Isolation and identification of the alga-symbiotic bacterium Gordonia and characterisation of its exopolysaccharide

Abstract

An exopolysaccharide (EPS)-producing bacterium TD18, isolated from the culture broth of green alga Scenedesmus obliquus, was identified as Gordonia terrae based on the 100% identity of 16S rRNA sequences and designated Gordonia terrae TD18. The results of compositional and structural analyses and physiochemical tests show that (1) the exopolysaccharide produced by G. terrae TD18 (TD18-EPS) is an acidic hetero-polysaccharide with a molecular weight of 23 kDa, consisting of glucose, mannose, galactose and glucuronic acid, and (2) TD18-EPS is of high thermal stability with a degradation temperature of 308 °C, the solution of which is non-Newtonian pseudoplastic fluid exhibiting good emulsifying properties over a wide range of temperatures, pH and NaCl concentrations. Hence, Gordonia terrae TD18 is the first alga-symbiotic Gordonia strain identified thus far, while TD18-EPS is unique in terms of composition and structure, different from the known Gordonia EPS, with excellent physiochemical properties and thus has potential applications in industry.

Graphical Abstract

Keywords:

• Gordonia terrae
• alga-symbiotic
• exopolysaccharide
• NMR spectrum
• emulsifying activity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (grant number 22002033) and the Natural Science Foundation of Hebei Province, China (grant number D2020202004).