Improved screening of microcystin genes and toxins in blue-green algal dietary supplements with PCR and a surface plasmon resonance biosensor

•PCR method used to detect Microcystis toxin biosynthesis genes in BGA supplements.•SPR assay developed for quantification of microcystins in complex matrices.•Sensor employed an Adda-directed antibody for broad microcystin analog detection.•Sensitive, rapid biosensor used for screening small sampli...

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Published inHarmful algae Vol. 47; pp. 9 - 16
Main Authors Yakes, Betsy Jean, Handy, Sara M., Kanyuck, Kelsey M., DeGrasse, Stacey L.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.07.2015
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Summary:•PCR method used to detect Microcystis toxin biosynthesis genes in BGA supplements.•SPR assay developed for quantification of microcystins in complex matrices.•Sensor employed an Adda-directed antibody for broad microcystin analog detection.•Sensitive, rapid biosensor used for screening small sampling of BGA supplements.•SPR assay data supported by PCR detection of toxic Microcystis. Microcystins (MCs) comprise a group of cyclic heptapeptide toxins that share a common backbone and have two variable l-amino acids that yield at least 21 known analogs of varying potency. These hepatotoxins and potential tumor promoters are produced by certain cyanobacteria, including Microcystis aeruginosa. The cyanobacterium M. aeruginosa blooms in freshwater lakes and can potentially co-occur with other species such as Aphanizomenon flos-aquae, which is targeted and harvested for the production of dietary supplements known as blue-green algae (BGA). BGA supplements are currently marketed in the U.S. and internationally as a product that may elevate mood, increase energy, and alleviate attention deficit hyperactivity disorder. However, the potential for BGA dietary supplements to be contaminated with MCs is of concern, and there are currently no validated methods for detection of MCs in these products. This research focused on establishing screening methods for toxic Microcystis and MCs in BGA supplements. A DNA-based method employing polymerase chain reaction (PCR) was used as a prescreening tool to evaluate the dietary supplements and to detect the presence of toxin genes (i.e., presence of toxic Microcystis). A rapid, sensitive surface plasmon resonance (SPR) biosensor, directed towards recognition of all MC forms, was also developed and validated. This improved SPR biosensor incorporates a commercial Adda-group antibody (Ab) that has the capacity for broader recognition of MCs than previously developed sensors for BGA supplements that rely solely on an arginine-reactive Ab and can quantitate MC levels down to 0.24ng/mL (equivalent to 0.24μg per gram of BGA supplement) in less than 10min. Such a rapid, quantitative screening method may allow for further surveillance of BGA products to assist risk assessment efforts, establishment of regulatory guidance levels, and response to potential consumer complaints related to BGA products. The PCR technique and SPR biosensor may be used in concert as prescreening and screening tools, respectively or individually, thereby limiting the number of samples that must be evaluated with confirmatory methods.
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ISSN:1568-9883
1878-1470
DOI:10.1016/j.hal.2015.05.001