Application of Meta-Omics Technologies Reveals Microbial Ecology in Anaerobic Digestion
Advisor: Professor Wen-Tso Liu
Zoom: https://illinois.zoom.us/j/83369406336?pwd=VlllOHluTkdETlgzK1BieFgwemVyUT09
(Meeting ID: 833 6940 6336 Password: 173971)
Abstract
Anaerobic digester (AD) is an essential biological process in wastewater treatment to reduce excessive
sludge. In AD, wasted sludge is converted to biogas and more biologically stable solids by a series of
reactions carried out by microbes. As microbial activity is critical in AD, understanding the factors that
affect microbial assembly is beneficial to improve AD performance. Conventionally, microbial studies
rely on culture-based approaches or 16S rRNA gene sequencing, restricting the investigation on the
microbial functions of the vast majority of uncultivated microbes. Meta-omics technologies enable
characterization of microbes in silico, bypassing the necessity of cultivation and PCR amplification.
The main objective of this dissertation is to utilize meta-omics to reveal the AD microbial ecology
under the influence of different impact factors, including of microbial immigration, temperature and
feed type, and virus. Previously, 16S rRNA gene was coupled with ecogenomics-based mass balance
(EGMB) model to evaluate the effect of microbial immigration in AD. The 16S rRNA gene-based
EGMB model identified the microbial immigrants by the estimation of microbial growth rate. However,
substantial proportion of uncultivated microbes were also revealed. Characterization of these
uncultivated microbes is unavailable using 16S rRNA gene sequencing but is attainable through
metagenomic analysis. In this dissertation, the effectiveness of both 16S rRNA gene- and metagenomebased
EGMB model is firstly verified in a lab-scale bioreactor. The feasibility of metagenome-based
EGMB model in full-scale ADs for the characterization of microbial activity and microbial function is
further evaluated. As temperature and feed type impact AD microbiome, this dissertation investigated
the microbial ecology and the potential roles of microbes in thermophilic AD fed with domestic waste
or manure. Finally, knowledge of the impact of viruses in AD is limited. The viral ecology, the
connection between AD viruses and upstream AS viruses, the potential hosts, and the functional genes
in viral genomes were explored in this dissertation.
Overall, this dissertation provides insight of the microbial ecology under the influences of microbial
immigration, temperature and feed type, and virus in AD. These findings can be added to the
fundamental knowledge for better AD practices. Implications of the findings, such as AD performance
diagnosis, bioaugmentation, and phage mediation, can be beneficial for the enhancement of AD
processes.
