Title: Laboratory of Microbial Ecology and Technology (LabMET)
1Laboratory of Microbial Ecology and Technology
(LabMET)
- Research topics and expertise
- Tom Van de Wiele, PhD
2Mission
Microbial Ecology
Strategic research
Applied research
Technology
3Strategic Research
- Microbial communities
- Quorum sensing
- Electron shuttling
- Horizontal gene transfer
- Metabolomics
4Applied Research
- Environmental Microbiology
- Wastewater
- Microbial fuel cells
- Biodegradation
- Anaerobic treatment
- Nitrogen removal strategies
- Minimizing wast sludge
5Applied Research
- Environmental Microbiology
- Soil / Sediments
- Bioprecipitation of catalytic particles
- Anaerobic removal of organochlorine contaminants
- Soil and river sludge clean-up
- Pesticide degradation and ecotoxicology
6Applied Research
- Environmental Microbiology
- Solid Wastes
- Solid waste treatment
- De-icing
- Buildings and structures
- Biologically mediated CaCO3 formation
- Microbial induced corrosion
- Air
- Indoor air pollution
- Biotrickling filtration
7Applied Research
- Gastrointestinal Microbiology
- Functional foods
- Pro- / pre- / synbiotics
- Bioactivation of food components
- Rumen microbiology
- Risk assessment
- Environmental contaminants
- Toxic food processing metabolites
- Phage therapy
8Applied Research
- Foodchain Microbiology
- Drinking water
- Hygienisation
- Water recycling
- Pathogen abatement
- Aquaculture systems
- Habitat research
- Epiphytes on grain
- Space station life cycles
- Deep sea methane oxidation
9Tools and instruments
- Reactor Technology
- Microbial Fuel cells
- Activated sludge systems
- Upflow Anaerobic Sludge Bed reactors
- Membrane reactors
- Rotating disc reactors
- Simulator of the Human Intestinal Microbial
Ecosystem (SHIME) - Dialysis reactors
10Tools and instruments
- Molecular Analysis
- PCR
- DGGE
- FISH
- Realtime PCR
- Cloning
- Flow Cytometry
11Tools and instruments
- Microbial analysis
- Epifluorescence and light microscopy
- Growth kinetics
- Microbial isolations and enrichments
- Metabolic activity
- Bioassays
- Biodegradation assays
12Tools and instruments
- Physico chemical analysis
- Gas chromatography
- HPLC
- Ion chromatography
- Spectrophotometry
- Atom absorption
- BOD, COD, TSS, VSS, NOX, TOC,
13Gastrointestinal microbial ecology
- Microbial biotransformation of
- environmental and food compounds
- in the gut and the consequences for biological
activity assessment
14Colonmicrobiota and health
- Colon ascendens, colon transversum, colon
descendens - Water- and salt resorption
- Microbiota
- 500 species, 1014 CFU/mL
- stabile community
15Colonmicrobiota and health
Health effects
- Further digestion
- Production of SCFA as energy source for
colonocytes - Immunostimulation
- Production of vitamins (K en B12)
- Colonization resistance against pathogens
- Formation of health-promoting components from
food
16Colon microbiota and health
Health effects
- Colonization by pathogens
- Formation of toxins
- Putrefaction
- Formation of (geno-)toxic compounds from food
(contaminants) - Recent (!) microbiota stimulate fat uptake and
synthesis
17Colon microbiota and health
- A microbial community in balance
(Gibson Robertfroid ,1995)
18SHIME-Tec gastrointestinal in vitro technology
Simulator of the Human Intestinal Microbial
Ecosystem
19Twin SHIME parallel treatment and control
20Oral exposure to bioactive compounds
- Food
- Soy and hop isoflavones
- Heterocyclic aromatic amines from grilled meat
- ...
- Environment
- Soil ingestion
- Inhalation of dust and subsequent ingestion
- ...
