[Enviro-lunch] Enviro-lunch: Dr. Jennifer Pett-Ridge "Imaging microbes and minerals in the Rhizosphere", 02/02, SE2-302, 12:00:1:30pm

[Fernanda Santos]

​
Dear all,

Please support our community in Life and Environmental Sciences by
attending our weekly events. This week's speaker in our Enviro-lunch brown
bag seminar series will be *Dr. Jennifer Pett-Ridge*, a senior staff
scientist at Lawrence Livermore National Laboratory (LLNL) who uses the
tools of system biology and biogeochemistry to link identity and function
in environmental microbial communities. The talk abstract follows below.

* Dr. Jennifer Pett-Ridge*
Imaging microbes and minerals in the Rhizosphere


Where: SE2-302

When: Thursday (FEB 2nd, from 12-1:30PM)

*Talk Abstract*

Stimulated by exudates and root decay, rhizosphere organisms control the
critical pathways that move C from root tissue to mineral surfaces, and
ultimately regulate how soil C is sequestered and stabilized. Yet we have a
poor understanding of how roots affect the molecular ecology of microbial
decomposers, and how this translates into altered rates of organic matter
breakdown. In a collaborative UC Berkeley-LLNL-LBL-University of Oklahoma
project, we have examined the effects of live and dead roots on
decomposition in a grassland soil and quantified characteristics of
relevant bacterial and fungal communities using gene arrays,
transcriptomics, isotope tracing and proteomics. The presence of live roots
consistently suppressed rates of dead root litter decomposition and
significantly altered the abundance, composition and functional potential
of microbial communities. Plant-influenced soils had relatively more genes
involved in low molecular weight compound degradation (e.g.
polysaccharides) whereas unplanted soil microbes had more macromolecule
degradation genes. Higher abundances of proV and proW genes (glycine
betaine transport) in planted soils suggest microbes experience more severe
water stress in planted soils. RNA-seq and stable isotope probing analysis
showed that living roots in the presence of decaying root material had
differential effects on soil food webs and organisms participating in
co-metabolism of exudates and decaying biomass. We found significant
differences between the microbial community composition associated with
different mineral types for both bacteria and fungi, and nanoscale
secondary ion mass spectrometry (NanoSIMS) imaging of these minerals
suggests fungal hyphae may be moving C directly from roots to mineral
surfaces. In sum, we find microbial functional potential is the primary
factor driving rhizosphere litter decomposition and that microbial
functional capacities differ in rhizosphere versus bulk soils.


We look forward to seeing you,


*Organizers for 2016-17: Rebecca Abney and Fernanda Santos*

*Faculty coordinator: Asmeret Asefaw Berhe*
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