Carotenoids’ influence on radiotolerance of Pantoea agglomerans , a plant pathogen

Aim:  The aim of this study was to evaluate the effect of γ radiation on the carotenoid content of two strains of the Enterobacteriaceae : Pantoea agglomerans . Methods and Results:  Pantoea agglomerans strains ATCC 49174 and RL1 were used for this study. Successive radiation treatments were performed to study the radiotolerance. Total carotenoids were obtained by multiple extraction using chloroform/methanol (2 : 1), quantified by measuring the optical density at 453 nm and their antioxidant activity measured by a colorimetric method. The D 10 studies were conducted using a UC‐15A irradiator loaded with 60 Co. Bacterial counts from various dilutions were carried out after irradiation. Strain ATCC 49174 irradiated at 1 kGy produced 4·3 times more carotenoids than the control, whereas carotenoid synthesis increased by 2·9‐fold in the strain RL1. However, there was no significant difference in the D 10 values. Conclusion:  Carotenoid increased production is influenced by γ radiation but does not modify the tolerance to radiations. Significance and Impact of the Study:  To our knowledge, this is the first study to demonstrate the effects of γ radiation on carotenoid production levels.