Environmental Engineering Reference
In-Depth Information
3.3. Archaea
3.3.1. Euryarchaeota
Euryarchaeota comprised 925 sequences, approximately 53.3% archaeal sequences. They
were clustered into 418 OTUs with a Simpson diversity index of 0.0054 (Figure 8). The
majority (70.9%) of Euryarchaeota sequences was assigned to the methanogenic class
Methanomicrobia (656 sequences). Following the class Thermoplasmata comprised 132
sequences, while the class Methanobacteria comprised by 75 sequences. Only 59 sequences
were classified into class Halobacteria. Class Archaeoglobi and Methanopyri represented only
2 and 1 sequences, respectively. Methanomicrobia contributes a large proportion of methane
emissions in wetlands, in both cold or subtropical places [19, 62]. As seen in Figure 6
,
the
most predominate Methanomicrobia genus (223 sequences) was
Methanosaeta
(formerly
Methanothrix
), which was also the second most abundant archaeal genus. It
was reported
precisely as the dominant acetoclastic methanogen in the high arctic wetlands [63]. The
methanogens genera
Methanosarcina
,
Methanocella
,
Methanolinea
, and
Methanoregula
each
represented nearly 10% of Eyarchaeota sequences. The other 12 genera were only represented
by a small number of sequences in the dataset. The largest genus in class Thermoplasmata
was
Thermogymnomonas
(120 sequences), which was detected widely even at low pH
wetlands. It was known as a kind of iron-oxidizing microorganisms [64]. The other of 12
sequences of Euryarchaeota were assigned to genus
Ferroplasma
, an anaerobic and
acidophilic archaea, which coupled to the reduction of ferric iron [5].
Of the class
Methanobacteria, there were two genera,
Methanobacterium
and
Methanosphaera
with 57
and 18 sequences, respectively. Both of these genera were detected from water and sediments
of a high-altitude athalassohaline wetland [25]. As a kind of grow aerobically or anaerobically
archaea, Halobacteria was common in most environments where large amounts of salt,
moisture, and organic material are available [25].
3.3.2. Crenarchaeota
Crenarchaeota owned less abundant sequences than Euryarchaeota in the dataset, with
810 sequences.
Figure 8. Treemap of observed Euryarchaeota taxons shown in their hierarchical order.
