Antenna Modification Leads to Enhanced Nitrogenase Activity in a High Light-Tolerant Cyanobacterium

The function of phycobilisomes, the large antenna protein complexes in heterocysts has long been debated. This study provides direct evidence of the involvement of these proteins in supporting nitrogenase activity in Anabaena 33047, a heterocystous cyanobacterium that has an affinity for high light intensities.

Response of paddy field cyanobacterium, Westiellopsis prolifica Janet to the inorganic nitrogenous fertilizers

Cyanobacteria are prokaryotic nitrogen fixing microorganism which played a significant role in the nitrogen fixation and contributed much to the submerged rice cropping system of the world. It can luxuriantly flourish in paddy fields and providing nitrogen as well as various growth promoting substances that influence the growth of paddy plants. India, being an important rice producing country of the world, depends upon various inorganic fertilizers for rice cultivation. The heterocystous cyanobacterium, Westiellopsis prolifca is a common inhabitant in most of the paddy fields of Kerala. The growth and other biochemical parameters upon the growth of cyanobacterium were assayed. The nitrogenous fertilizer ammonium sulphate influences the chlorophyll-a synthesis, protein content and growth rate. But the ammonia excretion was drastically reduced in cyanobacterial cultures upon the treatment with inorganic fertilizers.

Adverse effects of nitrogenous compounds on nitrogen-fixing cyanobacterium Anabaena solitaria Klebahn

The nitrogen-fixing heterocystous cyanobacterium Anabaena solitaria was tested for its response to different concentrations of nitrogen sources, namely nitrate and ammonia. To compare both the effect of concentration and type of nitrogen source, gradual concentrations were prepared for both ammonia and nitrate. The results showed concentration was significantly important on the frequency of heterocyst formation where highest nitrogen compounds concentrations were inhibitory for heterocyst formation. On the other hand, the effect of the type of nitrogenous compounds tested was insignificant which only proves that they are equally usable by cyanobacteria which will use them instead of transforming one of its cells to heterocyst thus not performing nitrogen fixation. Results also revealed the massive growth of heterotrophic bacteria in presence of nitrogenous compounds. This indicates that the presence of nitrogenous compounds in fields in which nitrogen-fixing cyanobacteria are to be used as biofertilizers can be inhibitory for nitrogen fixation and stimulatory for heterotrophic bacterial growth which could be pathogenic and harmful to plants. The use of more nitrogen-fixing cyanobacteria with the minimum amount of nitrogenous compounds is recommended.

Lyngbya regalis sp. nov. (Oscillatoriales, Cyanophyceae), a new tropical marine cyanobacterium

A new species of tropical marine cyanobacterium was isolated from the coast of Singapore. Lyngbya regalis is a filamentous, non-heterocystous cyanobacterium that forms a brown-green macroscopic thallus of filaments that are straight to wavy. Filaments are enclosed in a transparent, lamellated sheath with distinct cross-wall constrictions observed and apical cells that are widely rounded. The combined phenotypic, phylogenetic (16S rRNA sequences) and ecological characteristics observed indicate that Lyngbya regalis is a novel species within the genus Lyngbya C. Agardh ex Gomont.