Department of Hydrology and Water Resources, School of Environmental Sciences, University of Venda, Thohoyandou 0950, South Africa.
Council for Scientific and Industrial Research, Natural Resources and the Environment, Stellenbosch 7600, South Africa.
Toxins (Basel). 2018 Jul 3;10(7):269. doi: 10.3390/toxins10070269.
The presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analysis of the 16S rRNA gene. Bottom sediment samples were collected from selected rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand Rivers (South Africa); Notwane (Botswana); and Shashe River and Mzingwane River (Zimbabwe). A physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/L, in most of the river sediments, while alkalinity, pH and salinity were in excess of 500 mg/L. The FlowCam showed the dominant cyanobacteria species that were identified from the sediment samples, and these were the species, followed by , and species. The latter species were also confirmed by molecular techniques. Nevertheless, two samples showed an amplification of the cylindrospermopsin polyketide synthetase gene (S3 and S9), while the other two samples showed an amplification for the microcystin/nodularin synthetase genes (S8 and S13). Thus, these findings may imply the presence of toxic cyanobacteria species in the studied river sediments. The presence of cyanobacteria may be hazardous to humans because rural communities and farmers abstract water from the Limpopo river catchment for human consumption, livestock and wildlife watering and irrigation.
有害藻类水华（HABs）和蓝藻毒素存在于饮用水源中，对人类健康构成了极大的威胁。本研究采用分子技术，根据 16S rRNA 基因的系统发育分析，确定林波波河流域无毒和有毒蓝藻物种的存在情况。从选定的河流中采集底泥样本：林波波河、鳄鱼河、莫科洛河、莫高拉文河、恩泽勒勒河、莱法勒河、桑河（南非）；诺特瓦讷河（博茨瓦纳）；沙舍河和姆津加韦河（津巴布韦）。底泥的物理化学分析表明，大多数河底泥中存在超过 0.5mg/L 的营养物质硝酸盐和磷酸盐，而碱度、pH 值和盐度超过 500mg/L。FlowCam 显示了从沉积物样本中鉴定出的优势蓝藻物种，其中 物种最为常见，其次是 、 和 物种。后两种物种也通过分子技术得到了证实。然而，有两个样本显示出 cylidrospermopsin 聚酮合酶基因（S3 和 S9）的扩增，而另外两个样本显示出微囊藻/节球藻合酶基因（S8 和 S13）的扩增。因此，这些发现可能意味着研究中的河底泥中存在有毒蓝藻物种。蓝藻的存在可能对人类有害，因为农村社区和农民从林波波河流域抽取饮用水供人类消费、牲畜和野生动物饮水和灌溉。
