<s>
MEGAN	B-Application
(	O
"	O
MEtaGenome	O
ANalyzer	O
"	O
)	O
is	O
a	O
computer	B-Application
program	I-Application
that	O
allows	O
optimized	O
analysis	O
of	O
large	O
metagenomic	O
datasets	O
.	O
</s>
<s>
A	O
large	O
term	O
goal	O
of	O
most	O
metagenomics	O
is	O
to	O
inventory	O
and	O
measure	O
the	O
extent	O
and	O
the	O
role	O
of	O
microbial	B-Application
biodiversity	O
in	O
the	O
ecosystem	O
due	O
to	O
discoveries	O
that	O
the	O
diversity	O
of	O
microbial	B-Application
organisms	O
and	O
viral	O
agents	O
in	O
the	O
environment	O
is	O
far	O
greater	O
than	O
previously	O
estimated	O
.	O
</s>
<s>
Tools	O
that	O
allow	O
the	O
investigation	O
of	O
very	O
large	O
data	O
sets	O
from	O
environmental	O
samples	O
using	O
shotgun	O
sequencing	O
techniques	O
in	O
particular	O
,	O
such	O
as	O
MEGAN	B-Application
,	O
are	O
designed	O
to	O
sample	O
and	O
investigate	O
the	O
unknown	O
biodiversity	O
of	O
environmental	O
samples	O
where	O
more	O
precise	O
techniques	O
with	O
smaller	O
,	O
better	O
known	O
samples	O
,	O
cannot	O
be	O
used	O
.	O
</s>
<s>
Fragments	O
of	O
DNA	O
from	O
an	O
metagenomics	O
sample	O
,	O
such	O
as	O
ocean	O
waters	O
or	O
soil	O
,	O
are	O
compared	O
against	O
databases	O
of	O
known	O
DNA	O
sequences	O
using	O
BLAST	B-Application
or	O
another	O
sequence	O
comparison	O
tool	O
to	O
assemble	O
the	O
segments	O
into	O
discrete	O
comparable	O
sequences	O
.	O
</s>
<s>
MEGAN	B-Application
is	O
then	O
used	O
to	O
compare	O
the	O
resulting	O
sequences	O
with	O
gene	O
sequences	O
from	O
GenBank	O
in	O
NCBI	O
.	O
</s>
<s>
MEGAN	B-Application
is	O
an	O
easy	O
to	O
use	O
tool	O
for	O
analysing	O
such	O
metagenomics	O
data	O
.	O
</s>
<s>
First	O
version	O
of	O
MEGAN	B-Application
was	O
released	O
in	O
2007	O
and	O
the	O
most	O
recent	O
version	O
is	O
MEGAN6	O
.	O
</s>
<s>
MEGAN	B-Application
analysis	O
starts	O
with	O
collecting	O
reads	O
from	O
any	O
shotgun	O
platform	O
.	O
</s>
<s>
Then	O
,	O
the	O
reads	O
are	O
compared	O
with	O
sequence	O
databases	O
using	O
BLAST	B-Application
or	O
similar	O
.	O
</s>
<s>
Third	O
,	O
MEGAN	B-Application
assigns	O
a	O
taxon	O
ID	O
to	O
processed	O
read	O
results	O
based	O
on	O
NCBI	O
taxonomy	O
which	O
creates	O
a	O
MEGAN	B-Application
file	O
that	O
contains	O
required	O
information	O
for	O
statistical	O
and	O
graphical	O
analysis	O
.	O
</s>
