Premium
Root exudates modify bacterial diversity of phenanthrene degraders in PAH‐polluted soil but not phenanthrene degradation rates
Author(s) -
Cébron Aurélie,
Louvel Brice,
Faure Pierre,
FranceLanord Christian,
Chen Yin,
Murrell J. Colin,
Leyval Corinne
Publication year - 2011
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2010.02376.x
Subject(s) - phenanthrene , exudate , stable isotope probing , biology , arthrobacter , bacteria , 16s ribosomal rna , pseudomonas , rhizosphere , microbacterium , rhodococcus , temperature gradient gel electrophoresis , microbiology and biotechnology , polycyclic aromatic hydrocarbon , soil microbiology , pseudomonas putida , food science , botany , microorganism , genetics , astrobiology
Summary To determine whether the diversity of phenanthrene‐degrading bacteria in an aged polycyclic aromatic hydrocarbon (PAH) contaminated soil is affected by the addition of plant root exudates, DNA stable isotope probing (SIP) was used. Microcosms of soil with and without addition of ryegrass exudates and with 13 C‐labelled phenanthrene (PHE) were monitored over 12 days. PHE degradation was slightly delayed in the presence of added exudate after 4 days of incubation. After 12 days, 68% of added PHE disappeared both with and without exudate. Carbon balance using isotopic analyses indicated that a part of the 13 C‐PHE was not totally mineralized as 13 CO 2 but unidentified 13 C‐compounds (i.e. 13 C‐PHE or 13 C‐labelled metabolites) were trapped into the soil matrix. Temporal thermal gradient gel electrophoresis (TTGE) analyses of 16S rRNA genes were performed on recovered 13 C‐enriched DNA fractions. 16S rRNA gene banding showed the impact of root exudates on diversity of PHE‐degrading bacteria. With PHE as a fresh sole carbon source, Pseudoxanthomonas sp. and Microbacterium sp. were the major PHE degraders, while in the presence of exudates, Pseudomonas sp. and Arthrobacter sp. were favoured. These two different PHE‐degrading bacterial populations were also distinguished through detection of PAH‐ring hydroxylating dioxygenase (PAH‐RHD α ) genes by real‐time PCR. Root exudates favoured the development of a higher diversity of bacteria and increased the abundance of bacteria containing known PAH‐RHD α genes.