Oberholster, Paul JBotha, AM2011-07-122011-07-122010-12Oberholster, P.J., and Botha, A.M. 2010. Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa. African Journal of Biotechnology, Vol. 9(51), pp 8791-87991684-5315http://www.academicjournals.org/AJB/abstracts/abs2010/20Dec/Oberholster%20and%20Botha.htmhttp://hdl.handle.net/10204/5094Copyright: 2010 Academic Journals. This is a post print version of the work. The definitive version is published in the African Journal of Biotechnology, Vol. 9(51), pp 8791-8799In this study, we monitored the formation of cyanobacterial hyperscum and crust formation in Lake Hartbeespoort using satellite images and ground monitoring. The hyperscum that formed near the reservoir wall was characterised by a distinctive white surface layer of crust. Hyperscum is the result of exposure of the cells to high radiation, inflicting irreversible damage to the genetic constitution of the upper layer of Microcystis aeruginosa cells. Under the 3 mm thick layer of crust, dark (<0.93 μmol of photons m-2s-1) anaerobic conditions (0.4 mg/l, 3% saturation) prevailed with high levels of microcystin (12,300 μg/l) in the absence of sunlight irradiation and photolysis by UV light. Real time polymerase chain reaction (PCR) analysis indicated low levels of transcription of the mcyA, mcyB and mcyD genes which are responsible for synthesis of cyanotoxins under these low light intensity conditions. At other sampling sites where cyanobacterial scum occurred and hyperscum crust was absent, only the mcyB and mcyD genes were transcribed. A plausible explanation for the transcription of the mcyA gene in the hyperscum and not at the other sampling sites, was the presence of environmental stress-inducing factors, e.g. low light intensity (0.93 μmol of photon m-2 s-1) and pH 6.1. At the sampling site where no cyanobacterial scum was visible on the satellite images, low cell abundance (2.4 x 104 μg/l) and chlorophyll a (12.2 μg/l) was measured in comparison with sites where cyanobacterial scum was visible on the satellite images.enHyperscum crustReverse-transcription PCRMcyA levelsMicrocystinSatellite imagingCyanobacteriaArticleOberholster, P. J., & Botha, A. (2010). Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa. http://hdl.handle.net/10204/5094Oberholster, Paul J, and AM Botha "Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa." (2010) http://hdl.handle.net/10204/5094Oberholster PJ, Botha A. Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa. 2010; http://hdl.handle.net/10204/5094.TY - Article AU - Oberholster, Paul J AU - Botha, AM AB - In this study, we monitored the formation of cyanobacterial hyperscum and crust formation in Lake Hartbeespoort using satellite images and ground monitoring. The hyperscum that formed near the reservoir wall was characterised by a distinctive white surface layer of crust. Hyperscum is the result of exposure of the cells to high radiation, inflicting irreversible damage to the genetic constitution of the upper layer of Microcystis aeruginosa cells. Under the 3 mm thick layer of crust, dark (<0.93 μmol of photons m-2s-1) anaerobic conditions (0.4 mg/l, 3% saturation) prevailed with high levels of microcystin (12,300 μg/l) in the absence of sunlight irradiation and photolysis by UV light. Real time polymerase chain reaction (PCR) analysis indicated low levels of transcription of the mcyA, mcyB and mcyD genes which are responsible for synthesis of cyanotoxins under these low light intensity conditions. At other sampling sites where cyanobacterial scum occurred and hyperscum crust was absent, only the mcyB and mcyD genes were transcribed. A plausible explanation for the transcription of the mcyA gene in the hyperscum and not at the other sampling sites, was the presence of environmental stress-inducing factors, e.g. low light intensity (0.93 μmol of photon m-2 s-1) and pH 6.1. At the sampling site where no cyanobacterial scum was visible on the satellite images, low cell abundance (2.4 x 104 μg/l) and chlorophyll a (12.2 μg/l) was measured in comparison with sites where cyanobacterial scum was visible on the satellite images. DA - 2010-12 DB - ResearchSpace DP - CSIR KW - Hyperscum crust KW - Reverse-transcription PCR KW - McyA levels KW - Microcystin KW - Satellite imaging KW - Cyanobacteria LK - https://researchspace.csir.co.za PY - 2010 SM - 1684-5315 T1 - Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa TI - Use of remote sensing and molecular markers to detect toxic cyanobacterial hyperscum crust: A case study on Lake Hartbeespoort, South Africa UR - http://hdl.handle.net/10204/5094 ER -