The abundant occurrence of hydrocarbon-utilizing bacteria in the phyllospheres of cultivated and wild plants in Kuwait

Thirteen cultivated and four wild plant species from Kuwait harbored on their leaves cultivable hydrocarbon-utilizing bacteria in the magnitude of 103–104 colony forming units g−1. According to their 16S rRNA gene sequences, these bacteria belonged predominantly to the subdivisions Actinobacteria and Firmicutes. Leaves of each of the studied plant species accommodated between 3 and 14 different bacterial species, whose identities varied from one plant species to another. Those bacteria belonged totally to 27 genera; the most frequent of which were Microbacterium, Kocuria, Arthrobacter, Agrococcus, Bacillus, Klebsiella, Planomicrobium and Rhodococcus. Individual representative bacterial isolates grew on aromatic hydrocarbons better than on the aliphatics. Most isolates grew on all tested n-alkanes with carbon chains ranging between C10 and C40, although as expected, each isolate grew best on a rather narrow range of alkanes. Bacterial consortia on leaves of the studied plant species comprised partners capable of utilizing a broad hydrocarbon spectrum of the crude oil. It was concluded that cropping and vegetation could be feasible managements for removing atmospheric hydrocarbon pollutants via the hydrocarbon-utilizing bacteria associated with the plant leaves.