Analysis of the Genes Involved in Thiocyanate Oxidation during Growth in Continuous Culture of the Haloalkaliphilic Sulfur-Oxidizing Bacterium Thioalkalivibrio thiocyanoxidans ARh 2(T) Using Transcriptomics

作者：Berben Tom; Balkema Cherel; Sorokin Dimitry Y; Muyzer Gerard

来源：mSystems, 2017, 2(6): UNSP e00102-17.

DOI：10.1128/mSystems.00102-17

<jats:title>ABSTRACT</jats:title>
<jats:p>
Thiocyanate (N=C−S
<jats:sup>−</jats:sup>
) is a moderately toxic, inorganic sulfur compound. It occurs naturally as a by-product of the degradation of glucosinolate-containing plants and is produced industrially in a number of mining processes. Currently, two pathways for the primary degradation of thiocyanate in bacteria are recognized, the carbonyl sulfide pathway and the cyanate pathway, of which only the former has been fully characterized. Use of the cyanate pathway has been shown in only 10 strains of
<jats:italic>Thioalkalivibrio</jats:italic>
, a genus of obligately haloalkaliphilic sulfur-oxidizing
<jats:italic>Gammaproteobacteria</jats:italic>
found in soda lakes. So far, only the key enzyme in this reaction, thiocyanate dehydrogenase (TcDH), has been purified and studied. To gain a better understanding of the other genes involved in the cyanate pathway, we conducted a transcriptomics experiment comparing gene expression during the growth of
<jats:italic>Thioalkalivibrio thiocyanoxidans</jats:italic>
ARh 2
<jats:sup>T</jats:sup>
with thiosulfate with that during its growth with thiocyanate. Triplicate cultures were grown in continuous substrate-limited mode, followed by transcriptome sequencing (RNA-Seq) of the total mRNA. Differential expression analysis showed that a cluster of genes surrounding the gene for TcDH were strongly upregulated during growth with thiocyanate. This cluster includes genes for putative copper uptake systems (
<jats:italic>copCD</jats:italic>
, ABC-type transporters), a putative electron acceptor (
<jats:italic>fccAB</jats:italic>
), and a two-component regulatory system (histidine kinase and a σ
<jats:sup>54</jats:sup>
-responsive Fis family transcriptional regulator). Additionally, we observed the increased expression of RuBisCO and some carboxysome shell genes involved in inorganic carbon fixation, as well as of
<jats:italic>aprAB</jats:italic>
, genes involved in sulfite oxidation through the reverse sulfidogenesis pathway.
</jats:p>
<jats:p>
<jats:bold>IMPORTANCE</jats:bold>
Thiocyanate is a moderately toxic and chemically stable sulfur compound that is produced by both natural and industrial processes. Despite its significance as a pollutant, knowledge of the microbial degradation of thiocyanate is very limited. Therefore, investigation of thiocyanate oxidation in haloalkaliphiles such as the genus
<jats:italic>Thioalkalivibrio</jats:italic>
may lead to improved biotechnological applications in wastewater remediation.
</jats:p>

• 出版日期2017-12
• 单位Delft University of technology