Determining the environmental fate of a filamentous fungus, Trichoderma reesei, in laboratory-contained intact soil-core microcosms using competitive PCR and viability plating.
Trichoderma spp. are used extensively in industry and are routinely disposed of in landfill sites as spent biomass from fermentation plants. However, little is known regarding the environmental fate of this biomass. We tracked the survival of T. reesei strain QM6A#4 (a derivative of strain QM6A marked with a recombinant construct) over a 6-month period in laboratory-contained, intact soil-core microcosms incubated in a growth chamber. Survival was tested in 3 different soils and the effect of a plant rhizosphere (bush lima beans, Phaseolus limensis) was investigated. Levels and viability of the fungus were determined, respectively, by quantitative competitive polymerase chain reaction analysis of total soil DNA extracts and dilution-plating of soil on a semiselective growth medium. Whereas chemically killed QM6A#4 became undetectable within 3 d, QM6A#4 added as a live inoculum decreased approximately 4- to approximately 160-fold over the first 1-3 months and then reached a steady state. After 4 months, soil cores were subjected to a 1.5-month simulated winter period, which did not significantly affect QM6A#4 levels. Throughout the experiment, QM6A#4 remained viable. These results indicate that, following release into the environment, live T. reesei will persist in soil for at least 2 seasons.
Institute of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada. miguelprovidenti@pigeon.carleton.ca
Miguel A
MA
Providenti
Selma I
SI
Mautner
Omar
O
Chaudhry
Manon
M
Bombardier
Richard
R
Scroggins
Edward
E
Gregorich
Myron L
ML
Smith
D001483:Base Sequence; D003470:Culture Media; D025141:Drug Resistance, Fungal / Q000235:genetics; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D006921:Hygromycin B / Q000494:pharmacology; D007753:Laboratories; D008969:Molecular Sequence Data; D009172:Mycology / Q000379:methods; D030781:Organisms, Genetically Modified; D027805:Phaseolus / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D014242:Trichoderma / Q000235:genetics / Q000254:growth & development*
D003470:Culture Media; D012987:Soil; D006921:Hygromycin B