Brown Sydney M, Blaszczak Joanna R, Shriver Robert K, Jones R Christian, Sohrab Abeer, Goel Ramesh, Boyer Gregory L, Wei Bofan, Manoylov Kalina M, Nelson T Reid, Zabrecky Jordan M, Stancheva Rosalina
Department of Environmental Science and Policy, George Mason University, Fairfax, VA 22030, USA; Potomac Environmental Research and Education Center, Woodbridge, VA 22191, USA.
Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV, USA.
Harmful Algae. 2025 Apr;144:102834. doi: 10.1016/j.hal.2025.102834. Epub 2025 Mar 2.
Benthic cyanobacterial proliferations are an emerging concern globally due to their potential for toxin production and subsequent negative environmental and health impacts. Microcoleus is a common mat-forming genus reported to produce potent neurotoxin, anatoxin-a, ingestion of which has been associated with animal mortalities. Six different unialgal monoclonal strains of Microcoleus were isolated from streams in California and grown in batch culture for 49 days. The four toxic strains were identified using a polyphasic approach as belonging to the species Microcoleus anatoxicus, which expands its known distribution throughout the Klamath River and Rock Creek watersheds in northern California. The non-toxic strains from the Eel River belonged to Microcoleus sp. 1. Maximum toxin production occurred during the exponential growth phase, and peaked 6-13 days later in more toxic strains, with a persistently higher fraction of extracellular toxins compared to less toxic strains, which had maximum toxin concentrations at day 13. The proposed mechanism of toxin release into culture medium was through damage to the cell walls of unhealthy filaments. Peak toxin production was energetically expensive for all M. anatoxicus strains, evidenced by reduced specific growth rates at the time of peak toxin production, followed by quick recovery of cell division. Despite this, more toxic strains achieved faster maximum growth rates than the less toxic and non-toxic strains under luxurious nutrient culture conditions. Differential toxin and growth rate responses of M. anatoxicus strains from wide geographical ranges under the same laboratory-controlled conditions suggest high intraspecific variation, which may represent challenges for harmful algal blooms mitigation. More toxic strains have the potential to proliferate and consistently release extracellular anatoxins into the environment. This study provides a baseline to understanding the growth and toxin kinetics of two commonly occurring Microcoleus species in northern California which may help benthic harmful cyanobacteria management.
由于底栖蓝藻增殖具有产生毒素的潜力以及随之而来的负面环境和健康影响，它已成为全球范围内一个日益受到关注的问题。微鞘藻属是一种常见的形成席状的属，据报道能产生强效神经毒素——anatoxin-a，动物摄入含有该毒素的物质后会死亡。从加利福尼亚州的溪流中分离出六种不同的微鞘藻单藻落单克隆菌株，并在分批培养中培养49天。采用多相方法鉴定出四种有毒菌株属于微鞘藻无毒素种，这扩大了其在加利福尼亚州北部克拉马斯河和岩石溪流域的已知分布范围。来自鳗鱼河的无毒菌株属于微鞘藻属1。最大毒素产量出现在指数生长期，毒性更强的菌株在6 - 13天后达到峰值，与毒性较弱的菌株相比，其细胞外毒素的比例持续更高，毒性较弱的菌株在第13天达到最大毒素浓度。毒素释放到培养基中的推测机制是通过对不健康丝状体细胞壁的破坏。对于所有微鞘藻无毒素种菌株来说，峰值毒素产量在能量上代价高昂，这表现为在峰值毒素产量时比生长速率降低，随后细胞分裂迅速恢复。尽管如此，在丰富营养培养条件下，毒性更强的菌株比毒性较弱和无毒的菌株达到更快的最大生长速率。在相同实验室控制条件下，来自广泛地理范围的微鞘藻无毒素种菌株对毒素和生长速率的不同反应表明种内差异很大，这可能对缓解有害藻华构成挑战。毒性更强的菌株有可能增殖并持续向环境中释放细胞外anatoxins。这项研究为了解加利福尼亚州北部两种常见微鞘藻属物种的生长和毒素动力学提供了基线，这可能有助于底栖有害蓝藻的管理。
