Publications by authors named "Sora Ko"

A novel rod-shaped, Gram-stain-negative bacterial strain MS17 was obtained from a co-culture of Microcystis aeruginosa and Myriophyllum spicatum. The examination of the 16S ribosomal RNA gene sequence showed a significant degree of similarity between strain MS17 and Paucibacter sediminis S2-9 (98.4%), Roseateles violae PFR6 (98.

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A novel Gram-negative bacterial strain, 20NA77.7, was isolated from fresh water of the Nakdong River. Strain 20NA77.

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Cyanobacterial harmful algal blooms, particularly those dominated by Microcystis, pose significant ecological and health risks worldwide. This review provides an overview of the latest advances in biotechnological approaches for mitigating Microcystis blooms, focusing on cyanobactericidal bacteria, fungi, eukaryotic microalgae, zooplankton, aquatic plants, and cyanophages. Recently, promising results have been obtained using cyanobactericidal bacteria: not through the inoculation of cultured bacteria, but rather by nurturing those already present in the periphyton or biofilms of aquatic plants.

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The number of cyanobacterial harmful algal blooms (cyanoHABs) has increased, leading to the widespread development of prediction models for cyanoHABs. Although bacteria interact closely with cyanobacteria and directly affect cyanoHABs occurrence, related modeling studies have rarely utilized microbial community data compared to environmental data such as water quality. In this study, we built a machine learning model, the multilayer perceptron (MLP), for the prediction of Microcystis dynamics using both bacterial community and weekly water quality data from the Daechung Reservoir and Nakdong River, South Korea.

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A novel Gram-negative, white-pigmented, and auxin-producing strain, 20NA77.5, was isolated from fresh water during cyanobacterial bloom period. Pairwise comparison of the 16S rRNA gene sequences showed that strain 20NA77.

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Article Synopsis
  • Cyanobacteria are photosynthetic bacteria that produce oxygen and can create harmful blooms when conditions are right, threatening freshwater ecosystems and human health.
  • Understanding how these blooms form is essential for managing them effectively, and recent advancements in omics technologies have improved our knowledge of their mechanisms.
  • This review explores the genetic and adaptive features of cyanobacteria, their interactions with other microbes, and their ecological impacts, suggesting further research opportunities for better control of harmful cyanobacterial blooms.
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Microalgae, including cyanobacteria and eukaryotic algae, are hotspots of primary production and play a critical role in global carbon cycling. However, these species often form blooms that poses a threat to aquatic ecosystems. Although the use of bacteria-derived cyanocides is regarded as an environmentally friendly method for controlling cyanobacterial blooms, only a few studies have examined their potential impact on ecosystems.

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A novel Gram-stain-negative, yellow-pigmented, short rod-shaped bacterial strain, HBC34, was isolated from a freshwater sample collected from Daechung Reservoir, Republic of Korea. The results of 16S rRNA gene sequence analysis indicated that HBC34 was affiliated with the genus and shared the highest sequence similarity to the type strains of (98.01 %), (97.

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Various environmental factors play a role in the formation and collapse of Microcystis blooms. This study investigates the impact of heavy rainfall on cyanobacterial abundance, microbial community composition, and functional dynamics in the Nakdong River, South Korea, during typical and exceptionally rainy years. The results reveal distinct responses to rainfall variations, particularly in cyanobacterial dominance and physicochemical characteristics.

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The massive proliferation of Microcystis threatens freshwater ecosystems and degrades water quality globally. Understanding the mechanisms that contribute to Microcystis growth is crucial for managing Microcystis blooms. The lifestyles of bacteria can be classified generally into two groups: particle-attached (PA; > 3 µm) and free-living (FL; 0.

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Article Synopsis
  • Blooms in water ecosystems can harm both ecological balance and the economy, prompting a need for effective control methods.
  • The study examined strain DH15, a cyanobactericidal bacterium, to understand its genome and how it effectively targets harmful cyanobacteria.
  • Insights gained from this research highlight the adaptability of the genus, revealing its potential role in nutrient provision and its ecological interactions within the ecosystem.
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A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain, HBC54, was isolated from periphyton during a bloom. Based on the results of the 16S rRNA gene sequence analysis, strain HBC54 was closely related to 4Y4 (98.36 %), DSM 12444 (98.

