Los días 7 y 8 de mayo organizamos en la Fundación Ramón Areces con la Fundación General CSIC el Simposio Internacional 'Microbiología: transmisión'. La "transmisión" en microbiología hace referencia al proceso por el que material genético es transferido de una célula a otra, de una población a otra. Es un proceso clave para entender el origen y la evolución de los seres vivos. El objetivo de esta reunión era conocer mejor la logística de la transmisión para ser capaces de modular o suprimir algunos procesos de transmisión dañinos.

1. 1
Transmission of antibiotic resistance genes from
organic fertilizers to soil and to plants
Kornelia Smalla
Julius Kühn-Institute - Federal Research Centre for Cultivated Plants (JKI)
Braunschweig, Germany
kornelia.smalla@jki.bund.de

2. Proliferation subpopulations carrying MGE and horizontally
transferred MGEs ensure soil bacterial communities to rapidly
adaptation to environmental stresses
Our research hypothesis
Hot spots:
Mixing animal and humane microbiome with indigenous soil bacteria
High cell densities
Nutrient availability,
Selective pressure
Antibiotics, metal or disinfectants introduced via manure or sewage into
agricultural soils
Pesticide contaminated water

3. Response of bacterial populations to organic fertilizers
Shifts in the relative abundance of bacterial populations
Changes in microbe-driven functions
Abundance and diversity of antibiotic resistance genes and
mobile genetic elements conferring antibiotic resistances
Impact on the plant microbiome
and its resistome?

4. 4
Monitoring the transmission of antibiotic resistance genes
Organic
fertilizer
Manure
Digestates
Sewage
Irrigation water
Soil Crops Fresh produce Human gut
microbiome

5. DNA/RNA extraction
Microscopy
Marker and
reporter genes
FISH analysisPCR-amplification of
16S rRNA genes or
other functional genes
Quantitative PCR Fingerprinting methods
DGGE
PhyloChips
Amplicon sequencing
Functional metagenomics
Exogenous isolation of MGE
Monitoring the response of bacterial populations to organic
fertilizers by cultivation-independent methods

6. Wulf Amelung, Jan Siemens, Ingrid Rosendahl
Institute of Crop Science and Resource Conservation, Soil Science and Ecology,
University of Bonn
Joost Groeneweg, Institute of Bio- and Geosciences, Agrosphere,
Forschungszentrum Jülich
Andreas Fox, Wageningen University, Aquatic Ecology and Water Quality
Management, Wageningen, The Netherlands
Michael Schloter, Helmholtz Zentrum München, German Research Center for
Environmental Health, Neuherberg, Germany
The objective of the “DFG research group FOR566“ was to identify the key
processes that control both the fate and the effects of veterinary medicines in soil.

7. KS: loamy sand (gleyic Cambisol), manure fertilized
ML: silt loam (orthic Luvisol), chemically fertilized
Effect of antibiotics and manure on ARG
abundance and transferability in soil
Sampling at different time points
Recovery of the microbial pellet
Total soil DNA extraction
qPCR of sul1, sul2, intI1, korB
Exogenous isolation of
SDZ conferring MGE
Untreated
soil
+ Manure + Manure
+ SDZ10
+ Manure
+ SDZ100

8. Repeated manure application results in an accumulation of
sul1 and sul2 resistance genes only when manure contained SDZ
Heuer et al., AEM 2011In situ selection occurs in the soil environment!

9. E. coli Rifr
Kmr
Filter mating,
selection with Rif Km SDZ
Soil or manure bacteria with
conjugative plasmids
E. coli transconjugants with sulfonamide resistance plasmids
Transferable SDZ resistance in manure and manure
treated soils studied by cultivation independent methods
This approach was successfully used in microcosm, mesocosm and field
experiments to assess transferable SDZ resistance

10. Soil ML
Soil KS
Soil
Soil + Manure
Soil + Manure + SDZ10
Soil + Manure + SDZ100
Transfer frequencies in exogenous isolations significantly
increased in the presence of manure containing SDZ
Nutrient availability required to activate transfer potential
Less transconjugants from manure than from manure treated soil
Heuer, H. and K. Smalla. 2007. Environ Microbiol 9:657-666; Heuer et al., 2009; 2012.

