ms project poster
TRANSCRIPT
Us
Us
Maya Sederholm, Bradley Schmitz, Luisa Ikner, Alexander Wassimi, Maria Campillo, and Ian Pepper
Department of Soil, Water and Environmental Science ! College of Agriculture and Life Sciences The University of Arizona
Objec)ves • Determine the effects of a commonly used soil fumigant on soil microbes in terms of numbers, acHvity, and diversity • Does the community return to pre-‐applicaHon condiHons? • Is the soil quality diminished for future agricultural use? • Can it be used to convert Class B biosolids to Class A?
Background Informa)on • Metam sodium (MS) is one of the most widely used soil fumigants in the United States (EPA) • Primarily used as an agricultural crop pretreatment for pests • MS hydrolyzes to MITC (a tear gas, the acHve component) in water • MITC infiltrates cell walls to adversely impact or kill organisms • Studies have been conducted on pathogens in MS-‐treated biosolids, but not much is known about the effects of MS on soil microbial populaHons
Methods
Sampling Times " Pre-‐applicaHon " APer 24 hours " APer 7 days " APer 14 days " APer 21 days " APer 28 days
Culturable & Biochemical Assays • Heterotrophic plate counts (HPCs)-‐ Number of culturable heterotrophic bacteria in the soil • LuminUltra®-‐ Total ATP producHon and microbial equivalents (MEs) • Dehydrogenase Assay-‐ Total TTC reducHon to TPF
Molecular Methods DNA extracHon (MoBio PowerSoil DNA IsolaHon Kit) > PCR > Illumina HiSeq 2500 sequencing > BioinformaHc analysis
Questions? Email [email protected]
Schema)cs & Sampling
Control plots
Treated plots
1
2
3 3
2
1
Triplicate cores per plot
Composite sample
10 g soil in 95 mL water to start dilu)on series (10-‐1 to 10-‐9)
Photo by Rich Wagner, U of A Campus Agricultural Center
Results: Numbers
Applica)on of Metam Sodium • ApplicaHon rate = 75 gallons Vapam/acre soil • Plots= 3 square feet • 36-‐gallon carboys gravity-‐fed through drip system onto the plots • Plots covered with clear plasHc tarp
0%
5%
10%
15%
20%
6
6.5
7
7.5
8
8.5
Pre-‐applicaH
on 24 hou
rs 7 days
14 days
21 days
28 days
Moisture Co
nten
t
Log 1
0 CFU
s or M
Es/g dry soil
HPC Control
HPC Treated
LU Control
LU Treated
MC
0
10
20
30
40
50
Pre-‐applicaH
on 24 hou
rs 7 days
14 days
21 days
28 days
μg TPF/g dry soil
Dehydrogenase Assay
C
C+G
T
T+G
3
3.5
4
4.5
5
5.5
6
Pre-‐applicaH
on 24 hou
rs 7 days
14 days
21 days
28 days
Log 1
0 pg AT
P/g dry soil
LuminUltra®
Control
Treated
Results: Total Ac)vity
Results: Diversity (ongoing)
Heterotrophic Plate Counts (HPC): CFUs LuminUltra® (LU): MEs
0% 20% 40% 60% 80% 100%
Control
Treated
Control
Treated
Control
Treated
Control
Treated
Pre-‐
applicaH
on
�24 hou
rs
7 days
28 days
Rela)ve Abundance
Alphaproteobacteria
Clostridia
AcHnobacteria
Gammaproteobacteria
Bacilli
Deltaproteobacteria
Other
Unclassified
RelaHve abundances of top 6 classes from each Hme period. Other top classes not listed: Betaproteobacteria, Sphingobacteriia, and Thermoleophilia.
Richness and evenness throughout the study TBD.