Effect of light and temperature on the cyanobacterium Arthronema africanum - a prospective phycobiliprotein-producing strain

Abstract

The effect of light intensity (50-300 μmol photons m −2 s −1 ) and temperature (15-50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied. Maximum growth rate was measured at 300 μmol photons m −2 s −1 and 36°C after 96 h of cultivation. The chlorophyll a content increased along with the increase in light intensity and temperature and reached 2.4% of dry weight at 150 μmol photons m −2 s −1 and 36°C, but it decreased at higher temperatures. The level of carotenoids did not change significantly under temperature changes at illumination of 50 and 100 μmol photons m −2 s −1 . Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m −2 s −1 . Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin. The total phycobiliprotein content was extremely high, more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin. A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m −2 s −1 and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass. Extremely low (<15°C) and high temperatures (>47°C) decreased phycobiliprotein content regardless of light intensity.

Crecimiento y composición bioquímica de <i>Thalassiosira pseudonana</i> (Thalassiosirales: Thalassiosiraceae) bajo cultivo semi-continuo en diferentes medios y niveles de irradiancias

“…Al observar las diferentes variables estudiadas y compararlas entre medios de cultivo, es posible inferir sobre la deficiencia de uno o varios nutrientes en Humus, entre ellos, los tipos y proporciones de las distintas fuentes nitrogenadas. Se ha demostrado que el nitrato como fuente de nitrógeno, ofrece mejores beneficios en cultivos intensivos que el nitrógeno amoniacal (Chaneva et al 2007). Young & Beardall (2003) mencionan sobre los cambios que sufren células microalgales en la fluorescencia de la clorofila por limitación de nitrato o adición de amonio a los cultivos; comportamiento que se ha interpretado como interacciones entre la fotosíntesis y asimilación de nitrógeno.…”

Effect of external pH on cyanobacterial phycobiliproteins production and ammonium excretion

“…These pigments could be used as natural colorants for food and cosmetic products as well as molecular fluorescent markers, depending on their purity grade [2]. The use of phycobiliproteins as non-toxic and non-carcinogenic natural food colorants is gaining importance because of the potential toxicity and carcinogenicity of the currently used synthetic food colourants or additives [3]; [4]. US$ 1500 mg -1 for highly purified molecular markers (with antibodies or other fluorescent molecules).…”

Modulation of phycobiliprotein production in Nostoc muscorum through culture manipulation

“…These are common lightharvesting proteins with chromatic sensors, which are non-toxic and non-carcinogenic natural food colorants, a much needed alternative to the widely used synthetic food colorants/additives having toxicity and carcinogenicity [2]. Besides food and drug industry, these also have potential in cosmetic preparations by replacing the synthetic dyes [3].…”

“…Besides food and drug industry, these also have potential in cosmetic preparations by replacing the synthetic dyes [3]. The potential of cyanobacteria for commercial production of phycobiliproteins has been reported by many workers [2,4,5]. Environmental variables particularly light can influence the rate of photosynthesis and growth of cyanobacteria as these are photoautotrophs [6].…”