11. -8
-7
-6
-5
-4
-3
-2
-8
-7
-6
-5
-4
-3
-2
log(transferfrequency)
Day 48 Day 132
BS RH BS RH BS RH BS RH
Grass GrassMaize Maize
bc
d
bc
bc
a
ba
dc
d
aa
b
a
a
c
b
c
Transfer frequencies were mainly increased in the SDZ-treatment
The highest transfer frequencies were observed in the rhizosphere
of grass and young maize plants
Capturing SDZ resistance plasmids from field soil
Jechalke et al., AEM 2013

12. 36% G+C (26% GC3)
Transfer and maintenance genes with moderate homology to
pIPO2/pSB102/pTer331 (average similarity less than 42 % aa)
Replication module (5% lower G+C content; rep and oriV) of other
descent (closest hit Acinetobacter baumanni – 26%)
orf128
CD
rep
O N M L K J F H E
Repeat
BA
p32
orf106
pal2
tra
incC
korB
mobCtraR
orf172orf126
orf311orf112
oriToriV
Promoter
Insert
rep incCtraB
Iterons
DnaA-boxes
DnaA-boxes
IHF
IHF
pal2
pal2
pal2
pal2
pal2
pal2
pal1
GC skew switch
pal2
36% G+C 31% G+C 36% G+C
%G+C
A
B
Insert
Insert
Sequence analysis of three LowGC plasmids:
Common 30 kbp backbone

13. pHHV35
27.0 kbp
ISAba1
tnpA
insB
sul2
'insA
strB
strA
aacC2
tnp5btnp'
tnp5a
orf180
tnpR
tnp5atnp5becf
tnp
ORF2
ORF1
tnp3
tnp'
glmM
rumB
phcLK
ISAba2
ori ISCR2
IS1006
Tn5393c
pAV2
pRL10
pWP
IS1422
-like
IS1422
-like
rmsM
rmsR
Lactobacillus-like
RM-system
pHHV216
28.3 kbp
rumA
tnp
strA
strB
tetH
tetR
orf314
tnpA
tnpR
strB
strA
'insA
floR
orf101
insA
glmM
sul2
ORF1ORF2
insB
tnpR
orf204
orf376
int
phcKL'
rumB
pAV2ISAba2ISAba1
Plasmid 10660-1
'sul1
ori ISCR2
Tn5393c'Tn5393c
IS1007
pHH1107
28.0 kbp
rumB
rumA
sul2
tetX
strA
sul2
glmM
glmM
tpnF
tnpR
parA
insA
ORF513
phcLK
insB
tnpA'
tnp
'tnpA
tnp
'insA
tnpR
s2706
Tn4351
-like
Tn5393c
IS26
strB
insA
IS1007
ORF1ORF2
ori ISCR2
ISAba1 ISAba2ISCR2ISCR2
int
orf376
pAV2
tnpR
orf204
Mosaic structure of accessory regions:
antibiotic resistance genes, Tn, IS, and ISCR2
Heuer et al. 2009. Spreading antibiotic resistance through spread manure: characteristics of a novel
plasmid type with low %G+C content. Environ. Microbiol. 11:937-949

14. Accessory regions of IncP-1e plasmids
A fragment of the IncP-1a oriV was found in plasmid pHH128 and pKS77
adjacent to IS1326, as previously reported for pKJK5, indicating
recombination between incompatible plasmids

