title: Effects of intermediate metabolite carboxylic acids of TCA cycle on Microcystis with overproduction of phycocyanin.
abstract: Toxic Microcystis species are the main bloom-forming cyanobacteria in freshwaters. It is imperative to develop efficient techniques to control these notorious harmful algal blooms (HABs). Here, we present a simple, efficient, and environmentally safe algicidal way to control Microcystis blooms, by using intermediate carboxylic acids from the tricarboxylic acid (TCA) cycle. The citric acid, alpha-ketoglutaric acid, succinic acid, fumaric acid, and malic acid all exhibited strong algicidal effects, and particularly succinic acid could cause the rapid lysis of Microcystis in a few hours. It is revealed that the Microcystis-lysing activity of succinic acid and other carboxylic acids was due to their strong acidic activity. Interestingly, the acid-lysed Microcystis cells released large amounts of phycocyanin, about 27-fold higher than those of the control. On the other hand, the transcription of mcyA and mcyD of the microcystin biosynthesis operon was not upregulated by addition of alpha-ketoglutaric acid and other carboxylic acids. Consider the environmental safety of intermediate carboxylic acids. We propose that administration of TCA cycle organic acids may not only provide an algicidal method with high efficiency and environmental safety but also serve as an applicable way to produce and extract phycocyanin from cyanobacterial biomass.
authors.affiliation: Institute of Hydrobiology, The Chinese Academy of Sciences and University of Chinese Academy of Sciences, Wuhan, 430072, China.
authors.forename: Shijie
authors.initials: S
authors.lastname: Bai
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Dai
authors.forename: Ming
authors.initials: M
authors.lastname: Xia
authors.forename: Jing
authors.initials: J
authors.lastname: Ruan
authors.forename: Hehong
authors.initials: H
authors.lastname: Wei
authors.forename: Dianzhen
authors.initials: D
authors.lastname: Yu
authors.forename: Ronghui
authors.initials: R
authors.lastname: Li
authors.forename: Hongmei
authors.initials: H
authors.lastname: Jing
authors.forename: Chunyuan
authors.initials: C
authors.lastname: Tian
authors.forename: Lirong
authors.initials: L
authors.lastname: Song
authors.forename: Dongru
authors.initials: D
authors.lastname: Qiu
mesh_terms: D000704:Analysis of Variance; D002264:Carboxylic Acids / Q000378:metabolism / Q000633:toxicity*; D002952:Citric Acid Cycle; D017931:DNA Primers / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005618:Fresh Water / Q000382:microbiology*; D057097:Harmful Algal Bloom / Q000187:drug effects*; D046931:Microcystis / Q000187:drug effects* / Q000378:metabolism*; D010575:Pesticides / Q000378:metabolism / Q000633:toxicity*; D010798:Phycocyanin / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012394:Rosaniline Dyes; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002264:Carboxylic Acids; D017931:DNA Primers; D010575:Pesticides; D012394:Rosaniline Dyes; D010798:Phycocyanin; C024757:Coomassie brilliant blue R