21Case 1. Microbial conversion of phytoestrogens
- Soy phytoestrogens
- Daidzine ? daidzein ? equol (microbial action)
- Equol has beneficial health effects
- Microbial consortium applicable as probiotic
- K. Decroos et al. (2005)
- Hop phytoestrogens
- Isoxanthohumol ? hoppein (8-prenylnaringenin or
8-PN) - Carried out by colon microbiota
- Importance for hop supplements, beer industry
- S. Possemiers et al. (2006)
22Hop phytoestrogens
- Beer
- Isoxanthohumol mg/L range
- 8-prenylnaringenin traces
- Menohop food supplement for relief of menopausal
symptoms - 100 ?g 8-PN / d (1 tablet / d)
- IX mg/L range
23Large interindividual variability
Batch incubation of IX with fecal microbiota from
51 women
248-PN production in vitro
- isoxanthohumol addition to SHIME
- no conversion in ascending colon
- conversion in transverse and especially
descending colon - estrogenic activity as observed with estrogen
bioassay - moderate in transverse colon
- high in descending colon
25In vitro - in vivo comparison
- SHIME run with fecal microbiota from
- woman A high 8-PN producer
- woman B moderate 8-PN producer
- woman C low 8-PN producer
- In vivo urinary excretion of 8-PN corresponds
to in vitro incubation
26Biological activity assessment
- Uptake of food supplement
- IX intake of 1 mg/d
- 8-PN producing intestinal microbiota
- 8-PN exposure of more than 500 ?g/d
- Range of biological activity
- Risk assessment process needs to incorporate
bioactivation by intestinal bacteria - Complexity interindividual variability
27Case 2. Oral exposure to PAH Polycyclic Aromatic
Hydrocarbons
- Ingestion of contaminated soil
- Industrial and urban areas
- Atmospheric deposition of PAH 50 g.ha-1.yr-1
- Oral uptake
- Adults 50 mg.d-1
- Children 200 mg.d-1
- Occasionally 1-20 g.d-1
- HUMAN HEALTH RISK ASSESSMENT
- Focus on intestinal absorption
- and bioactivation by human enzymes
28Current knowledge on PAH bioactivation
3. Gene expression
1. PAH release from soil / nutrition
2. Intestinal absorption
Intestine or liver cells
4. Possible bioactivation to toxic compounds
29What happens to non-absorbed PAHs ?
- Are colon microbiota capable of biotransforming
PAHs? - Are microbial PAH metabolites bioactive?
30Experimental set-up
- Incubate PAH in samples from SHIME reactor
- Screen for PAH metabolites
- Estrogen receptor bioassay estrogenicity
- LC-ESI-MS hydroxy-PAH
- Pure PAH compounds
- PAH contaminated soil samples
31Yeast Estrogen test
- Human estrogen receptor in yeast cell
- Estrogen responsive elements in plasmid
- Reporter gene lacZ
32SHIME colon microbiota activate PAHs
33Chemical analysis
- LC-ESI-MS hydroxylation of PAHs
- 1-OH pyrene 4.3 µg/L
- 7-OH B(a)P 1.9 µg/L
OH
EE2 7-OH B(a)P
34Urban playground soil sample 50 ppm PAH
35Biological activity assessment
- PAH exposure
- Adult 5 ?g PAH/d Child50 ?g PAH/d
- Colon microbiota convert PAH to pseudo-estrogenic
metabolites - Hydroxylation under anaerobic conditions?
- Enterococcus faecalis
- Mucosa associated bacteria micro-aerophilic
conditions - Relevant biological activity in vivo ?
36Chemopreventive effect from prebiotics
- Prebiotic inulin add to SHIME reactor
- Evaluate inulin as chemopreventive agent
- Start-up, inulin treatment (2.5 g/d)
- Incubate SHIME suspension with 40 µM B(a)P
- Monitor PAH bioactivation with yeast estrogen
bioassay - Relate to prebiotic effects
- Metabolic analysis
- PCR-DGGE-sequencing
- Real-time PCR quantification Bifidobacterium sp.
37Ascending colon inhibitory effect
38SCFA colon ascendens
- 26 increase
- Towards propionic and butyric acid
- Reversible effect
Start-up Treat-ment Con-trol
AA 57 37 48
PA 19 33 19
BA 21 27 29
39Case-study inuline (Resultaten)
- PCR-DGGE van bifidobacteria
2
1
3
1. Bifidobacterium sp.
2. Bifidobacterium infantis (96 sim.)
Inulin treatment samples
3. Bifidobacterium longum (95 sim.)
Start-up and control samples
INULINE stimulatie van de BIFIDOBACTERIA
40Take home messages
- Metabolic potency from gut microbiota
- Higher than currently anticipated
- Consider this process for risk assessment
- Interindividual variability !
- Identification of responsible bacteria and
process conditions needed - Modulation of biological activation through
dietary factors, microbial community
composition...
41Contact information
- LabMET Ghent University
- Coupure Links 653
- B-9000 Gent
- http//labMET.ugent.be/
- http//www.shimetec.be
- 32/9/264.59.76