Rose Julie M, Vora Neil M, Countway Peter D, Gast Rebecca J, Caron David A
Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
ISME J. 2009 Feb;3(2):252-60. doi: 10.1038/ismej.2008.96. Epub 2008 Oct 9.
The effects of temperature on the growth rate and gross growth efficiency (GGE) of the heterotrophic nanoflagellate, Paraphysomonas imperforata, cultured from the Ross Sea, Antarctica were investigated using five experimental temperatures (range=0-20 degrees C). This bacterivorous protist exhibited measurable growth over the temperature range examined, although temperature exerted a significant effect on its growth rate. There was no evidence for an effect of temperature on GGE. The growth rates and GGE of our Antarctic P. imperforata isolate were compared to values reported for other cultures of species from this genus. A wide range of growth efficiencies have been reported for different strains of Paraphysomonas spp., but our estimates were comparable to mean/median values reported in the literature. The growth rates of our Antarctic P. imperforata were similar to rates obtained for an Arctic conspecific at low temperatures (0-5 degrees C), among the highest reported rates for any Paraphysomonas species at intermediate temperatures (10-15 degrees C) and similar to rates reported for temperate congeners and conspecifics at 20 degrees C. Q(10) values of 15, 2.2, 3.6 and 0.93 were calculated for growth rates at 5 degrees C intervals between 0 and 20 degrees C, respectively. Results indicated that our Antarctic P. imperforata grew at rates comparable to other polar isolates at ambient polar temperatures, but these low temperatures may be outside the physiological optimum for the isolate.
利用五个实验温度（范围为0 - 20摄氏度）研究了温度对从南极罗斯海培养的异养型纳米鞭毛虫——无孔副单胞菌的生长速率和总生长效率（GGE）的影响。尽管温度对其生长速率有显著影响，但这种食细菌原生生物在所研究的温度范围内呈现出可测量的生长。没有证据表明温度对GGE有影响。将我们分离的南极无孔副单胞菌的生长速率和GGE与该属其他培养物所报道的值进行了比较。对于不同菌株的副单胞菌属，已经报道了广泛的生长效率范围，但我们的估计值与文献中报道的平均值/中值相当。我们分离的南极无孔副单胞菌在低温（0 - 5摄氏度）下的生长速率与北极同种的生长速率相似，在中等温度（10 - 15摄氏度）下是所报道的任何副单胞菌物种中最高的生长速率之一，并且在20摄氏度时与温带同属和同种所报道的速率相似。分别计算了在0至20摄氏度之间以5摄氏度间隔的生长速率的Q(10)值，分别为1.5、2.2、3.6和0.93。结果表明，我们的南极无孔副单胞菌在极地环境温度下的生长速率与其他极地分离株相当，但这些低温可能超出了该分离株的生理最适温度范围。
