[metagenomics-jclub] Tiedje lab prospective postDoc seminar

[Adina Chuang Howe]

Hi all:

    Vaibhav Tale, a PostDoc candidate from Marquette University, will be
discussing his work with "Bioaugmentation for recovery of anaerobic
digesters subjected to organic overload."

This will take place on Wednesday (tomorrow) July 28 in PSB Room 271.

Adina
===========

    *Seminar, Wednesday, July 28, 9:30am, Rm 271, Plant and Soil Science
Bldg*

*BIOAUGMENTATION FOR RECOVERY OF ANAEROBIC DIGESTERS SUBJECTED TO ORGANIC
OVERLOAD***

Dr. Vaibhav P. Tale

Dept of Civil and Environmental Engineering

Marquette University

Post-doc candidate



Anaerobic digester upset due to organic overload is common and methods to
reduce recovery time would be beneficial. One potential method is
bioaugmentation, the addition of an external culture for performance
improvement. Methanogenic community structure differs from digester to
digester and there may exist a relation between specific methanogenic
activity (SMA) and microbial community composition. The research presented
herein tested whether there is a relationship between SMA and community
structure. Also, the effectiveness of bioaugmentation was tested by
hypothesizing that bioaugmenting with a methanogenic, propionate-degrading
culture acclimated to small oxygen doses will help rapid recovery of
organically overloaded digesters.

Fourteen different anaerobic cultures were tested for SMA and microbial
community using the *mcrA* gene and DGGE to establish a relationship between
SMA and community structure. The culture with the highest SMA was enriched
by feeding 0.17g propionate/L-day and different oxygen doses. The enrichment
cultures were used to bioaugment organically overloaded anaerobic digesters.
Microbial communities present in bioaugmented, non-bioaugmented and
undisturbed control digesters as well as the bioaugmentation culture were
analyzed using 16S rDNA.

A statistically significant quantitative structure-activity relationship
(QSAR) between SMA and community structure could not be established,
highlighting the difficulty in establishing activity/community structure
relationships. However, the results indicated that there may be a relation
between SMA and methanogenic community compositions studied. Enriching a
culture for 25 mgO2/L-day increased its SMA by 29.7%, but higher oxygen
doses yielded lower SMA values. Bioaugmentation with this enrichment culture
reduced the time required for upset digester effluent to decrease below 1000
mg SCOD/L by 114 days (11.4 SRTs) and the time required to reach 25 mLCH4/day
by 37 days (3.7 SRTs) respectively. Bioaugmented digesters consistently
produced lower effluent SCOD and more methane than non-bioaugmented
digesters. Bioaugmentation is a promising approach for speeding up recovery
of organically overloaded digesters. Bacterial and archaeal communities of
the bioaugmented and undisturbed control digesters had similar phylogenetic
tree structures (p>0.3), whereas the tree structures of non-bioaugmented and
undisturbed control digesters differed significantly (p<0.01).
Bioaugmentation helped restore the microbial communities of overloaded
digesters to their original undisturbed state. Higher relative abundance of
clones related to *Methanospirillum hungatei* may have caused better
performance of bioaugmented digesters.
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