Open AccessAnaerobic naphthalene degradation by G ram‐positive, iron‐reducing bacteria
Author(s) -
Kleemann Rita,
Meckenstock Rainer U.
Publication year - 2011
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2011.01193.x
Subject(s) - biology , bacteria , gram , microbiology and biotechnology , anaerobic exercise , degradation (telecommunications) , gram positive bacteria , naphthalene , gram negative bacteria , biochemistry , escherichia coli , physiology , chemistry , genetics , organic chemistry , telecommunications , computer science , gene
An anaerobic naphthalene‐degrading culture ( N 49) was enriched with ferric iron as electron acceptor. A closed electron balance indicated the total oxidation of naphthalene to CO 2 . In all growing cultures, the concentration of the presumed central metabolite of naphthalene degradation, 2‐naphthoic acid, increased concomitantly with growth. The first metabolite of anaerobic methylnaphthalene degradation, naphthyl‐2‐methyl‐succinic acid, was not identified in culture supernatants, which does not support a methylation to methylnaphthalene as the initial activation reaction of naphthalene, but rather a carboxylation, as proposed for other naphthalene‐degrading cultures. Substrate utilization tests revealed that the culture was able to grow on 1‐methyl‐naphthalene, 2‐methyl‐naphthalene, 1‐naphthoic acid or 2‐naphthoic acid, whereas it did not grow on 1‐naphthol, 2‐naphthol, anthracene, phenanthrene, indane and indene. Terminal restriction fragment length polymorphism and 16 S r RNA gene sequence analyses revealed that the microbial community of the culture was dominated by one bacterial microorganism, which was closely related (99% 16 S sequence similarity) to the major organism in the iron‐reducing, benzene‐degrading enrichment culture BF [ ISME J (2007) 1: 643; Int J Syst Evol Microbiol (2010) 60: 686]. The phylogenetic classification supports a new candidate species and genus of G ram‐positive spore‐forming iron‐reducers that can degrade non‐substituted aromatic hydrocarbons. It furthermore indicates that G ram‐positive microorganisms might also play an important role in anaerobic polycyclic aromatic hydrocarbon‐degradation.