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

Abstract

The terrestrial cyanobacterium Nostoc flagelliforme, which contributes to carbon and nitrogen supplies in arid and semi-arid regions, adopts a filamentous colony form. Owing to its herbal and dietary values, this species has been overexploited. Largely due to the lack of understanding on its morphogenesis, artificial cultivation has not been achieved. Additionally, it may serve as a useful model for recognizing the morphological adaptation of colonial cyanobacteria in terrestrial niches. However, it shows very slow growth in native habitats and is easily disintegrated under laboratory conditions. Thus, a novel experimental system is necessary to explore its morphogenetic mechanism. Liquid-cultured N. flagelliforme has been well developed for exopolysaccharide (EPS) production, in which microscopic colonies (micro-colonies) are generally formed. In this study, we sought to gain some insight into the morphogenesis of N. flagelliforme by examining the effects of two external factors, the EPS and environmental stress-related growth rate, on the morphological shaping of micro-colonies. Our findings indicate that the EPS matrix could act as a basal barrier, leading to the bending of trichomes during their elongation, while very slow growth is conducive to their straight elongation. These findings will guide future cultivation and application of this cyanobacterium for ecological improvement.

Exopolysaccharides from Cyanobacteria: Strategies for Bioprocess Development

“…They are structurally similar to Gram-negative bacteria, although some features and thickness of peptidoglycan resemble Gram-positive bacteria. In nature, cyanobacterial EPS can play a variety of functions such as adhesive, structural, protection against abiotic stress, bio weathering processes, gliding motility, and nutrient repositories in phototrophic biofilms or biological soil crusts [22][23][24]. The excretion of EPS, and in particular CPS, can occur via a junctional pore complex (JPC).…”

Modeling the effects of light wavelength on the growth of Nostoc ellipsosporum

“…Hence, an increasing number of researchers are focusing on how to increase cyanobacterial bioproducts yields by optimizing specific culture conditions, such as light, pH, carbon source and nitrogen source (Andersen, 2005;Xu et al, 2019). This is closely linked to the species physiology and the requirements of each growth phase, lag and exponential (Crnkovic et al, 2017;Cui et al, 2017). Cellular division during these growth phases depends on light and nutrient availability, as those are vital for the photosynthetic system (Barsanti & Gualtieri, 2006;Celekli et al, 2009;De Oliveira et al, 2014;Crnkovic et al, 2017).…”

Biotechnological Production of the Sunscreen Pigment Scytonemin in Cyanobacteria: Progress and Strategy

“…In nitrogen-deficiency medium, the N. flagelliforme culture treated with 0.2 W•m −2 UV-B for 30 days produced nearly 5 times more scytonemin than the nontreated samples. It was also observed that a light of 60-90 µmol photons•m −2 •s −1 induced the production of scytonemin in the exopolysaccharides of N. flagelliforme culture [23].…”

“…Scytonemin does not dissolve in water, but dissolves readily in lipids. In liquid suspension culture of Nostoc flagelliforme, yellow-brown scytonemin was observed to be tightly associated with the released exopolysaccharides [23]. Scytonemin was usually extracted from samples with solvents such as 100% acetone or 100% ethyl acetate [11], 100% acetonitrile [24], 80% tetrahydrofuran [13], and methanol:ethyl acetate (1:1, v/v) [9,21].…”

“…In contrast to scytonemin, the exopolysaccharide is more widely biosynthesized in prokaryotic microorganisms with seemingly more complex mechanisms [56,57]. Without UV induction, scytonemin was rarely biosynthesized in the N. flagelliforme culture [58], but the exopolysaccharide can still be massively biosynthesized [23]. Using a non-scytonemin-producing N. punctiforme mutant, it was found that the exopolysaccharide production was more closely related to oxidative stress than UV-A radiation [59].…”