Efficient phenanthrene biodegradation by nitrogen-fixing marine diazotrophs isolated from the Musa Estuary

Authors

1 Department of Marine Biology, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran

2 Department of Marine Chemistry, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran

10.22092/ijfs.2026.136427

Abstract

Polycyclic aromatic hydrocarbons are persistent environmental pollutants that pose significant risks to aquatic ecosystems. Microorganisms capable of degrading hydrocarbons under nitrogen-limited conditions may provide an effective and sustainable approach for the bioremediation of contaminated environments. In this study, four putative diazotrophic bacterial isolates were obtained from water and sediment samples of the Musa Estuary (Persian Gulf). The isolates were identified as Bacillus cereus strain BP1, Bacillus subtilis strain BP2, Microbacterium sp. strain BP3, and Microbacterium trichothecenolyticum strain BP4, based on morphological, biochemical, and 16S rRNA gene analyses. HPLC quantified phenanthrene biodegradation. All isolates were able to grow in a nitrogen-free medium supplemented with phenanthrene and exhibited high phenanthrene degradation efficiencies, ranging from 85.56% to 93.44%. Among the tested isolates, Microbacterium sp. strain BP3 achieved the highest degradation efficiency, whereas Bacillus subtilis strain BP2 exhibited the lowest. These findings highlight the potential of indigenous estuarine bacteria adapted to nitrogen-limited conditions for the biodegradation of PAHs and suggest their possible application in the bioremediation of contaminated marine environments.

Keywords

Iranian Journal of Fisheries Sciences
Volume 25, Issue 6
November 2026
Pages 947-965

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