title: Responses of the Microalga Chlorophyta sp. to Bacterial Quorum Sensing Molecules (N-Acylhomoserine Lactones): Aromatic Protein-Induced Self-Aggregation.
abstract: Bacteria and microalgae often coexist during the recycling of microalgal bioresources in wastewater treatment processes. Although the bacteria may compete with the microalgae for nutrients, they could also facilitate microalgal harvesting by forming algal-bacterial aggregates. However, very little is known about interspecies interactions between bacteria and microalgae. In this study, we investigated the responses of a model microalga, Chlorophyta sp., to the typical quorum sensing (QS) molecules N-acylhomoserine lactones (AHLs) extracted from activated sludge bacteria. Chlorophyta sp. self-aggregated in 200 μm bioflocs by secreting 460-1000 kDa aromatic proteins upon interacting with AHLs, and the settling efficiency of Chlorophyta sp. reached as high as 41%. However, Chlorophyta sp. cells were essentially in a free suspension in the absence of AHLs. Fluorescence intensity of the aromatic proteins had significant (P < 0.05) relationship with the Chlorophyta sp. settleability, and showed a positive correlation, indicating that aromatic proteins helped aggregate microalga. Transcriptome results further revealed up-regulation of synthesis pathways for aromatic proteins from tyrosine and phenylalanine that was assisted by anthranilate accumulation. To the best of our knowledge, this is the first study to confirm that eukaryotic microorganisms can sense and respond to prokaryotic QS molecules.
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.|Jilin Engineering Research Centre for Municipal Wastewater Treatment and Water Quality Protection, Changchun, 130117, China.
authors.forename: Dandan
authors.identifier: 0000-0001-5072-9033
authors.initials: D
authors.lastname: Zhou
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.
authors.forename: Chaofan
authors.initials: C
authors.lastname: Zhang
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.|Jilin Engineering Research Centre for Municipal Wastewater Treatment and Water Quality Protection, Changchun, 130117, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Fu
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.|Jilin Engineering Research Centre for Municipal Wastewater Treatment and Water Quality Protection, Changchun, 130117, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Cui
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.
authors.forename: Qingcheng
authors.initials: Q
authors.lastname: Li
authors.affiliation: School of Environment, Northeast Normal University , Changchun 130117, China.|Brook Byers Institute for Sustainable Systems, and School of Civil & Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: John C
authors.identifier: 0000-0002-9048-7208
authors.initials: JC
authors.lastname: Crittenden
mesh_terms: D054742:Acyl-Butyrolactones; D000460:Chlorophyta / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D058086:Microalgae / Q000378:metabolism; D053038:Quorum Sensing; D015854:Up-Regulation
chemical_list: D054742:Acyl-Butyrolactones; D007783:Lactones