Q.25 Which of the following essential element(s) is/are required as major supplement to enhance the
bioremediation of oil spills by the resident bacteria?
(A) Sulfur (B) Nitrogen and phosphorus
(C) Iron (D) Carbon
Essential Nutrients for Oil Spill Bioremediation: Nitrogen and Phosphorus Key to Enhancing Bacterial Degradation
Oil spills pose severe environmental threats, but bioremediation using resident bacteria offers an eco-friendly cleanup solution. The major supplements needed to boost this process are nitrogen and phosphorus, making option (B) the correct answer in this multiple-choice question.
Correct Answer
The correct answer is (B) Nitrogen and phosphorus. Oil spills create nutrient-limited environments, especially in marine settings where hydrocarbons abound but nitrogen (N) and phosphorus (P) are scarce. Resident bacteria like Pseudomonas species degrade oil via enzymes, but their growth explodes with N and P fertilizers, accelerating hydrocarbon breakdown into CO₂ and water. This biostimulation was proven in the 1989 Exxon Valdez spill, where shoreline fertilizers tripled biodegradation rates.
Option Analysis
(A) Sulfur
Sulfur supports some microbial metabolism but is not a major supplement for oil-degrading bacteria. Oil already contains sulfur compounds like thiophenes, so additional sulfur rarely limits bioremediation. Studies show it plays a minor role compared to N and P.
(B) Nitrogen and Phosphorus
These macronutrients are critical as bacteria need them for proteins, DNA, and ATP during rapid oil metabolism. Oil spills cause C:N:P imbalances (high carbon from hydrocarbons), so supplements like urea (N) and phosphates restore ratios like 100:10:1, boosting degradation 5-10 fold. Field trials confirm this enhances resident consortia without introducing foreign microbes.
(C) Iron
Iron acts as a cofactor in enzymes like monooxygenases for alkane breakdown, but seawater provides ample iron via natural chelation. It’s a trace element, not a major supplement, and excess can be toxic.
(D) Carbon
Carbon is abundant in oil spills as the pollutant itself serves as the bacteria’s energy source. Supplementing more carbon would hinder remediation by fueling unwanted growth without targeting degradation.
Bioremediation Mechanism
Resident bacteria oxidize hydrocarbons through beta-oxidation and ring cleavage, limited by nutrient scarcity post-spill. Adding N and P via slow-release fertilizers ensures safe, cost-effective cleanup over chemical dispersants. This suits biotech applications in marine pollution control.