15. The majority of SDZ plasmids captured from manure and manure treated
soils (soil microcosm and mesocosms, field experiment) belonged
to the novel Low GC plasmids and to the IncP-1e
These plasmids seem to be important vectors for disseminating multiple
antibiotic resistances in agroecosystems
A remarkable diversity was observed in the accessory genes
Summary and conclusions
The presence of antibiotics in manure increases the abundance of
antibiotic resistance genes and their transferability
The number of taxa significantly affected by the presence of SDZ increased
with the times of application and was highest in the manure treatments with
high SDZ-concentration (data not shown here)

16. Birgit Wolters, Guo-Chun Ding, Arum Widyasari,
Susen Hartung, Robert Kreuzig & Kornelia Smalla
Organic fertilizers - a reservoir of resistance genes and
mobile genetic elements?
Do mesophilic biogas plants represent a suitable mitigation strategy?

17. A) Analysis of bacterial community composition:
17
Phylum BGA1 BGA2 BGA3 BGA4 BGA5 BGA7 BGA8 BGA9
Bacteroidetes 26±8 11.8±1 21.1±3 7.5±1 16.4±1 12.7±1 6.9±1 9.7±1
Firmicutes 60.5±8 74.6±1 61.6±3 65.5±1 59.9±1 73.6±0 54.7±1 75.3±1
Proteobacteria 1.3±0 1.5±0 2.7±0 0.1±0 2.2±1 2.4±0 3±0 2.8±1
Spirochaetes 1.6±1 0.4±0 1.5±1 0.7±0 0.7±0 0.6±0 0.5±0 0.4±0
Tenericutes 0.8±0 0.2±0 1.1±0 0.3±0 1.2±0 0.5±0 0.3±0 1±0
Comparison of bacterial communities of 8 digestates from different biogas plants (BGA) at the phylum level (values
in % with standard deviation, n=3).
Bacterial communities of all digestates were dominated by Firmicutes
& Bacteroidetes, but differed significantly in their overall composition.
Some sequences showed high similarity to known pathogens:
• C. difficile (100%): antibiotic-associated colitis
• C. chauvoei (95%): blackleg
• C. botulinum (99%): botulism

18. B) RGs and antibiotics in BGP digestates
18
Farm Source sul1 sul2 sul3 tetA tetM tetX qacE qacE∆1 Detected antibiotics
[mg/kg DW]
BGP1 Digestate +++ ++ - + ++ ++ - +++ Tc 1.60, Doxy 1.30
BGP2 Digestate +++ ++ - + ++ ++ - +++ Doxy 7.40
BGP3 Digestate +++ ++ (+) ++ ++ ++ - +++ Doxy 2.10
BGP4 Digestate +++ ++ - + ++ ++ - +++ Tc 2.10, Doxy 10.10,
Enr 0.20
BGP5 Digestate +++ ++ - ++ ++ ++ - +++ Doxy 3.20
BGP6 Digestate +++ ++ - ++ ++ ++ - +++ Tc 6.40, Doxy 2.20
BGP7 Digestate +++ ++ - ++ ++ ++ - +++ Tc 0.41
BGP8 Digestate ++ ++ - + ++ ++ - ++ -
 Except for sul3 and qacE, all RGs monitored were detected in all
digestates
 Doxycycline and tetracycline were by far the most frequently detected
antibiotics (antibiotic residues were detected in all samples except for
digestate of BGP#8)

19. B) Plasmids & integrons in BGP digestates
19
Farm Source IncN IncP-1 IncQ IncW LowGC intI1 intI2 Detected antibiotics
[mg/kg DW]
BGP1 Digestate - + +++ ++ - ++ ++ Tc 1.60, Doxy 1.30
BGP2 Digestate - + +++ ++ (+) ++ ++ Doxy 7.40
BGP3 Digestate - + +++ + - ++ ++ Doxy 2.10
BGP4 Digestate - + +++ + - ++ ++ Tc 2.10, Doxy 10.10,
Enr 0.20
BGP5 Digestate - (+) +++ ++ (+) ++ ++ Doxy 3.20
BGP6 Digestate - (+) +++ ++ + ++ ++ Tc 6.40, Doxy 2.20
BGP7 Digestate - -* +++ ++ - ++ ++ Tc 0.41
BGP8 Digestate - (+) +++ ++ - ++ ++ -
*: IncP-1ε plasmids were captured from this digestate via exogenous plasmid isolation
 Except for IncN plasmids (no detection) and LowGC plasmids (detected in
3 of 8 digestates), all mobile genetic elements monitored were detected in all
samples.

