Concerns of the application of mcy genes analysis in the toxic Microcystis population screening and observations on the release of microcystins
Date Issued
2007
Date
2007
Author(s)
Lin, Jian-Zhi
DOI
zh-TW
Abstract
The suitability of using mcy genes analysis for screening toxic Microcystis populations and the release of microcystins were determined. Seven characteristic segments, mcyA~E, J, and the promoter of the microcystin synthetase gene cluster, designed in a Q-PCR amplification were applied for the quantitative measurement of toxic populations in environmental samples. Observations during the method-development experiments against 8 toxic and 4 non-toxic clones of Microcystis were: (i) the expected specific amplicons were found in all toxic clones but absent or less amount in non-toxic clones; (ii) all the toxic clones showed consistent Tm values of mcyD, implying this partial mcyD segment to be the most conserved one among tested mcys; (iii) a linear correlation was obtained between the microscopically determined cell numbers and the PCR threshold cycles; (iv) cell concentration of the toxic Microcystis from Q-PCR measurement was not affected by field sample and the addendum of non-toxic populations. Q-PCR is sensitivity and provides an efficient technology suitable for toxic Microcystis population screening.
Microcystins are considered primary intracellular and microcystins release was generally considered to be linked to a decrease in the integrity of the cells. However, from a strain of M. aeruginosa designated as M.TY-1, it was found that microcystins are released during the log phase of growth and continuously accumulated in the cell-free medium. A single amino acid difference of the sequence McyH was found in the toxin-releasing strain in comparison with other non-toxin-releasing strains. Sequence of McyH was known to be homologous to the bacteria ABC transporter, but also known as a key protein that maintained the integrity of microcystin synthetase clusters. This significant toxin release strain would be a model for the research of the M. aeruginosa toxin release system.
Subjects
微囊藻
微囊藻毒
定量PCR
藻毒釋放
Microcystis
Microcystins
Real-Time PCR
Toxin release
Type
other
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