Effects of lindane on the photosynthetic apparatus of the cyanobacteriumanabaena

• Published in: Environmental science and pollution research international 2004-03, Vol.11 (2), p.98-106
• Main Authors: Bueno, Marta, Fillat, Maria F., Strasser, Reto J., Maldonado-Rodriguez, Ronald, Marina, Nerea, Smienk, Henry, Gómez-Moreno, Carlos, Barja, Francisco
• Format: Article
• Language: English
• Subjects: Biodegradation; Bioremediation; Bleaching; Cyanobacteria; Electron microscopy; Fluorescence; Light quality; Lindane; Microscopy; Nitrogen fixation; Oxidative stress; Pesticides; Photosynthesis; Phytoremediation; Pollutants
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/BF02979709

Cyanobacteria have the natural ability to degrade moderate amounts of organic pollutants. However, when pollutant concentration exceeds the level of tolerance, bleaching of the cells and death occur within 24 hours. Under stress conditions, cyanobacterial response includes the short-term adaptation of the photosynthetic apparatus to light quality, named state transitions. Moreover, prolonged stresses produce changes in the functional organization of phycobilisomes and in the core-complexes of both photosystems, which can result in large changes in the PS II fluorescence yield. The localization of ferredoxin-NADP+ reductase (FNR) at the ends of some peripheral rods of the cyanobacterial phycobilisomes, makes this protein a useful marker to check phycobilisome integrity. The goal of this work is to improve the knowledge of the mechanism of action of a very potent pesticide, lindane (γ-hexaclorociclohexane), in the cyanobacteriumAnabaena sp., which can be considered a potential candidate for bioremediation of pesticides. We have studied the effect of lindane on the photosynthetic apparatus ofAnabaena using fluorescence induction studies. As ferredoxin-NADP+ reductase plays a key role in the response to oxidative stress in several systems, changes in synthesis, degradation and activity of FNR were analyzed. Immunolocalization of this enzyme was used as a marker of phycobilisome integrity. The knowledge of the changes caused by lindane in the photosynthetic apparatus is essential for rational further design of genetically-modified cyanobacteria with improved biorremediation abilities. Polyphasic chlorophylla fluorescence rise measurements (OJIP) have been used to evaluate the vitality and stress adaptation of the nitrogen-fixing cyanobacteriumAnabaena PCC 7119 in the presence of increasing concentrations of lindane. Effects of the pesticide on the ultrastructure have been investigated by electron microscopy, and FNR has been used as a marker of phycobilisome integrity. Cultures ofAnabaena sp. treated with moderate amounts of lindane showed a decrease in growth rate followed by a recovery after 72 hours of pesticide treatment. Concentrations of lindane below 5 ppm increased the photosynthetic performance and activity of the cells. Higher amounts of pesticide caused a decrease in these activities which seems to be due to a non-competitive inhibition of PS II. Active PS II units are converted into non-Q^sub A^ reducing, so called heat sink centers. Specific activi