20. C) Exogenous plasmid isolation from digestates
20
BGP
Recipien
t IncN IncP-1 IncP-7 IncP-9 IncQ IncW LowGC
intI1 Total nr. testet
1 Ps - - - - - - - - 10
2 Ps - 8/9 - - - - - 8/9 9
3 Ps - - - - - - - - 23
4 Ps - - - - - - - - 10
5 Ps - 4/9 - - - - - 4/9 9
6 Ps - 10/10 - - - - - 10/10 10
7 Ps - 9/9 - - - - - 9/9 9
1 E - 9/21 - - - - - 9/21 21

21. C) IncP-1ε plasmids isolated from digestates
21
# TF BG
P
Detected markers Gene
cassette size
[bp]
Resistance Moderate
resistance
# rp
Ps26 2 intI1, qacE∆1, sul1, tet(A), aadA1 1000 SDZ, TET* DOX 3
Ps28 2 intI1, qacE∆1, sul1, tet(A) 1600 SDZ, TET*, TMP DOX, SM 1
Ps29 2 intI1, qacE∆1, sul1, tet(A), aadA1 2300 + 1700 SDZ, CM, SM,
TET*
DOX 2
Ps32 2 intI1, qacE∆1, sul1, tet(A), aadA1 1000 SDZ, SM, TET* DOX 4
Ps10
1
5 intI1, qacE∆1, sul1, tet(A), aadA1 1700 SDZ, SM, TET* DOX, CM 5
Ps110 5 intI1, qacE∆1, sul1, tet(A), aadA1 1000 SDZ, TET* DOX, SM 6
Ps15
1
6 intI1, qacE∆1, sul1, tet(A) 1500 SDZ, TET*, TMP DOX, SM 1
Ps15
2
6 intI1, qacE∆1, sul1, tet(A) 2200 SDZ, TET*, TMP DOX, SM 1
Ps15
4
6 intI1, qacE∆1, sul1, tet(A) 2200 SDZ, TET*, TMP DOX, SM 1
Ps15
6
6 intI1, qacE∆1, sul1, tet(A) 2200 SDZ, TET*, TMP DOX, SM 1
Ps12 7 intI1, qacE∆1, sul1, tet(A) 2200 SDZ, TET*, TMP DOX, SM 1
Wolters et al., 2015

22. Summary
A) - Bacterial community compositions of the digestates were dominated by
Firmicutes and Bacteriodetes
- No Enterobacteriaceae (putative hosts of IncN- & IncU-plasmids) detected
- Proteobacteria present in all samples but at a low abundance
B) - In all samples sequences specific for several transferable broad host range
plasmids, integrons and RGs were detected
- Doxycyline and/or tetracycline were most frequently detected antibiotics
C) - All IncP-1ε plasmids (captured from digestates) analyzed in more detail carried
class 1 integrons with gene cassette amplicons of varying sizes, tet(A), qacE∆1
and sul1.
- all these IncP-1ε plasmids conferred several antibiotic resistances to an
otherwise susceptible host.
22

