Aphanizomenon
Aphanizomenon is a genus of cyanobacteria that inhabits freshwater lakes and can cause dense blooms. These cyanobacteria are unicellular organisms that form linear chains known as trichomes. Parallel trichomes can further unite into aggregates called rafts. Cyanobacteria such as Aphanizomenon are known for using photosynthesis to create energy and thus rely on sunlight as their energy source. Aphanizomenon bacteria also play a significant role in the Nitrogen cycle due to their ability to perform nitrogen fixation. Studies on the species Aphanizomenon flos-aquae have shown that it can regulate buoyancy through light-induced changes in turgor pressure. The genus is also capable of gliding motility, although the specific mechanism responsible for this ability remains unknown.
Species
Species and synonymy from AlgaeBase:Aphanizomenon americanum S → Aphanizomenon flos-aquaeAphanizomenon aphanizomenoides S → Sphaerospermopsis aphanizomenoidesAphanizomenon balticum UAphanizomenon capricorni S → Cuspidothrix capricorniAphanizomenon chinense C- "Aphanizomenon cyaneum" S → Aphanizomenon flos-aquaeAphanizomenon elenkinii S → Aphanizomenon flos-aquaeAphanizomenon favaloroi CAphanizomenon flexuosum CAphanizomenon flos-aquae C - see noteAphanizomenon gracile CAphanizomenon holsaticum S → Aphanizomenon flos-aquaeAphanizomenon hungaricum CAphanizomenon incurvum CAphanizomenon issatschenkoi → Cuspidothrix issatschenkoiAphanizomenon kaufmannii S → Cylindrospermopsis raciborskiiAphanizomenon klebahnii CAphanizomenon manguinii CAphanizomenon morrenii CAphanizomenon ovalisporum S → Umezakia ovalisporumAphanizomenon paraflexuosum CAphanizomenon platense CAphanizomenon schindleri CAphanizomenon skujae CAphanizomenon slovenicum CAphanizomenon sphaericum S → Aphanizomenon aphanizomenoidesAphanizomenon strictum UAphanizomenon tropicale S → Cuspidothrix tropicalisAphanizomenon ussaczevii S → Cuspidothrix ussaczeviiAphanizomenon volzii S → Macrospermum volziiAphanizomenon yezoense C
Ecology
Overcoming phosphate limitation
Aphanizomenon may become dominant in a water body partially due to their ability to induce phosphate-limitation in other phytoplankton while also increasing phosphate availability to itself through release of cylindrospermopsin. The cylindrospermopsin causes other phytoplankton to increase their alkaline phosphatase activity, increasing inorganic phosphate availability in the water to Aphanizomenon during times when phosphate becomes limiting.Photosynthesis
All species in the cyanobacteria phylum can perform photosynthesis. They use a similar photosynthesis to plants, using two photosystems which is called the Z-scheme. This is different from other photosynthetic bacteria that only use one photosystem and do not have thylakoids. Cyanobacteria species such as Aphanizomenon also use Oxygen as their final electron acceptor in the Electron Transport Chain, which is also different from other photosynthetic bacteria, which perform a type of photosynthesis called anoxygenic photosynthesis.Nitrogen fixation
Aphanizomenon are a special type of cyanobacteria called heterocysts, which are capable of producing biologically useful nitrogen by the process of nitrogen fixation from atmospheric nitrogen.A large proportion of fixed nitrogen may be released into the surrounding water, providing an important source of biologically available nitrogen to the ecosystem. Since Aphanizomenon are one of the few species of bacteria that can perform nitrogen fixation, other bacterial species that use nitrogen ions as a reactant will start to rely on the species as a source of usable nitrogen. This will cause a bacterial bloom to form, which is a condition under which the number of bacterial colonies in an area will suddenly increase.