Open AccessExpansion of ability of denitrification within the filamentous colorless sulfur bacteria of the genus T hiothrix
Author(s) -
Trubitsyn Ivan V.,
Belousova Elena V.,
Tutukina Maria N.,
Merkel Alexander Y.,
Dubinina Galina A.,
Grabovich Margarita Y.
Publication year - 2014
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12548
Subject(s) - denitrifying bacteria , nitrite reductase , biology , nitrous oxide reductase , bacteria , denitrification , nitrite , nitrate reductase , microbiology and biotechnology , biochemistry , nitrate , chemistry , enzyme , ecology , genetics , nitrogen , organic chemistry
Filamentous sulfur bacteria of the genus T hiothrix are able to respire nitrate ( NO 3 − → NO 2 − ) under anaerobic growth. Here, T hiothrix caldifontis ( G 1 T , G 3), T hiothrix unzii ( A 1 T , TN ) and T hiothrix lacustris AS were shown to be capable of further reduction of nitrite and/or nitrous oxides (denitrification). In particular, in the genomes of these strains, excluding T . unzii TN , the nirS gene encoding periplasmic respiratory nitrite reductase was detected, and for T . lacustris AS the nirS expression was confirmed during anaerobic growth. The nirK gene, coding for an alternative nitrite reductase, and the nrfA gene, encoding nitrite reduction to ammonia, were not found in any investigated strains. All T hiothrix species capable of denitrification possess the cnorB gene encoding cytochrome c‐dependent NO reductase but not the qnorB gene coding for quinol‐dependent NO reductase. Denitrifying capacity (‘full’ or ‘truncated’) can vary between strains belonging to the same species and correlates with physical‐chemical parameters of the environment such as nitrate, hydrogen sulfide and oxygen concentrations. Phylogenetic analysis revealed the absence of recent horizontal transfer events for narG and nirS ; however, cnorB was subjected to gene transfer before the separation of modern species from a last common ancestor of the T hiothrix species.