovery of vegetatiion and soil properties in the burned fields after forest fire were studied in Chung Cheong Buk Do area, Korea, from July 23 to 28, 1981. Miscanthus sinensis var. purpurascens, Carex humilis and Lespedeza bicolor were dominant species in the burned field of the second year after forest fire as well as unburned field. Especially, Lespedeza bicolor was gradually grown to the dominant species. Lespedeza bicolor, Carex humilis and Miscanthus sinensis var. purpurascens were the dominant species in the burned field of the fifth year after forest fire. Biological spectra of the burned fields were similar to the umburned fields with $H-e-D_1-R_5$ or $Ph-e-D_1-R_5$ from the second year after forest fire. Accordingly, biological spectra were recovered to the unburned fields from the second year. Degree of successiion was DS=423 in the burned field and DS=524 in the unburned field in 1981. The DS of the burned fields was gradually increased and recovered to be similar to the unburned from the second year. In the species diversities and evenness index, H,e and $\beta$ of the burned field in 1981 were higher and $\lambda$ was lower than the unburned field, but all of the indices were recovered to the unburned field from the second or third years. Accordingly, the vegetation of the first year was the complex community in view floristic composition, but it was recovered to the simple community as unburned field fromthe second or third years. In the soil preperties, pH, total nitrogen, available phosphorus, exchangeable potassium, exchangeable calcium and exchangeable magnesium were increased and organic matter was decreased due to forest fire, and then was recovered to the unburned field from the second or third years. The vegetation and soil properties of the burned field after forest fire were similary recovered to the unburned field from the second or third years. Accordingly, there was a close relationship between the trend of vegetation recovery and the changes of soil characteristics after forest fire.