Isolation And Identification Of Anaerobic Bacteria Capable Of Degrading Benzoate And Reducing Fe(?) Oxides

Petroleum is an important energy,while promoting economic development,it also has a huge impact and pollution on the environment.A variety of petroleum pollutants such as alkanes,cycloalkanes,aromatic hydrocarbons,polycyclic aromatic hydrocarbons,etc.enter soil through natural sedimentation,seriously threaten ecological security and human health.Anaerobic biodegradation is an effective method for remediation of PAHs pollution.In this study,anaerobic bacteria capable of degrading benzoate(an intermediate product of PAHs degradation)were isolated and purified from petroleum-contaminated soils using benzoate as electron donor and Fe(?)oxide as electron acceptor.Two of these isolates were systematically identified,and functional genes for benzoate degradation coupled with iron reduction were analyzed.The main results are as follows:1.Seven benzoate-degrading anaerobes were successfully isolated,among which two potential novel strains(Jerry-YX~T and PLL0~T)were studied systematically.The results showed that strain Jerry-YX~T is a strictly anaerobic gram-negative bacterium,which showed the highest 16S r RNA gene sequence similarity to Geobacter metallireducens GS-15~T(98.2%similarity);the d DDH value of strain Jerry-YX~T and GS-15~T is 35.4%.Strain PLL0~T is a strictly anaerobic gram-positive bacterium.The16S r RNA gene sequence similarity to its closest relative,Paradesulfitobacterium aromaticivorans UKTL~T,is 95.4%.The results of the polyphasic study allowed the differentiation of strains Jerry-YX~T and PLL0~T from its closest species,which suggested that strains Jerry-YX~Tand PLL0~T represent novel species and genus,respectively.The name for the proposed new species and genus is Geobacter benzoelyticum sp.nov.and Paradesulfitobacterium ferrireducens gen.nov.,sp.nov.,respectively.2.Both strains Jerry-YX~T and PLL0~T can degrade benzoate anaerobically with Fe(?)as the electron acceptor.Genomic analysis results showed that in the Jerry-YX~T genome there are 54 cytochrome c coding genes that are potentially involved in Fe(?)reduction,and 3 genes related to the anaerobic degradation of benzoate;In the genome of strain PLL0~T,there are 14 genes potentially involved in the process of anaerobic degradation of benzoate but only 3 cytochrome c coding genes.The role of these genes in Fe(?)reduction and benzoate degradation needs to be further explored.