ORIGINAL RESEARCH PAPER Enhanced degradation of hydrocarbons by gamma ray induced mutant strain of Pseudomonas putida Razia Tahseen . Muhammad Arslan . Samina Iqbal . Zafar M. Khalid . Muhammad Afzal Received: 12 September 2018 / Accepted: 1 January 2019 Ó Springer Nature B.V. 2019 Abstract Soil contamination due to petroleum hydrocarbons is a ubiquitous environmental problem for which efficient remediation alternatives are required. Application of hydrocarbons degrading bacteria with enhanced degradation potential is such an alternative. The aim of present investigation was to induce mutagenicity in Pseudomonas putida through gamma-ray irradiation for the enhanced degradation of crude oil. A total of mutant 10 bacterial strains (300A-J) were screened for their degradation abilities in vitro; among which the performance of 300-B was outstanding. Subsequently, spiked soil (30 g/kg crude oil) was augmented with the wild-type parent strain and mutant 300-B strain in individual experiments. Bacterial inoculation in both experiments enhanced hydrocarbons degradation; however, degradation was 46.3% higher when 300-B mutant strain was employed. This improved oil degradation was found to have a strong positive correlation with the gene abundance and expression of the mutant strain, suggesting its successful survival and catabolic poten- tial in situ. Concomitantly, a better nutrients assimi- lation and water utilization was observed in the experiment containing 300-B mutant. Yet prelimi- nary, these findings highlight the importance of gamma ray irradiation towards improved degradation potential of previously isolated hydrocarbons degrad- ing bacteria. Keywords Pseudomonas putida Á Gamma ray mutation Á Biodegradation Á Crude oil Á Metabolic activity Introduction Petroleum products and their derivatives are widely used chemicals in modern society. From exploration to transportation, considerable amounts of oily sludge and/or hydrocarbons polluted water are generated inevitably (Afzal et al. 2014; Khan et al. 2013a; Rehman et al. 2018). Their unwarranted presence in the soil affects natural biogeochemical processes as well as the growth of biotic entities (Afzal et al. 2013; Kirk et al. 2005; Rehman et al. 2019). If persist longer, these compounds are toxic to animal and plant health R. Tahseen Á M. Arslan (&) Á S. Iqbal Á M. Afzal (&) Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P.O. Box 577, Jhang Road, Faisalabad, Pakistan e-mail: arsilan324@gmail.com M. Afzal e-mail: manibge@yahoo.com M. Arslan Environmental Biotechnology Department, Helmholtz Centre for Environmental Research, Leipzig, Germany Z. M. Khalid Biotechnology Department, Islamic International University, Islamabad, Pakistan 123 Biotechnol Lett https://doi.org/10.1007/s10529-019-02644-y