Guluronic acid content as a factor affecting turbidity removal potential of alginate

Abstract

Alginates are natural polymers composed of mannuronic and guluronic acid residues.They are currently extracted from brown algae, however, alginate can also be synthesized by some species of Azotobacter and Pseudomonas. Alginates with different proportion of mannuronic and guluronic acids are known to have different characteristics and form gels at different extents in the presence of calcium ions. The aim of this work was to investigate the usefulness of alginate as a non-toxic coagulant used in purification of drinking water. This study utilized alginates from Azotobacter vinelandii having different guluronic acid levels. These were obtained partly by changing the cultivation parameters, partly by epimerizing a purified alginate sample in vitro using the A. vinelandii mannuronan-C-5-epimerase AlgE1. The different alginates were then used for coagulation together with calcium. The results showed that turbidity removal capability was dependent on the content of guluronic acid residues. For the best performing samples the turbidity decreased from 10 NTU to 1 NTU by the use of only 2 mg/L of alginate and 1.5 mM of calcium chloride.

Growth, respiratory activity and chlorpyrifos biodegradation in cultures of Azotobacter vinelandii ATCC 12837

“…The OTR max values in the cultures of A. vinelandii in BS medium increased considerably by decreasing the filling volume (Fig. 3 ), obtaining a typical oxygen limitation and non-oxygen limitation profiles as previously reported in cultures of A. vinelandii in stirrer tank and shaken flasks (Peña et al 2007 ; Díaz-Barrera et al 2007 ; Moral et al 2016 ). In contrast, the RQ values were not modified by the filling volume.…”

Growth, respiratory activity and chlorpyrifos biodegradation in cultures of Azotobacter vinelandii ATCC 12837

“…The OTR max values in the cultures of A. vinelandii in BS medium increased considerably by decreasing the lling volume (Fig. 3), obtaining a typical oxygen limitation and non-oxygen limitation pro les as previously reported in cultures of A. vinelandii in stirrer tank and shaken asks (Peña et al 2007;Díaz-Barrera et al 2007;Moral et al 2016). In contrast, the RQ values were not modi ed by the lling volume.…”