Accumulation of Exopolysaccharides in Liquid Suspension Culture of Nostoc flagelliforme Cells

Abstract

The liquid suspension culture of dissociated Nostoc flagelliforme cells was investigated. It was found that the growth rate of N. flagelliforme cells and the accumulation of exopolysaccharides (EPS) increased prominently when NaNO(3) and KH(2)PO(4) were added in the liquid BG-11culture medium though phosphate had little effect on EPS yield for specific mass of cells. N. flagelliforme cells grew well at 25 degrees C and neutral pH, however, a lower or higher temperature and weak alkaline can promote EPS accumulation. With the increase of the light intensity, the growth rate of N. flagelliforme cells and the EPS accumulation increase accordingly. When N. flagelliforme cells was cultured in BG-11 medium added with 2.5 g L(-1) of NaNO(3) and 0.956 g L(-1) of KH(2)PO(4) at 25 degrees C with 60 micromol photon m(-2) s(-1) of light intensity, 1.05 g L(-1) cell density and 89.9 mg L(-1) EPS yield were achieved respectively. Adopting the optimal conditions established in flask culture, the liquid culture of N. flagelliforme cells in 20-L photobioreactor for 16 days was conducted and a maximum biomass of 1.32 g L(-1) was achieved, which was about 17.6-fold of that in the initial inoculation. The yield of EPS was 228.56 mg L(-1)and about 2.23-fold of that in flask culture. Moreover, the polysaccharides' material was released into the culture medium during cell growth. These released polysaccharides (RPSs), which can be easily recovered from the medium, are favorable for industrial applications.

The effects of the exopolysaccharide and growth rate on the morphogenesis of the terrestrial filamentous cyanobacterium Nostoc flagelliforme

“…Many species of cyanobacteria, including N. flagelliforme , show a combined nitrogen-dependent rapid growth and EPS synthesis in liquid culture conditions (Otero and Vincenzini, 2003; Pereira et al, 2009; Yu et al, 2010). However, the trichomes or micro-colonies of N. flagelliforme could be induced to exhibit relatively straight elongation in nitrogen-free BG11 0 solution (Rippka et al, 1979), as described in the Materials and Methods (Fig.…”

“…The relative proportion of strip-like N. flagelliforme is also found to increase on relatively humid slopes or shaded lands. Liquid-cultured N. flagelliforme has been developed and serves as a valuable source for producing EPS (Gao and Ye, 2003; Su et al, 2008; Yu et al, 2010; Han et al, 2014a). In a long-term induction (1–3 months) by low ultraviolet (UV)-B radiation and/or periodic desiccation, single trichomes from the liquid culture could develop into colonial filaments 1–3 cm long on solid media (Feng et al, 2012).…”

Using extracellular polymeric substances (EPS)-producing cyanobacteria for the bioremediation of heavy metals: do cations compete for the EPS functional groups and also accumulate inside the cell?

“…This type of linear growth is not unknown for cyanobacteria, particularly for strains that produce large amounts of structured extracellular polysaccharides, and may be related to the considerable amount of energy spent in the production of EPS and the physical constraints caused by these extracellular complex structures (Yu et al, 2009(Yu et al, , 2010. The higher tolerance exhibited by Gloeothece wild-type and mutant for Pb 2+ strongly indicates that these organisms are more severely affected by Cu 2+ than by Pb 2+ .…”

Effects of light intensity on components and topographical structures of extracellular polysaccharides from the cyanobacteria Nostoc sp.

“…Several recent studies on the influence of light intensity (Friedman et al, 1991;Moreno et al, 1998;Otero and Vincenzini, 2003;Trabelsi et al, 2009;Yu et al, 2010;Mota et al, 2013) and wavelengths (Ehling-Schulz et al, 1997;Chen et al, 2009) on EPS yield have been reported. Different light regimens (continuous light and light-dark cycles) do not significantly affect the monosaccharidic composition of EPS (Vincenzini et al, 1993;De Philippis and Vincenzini, 1998).…”

“…1). (Friedman et al, 1991;Moreno et al, 1998;Otero and Vincenzini, 2003;Trabelsi et al, 2009;Yu et al, 2010;Mota et al, 2013), suggesting that energy availability significantly affects the EPS biosynthesis of cyanobacteria. Higher light intensity results in higher EPS production, which may constitute mechanism of releasing the excess energy absorbed by the cells (Mota et al, 2013) and increasing CO2 fixation rate in the cells under high light intensity.…”