Aims It was aimed to study the genetic, structural and pharmacological characteristics of polymannuronate synthesized by Pseudomonas aeruginosa CMG1421. Methods and Results Synthesis was analysed by transmission electron microscopy, FT/IR, H-1-NMR and gel permeation chromatography followed by in vitro bioassays. Colony PCR followed by sequence analysis was employed for screening of structural genes. FT/IR analysis indicated the presence of hydroxyl, carboxyl and O-acetyl groups linked to mannuronate. H-1-NMR analysis indicated M-M bond characteristics for mannuronic acid residues. The average relative molecular weight was found in range of 20 000-250 000 Da. The amplified DNA fragments were identified as 16S rRNA, algD, alg8, alg44, algG, algE and algX genes showing 99-100% homology with those of P. aeruginosa. However, in algG there were transition mutations of adenine and cytosine at nucleotide position 766 and 769, and 878 and 881 respectively. Polymannuronate and its oligomannuronates respectively showed moderate and significant antioxidant, anti-inflammatory, anti-obesity and antidiabetic activities. Conclusions Alginate synthesized by increment algG mutant P. aeruginosa CMG1421 was bioactive and solely consists of acetylated d-mannuronates. Significance and Impact of the Study We investigated biocompatible, nonimmunogenic and nontoxic pharmacological agents for treatment and attenuation of degenerative, inflammatory, autoimmune disease, and metabolic disorders such as obesity and diabetes.