Growth and special structures production of Nostoc paludosum (Nostocaceae, Cyanobacteria) under nutrient starvation and different light intensities

Abstract

The effects of the absence of nitrogen and phosphorus on AA media and three different light intensities (100% Light, 60.0± 2.7 μmol m-2 s-1, 50% Light, 30.0± 2.7 μmol m-2 s-1, and 13.5% Light, 8.1± 2.7 μmol m-2 s-1) on cell production and synthesis of heterocytes and akinetes were determined in a strain of Nostoc paludosum. In the experiment concerning the absence of nutrients, significant variations were observed between the control group and the groups with absence of nutrients, especially in cell numbers and in synthesis of heterocytes and akinetes. The absence of nitrogen boosted the formation of heterocytes and the absence of phosphorus produced the most akinetes. As for the different light conditions, the growth curves determined for each treatment showed that cell synthesis is slightly affected by the reduction of illuminance. The different light intensities are capable of reducing the maximum growth rates of Nostoc paludosum, with 13.5% light restriction being the most effective on limiting the cell growth rate and inducing the formation of akinetes. The synthesis of heterocyte does not seem directly correlated to light intensity, being better explained by nutritional factors. The data found contributes to the understanding of some of the factors involving growth and synthesis of special structures in Nostoc paludosum.

Survival and Development Strategies of Cyanobacteria through Akinete Formation and Germination in the Life Cycle

“…Reducing the light intensity from 60 µmol m s −2−1 to 8.1 µmol m −2 s −1 induced a 50-fold increase in akinete formation, whereas vegetative cell growth showed the opposite trend. Moreover, akinetes formed at high light intensity were significantly smaller in size [63]. Consistent with the hypothesis suggesting that light restriction induces akinete formation, studies have reported that self-shading by a high density of cells during cyanobacteria bloom leads to an explosion of akinetes in situ [72] and experimental culture conditions [11].…”

“…On the other hand, Nostoc paludosum promoted akinete formation under very low light conditions (experimental condition: temperature 25 • C, light 60, 30, 8.1 µmol m −2 s −1 , AA medium) (Figure 2. 12 ⃝) [63]. Reducing the light intensity from 60 µmol m s −2−1 to 8.1 µmol m −2 s −1 induced a 50-fold increase in akinete formation, whereas vegetative cell growth showed the opposite trend.…”

“…It has long been known that nutrient limitation affects cyanobacteria growth and is a potential factor in akinete formation [43,63,79,80]. However, some researchers have reported that nutrient deficiencies do not necessarily induce akinete formation [34,61,76].…”

Effect of Ultraviolet-C Radiation on the Morphology of Cyanobacteria Nostoc sp. LBALBR-2 Isolated from Supply Reservoir (Belém, Pará, Brazil)

“…On the other hand, lack of nutrients generated short trichomes with terminal heterocytes and scattered solitary akinetes. On this, Dextro et al (2018) observed that the absence of nutrients, especially nitrogen, induces heterocyte formation and low light intensity induces akinetes formation in Nostoc strains.…”

Ciências Biológicas e da Saúde: Investigação e Prática II

“…É possível relacionar a redução na capacidade fotossintética com a diminuição na densidade celular, uma vez que células expostas a estresse tendem a não se dividir a fim de sobreviver (PERALES-VELA et al, 2007). Este efeito já foi relatado também em cianobactérias e em co-cultivos de microalgas (DEXTRO et al, 2018;DEXTRO, 2021).…”