Guyoneaud R, Borrego C M, Martínez-Planells A, Buitenhuis E T, Garcia-Gil L J
Laboratoire d'Ecologie Moléculaire-Microbiologie, Université de Pau, BP1155, 64013 Pau Cedex, France.
Arch Microbiol. 2001 Oct;176(4):278-84. doi: 10.1007/s002030100320.
The morphology (mainly prosthecae length), ultrastructure, and antenna pigment composition of the green sulfur bacterium Prosthecochloris aestuarii changed when grown under different light intensities. At light intensities of 0.5 and 5 micromol quanta m(-2) s(-1), the cells had a star-like morphology. Prosthecae, the characteristic appendages of the genus Prosthecochloris, were 232 nm and 194 nm long, respectively. In contrast, when grown at 100 micromol quanta m(-2) s(-1), these appendages were shorter (98 nm) and the cells appeared more rod-shaped. Transmission electron microscopy revealed a significant decrease in the cell perimeter to area ratio and in the number of chlorosomes per linear microm of membrane as light intensity increased. In addition to these morphological and ultrastructural responses, Prosthecochloris aestuarii exhibited changes in its pigment composition as a function of light regime. Lower specific pigment content and synthesis rates were found in cultures grown at light intensities above 5 micromol quanta m(-2) s(-1). A blue shift in the bacteriochlorophyll (BChl) c Q(y) absorption maximum of up to 17.5 nm was observed under saturating light conditions (100 micromol quanta m(-2) s(-1)). This displacement was accompanied by changes in the composition of BChl c homologs and by a very low carotenoid content. The morphological, ultrastructural and functional changes exhibited by Prosthecochloris aestuarii revealed the strong light-response capacity of this bacterium to both high and low photon-flux densities.
当在不同光照强度下生长时，绿色硫细菌埃氏滑行绿菌（Prosthecochloris aestuarii）的形态（主要是菌柄长度）、超微结构和触角色素组成会发生变化。在光照强度为0.5和5微摩尔光子·米⁻²·秒⁻¹时，细胞呈星状形态。菌柄是滑行绿菌属的特征性附属物，长度分别为232纳米和194纳米。相比之下，当在100微摩尔光子·米⁻²·秒⁻¹下生长时，这些附属物较短（98纳米），细胞看起来更呈杆状。透射电子显微镜显示，随着光照强度增加，细胞周长与面积之比以及每线性微米膜上的绿体数量显著减少。除了这些形态和超微结构反应外，埃氏滑行绿菌的色素组成也随光照条件而变化。在光照强度高于5微摩尔光子·米⁻²·秒⁻¹的培养物中，发现特定色素含量和合成速率较低。在饱和光照条件（100微摩尔光子·米⁻²·秒⁻¹）下，观察到细菌叶绿素（BChl）c Q(y)吸收峰的蓝移高达17.5纳米。这种位移伴随着BChl c同系物组成的变化以及极低的类胡萝卜素含量。埃氏滑行绿菌表现出的形态、超微结构和功能变化揭示了这种细菌对高和低光子通量密度都具有很强的光响应能力。
