Selenium Biotransformation By Bacteria Isolated From Lahore And Exploring Their Biochemical Properties
Abstract
Background: Selenium is an important micronutrient for living organisms. However, its higher concentrations can be toxic to ecosystems due to its high bioavailability. In biogeochemical cycles, selenite is converted into elemental selenium by microorganisms. These processes can help depollute the environment and promote eco-friendly practices. The purpose of this study was to examine the distribution, diversity, and potential of selenite-reducing bacteria from samples of Lahore, Pakistan.
Materials & Methodology: The experiment involved the collection of a total of 6 different water and soil samples from all over Lahore. These samples were processed within 24 hours. Samples were grown on nutrient agar supplemented with 400 µg/mL sodium selenite. Twenty selenite-reducing isolates were collected and further tested for morphological, biochemical, physiological, and plant growth-promoting characteristics. Biochemical tests included catalase, oxidase, starch hydrolysis, nitrate reduction, MR/VP, citrate, and urease. Functional traits like producing indole-3-acetic acid, ammonia, and phosphate solubilization were examined to check for plant growth-promoting potential. The bacterial response to antibiotics and resistance to heavy metals was also tested. Physiological responses were measured under varying pH, temperature, salinity, and selenite concentrations using optical density at 500 nm. The data were analyzed descriptively and comparatively.
Results: The results showed that all samples reduced selenite and formed red elemental selenium. Most of the isolates were positive for catalase, oxidase, and nitrate reduction. This showed strong metabolic and redox potential. Many isolates produced significant amounts of auxin and ammonia, though no phosphate solubilization activity was observed. Discrete patterns of antibiotic and multidrug resistance were recorded among strains. The best selenite reduction occurred at optimal pH and temperature.
Conclusion: Significant ecological and metabolic versatility and the ability to promote plant growth were recorded in these bacteria native to Lahore. This indicates that they have great potential to be used for selenium bioremediation and sustainable agriculture practices.
