Adolf Jason E, Bachvaroff Tsvetan R, Place Allen R
University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA.
J Phycol. 2009 Feb;45(1):176-92. doi: 10.1111/j.1529-8817.2008.00641.x.
We examined the influence of N or P depletion, alternate N- or P-sources, salinity, and temperature on karlotoxin (KmTx) production in strains of Karlodinium veneficum (D. Ballant.) J. Larsen, an ichthyotoxic dinoflagellate that shows a high degree of variability of toxicity in situ. The six strains examined represented KmTx 1 (CCMP 1974, MD 2) and KmTx 2 (CCMP 2064, CCMP 2283, MBM1) producers, and one strain that did not produce detectable karlotoxin under nutrient-replete growth conditions (MD 5). We hypothesized that growth-limiting conditions would result in higher cell quotas of karlotoxin. KmTx was present in toxic strains during all growth phases and increased in stationary and senescent phase cultures under low N or P, generally 2- to 5-fold but with some observations in the 10- to 15-fold range. No karlotoxin was observed under low-N or low-P conditions in the nontoxic strain MD 5. Nutrient-quality (NO3 , NH4 , urea, and glycerophosphate) did not affect growth rate, but growth on NH4 produced 2- to 3-fold higher cellular toxicity and a 50% higher ratio of KmTx 1-1:KmTx 1-3 in CCMP 1974. CCMP 1974 showed higher cellular toxicity at low salinity (≤5 ppt) and high temperature (25°C). Our results suggested that given the presence of a toxic strain of K. veneficum in situ, the existence of environmental conditions that favor cellular accumulation of karlotoxin is likely a significant factor underlying K. veneficum-related fish kills that require both high cell densities (10(4) · mL(-1) ) and high cellular toxin quotas relative to those generally observed in nutrient-replete cultures.
我们研究了氮或磷缺乏、交替的氮源或磷源、盐度和温度对剧毒卡尔藻（Karlodinium veneficum (D. Ballant.) J. Larsen）菌株中卡罗毒素（KmTx）产生的影响，剧毒卡尔藻是一种对鱼类有毒的甲藻，其原位毒性具有高度变异性。所检测的六个菌株包括产生卡罗毒素1（CCMP 1974，MD 2）和卡罗毒素2（CCMP 2064，CCMP 2283，MBM1）的菌株，以及一个在营养充足的生长条件下未产生可检测到的卡罗毒素的菌株（MD 5）。我们假设生长限制条件会导致卡罗毒素的细胞配额更高。在所有生长阶段，有毒菌株中均存在卡罗毒素，并且在低氮或低磷条件下，稳定期和衰老期培养物中的卡罗毒素含量增加，通常增加2至5倍，但在某些情况下增加幅度在10至15倍之间。在无毒菌株MD 5中，低氮或低磷条件下未观察到卡罗毒素。营养质量（硝酸盐、铵、尿素和甘油磷酸盐）不影响生长速率，但在CCMP 1974中，以铵为营养源生长时，细胞毒性高2至3倍，卡罗毒素1-1:卡罗毒素1-3的比例高50%。CCMP 1974在低盐度（≤5 ppt）和高温（25°C）下表现出更高的细胞毒性。我们的结果表明，鉴于原位存在剧毒卡尔藻的有毒菌株，有利于卡罗毒素细胞积累的环境条件的存在可能是与剧毒卡尔藻相关的鱼类死亡的一个重要因素，这种鱼类死亡既需要高细胞密度（10⁴·mL⁻¹），又需要相对于营养充足培养物中通常观察到的细胞毒素配额更高。
