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Updated: Nov 25, 2025

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Community composition and functional genes explain different ecological roles of heterotrophic bacteria attached to
Liu Yang1, Xiu-Yun Cao2, Xiao-Yan Chen3
1State key laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan 430072, PR China; College of Chemistry and Chemical Engineering, Neijiang Normal University, Neijiang 641100, PR China.
Abstract:
Eutrophication leads to frequent outbreaks of cyanobacterial blooms, however, the effect of heterotrophic bacteria attached to cyanobacterial cells is unclear. Field investigations were carried out to gain a deeper understanding of the community composition and functional role of heterotrophic bacteria attached to Dolichospermum and Microcystins cells. The significantly positive relationships between Dolichospermum density and total nitrogen (TN) and between Microcystins density and particle nitrogen (PN) indicated the strong nitrogen (N) demand of these two species. The lack of functional genes that mediate the nitrification process in bacteria attached to both Microcystins and Dolichospermum cells indicated that these two genera preferred ammonium (NH4+-N). Dolichospermum cells obtained more available N through N2 fixation, which was expressed by high nitrogenase gene abundance. Bacteria attached to Microcystins cells showed a higher activity of leucine aminopeptidase and a significantly higher abundance of functional genes that mediate dissimilatory nitrate reduction to ammonium (DNRA) than those attached to Dolichospermum cells. The significantly higher abundance of carbon degradation genes and β-glucosidase activity of bacteria attached to Microcystins cells compared with those of bacteria attached to Dolichospermum cells suggested that abundant organic carbon was bound to Microcystins cells, which is a prerequisite for DNRA. In addition, Microcystins cells exhibited a great advantage in soluble reactive phosphorus (SRP) production through high levels of organic phosphorus (P) hydrolysis associated with high levels of phosphatase genes of attached bacteria. In conclusion, bacteria attached to Microcystins cells performed more important functions on NH4+-N and SRP production through ammonification and DNRA, as well as phosphatase hydrolysis respectively, compared to those attached to Dolichospermum. Thus, algal growth is the result of different variables such as nutrient concentration, their ratio and the microbial ability.
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