Hsieh Paul, Pedersen Jens Z, Bruno Laura
Laboratory of Biology of Algae, Department of Biology, University of Rome 'Tor Vergata', Rome, Italy.
Photochem Photobiol. 2014 May-Jun;90(3):533-43. doi: 10.1111/php.12208. Epub 2013 Dec 10.
Light has bilateral effects on phototrophic organisms. As cyanobacteria in Roman hypogea are long acclimatized to dim environment, moderate intensity of illumination can be used to alleviate biodeterioration problems on the stone substrata. Moderate intensity of light inactivates cyanobacteria by causing photoinhibition, photobleaching and photodamage to the cells. The effectiveness of light depends not only on its intensity but also on the composition and pigmentation of the component cyanobacteria in the biofilms. Red light is the most effective for the species rich in phycocyanin and allophycocyanin, such as Leptolyngbya sp. and Scytonema julianum, whereas green light is effective to inhibit the species rich in phycoerythrin, like Oculatella subterranea. White light is effective to control the grayish and the black cyanobacteria, such as Symphyonemopsis sp. and Eucapsis sp. abundant in all of these pigments. Blue light is the least effective. 150 μmol photons m(-2) s(-1) of blue light cannot cause biofilm damage while the same intensity of red, green or white irradiation for 14 days can severely damage the cyanobacterial cells in the biofilms due to ROS formation. Electron spin resonance spectroscopy detected the formation of radicals in different cyanobacterial cellular extracts exposed to 80 μmol photons m(-2) s(-1) of light.
光对光合生物具有双向影响。由于罗马地下洞穴中的蓝细菌长期适应昏暗环境，因此可利用适度光照强度来缓解石质基质上的生物劣化问题。适度光照强度会通过对细胞造成光抑制、光漂白和光损伤，从而使蓝细菌失活。光的有效性不仅取决于其强度，还取决于生物膜中蓝细菌组分的组成和色素沉着。红光对富含藻蓝蛋白和别藻蓝蛋白的物种最为有效，例如纤细席藻和朱利安伪枝藻，而绿光对抑制富含藻红蛋白的物种有效，如地下眼状藻。白光对控制富含所有这些色素的灰色和黑色蓝细菌有效，例如共生藻属和真囊藻属。蓝光效果最差。150 μmol光子·m(-2)·s(-1)的蓝光不会导致生物膜损伤，而相同强度的红光、绿光或白光照射14天会因活性氧的形成而严重损伤生物膜中的蓝细菌细胞。电子自旋共振光谱法检测到暴露于80 μmol光子·m(-2)·s(-1)光照下的不同蓝细菌细胞提取物中自由基的形成。
