title: Simultaneous production of biopesticide and alkaline proteases by Bacillus thuringiensis using sewage sludge as a raw material.
abstract: The simultaneous production of Bacillus thuringiensis (Bt) based biopesticide and proteases was studied using synthetic medium and wastewater sludge as a raw material. The studies were conducted in shake flask and computer controlled 15-L capacity fermentors. Measuring viable cell and spore counts, entomotoxicity and protease activity monitored the progress of the biopesticide production process. A higher viable cell count and spore count was observed in synthetic Soya medium, however, higher entomotoxicity and protease activity were observed in wastewater sludge medium. Thus, the wastewater sludge is a better raw material than commercial Soya medium for the biopesticides and enzyme production. The maximum entomotoxicity and protease activity observed in the fermentor was 9,332 IU/microL and 4.58 IU/mL, respectively. The proteases produced by Bt were also characterised. Two types of proteases were detected; neutral proteases with pH optimum 7.0 and alkaline proteases with pH optimum 10-11. Further, two types of alkaline proteases were detected; one having a pH and temperature optimum at 10 and 50 degrees C while the other at 11 and 70 degrees C. The protease thermal stability was found to increase in the presence of CaCl2, indicating the proteases were metalloproteases.
authors.affiliation: INRS-Eau, 2700 rue Einstein, Sainte-Foy, Québec, Canada G1 V 4C7. tyagi@inrs-eau.uquebec.ca
authors.forename: R D
authors.initials: RD
authors.lastname: Tyagi
authors.forename: V
authors.initials: V
authors.lastname: Sikati Foko
authors.forename: S
authors.initials: S
authors.lastname: Barnabe
authors.forename: A S
authors.initials: AS
authors.lastname: Vidyarthi
authors.forename: J R
authors.initials: JR
authors.lastname: Valéro
authors.forename: R Y
authors.initials: RY
authors.lastname: Surampalli
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000201:enzymology* / Q000472:pathogenicity; D019149:Bioreactors; D010450:Endopeptidases / Q000096:biosynthesis*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D009036:Moths; D010572:Pest Control, Biological; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D018675:Toxicity Tests
chemical_list: D012722:Sewage; D010450:Endopeptidases