Discerning biodegradation and adsorption of microcystin-LR in a shallow semi-enclosed bay and bacterial community shifts in response to associated process.
Hepatotoxic microcystins (MCs) produced by cyanobacteria pose serious risks to aquatic ecosystems and human health, to understand elimination pathways and mechanisms for MCs, especially in a shallow and semi-enclosed eutrophic area, is of great significance. This study succeed in discerning biodegradation and adsorption of microcystin-LR (MCLR) mediated by water and/or sediment in northern part of Meiliang Bay in Lake Taihu, China, and among the first to reveal the shifts of indigenous bacterial community composition in response to MCLR-biodegradation in sediment by Illumina high-throughput sequencing (HTS). Results confirmed that biodegradation predominantly governed MCLR elimination as compared to adsorption in study area. Through faster biodegradation with a rate of 49.21μgL(-1)d(-1), lake water contributed more to overall MCLR removal than sediment. Sediment also played indispensable role in MCLR removal via primarily biodegradation by indigenous community (a rate of 17.27μgL(-1)d(-1)) and secondarily adsorption (<20% of initial concentration). HTS analysis showed that indigenous community composition shifted with decreased phylogenetic diversity in response to sediment-mediated MCLR-biodegradation. Proteobacteria became predominant (39.34-86.78%) in overall composition after biodegradation, which was mostly contributed by sharp proliferation of β-proteobacteria (22.76-74.80%), and might closely link to MCLR-biodegradation in sediment. Moreover, the members of several genera belonging to α-proteobacteria, β-proteobacteria and γ-proteobacteria seemed to be key degraders because of their dominance or increasing population as MCLR degraded. This study expands understanding on natural elimination mechanism for MCs, and provides guidance to reduce MCs' biological risks and guarantee ecosystem safety in aquatic habitats.
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing 100193, China. Electronic address: lijieming@cau.edu.cn.
Jieming
J
Li
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing 100193, China.
Ji
J
Li
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Ge
G
Shi
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Zulin
Z
Mei
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing 100193, China.
Ruiping
R
Wang
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Dianyue
D
Li
D000327:Adsorption; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D061006:Bays / Q000382:microbiology; D001673:Biodegradation, Environmental; D002681:China; D060106:Lakes / Q000382:microbiology; D008387:Marine Toxins; D052998:Microcystins / Q000737:chemistry* / Q000378:metabolism*; D010802:Phylogeny; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism*
D008387:Marine Toxins; D052998:Microcystins; D014874:Water Pollutants, Chemical; C057862:cyanoginosin LR
Biodegradation; Community composition; Elimination mechanism; Microcystin; Sediment