Bacterial foraging facilitates aggregation of Chlamydomonas microsphaera in an organic carbon source-limited aquatic environment. (April 2020)

• Record Type: Journal Article
• Authors: Zhao, Ranran; Chen, Guowei; Liu, Li; Zhang, Wei; Sun, Yifei; Li, Baoguo; Wang, Gang
• Is Part Of: Environmental pollution. Volume 259(2020)
• Publication Date: 2020-04
• Subjects: C. microsphaera aggregation -- Motility -- Organic carbon source-limited environment -- Resource foraging; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.113924
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Microalgal aggregation is a key to many ecosystem functions in aquatic environments. Yet mechanistic understanding of microalgae aggregation, especially the interactions with ubiquitous bacteria populations, remains elusive. We reported an experimental study illustrating how the emerging bacterial populations interacted with a model microalga ( Chlamydomonas microsphaera ) cells and the consequent aggregation patterns. Results showed that the emergence of bacterial populations significantly stimulated C. microsphaera aggregation. Both bacterial and C. microsphaera motilities were remarkably excited upon coculturing, with the mean cell velocity being up to 2.67 and 1.80 times of those of separate bacterial and C. microsphaera cultures, respectively. The stimulated bacterial and C. microsphaera cell velocity upon coculturing would likely provide a mechanism for enhanced probability of cell-cell collisions that led to amplified aggregation of C. microsphaera population. Correlation analysis revealed that bacterial resource foraging (for polysaccharides) was likely a candidate mechanism for stimulated cell motility in an organic carbon source-limited environment, whereby C. microsphaera -derived polysaccharides serve as the sole organic carbon source for heterotrophic bacteria which in turns facilitates bacteria- C. microsphaera aggregation. Additional analysis showed that bacterial populations capable of successive decomposing algal-derived organic matters dominated the cocultures, with the top five abundant genera of Brevundimonas (24.78%), Shinella (17.94%), Sphingopyxis (11.62%), Dongia (5.82%) and Hyphomicrobium (5.45%). These findings provide new insights into full understanding of microalgae-bacteria interactions and consequent microbial aggregation characteristics in aquatic ecosystems. Graphical abstract: Image 1 Highlights: Emergence of bacterial populations stimulated microalgal aggregation. Bacterial and algal cell motilities were simultaneously excited upon coculturing. Algae-derived polysaccharides may serve a sole organic carbon source for bacteria. Foraging motility enhanced cell-cell collisions and thus facilitates aggregation. Abstract : Main finding Microalgal derived EPS function as nutrient attractants that stimulate cell motility, facilitating aggregation of C. microsphaera in aquatic environment.