A Novel Study on Anionic Surfactant Degradation Potential of Psychrophillic and Psychrotolerant Pseudomonas spp. Identified from Surfactant-contaminated River Water

The Yamuna River, a tributary of the holy Ganga, is heavily polluted in the Delhi-NCR region, India and has been gaining attention due to the excessive foaming of the river over the past few years. This can be directly or indirectly related to the overuse of surfactants and the discharge of untreated domestic and textile wastewater into the river. To determine the surfactant load and investigate potential surfactant-degrading bacteria in the region, 96 water samples from four sites in the Okhla Barrage stretch of the river were collected and analysed. The results showed that the selected sites have surfactant concentrations more than the permissible limit (1.00 mgL⁻¹). Also, at most of the sites, the concentration crossed the desirable limit of BIS (0.2 mgL⁻¹) during the period of analysis. The concentration of anionic surfactant reported in the region was found in the range of 0.29 mgL⁻¹ and 2.83 mgL⁻¹. A total of 38 different bacteria were isolated using selective media from the same water samples, out of which 7 bacterial isolates were screened for sodium dodecyl sulphate (SDS) tolerance activity. Based on 16S rRNA gene sequencing, 2 species, namely Pseudomonas koreensis YRW-02 and Pseudomonas songnenensis YRW-05 have been identified and their degradation potential was assessed at different SDS concentrations. The results showed that our strains YRW-02 and YRW-05 degraded 78.29 and 69.24% of SDS respectively. Growth optimization was also performed at different substrate concentrations, pH, and temperature to investigate optimum degradation conditions. This study plays a significant role in assessing the surfactant load and also gives a promising background for future use in in-situ bioremediation experiments.