23. 23
inorganic inorgani
c
manure manure
digestate manure digestat
e
digestat
e
digestate inorgani
c
manure inorgani
c
Soil (0-30 cm): sieving 2 mm
Rhizosphere: stomacher treatment
Roots: maceration
Quantification of ARGs & MGEs
(quantitative real-time PCR)
TC-DNA
extraction
The effect of different organic fertilizers (manure, digestate) vs. inorganic
fertilizer on the abundance of ARGs, disinfectant resistance genes, integrons
and plasmids in agro-ecosystems (bulk soil, rhizosphere and roots of maize
plants) was analyzed in a field plot study
Sampling times: before (t0; 03/2014) and after fertilization (t1; 04/2014) and at harvest (t2; 10/2014).
Gene copy numbers of rrn, sul1, sul2, tet(A), tet(M), tet(Q), tet(W), intI1, intI2, qacE∆1 and of IncP-1 (korB), IncP-1ε
(trfA) and LowGC (traN) plasmids were determined in total community (TC)- DNA by real-time PCR assays.
Do organic fertilizers enhance resistance genes and mobile
genetic elements in field soils?
Experimental design & methodology:

24. 24
sul1 sul2 qacE∆1 tet(A) tet(M) tet(W) tet(Q)
manure (t0) M -1.72a ± 0.03 -1.94a ± 0.05 -1.95a ± 0.05 -2.79a ± 0.05 -1.49a ± 0.16 -1.83b ± 0.04 -2.69a ± 0.11
digestate (t0) D -2.59b ± 0.09 -1.94a ± 0.12 -2.91b ± 0.12 -3.38b ± 0.10 -2.19b ± 0.05 -1.55a ± 0.08 -3.18b ± 0.09
untreated (t0) C -3.93b ± 0.16 -4.05ab ± 0.19 -4.13b ± 0.06¹ b.d. -4.10a ± 0.07 -3.78a ± 0.09 b.d.
bulk soil M -3.76ab ± 0.28 -4.17b ± 0.50 -4.05b ± 0.30 b.d. -4.16a ± 0.10 -3.79a ± 0.15 b.d.
D -3.54a ± 0.09 -3.52a ± 0.15 -3.78a ± 0.12 -4.73 ± 0.10 -4.00a ± 0.11 -3.66a ± 0.07 b.d.
after C -4.02b ± 0.32 -4.39c ± 0.06 -4.40b ± 0.29 b.d. -4.31b ± 0.16 -3.93b ± 0.14 b.d.
treatment (t1) M -2.56a ± 0.31 -2.60a ± 0.33 -2.77a ± 0.33 -3.51 ± 0.26 -3.02a ± 0.23 -3.18a ± 0.28 -4.00 ± 0.15
bulk soil D -3.87b ± 0.10 -3.94b ± 0.17 -4.19b ± 0.07 b.d. -4.04b ± 0.04 -3.42a ± 0.06 b.d.
at harvest (t2) C -4.30a ± 0.18 -4.61a ± 0.35 -4.55a ± 0.12 b.d. -4.25a ± 0.01 -3.88a ± 0.06 b.d.
bulk soil M -4.14a ± 0.24 -4.51a ± 0.27 -4.36a ± 0.26 b.d. -4.24a ± 0.13 -3.77a ± 0.38 b.d.
D -4.04a ± 0.43 -4.27a ± 0.26 -4.27a ± 0.41 b.d. -4.10a ± 0.09 -3.46a ± 0.26 b.d.
rhizosphere C -4.89b ± 0.14 b.d.a b.d.ab b.d. -4.89a ± 0.12 -4.63b ± 0.16 b.d.
M -4.26a ± 0.28 -4.16a ± 0.42 -4.46a ± 0.28 b.d. -4.70a ± 0.22 -4.52b ± 0.11 b.d.
D -4.79b ± 0.06 -4.58a ± 0.18 -5.19b ± 0.10¹ b.d. -4.85a ± 0.18 -3.51a ± 0.13 b.d.
roots C b.d.a b.d.a b.d.b b.d. b.d.a. b.d.b b.d.
M -3.92a ± 0.50 -3.94a ± 0.61¹ -4.17a ± 0.48 b.d. -4.59a ± 0.40 b.d.b b.d.
D b.d.a -4.27a ± 0.27¹ b.d.b b.d. -4.52a ± 0.21 -2.94a ± 0.63 b.d.
Do organic fertilizers enhance resistance genes in soils and
in the maize roots under field conditions?

