Abstract
Nitrogen-fixing cyanobacteria not only cause severe blooms but also play an important role in the nitrogen input processes of lakes. The production of extracellular polymeric substances (EPS) and the ability to fix nitrogen from the atmosphere provide nitrogen-fixing cyanobacteria with a competitive advantage over other organisms. Temperature and nitrogen availability are key environmental factors in regulating the growth of cyanobacteria. In this study, Dolichospermum (formerly known as Anabaena) was cultivated at three different temperatures (10 °C, 20 °C, and 30 °C) to examine the impact of temperature and nitrogen availability on nitrogen fixation capacity and the release of EPS. Initially, confocal laser scanning microscopy (CLSM) and the quantification of heterocysts at different temperatures revealed that lower temperatures (10 °C) hindered the differentiation of heterocysts under nitrogen-deprived conditions. Additionally, while heterocysts inhibited the photosynthetic activity of Dolichospermum, the secretion of EPS was notably affected by nitrogen limitation, particularly at 30 °C. Finally, real-time quantitative polymerase chain reaction (qPCR) was used to measure the expression of nitrogen-utilizing genes (ntcA and nifH) and EPS synthesis-related genes (wzb and wzc). The results indicated that under nitrogen-deprived conditions, the expression of each gene was upregulated, and there was a significant correlation between the upregulation of nitrogen-utilizing and EPS synthesis genes (P < 0.05). Our findings suggested that Dolichospermum responded to temperature variation by affecting the formation of heterocysts, impacting its potential nitrogen fixation capacity. Furthermore, the quantity of EPS released was more influenced by nitrogen availability than temperature. This research enhances our comprehension of interconnections between nitrogen deprivation and EPS production under the different temperatures.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
