Journal of Microbiology

Minkyung Kim

1 Article

The β‑Lactamase Activity at the Community Level Confers β‑Lactam Resistance to Bloom‑Forming Microcystis aeruginosa Ce: Yerim Park , Wonjae Kim , Minkyung Kim , Woojun Park; J. Microbiol. 2023;61(9):807-820. Published online October 18, 2023; DOI: https://doi.org/10.1007/s12275-023-00082-0

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Many freshwater cyanobacteria, including Microcystis aeruginosa, lack several known antibiotic resistance genes; however, both axenic and xenic M. aeruginosa strains exhibited high antibiotic resistance against many antibiotics under our tested concentrations, including colistin, trimethoprim, and kanamycin. Interestingly, axenic PCC7806, although not the xenic NIBR18 and NIBR452 strains, displayed susceptibility to ampicillin and amoxicillin, indicating that the associated bacteria in the phycosphere could confer such antibiotic resistance to xenic strains. Fluorescence and scanning electron microscopic observations revealed their tight association, leading to possible community-level β-lactamase activity. Combinatory treatment of ampicillin with a β-lactamase inhibitor, sulbactam, abolished the ampicillin resistance in the xenic stains. The nitrocefin-based assay confirmed the presence of significant community-level β-lactamase activity. Our tested low ampicillin concentration and high β-lactamase activity could potentially balance the competitive advantage of these dominant species and provide opportunities for the less competitive species, thereby resulting in higher bacterial diversity under ampicillin treatment conditions. Non-PCR-based metagenome data from xenic NIBR18 cultures revealed the dominance of blaOXArelated antibiotic resistance genes followed by other class A β-lactamase genes (AST-1 and FAR-1). Alleviation of ampicillin toxicity could be observed only in axenic PCC7806, which had been cocultured with β-lactamase from other freshwater bacteria. Our study suggested M. aeruginosa develops resistance to old-class β-lactam antibiotics through altruism, where associated bacteria protect axenic M. aeruginosa cells.

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Sustainable control of Microcystis aeruginosa, a harmful cyanobacterium, using Selaginella tamariscina extracts
Wonjae Kim, Yerim Park, Minkyung Kim, Yeji Cha, Jaejoon Jung, Che Ok Jeon, Woojun Park
Ecotoxicology and Environmental Safety.2024; 277: 116375. CrossRef
Microcystis abundance is predictable through ambient bacterial communities: A data-oriented approach
Mingyeong Kang, Dong-Kyun Kim, Ve Van Le, So-Ra Ko, Jay Jung Lee, In-Chan Choi, Yuna Shin, Kyunghyun Kim, Chi-Yong Ahn
Journal of Environmental Management.2024; 368: 122128. CrossRef
Enhanced mechanical properties of living and regenerative building materials by filamentous Leptolyngbya boryana
Yongjun Son, Jihyeon Min, Indong Jang, Jiyoon Park, Chongku Yi, Woojun Park
Cell Reports Physical Science.2024; 5(8): 102098. CrossRef
Food Webs and Feedbacks: The Untold Ecological Relevance of Antimicrobial Resistance as Seen in Harmful Algal Blooms
Aabir Banerji, Nichole E. Brinkman, Benjamin Davis, Alison Franklin, Michael Jahne, Scott P. Keely
Microorganisms.2024; 12(11): 2121. CrossRef
Extensive Genomic Rearrangement of Catalase-Less Cyanobloom-Forming Microcystis aeruginosa in Freshwater Ecosystems
Minkyung Kim, Jaejoon Jung, Wonjae Kim, Yerim Park, Che Ok Jeon, Woojun Park
Journal of Microbiology.2024; 62(11): 933. CrossRef
Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms
Wonjae Kim, Yerim Park, Jaejoon Jung, Che Ok Jeon, Masanori Toyofuku, Jiyoung Lee, Woojun Park
Journal of Microbiology.2024; 62(3): 249. CrossRef
Alleviation of H2O2 toxicity by extracellular catalases in the phycosphere of Microcystis aeruginosa
Yerim Park, Wonjae Kim, Yeji Cha, Minkyung Kim, Woojun Park
Harmful Algae.2024; 137: 102680. CrossRef

Minkyung Kim

1 Article

Extensive Genomic Rearrangement of Catalase-Less Cyanobloom-Forming Microcystis aeruginosa in Freshwater Ecosystems: Minkyung Kim, Jaejoon Jung, Wonjae Kim, Yerim Park, Che Ok Jeon, Woojun Park; J. Microbiol. 2024;62(11):933-950. Published online October 8, 2024; DOI: https://doi.org/10.1007/s12275-024-00172-7

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Abstract: Many of the world's freshwater ecosystems suffer from cyanobacteria-mediated blooms and their toxins. However, a mechanistic understanding of why and how Microcystis aeruginosa dominates over other freshwater cyanobacteria during warmer summers is lacking. This paper utilizes comparative genomics with other cyanobacteria and literature reviews to predict the gene functions and genomic architectures of M. aeruginosa based on complete genomes. The primary aim is to understand this species' survival and competitive strategies in warmer freshwater environments. M. aeruginosa strains exhibiting a high proportion of insertion sequences (~ 11%) possess genomic structures with low synteny across different strains. This indicates the occurrence of extensive genomic rearrangements and the presence of many possible diverse genotypes that result in greater population heterogeneities than those in other cyanobacteria in order to increase survivability during rapidly changing and threatening environmental challenges. Catalase-less M. aeruginosa strains are even vulnerable to low light intensity in freshwater environments with strong ultraviolet radiation. However, they can continuously grow with the help of various defense genes (e.g., egtBD, cruA, and mysABCD) and associated bacteria. The strong defense strategies against biological threats (e.g., antagonistic bacteria, protozoa, and cyanophages) are attributed to dense exopolysaccharide (EPS)-mediated aggregate formation with efficient buoyancy and the secondary metabolites of M. aeruginosa cells. Our review with extensive genome analysis suggests that the ecological vulnerability of M. aeruginosa cells can be overcome by diverse genotypes, secondary defense metabolites, reinforced EPS, and associated bacteria.

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