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Incorporation of wastewater from industrial sectors into the design of microalgal biorefineries has significant potential for advancing the practical application of this emerging industry. This study tested various food industrial wastewaters to assess their suitability for microalgal cultivation. Among these wastewaters, defective soy sauce (DSS) and soy sauce wastewater (SWW) were chosen but DSS exhibited the highest nutrient content with 13,500 ppm total nitrogen and 3051 ppm total phosphorus.

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Article Synopsis
  • Three Gram-negative bacterial strains RS43, HBC28, and HBC61 were isolated from freshwater and identified as closely related to a specific genus based on 16S rRNA gene sequencing, showing high similarity percentages (98.14%, 98.21%, and 98.76%).
  • Phylogenetic and genomic analyses suggested that RS43 and HBC61 represent two novel species within the genus, supported by average nucleotide identity and digital DNA-DNA hybridization data.
  • The strains have potential applications in bioremediation, as they can metabolize compounds like benzoate and phenylacetate, making them valuable for treating contaminated water systems.
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Although nutrient availability is widely recognized as the driving force behind Microcystis blooms, identifying the microorganisms that play a pivotal role in their formation is a challenging task. Our understanding of the contribution of bacterial communities to the development of Microcystis blooms remains incomplete, despite the fact that the relationship between Microcystis and bacterial communities has been extensively investigated. Most studies have focused on their interaction for a single year rather than for multiple years.

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Article Synopsis
  • Strain RS28 is a newly identified Gram-negative bacterium isolated from rice straw used for periphyton growth, with a rod shape and no motility.
  • Phylogenetic analysis showed high genetic similarity to existing strains HMF7856 and DSM 26907, indicating its affiliation with a specific genus.
  • Strain RS28 thrives in pH ranges of 5.5-8.0 and temperatures from 17-40 °C, with a notable capacity for secondary metabolite production, leading to the proposal of it as a novel species designated as sp. nov.
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Margalefidinium polykrikoides causes significant economic losses in the aquaculture industry by red tide formation. Algicidal bacteria have attracted research interests as a potential bloom control approach without secondary pollution. Qipengyuania sp.

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A Gram-stain-negative, rod-shaped bacterial strain, JC4, was isolated from a freshwater sample and determined the taxonomic position. Initial identification based on 16S rRNA gene sequences revealed that strain JC4 is affiliated to the genus with a sequence similarity of 97.97% to WPCB133.

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Article Synopsis
  • A Gram-negative, non-motile bacterial strain named T2, isolated from microalgae, can degrade microcystin and thrives in specific temperature, pH, and salinity ranges.
  • The complete genome of T2 was sequenced, revealing a large circular chromosome and a plasmid with various genes, including those for critical metabolic pathways and enzymes that aid in microcystin degradation.
  • This research offers insights into the molecular evolution and function of T2, highlighting its unique efflux pumps and contributing to our understanding of bacterial response to environmental toxins.
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Microcystis blooms pose a major threat to the quality of drinking water. Cyanobactericidal bacteria have attracted much attention in the research community as a vehicle for controlling Microcystis blooms because of their ecological safety. Nonetheless, most studies on cyanobactericidal bacteria have been conducted on a laboratory scale but have not been scaled-up as field experiments.

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Microcystis sp., amongst the most prevalent bloom-forming cyanobacteria, is typically found as a colonial form with multiple microorganisms embedded in the mucilage known as extracellular polymeric substance. The colony-forming ability of Microcystis has been thoroughly investigated, as has the connection between Microcystis and other microorganisms, which is crucial for colony development.

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Haematococcus lacustris is a chlamydomonadalean with high biotechnological interest owing to its capacity to produce astaxanthin, a valuable secondary carotenoid with extraordinary antioxidation properties. However, its prolonged growth has limited its utility commercially. Thus, rapid growth to attain high densities of H.

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A Gram-negative, red-colored, and rod-shaped bacterial strain, DH14, was isolated from a eutrophic reservoir. The 16S rRNA gene sequence analysis showed that strain DH14 was most closely related to Hymenobacter terrigena (98.3% similarity) and Hymenobacter terrae (98.

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A Gram-stain-negative, rod-shaped bacterial strain DH6 was isolated from fresh water of the Daechung Reservoir during the Microcystis bloom period. The strain grew at pH 6.0-8.

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A marine phytoplankton dinoflagellate, Alexandrium sp. is known to cause worldwide harmful algal blooms, resulting in paralytic shellfish poisoning. In this study, we isolated a novel compound secreted by the marine bacterium Pseudoruegeria sp.

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