Abstract
Green algae are photosynthetic organisms and play an important role in coastal environment. The microbial community on the surface of green algae has an effect on the health and nutrition of the host. However, few species of epiphytic microbiota have been reported to play a role in promoting the growth of algae. In this study, 16S rDNA sequencing was used to study the changes of microbial composition on the surface of Ulva fasciata at different growth stages. Some growth promoting bacteria were identified. The possible growth-promoting behavior of the strains were verified by co-culture of pure bacteria obtained from the surface of U. fasciata with its sterile host. Among the identified species, a new bacterial species, Hyunsoonleella sp. HU1-3 (belonging to the family Flavobacteriaceae) significantly promoted the growth of U. fasciata. The results also showed that there were many genes involved in the synthesis of growth hormone and cytokinin in the genome of Hyunsoonleella sp. HU1-3. This study identified the bacterium Hyunsoonleella sp. HU1-3 for the first time, in which this bacterium has strong growth-promoting effects on U. fasciata. Our findings not only provide insights on the establishment of the surface microbiota of U. fasciata, but also indicate that Hyunsoonleella sp. HU1-3 is one of the important species to promote the growth of U. fasciata.
Highlights
Epiphytic microbiota refers to a specific community harboring the surface of plants and does not parasitize or interfere with the growth and development of its host (Gopal and Gupta, 2016)
The purpose of this study was to determine (1) whether the epiphytic microbial community on the surface of U. fasciata varies at different growth stages, (2) whether the epiphytic microbiota is related to the growth stage of U. fasciata, and (3) whether the selected bacteria can promote the growth of U. fasciata
The filtrates (0.22 μm filter membrane) were stored in sterile sampling bags and the filtered water was cryopreserved for the determination of physical and chemical parameters, including dissolved organic carbon (TOC), inorganic carbon (TIC), total nitrogen (TN), and total carbon (TC) according to the methods described by Urgun-Demirtas et al (2008)
Summary
Epiphytic microbiota refers to a specific community harboring the surface of plants and does not parasitize or interfere with the growth and development of its host (Gopal and Gupta, 2016). Long-term coexistence enables microorganisms to evolve adaptive characteristics closely relating to plants (Vorholt, 2012). Many epiphytes may have a mensal, commensal or parasitic relationships with plants, including macroalgae (Gopal and Gupta, 2016). Microbiota can help plants better absorb nutrients necessary for growth and development (Doty et al, 2016). Host-adapted microorganisms are more resistant to abiotic stresses such as harmful ultraviolet radiation (Kamo et al, 2018), oxidative stress and desiccation (Vorholt, 2012), and affect plant health by reducing biotic or abiotic stresses
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