Isolation and Characterisation of the Agarolytic Bacterium Pseudoalteromonas Ruthenica

Agar is a polysaccharide that primarily constitutes the cell wall of red algae. It is a good source of carbon and energy for many microbes. In the present study, an agarolytic bacterium, UQAD-3, was obtained from the waters of Al-Uqair, the Arabian Gulf, Al-Ahsaa, Saudi Arabia. UQAD-3 exhibited agarolytic activity when grown on agar as the sole source of carbon and energy. The strain was identified as Pseudoalteromonas ruthenica based on comparative analysis of the 16S rRNA, with 99.6% similarity. This finding was further confirmed by phylogenetic analyses based on 16S rRNA gene sequences, which highlighted that UQAD-3 was assembled within the Pseudoalteromonas clade and constituted a monophyletic subcluster with P. ruthenica, KMM 300^T. The strain was further characterised biochemically using the Biolog Gen III microtest system. UQAD-3 showed positive reactions to 16 (17%) of the 94 diverse traits assessed. Good growth was reported in 10% NaCl indicating its moderate halophilic nature. These observations indicate the agarolytic potential of the strain and opens new horizons for industrial applications in the future.