Oudra B, Dadi-El Andaloussi M, Vasconcelos V M
Faculty of Sciences Semlalia-Marrakech, Department of Biology, Laboratory of Biology and Biotechnology of Micro-organisms, Microbiology and Toxicology Environmental University, P.O. Box 2390, 40000 Marrakech, Morocco.
Environ Monit Assess. 2009 Feb;149(1-4):437-44. doi: 10.1007/s10661-008-0220-y. Epub 2008 Feb 21.
Health risks generated by cyanobacterial toxins in drinking and recreational waters are clearly recognised. During the monitoring programme on the distribution of toxic freshwater cyanobacteria in various water bodies including reservoirs, ponds and rivers of Morocco, many toxigenic cyanobacteria bloom-forming species have been identified. Particular attention was given to the investigation of the toxicology of a benthic Nostoc species-Nostoc muscorum Ag. (cyanobacteria, Nostocales, Nostocaceae)-that was found dominant in Oukaïmeden river located at 2,600 m of altitude in High-Atlas mountains of Marrakech. The massive growth of the mat-forming N. muscorum occurred yearly during the period of March-October, when the water temperature was above 10 degrees C. During 1997-1999, samples were collected from either floating or benthic mats. Hepatotoxicity associated to gastrointestinal (diarrhoea) intoxication symptoms was confirmed by intraperitoneal (i.p.) injection in mice of N. muscorum thallus extract. The survival time was estimated to be from 2-5 h, and the calculated i.p. LD(50) in mice ranged from 15 to 125 mg kg(-1) body weight. The application of the high performance liquid chromatography with photodiode array detection confirmed the occurrence of microcystin-LR (MC-LR) and three others microcystin variants from the methanolic Nostoc extract. The MC-LR represented a proportion of 39% of the total microcystin content however, the total concentration equivalents-eq-of MC-LR was estimated to be 139 microg MC-LR eq per gram dry weight. The existence of a benthic microcystin-producing N. muscorum strain under the particular environmental conditions of Oukaïmeden region may be a potential human health hazard and the ecological harmful effects of these cyanobacterial toxins need to be assessed. This paper constitutes the first report of the occurrence of a toxic benthic Nostoc in Morocco. So, the benthic species should be considered during monitoring of toxic Cyanobacteria particularly for river used for source of drinking water.
饮用水和娱乐用水中蓝藻毒素所产生的健康风险已得到明确认知。在对摩洛哥包括水库、池塘和河流在内的各类水体中有毒淡水蓝藻分布的监测项目期间，已鉴定出许多产毒蓝藻水华形成物种。特别关注了对一种底栖念珠藻物种——地木耳念珠藻（蓝藻门、念珠藻目、念珠藻科）——的毒理学研究，该物种在位于马拉喀什高阿特拉斯山脉海拔2600米处的乌卡伊梅登河中占主导地位。形成席状的地木耳念珠藻每年在3月至10月期间大量生长，此时水温高于10摄氏度。在1997年至1999年期间，从漂浮或底栖席状体中采集样本。通过向小鼠腹腔注射地木耳念珠藻藻体提取物，证实了与胃肠道（腹泻）中毒症状相关的肝毒性。估计存活时间为2至5小时，计算得出小鼠腹腔注射的半数致死量（LD50）范围为15至125毫克/千克体重。应用配有光电二极管阵列检测的高效液相色谱法证实了从地木耳念珠藻甲醇提取物中存在微囊藻毒素-LR（MC-LR）以及其他三种微囊藻毒素变体。MC-LR占微囊藻毒素总含量的39%，然而，MC-LR的总浓度当量（eq）估计为每克干重139微克MC-LR eq。在乌卡伊梅登地区特定环境条件下存在产微囊藻毒素的底栖地木耳念珠藻菌株可能对人类健康构成潜在危害，并且需要评估这些蓝藻毒素的生态有害影响。本文构成了摩洛哥有毒底栖念珠藻存在情况的首次报告。因此，在监测有毒蓝藻时应考虑底栖物种，特别是对于用作饮用水源的河流。
