title: Modulation of pigment profiles of Calothrix elenkenii in response to environmental changes.
abstract: Cyanobacteria are versatile tetrapyrrole synthesizers that can regulate their tetrapyrrole content and composition in response to environmental signals. The present investigation analyses the interplay between light and dark regimes (continuous light, light-dark cycles (16:8) and continuous darkness) and aerobic, air-tight, and anaerobic environments (argon-enriched), on the relative composition of various pigments and growth attributes of Calothrix elenkenii as a prelude to exploiting C. elenkenii's bioindustrial potential as a source of pigments. Incubation in an anaerobic environment stimulated hormogonia formation and induced colouration/thickening of cells. Aerobically grown cultures of Calothrix, under continuous illumination produced the maximum amount of total phycobiliproteins and sugars, although chlorophyll accumulation and nitrogenase activity were highest in the light-dark environment. However, the beta-carotene content was observed to vary under anaerobic conditions with different light-dark regimes. This C. elenkenii strain can be a valuable source of pigments under optimized environmental conditions.
authors.affiliation: National Centre for Conservation and Utilization of Blue-Green Algae, Indian Agricultural Research Institute, New Delhi 110 012, India. pabbyanjuli@hotmail.com
authors.forename: Radha
authors.initials: R
authors.lastname: Prasanna
authors.forename: Anjuli
authors.initials: A
authors.lastname: Pabby
authors.forename: Sudhir
authors.initials: S
authors.lastname: Saxena
authors.forename: Pawan Kumar
authors.initials: PK
authors.lastname: Singh
mesh_terms: D000222:Adaptation, Physiological; D000332:Aerobiosis; D000693:Anaerobiosis; D002734:Chlorophyll / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism* / Q000648:ultrastructure; D008027:Light; D010860:Pigments, Biological / Q000378:metabolism*; D019207:beta Carotene / Q000378:metabolism
chemical_list: D010860:Pigments, Biological; D019207:beta Carotene; D002734:Chlorophyll