Cyanobacteria are dependent on but can also be compromised by metals such as iron. On the one hand the demand for iron for photosystem functionality represents a challenge for the iron uptake machinery in iron limiting environments. On the other hand intoxication by iron causes a severe problem for growth and reproduction. To overcome this dilemma cyanobacteria have developed a regulatory network controlling iron uptake. They produce siderophores, which are distinct from that of other bacteria. Furthermore, the iron metabolism is linked to the nitrogen metabolism as documented for example in Anabaena sp. PCC 7120.

Further reading: Iron Uptake and Homeostasis in Microorganisms

Labels: Anabaena, cyanobacteria, Iron acquisition mechanisms, Iron deficiency, Iron transporters, Iron uptake in Cyanobacteria, Iron uptake systems, Iron-homeostasis, Iron-uptake, Siderophore, Siderophores

Cyanobacteria are a group of ecologically diverse photosynthetic bacteria. Because niche differentiation is ultimately the product of differences among individuals within populations, understanding the evolutionary origins of this diversity ultimately requires a population genetics perspective. Recent work has elucidated the mechanisms that generate variation in cyanobacteria, the distribution of this diversity and its potential functional importance, and has suggested a population genomics approach to address fundamental questions regarding the nature of adaptive variation and niche differentiation in Cyanobacteria. (Xu, 2010).

References:
Xu, J. (2010) Microbial Population Genetics. Caister Academic Press, Norfolk, UK.
Herrero, A. and Flores, E. (2008) The Cyanobacteria: Molecular Biology, Genomics and Evolution. Caister Academic Press, Norfolk, UK.

Labels: cyanobacteria, Photosynthetic bacteria, population genetics

The Cyanobacteria
"There is not much that isn't covered in this book, and the editors and authors have managed to produce a survey that is comprehensive and readable. It manages the difficult feat of having enough up-to-date and in depth information for the specialist yet covering the basics in way comprehensible to the beginner and those from other fields of study." from The Biochemist (2009).


Further reading: The Cyanobacteria: Molecular Biology, Genomics and Evolution

Labels: blue green algae, book review, cyanobacteria

Cyanobacteria possess a CO₂ concentrating mechanism that enables them to accumulate CO₂ from the environment. Cyanobacteria are able to fix CO₂ into carbohydrates.

Cyanobacteria vary considerably in their ability to consume organic carbon from their surroundings. Many strains are obligate photoautotrophs where the sole carbon source is CO₂, while others are able to perform photomixotrophic or even heterotrophic growth using a wide variety of organic substances. Cyanobacteria constitute a unique case where the anabolic and catabolic carbohydrate metabolisms function in the same cellular compartment. In addition, the photosynthetic and respiratory electron transport pathways share components in the thylakoid membranes. Despite its importance to our understanding of cyanobacterial metabolism, little is known about the mechanisms involved in the shifts between photoautotrophic, heterotrophic and photomixotrophic modes of growth, and their regulation; between the different pathways of carbohydrate breakdown—glycolysis, fermentation, the oxidative pentose phosphate, the Krebs cycle and the photorespiratory pathways. However recent advances have been made in our understanding of the CO₂ concentrating mechanism and carbon metabolism in cyanobacteria.

from Kaplan et al in The Cyanobacteria: Molecular Biology, Genomics and Evolution

Further reading:

1. The Cyanobacteria: Molecular Biology, Genomics and Evolution
2. Microbiology Books

Labels: carbon dioxide, cyanobacteria, environment, metabolism

The biochemical capacity to use water as the source for electrons in photosynthesis evolved once, in a common ancestor of extant cyanobacteria. The geological record indicates that this transforming event took place early in our planet's history, at least 2450-2320 million years ago (Ma), and possibly much earlier. Geobiological interpretation of Archean (>2500 Ma) sedimentary rocks remains a challenge; available evidence indicates that life existed 3500 Ma, but the question of when oxygenic photosynthesis evolved continues to engender debate and research. A clear paleontological window on cyanobacterial evolution opened about 2000 Ma, revealing an already diverse biota of blue-greens. Cyanobacteria remained principal primary producers throughout the Proterozoic Eon (2500-543 Ma), in part because the redox structure of the oceans favored photautotrophs capable of nitrogen fixation. Green algae joined blue-greens as major primary producers on continental shelves near the end of the Proterozoic, but only with the Mesozoic (251-65 Ma) radiations of dinoflagellates, coccolithophorids, and diatoms did primary production in marine shelf waters take modern form. Cyanobacteria remain critical to marine ecosystems as primary producers in oceanic gyres, as agents of biological nitrogen fixation, and, in modified form, as the plastids of marine algae.

From: Andrew H. Knoll in The Cyanobacteria: Molecular Biology, Genomics and Evolution

Labels: archaea, bacteriology, bacterium, cyanobacteria