25. 25
intI1 intI2 korB
manure (t0) M -2.40a ± 0.04 -3.88b ± 0.11 b.d.
digestate (t0) D -3.07b ± 0.12 -3.28a ± 0.15 -4.62 ± 0.21
untreated (t0) C -4.53a ± 0.24 b.d. -3.96a ± 0.54¹
bulk soil M -4.56a ± 0.39 b.d. -4.03a ± 0.31¹
D -4.19a ± 0.08 b.d. -3.97a ± 0.61
after C -4.89b ± 0.24 b.d. -4.14a ± 0.63
treatment (t1) M -2.94a ± 0.33 -4.01a ± 0.27 -4.10a ± 0.42
bulk soil D -4.55b ± 0.13 -4.98b ± 0.43 -4.05a ± 0.69
at harvest (t2) C -4.96a ± 0.17 b.d. -4.13a ± 0.62
bulk soil M -4.86a ± 0.31 b.d. -4.09a ± 0.70
D -4.76a ± 0.39 b.d. -4.02a ± 0.31
rhizosphere C b.d.b b.d. -3.11a ± 0.44
M -4.77a ± 0.27 b.d. -3.22a ± 0.77¹
D -5.60b ± 0.15¹ b.d. -2.97a ± 0.66
roots C b.d.b b.d. -3.61a ± 0.38
M -4.49a ± 0.51 b.d. -3.47a ± 0.60¹
D b.d.b b.d. -3.54a ± 0.62
 Sequences specific for IncP-1ε (trfA) & LowGC (traN) plasmids were below the detection limit in
most samples (data not shown).
Do organic fertilizers enhance resistance genes in soils and
in the maize roots under field conditions?

26. Summary
26
- Organic fertilizer (especially manure) increased the relative abundance
of resistance genes and integrons in bulk soil immediately after
application compared to inorganic fertilization.
- No effect of organic fertilizer on the abundance of ARG and MGE in bulk
soil at the time of harvest, but these effects were still detected for some of
the genes analyzed in root and rhizosphere samples from maize plants
grown in soils fertilized with manures or digestates.

27. Mobile genetic elements and resistance genes in sewage sludge
a
a
a
a
c
b
a
a
a
a
b
a
b
a
a
b
a
a
b
b b
b
a
1
3
5
7
9
11
13
16S qacE intI1 tetA tetM tetW aadA strA traN korB
log10genes/gdrysludge
dewatered sludge (Feb14)
sludge (Aug14)
sludge (Jan15)
27

28. 28
 Significantly higher abundance in soil samples treated with sludge
sludge
1
2
3
4
5
6
7
8
9
tetW
log10genes/gdrysludge
dew
ater
ed
slud
ge
(Fe
b14)
a
a
a
b b b
1
2
3
4
5
6
7
8
0dpi 14dpi 119dpi
lg10tetW/gdrysoil
sludge
no sludge
Soil with
sludge
control
Effects of sewage sludge on the abundance of ARG
Tetracycline tetW

29. 29
sludge
1
2
3
4
5
6
7
8
9
10
11
aadA
log10genes/gdrysludge
dew
ater
ed
slud
ge
(Fe
b14)
a
a
a
b b b
1
2
3
4
5
6
7
8
9
10
0dpi 14dpi 119dpi
log10aadA/gdrysoil
sludge
no sludge
Soil with
sludge
control
Streptomycin and spectinomycin resistance gene aadA
Effects of sewage sludge on the abundance of ARG

