• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1015-1025
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• 2014

Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants.

• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.14-35
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• 2023

Freshwater and brackish blue-green algae were collected at 43 freshwater and brackish sites (including lakes, ponds, swamps, streams, and rivers and estuaries) throughout South Korea from March 2017 to October 2018, and were identified using light microscopy. A total 223 taxa in freshwater and 230 taxa in brackish waters in 2017 and 274 taxa in fresh and brackish waters in 2018 were identified and among them, 20 taxa were unreported taxa of blue-green algae in Korea; The new recorded taxa were Aphanocapsa marina, Calothrix fusca f. durabilis, Calothrix littoralis, Calothrix parva, Chamaesiphon minimus, Chroococcidiopsis cubana, Chroococcidiopsis fissurarum, Coelosphaerium aerugineum, Dolichospermum mendotae, Eucapsis alpine, Gomphosphaeria cordiformis, Gomphosphaeria natans, Merismopedia danubiana, Lynbya aestuarii var. gaditana, Tolypothrix tenuis, Pseudocapsa maritima, Pseudocapsa sphaerica, Pseudophormidium tenue, Trichodesmus sp. and Woronichinia elorantae.