Subsurface Microbial Invasion Affects the Microbial Community of Coal Seams

Coal seam microorganisms have attracted
much attention for their
special functions that are closely related to secondary biogenic gas
formation, but the influence of subsurface microbial invasion on coal
microorganisms remains poorly understood. In this study, subsurface
microorganisms from soils at different depths were used to infect
coal samples, and the abundance and composition of the microbial community
were analyzed by quantitative polymerase chain reaction (PCR) and
high-throughput sequencing. The results showed that methane production
from the coal samples treated with soil extractions did not increase
significantly nor did the abundance and transcriptional activity of
archaeal 16S rRNA and mcrA genes. In contrast, two
soil extractions significantly improved the abundance and transcriptional
activity of the coal bacteria. There was no significant difference
in the effects of different soil extractions on bacterial abundance
and transcriptional activity, but differences in the effects on α-
and β-bacterial diversity between the coal samples treated by
different soil extractions were found. Soil extraction from the shallow
layer soil far away from the coal mine increased the bacterial α-diversity
of the coal samples and changed the bacterial community composition.
In addition, this soil extraction increased various bacterial groups
in the coal sample and changed the predictive metagenome functional
contents of the coal samples from the bacterial sequence data. In
summary, this study provides basic microbial information for subsurface
microbial invasion of coal seams and helps increase understanding
of the source of microorganisms in in situ coal seams and the changes
in the microbial community during subsurface microbial migration.