Isolation, biocharacterization, and wastewater treatment potential of purple photosynthetic bacterial strain from Lap An Lagoon, Vietnam

Abstract

The growth of the seafood industry, particularly aquaculture, will play a crucial role in enhancing global food security and driving economic growth, especially in nations such as Vietnam, where it is supporting the livelihoods of millions. However, the rapid expansion of aquaculture has brought about environmental issues, notably the discharge of nutrient-rich wastewater. While microbial treatments are well-established in wastewater management, the application of purple photosynthetic bacteria (PPB) in saline aquaculture systems remains underexplored. This study isolated and characterized a novel purple photosynthetic bacterial strain, LA5.1, from Lap An Lagoon in Vietnam. Strain LA5.1 exhibited robust growth across a salinity range of 0 to 30%o and reduced the chemical oxygen demand (COD) by 60–80% within six days, even when the initial COD concentration was as high as 800 mg/L. Additionally, the strain efficiently removed up to 80% of total ammonia nitrogen (TAN) in saline environments, demonstrating its robust potential in bioremediation. A phylogenetic analysis of the 16S rRNA gene confirmed the identity of the strain as Rhodopseudomonas julia. These findings indicate that R. julia LA5.1 is a promising candidate for sustainable aquaculture wastewater treatment systems, offering significant potential for large-scale applications in addressing the environmental challenges associated with intensive aquaculture practices.