Saadoun I M, Schrader K K, Blevins W T
Department of Biological Sciences, Jordan University of Science and Technology, P.O. Box 3030, Irbid-22110, Jordan.
Water Res. 2001 Apr;35(5):1209-18. doi: 10.1016/s0043-1354(00)00381-x.
A cyanobacterium isolated from a source-water reservoir during a spring odor and taste episode and identified as Anabaena sp. consistently produced geosmin during laboratory culture on modified BG-11 liquid medium. Maximal geosmin/biomass occurred at 20 degrees C and a light intensity of 17 microE/m2/s; geosmin/chla values directly correlated with increasing light intensity (r2 = 0.95, P < 0.01). It was concluded that at 20 degrees C, increasing light intensity favors less chla synthesis and higher geosmin synthesis; at 17 microE/m2/s, increasing temperature stimulates chla production (to 25 degrees C) while repressing geosmin synthesis (above 20 degrees C). Nutritional factors promoting biomass, chla, and geosmin synthesis by Anabaena sp. were also investigated. For cultures grown at 17 microE/m2/s and 20 degrees C for 20 days, both ammonium-N and nitrate-N generally enhanced the growth of Anabaena sp. Nitrate-N promoted more chla production (r2 = 0.99) than ammonium-N. Geosmin synthesis was directly correlated with ammonium-N concentrations (r2 = 0.89), with low nitrate-N (123.5 micrograms/l) favoring maximal geosmin production (2.8 micrograms/l). Increasing nitrate-N concentrations promoted a three-fold increase in chla content with geosmin synthesis decreased by two-fold. Geosmin/mg biomass was directly related to ammonium-N concentration; high nitrate-N levels suppressed geosmin production. No geosmin was detected at or below 118 micrograms phosphate-phosphorus/l. Geosmin, dry weight biomass, and chla production were correlated with increasing phosphorus (P) concentration (r2 = 0.76, 0.96 and 0.98, respectively). No geosmin was detected when copper was present in growth media at or above 6.92 micrograms Cu2+/l (CuSO4.5H2O). Dry weight biomass and chla production were negatively correlated with Cu2+ ion concentrations.
在一次春季气味和味道事件期间，从一个水源水库分离出一种蓝藻，并鉴定为鱼腥藻属，该蓝藻在改良的BG-11液体培养基上进行实验室培养时持续产生土臭素。土臭素/生物量在20℃和17微爱因斯坦/平方米/秒的光照强度下达到最大值；土臭素/叶绿素a值与光照强度增加直接相关（r2 = 0.95，P < 0.01）。得出的结论是，在20℃时，光照强度增加有利于较少的叶绿素a合成和较高的土臭素合成；在17微爱因斯坦/平方米/秒时，温度升高刺激叶绿素a产生（至25℃），同时抑制土臭素合成（高于20℃）。还研究了促进鱼腥藻属生物量、叶绿素a和土臭素合成的营养因素。对于在17微爱因斯坦/平方米/秒和20℃下培养20天的培养物，铵态氮和硝态氮通常都能促进鱼腥藻属的生长。硝态氮比铵态氮促进更多的叶绿素a产生（r2 = 0.99）。土臭素合成与铵态氮浓度直接相关（r2 = 0.89），低硝态氮（123.5微克/升）有利于最大土臭素产量（2.8微克/升）。硝态氮浓度增加促进叶绿素a含量增加三倍，而土臭素合成减少两倍。土臭素/毫克生物量与铵态氮浓度直接相关；高硝态氮水平抑制土臭素产生。在118微克磷-磷/升及以下未检测到土臭素。土臭素、干重生物量和叶绿素a产量与磷（P）浓度增加相关（分别为r2 = 0.76、0.96和0.98）。当生长培养基中铜的含量达到或高于6.92微克Cu2+/升（CuSO4·5H2O）时，未检测到土臭素。干重生物量和叶绿素a产量与Cu2+离子浓度呈负相关。
