The heterocystous cyanobacteria are currently placed in subsections IV and V, which are distinguished by cellular division in one plane (false branching) and in more than one plane (true branching), respectively. Published phylogenies of 16S rRNA gene sequence data support the monophyly of the heterocystous cyanobacteria, with members of subsection V embedded within subsection IV. It has been p...

Heterocystous, planktonic cyanobacteria capable of fixing atmospheric N2 into available nitrogen (N) are common and critically important to nutrient cycling in many lakes, yet they are rarely observed in estuaries at salinities >10 ppt, even when strongly N limited. In a series of mesocosm experiments using water from Narragansett Bay (Rhode Island), we manipulated top-down (grazing) and bottom...

Most of the research to date on cyanobacterial uptake hydrogenases has been performed on filamentous heterocystous strains. However, recent results on the hup gene cluster organization and its transcriptional regulation in non-heterocystous strains has contributed to the widening of knowledge in this field. In the present study, we outline the recent findings on uptake hydrogenases from non-het...

The effect of boron on heterocystous and nonheterocystous dinitrogen fixing Cyanobacteria was examined. The absence of boron in culture media inhibited growth and nitrogenase activity in Nodularia sp., Chlorogloeopsis sp., and Nostoc sp. cultures. Examinations of boron-deficient cultures showed changes in heterocyst morphology. However, cultures of nonheterocystous Cyanobacteria, Gloeothece sp....

cyanobacteria were collected and identified in five paddy fields with different soil textures of golestan province in iran. it was determined that nostoc ellipsosporum and nostoc muscorum were dominant in all sites among 20 species. to assess the ability of atmospheric nitrogen fixation by the species, their pure cultures were provided by growing on bg-11 solid culture medium. subsequently, eac...

The influence of soil pH was evaluated on the abundance and generic diversity of cyanobacteria in soil samples collected from diverse rice soil ecologies of India. Qualitative and quantitative studies of the 52 soil samples collected from nine agroecologies was carried out using enrichment, MPN (Most Probable Number) techniques and diversity indices were measured. A total of 166 forms, includin...

The recent proliferation of harmful cyanobacterial blooms (cyanoHABs) in the Baltic and other marginal seas poses a severe threat for the health of infested ecosystems as e.g. the massive export and decay of cyanobacterial biomass facilitates the spread of bottom water hypoxia. There is evidence that cyanoHABs occurred repeatedly in the Baltic Sea but knowledge of their spatiotemporal distribut...

antifungal and antibacterial activity of some heterocystous cyanobacteria from paddy-fields in the north of iran was studied. soil samples were collected from paddy-fields of gillan, mazandaran and golestan provinces and cyanobacteria were isolated. supernatants, methanolic and hexane extracts from biomass of 150 strains of cyanobacteria were isolated and screened against six strains of bacteri...

Discoveries in recent years have disclosed the importance of marine cyanobacteria in the context of primary production and global nitrogen cycling. It is hypothesized here that microbial mats in tropical coastal habitats harbour a rich diversity of previously uncharacterized cyanobacteria and that benthic marine nitrogen fixation in coastal zones is substantial. A polyphasic approach was used t...

Living stromatolites growing in a hot spring in Yellowstone National Park are composed of silica-encrusted cyanobacterial mats. Two cyanobacterial mat types grow on the stromatolite surfaces and are preserved as two distinct lithofacies. One mat is present when the stromatolites are submerged or at the water-atmosphere interface and the other when stromatolites protrude from the hot spring. The...