hcnABC Operon Transcription of Pseudomonas putida Under Varying Iron and Oxygen Concentrations and Culture Age

The species Pseudomonas putida produces hydrogen cyanide (HCN) through the transcription of the hcnABC operon. Previous research by Myrna Biswas (2010) demonstrated that microaerobic +FeCl3 cultures had the greatest HCN production, but the effects of varying iron and oxygen levels on HCN production were unclear. Isaac Kim (2011) assessed HCN production of P. putida in sand versus soil using different iron concentrations and found that iron was necessary for HCN production. The purpose of this experiment was to determine how the hcnABC operon is affected by varying levels of iron and oxygen, and the age of bacteria culture. To test this, P. putida was grown under four conditions: the presence of iron, the absence of iron, with aeration, and without aeration. At 8, 18, and 30 hours, the cultures were assessed for HCN production and cell density. HCN production was measured via bioluminescence; light emission occurs whenever HCN is produced because the modified form of P. putida contains the luciferase gene. The cell density was determined using spread plating. Bacterial cultures with iron and minimal aeration had higher bioluminescence levels, suggesting these conditions promote HCN production, but these results were not significant (F(3,2) = 0.561, p = 0.05)