Responses to Oxidative and Heavy Metal Stresses in Cyanobacteria: Recent Advances

Abstract

Cyanobacteria, the only known prokaryotes that perform oxygen-evolving photosynthesis, are receiving strong attention in basic and applied research. In using solar energy, water, CO2 and mineral salts to produce a large amount of biomass for the food chain, cyanobacteria constitute the first biological barrier against the entry of toxics into the food chain. In addition, cyanobacteria have the potential for the solar-driven carbon-neutral production of biofuels. However, cyanobacteria are often challenged by toxic reactive oxygen species generated under intense illumination, i.e., when their production of photosynthetic electrons exceeds what they need for the assimilation of inorganic nutrients. Furthermore, in requiring high amounts of various metals for growth, cyanobacteria are also frequently affected by drastic changes in metal availabilities. They are often challenged by heavy metals, which are increasingly spread out in the environment through human activities, and constitute persistent pollutants because they cannot be degraded. Consequently, it is important to analyze the protection against oxidative and metal stresses in cyanobacteria because these ancient organisms have developed most of these processes, a large number of which have been conserved during evolution. This review summarizes what is known regarding these mechanisms, emphasizing on their crosstalk.

Comparative Genomics of DNA Recombination and Repair in Cyanobacteria: Biotechnological Implications

“…In colonizing most waters (fresh, brackish and marine) and soils, where they face various challenges (Cassier-Chauvat and Chauvat, 2015), cyanobacteria have developed as widely diverse organisms (Narainsamy et al, 2013). Their genomes differ in size (from 1.44 to 12.07 Mb), ploidy (from two to more than 20 chromosome copies per cell) or GC content (30–60%), probably as a result from gains and losses of genes transferred by plasmids, insertion sequences (Alam et al, 1991; Cassier-Chauvat et al, 1997) and/or cyanophages (Hess, 2011; Shih et al, 2013).…”

“…Because of their photoautotrophic lifestyle, cyanobacteria are strongly challenged by solar UV rays and reactive oxygen species generated by photosynthesis (Cassier-Chauvat and Chauvat, 2015). Consequently, Synechocystis PCC6803 and Synechococcus PCC7942 are found to be more resistant to UV than the (non-photosynthetic) bacterium E. coli where DNA repair is best known (Baharoglu and Mazel, 2014).…”

“…Because of their photoautotrophic lifestyle, cyanobacteria are strongly challenged by DNA damages generated by solar UV rays and photosynthesis (for review see Cassier-Chauvat and Chauvat, 2015), likely explaining their resistance to radiations. Furthermore, many cyanobacteria engineered for biotechnological purposes appeared to be genetically unstable in using DNA recombination to inactivate/eliminate the newly introduced genes of industrial interest.…”

Assessment of the effects of As(III) treatment on cyanobacteria lipidomic profiles by LC-MS and MCR-ALS

“…They are responsible for about 50 % of earthly photosynthesis, and they are the main contributors of the global oxygen cycle. Metals, such as arsenic, are known to exercise a negative influence on cyanobacteria photosynthesis [7,8]. Cyanobacteria photosynthetic processes are known to occur in cyanobacteria thylakoid membrane [9].…”

Fully automated two-step assay for detection of metallothionein through magnetic isolation using functionalized γ-Fe2O3 particles

“…Despite the diversity of the amino acid sequences, the MTs are generally analogous in structure with respect to a high content of cysteine residues (up to 30%), and lack of aromatic amino acids [4]. MTs are involved in the metabolism of heavy metal ions, including their metal detoxification, homeostasis [8,9], storage of zinc [7], radical scavenging [2,10] and stress response [11]. MTs are overexpressed in several tumors and this overexpression is accompanied by an increased proliferation and protection against apoptosis.…”