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2017 IWA Symposium of Lake and Reservoir Management
Shanghai, China, 22-26 May, 2017
A biomolecule-based alternative method to estimate the risk associated with
cyanotoxins and odorants in drinking water sources
Keng-Yu Lu, Yi-Ting Chiu, and Tsair-Fuh Lin*
(Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan )
Presenting Author:
Keywords:
Tsair-Fuh Lin
Alert Level; Drinking Water; Cyanotoxins; 2-Methylisoborneol; Real-time PCR; Risk
Introduction
Proliferation of cyanobacteria in source water may cause problems for water industries as
many of the microorganisms are toxin or odorant producers. To manage the risks associated
with the harmful cyanobacteria in source water, the concentration levels of the toxins and
odorants need to be characterized first. Conventionally, the concentrations of toxins and
odorants in water are estimated from direct measurement of targeted metabolites or from
formation potentials based on cell numbers or biovolumes of harmful cyanobacteria (Chorus
and Bartram, 1999; Newcombe et al., 2010). Recently, biomolecular methods, such as real-time
polymerase chain reaction (qPCR), has been shown to successful quantify the genes responsible
for the formation of microcystin (MC), cylindrospermospin (CYN), and 2-methyisoborneol (2MIB) in reservoirs (Yen et al., 2012; Chiu et al., 2016). The qPCR-based approach may be used
as an alternative to estimate the risk associated with harmful cyanobacteria and metabolites in
reservoirs.
The aim of this study is to propose a biomolecule-based alternative means for estimating the
risk associated with cyanobacterial toxins and T&O compounds in drinking water reservoirs.
Materials and Methods
A database with 250 samples collected from 29 reservoirs in Taiwan from 2012 to 2015 and
from Laguna Lake in Philippine in August 18-22, 2016 were used for the evaluation. The
samples were analyzed for gene concentrations of MC producers (mcyB gene), CYN producers
(pks gene), 2-MIB producers (mibC gene) using qPCR, MC and CYN using an enzyme-linked
immunosorbent assay (ELISA), and 2-MIB using a solid-phase microextraction concentration
followed by a gas chromatograph-mass selective detector. In addition, cell enumerations were
also conducted for cyanobacteria in the samples. The data was compared with the cell
concentrations suggested for the alert levels for the management of cyanobacteria proposed by
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2017 IWA Symposium of Lake and Reservoir Management
Shanghai, China, 22-26 May, 2017
World Health Organization (WHO) (Chorus and Bartram, 1999) and Australian Water Quality
Centre (AWQC) (Newcombe et al., 2010).
Results and Discussion
The alert levels (ALs) suggested by WHO and AWQC (Chorus and Bartram, 1999;
Newcombe et al., 2010) for MC and CYN are 0.3, 1, and 10 µg/L for levels 1, 2, and 3,
respectively. Given that the guideline values for 2-MIB is at 10 ng/L (Japan Drinking Water
Quality Guideline), the ALs 1, 2, and 3 for the chemical are set at 3, 10, and 100 ng/L,
respectively. The ALs were linked with cell concentrations based on cell quotas of the
toxins/odorants for typical harmful cyanobacteria. However, field results showed that the cell
quotas may vary by 7-60 times for the studied toxins/odorants.
Good correlations between metabolite concentrations and corresponding producing gene
abundances were found for the field samples for MCs, CYN, and 2-MIB. Therefore, the
metabolite concentrations at each AL may be replaced by the abundance of corresponding
producing genes, as shown in Table 1. The gene abundances may thus serve as references for
the determination of ALs in source water for different toxins/odorants.
Table 1 Alert levels based on producing genes.
Alert Level
Toxins (µg/L)
mcyB (copies/mL)
pks (copies/mL)
T&O compound (ng/L)
mibC (copies/mL)
Detection
< 0.3
< 15
< 40
<3
< 70
1
0.3-1.0
15 - 30
40 - 140
3-10
70 - 160
2
1.0-10
30 - 770
140 – 15,000
10 -100
160 – 1,200
3
> 10
> 770
> 15,000
> 100
> 1,200
Conclusions
As the DNA-based method is more specific to targeted producers and less time consuming
in sample analysis as compared to the cell enumeration with microscope, the approach may
serve as an alternative means for setting the alert levels in risk assessment of cyanobacteria and
their metabolites in drinking water sources.
References
Chiu, Y.-T., Yen, H.-K., Lin, T.-F., 2016. An alternative method to quantify 2-MIB producing cyanobacteria in
drinking water reservoirs: Method development and field applications. Environ Res 151, 618-627.
Chorus, I., Bartram, J., 1999. Toxic cyanobacteria in water: a guide to their public health consequences, monitoring
and management, World Health Organization.
Yen, H.K., Lin, T.F.*, Tseng, I.C. (2012) Characterization and quantification of major toxigenic Microcystis
genotypes in Moo-Tan Reservoir and associated water treatment plant, J. Environ. Monit., 14(2), 687-696.
Newcombe, G., House, J., Ho, L., Baker, P., Burch, M., 2010. Management strategies for cyanobacteria (BlueGreen Algae): A guide for water utilities. Water Quality Research Australia (WQRA), Research Report 74.
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