30.  Diverse bacterial communities
 Phyllosphere: 106-107 CFU/g
 Dominant phyla
 Proteobacteria
 Firmicutes
 Actinobacteria
 Bacteroidetes
 Composition differs significantly between plant
species, cultivars and depending on the plant
developmental stage
Plant microbiome
30(Bulgarelli et al., 2013; Leff and Fierer, 2013)
Bulgarelli et al., 2013

31. Lettuce Corn salad After Enrichment
Detection of class 1 integron integrase on fresh produce
31
Pc
intI GC1 GC2
attI
qacEΔ1 sul1
M
M
Lettuce
mixCilantro

32. sul1 sul2 intI1 IncP-1 qacEΔ1 E. coli Salmonella
Blot qPCR Blot qPCR Blot qPCR
Blot
(trfA)
qPCR
(korB)
Blot
qPCR
(+qacE )
Blot
(gadA)
Blot
(hilA)
Lettuce
1 + - - - + - - + (+) (+) - -
2 + (+) + + + (+) (+) - ++ + - -
3 + - - - + - - - + (+) - -
4 (+) - - - - - - - - - - -
Corn salad
1 (+) - - - + - - - + (+) - -
2 (+) - + + + (+) - (+) (+) + - (+)
3 + (+) + (+) + + (+) + + + - -
4 + - + + (+) - - + + (+) - -
Cilantro
1 + - + + (+) - - (+) + (+) (+) -
2 + - + + + (+) (+) + ++ + (+) (+)
3 + (+) + (+) (+) - - - - (+) - -
4 (+) - + (+) + - - - - + + -
Lettuce Mix
1 - - - - + - - - + (+) - -
2 + (+) + + ++ + (+) - ++ + - -
3 + (+) + + + (+) - - ++ + - -
4 - - (+) - (+) - - - + (+) - -
Lettuce
After
enrichment
(+) - + + - - - - - (+) + -
Corn salad ++ + + + (+) (+) - - ++ + + -
Cilantro ++ + + + ++ + - - ++ + + -
Lettuce-Mix ++ + (+) (+) ++ + - - ++ + + -
32
++ starkes Signal
+ Signal
(+) schwaches Signal
Detection of ARG and MGE on fresh produce

33. 33
Dissemination of class 1 integron components
in bulk soil and rhizosphere of lettuce

34. 34
Cupriavidus necator rifrr
Filter mating selection with Rif40 + Km50 + Gm10 + Cyclo100
Rhizosphere bacteria with “Helper”
plasmids (mainly IncP-1)
Donor 1
E. coli pIE723 (Gm)
Donor 2
25
Triparental exogenous plasmid isolation

35. 2 3 5 7 8 9 11 12 16 18 21
pkjk5
25 26 27 30 33 34 41 43 50 52
pkjk5
2 3 5 7 8 9 11 12 16 18 21
pkjk5
25 26 27 30 33 34 41 43 50 52
pkjk5
Inc P-1 plasmids were captured from lettuce rhizosphere bacteria by
triparental mating based on mobilization of pSM1890
Southern blotted NotI digested plasmid DNA from 21 transconjugants
hybridized with the IncP-1 trfA probe targeting all subgroups

36. 36
Conclusions
Mixing the animal (manure, digestates) or the human gut microbiome (sewage sludge)
with soil bacteria in the presence of nutrients and selective pressure is enhancing the
proliferation of resistant population and likely fosters HGT processes
Organic fertilizers likely contribute to an increased abundance of bacteria carrying
transferable antibiotic resistance genes in the soil and plant microbiome
The plant microbiome might provide a reservoir of transferable antibiotic resistance
genes to the gut microbiota
What triggered the increased abundance of IncP-1 plasmids in the rhizosphere of
lettuce remains to be elucidated

37. Thank you for your
attention!

38. 38
Holger Heuer
Sven Jechalke
Kornelia Smalla
Ute Zimmerling
Ellen
Krögerrecklenfort
Eman Nour
Christoph Kopmann
Eva Top

39. AG Smalla & guests July 2014