title: Concurrent degradation of dimethyl phthalate (DMP) during production of Bacillus thuringiensis based biopesticides.
abstract: Bacillus thuringiensis var. kurstaki (Btk) predominantly used as a microbial insecticide was tested for concomitant degradation of dimethyl phthalate (DMP). Different concentrations of DMP, 100, 200, 500, 1000 and 2000 mg/l were initially spiked in tryptic soya broth medium. A control of tryptic soya broth without DMP was also included. The experiments were carried out for 48 h at 30 degrees C and 250 rpm and growth, enzyme and biocontrol assay was evaluated. DMP concentration until 500 mg/l did not affect Btk cell growth, however, for DMP concentration of 1000-2000 mg/l, there was a 10 and 100 times decrease in cell and spore concentration, respectively. The enzyme concentration reduced by a factor of 1.5, 2, and 2.3 times for protease, esterase and amylase, respectively, at 1000 and 2000 mg/l suggesting toxicity of DMP at higher concentrations. Interestingly, the entomotoxicity (insect toxicity, taken as measure of biocontrol) was higher at 1000 and 5000 mg/l with 12 and 13 billion spruce budworm units/l, as tested against spruce budworm larvae. After 48h of incubation, DMP concentration decreased to 1-3mg/l at initial concentrations ranging from 100 to 500 mg/l, and the removal was relatively lower with 89 and 87% at 1000 and 2000 mg/l of DMP, respectively. These results suggest that Btk produces panoply of enzyme systems which can assist in degradation of DMP.
authors.affiliation: INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, Canada G1K 9A9. satinder.brar@ete.inrs.ca
authors.forename: Satinder K
authors.initials: SK
authors.lastname: Brar
authors.forename: Mausam
authors.initials: M
authors.lastname: Verma
authors.forename: R D
authors.initials: RD
authors.lastname: Tyagi
authors.forename: J R
authors.initials: JR
authors.lastname: Valéro
authors.forename: R Y
authors.initials: RY
authors.lastname: Surampalli
mesh_terms: D000681:Amylases / Q000378:metabolism; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D001673:Biodegradation, Environmental; D049109:Cell Proliferation; D003470:Culture Media; D004950:Esterases / Q000378:metabolism; D007220:Industrial Waste; D007300:Insect Control; D010447:Peptide Hydrolases / Q000378:metabolism; D010572:Pest Control, Biological / Q000379:methods; D010575:Pesticides / Q000737:chemistry*; D010795:Phthalic Acids / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D003470:Culture Media; D007220:Industrial Waste; D010575:Pesticides; D010795:Phthalic Acids; C024629:dimethyl phthalate; D004950:Esterases; D000681:Amylases; D010447:Peptide Hydrolases