Metabolic potential of Azotobacter alginate producers and sustainable alternatives for alginate extraction

Abstract

This research aimed to assess the metabolic activities of Azotobacter vinelandii DT1 strain by assaying its alginate synthesizing enzymes and modifying genes, synthesize alginate from the agricultural residues, and eradicate the pathogenicity and risk associated with Pseudomonas aeruginosa alginate. Preliminary screening for alginate production revealed the presence of different alginate products. High-performance liquid chromatography (HPLC) confirmed the existence of varying alginate concentrations, such as sodium alginate (2.42754×10-1 g/ 100 ml), calcium alginate (1.09597×10-1 g/ 100 ml), acid alginate (1.39420×10-2 g/ 100 ml), alginate oligosaccharide (8.20576×10-2 g/100 ml), and potassium alginate (9.78836×10-2 g/ 100 ml). These were accompanied with the corresponding alginate synthesizing enzymes; mainly GDP-Mannose dehydrogenase (23.77± 0.13 U/ ml); glycosyltransferase (9.68± 0.53 U/ ml), phosphomannomutase (266.09± 0.16 U/ ml), mannose phosphate isomerase (95.87± 0.51 U/ ml), alginate lyase (24.50± 0.95 U/ ml), and mannuronan epimerase (49.93± 0.82 U/ ml). In this study, the expression of alginate-modifying genes such as alginate lyase and GDP-Mannose dehydrogenase amplicons of Azotobacter vinelandii DT1 strain corresponding to 766 bp, 43 ng and 600 bp, 33 ng molecular weights of the fast DNA marker; justified the synthesis of different alginate products. Azotobacter alginate synthesis using a low-cost substrate (i.e., corn cobs) and completely non-pathogenic bacteria (Azotobacter vinelandii DT1) may be desirable compared to the pathogenicity risks and poor jellying qualities linked to Pseudomonas alginate biosynthesis, its expensive production costs, and the adverse environmental effects of seaweed harvesting and processing.

Keywords

• alginate lyase
• gdp-mannose dehydrogenase
• mannose phosphate isomerase