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Abstract: Mathematic relationships between spore concentrations, delta-endotoxin concentrations and entomotoxicity (Tx) of Bacillus thuringiensis var. kurstaki HD-1 (Btk HD-1) preparations produced in six different media were analysed. The relationship between delta-endotoxin and spore concentration and SpTx-spore (specific Tx per 1000 spore) and spore concentration produced in the different media (starch industry wastewater (SIW) with total solids (TS) concentration of 15g/L, SIW with TS of 30g/L, SIW supplemented with 0.2% (w/v) colloidal chitin, SIW supplemented with 1.25% (w/v) cornstarch and 0.2% (v/v) Tween 80, secondary sludge, and semi-synthetic medium) strictly followed the Power law. Tx and delta endotoxin concentration followed the exponential relation whereas a definite relation between Tx and spore concentration could not be established. Spore and delta-endotoxin produced at the early time (12h) during fermentation might be more toxic than those produced during latter period of fermentation irrespective of media used. Tx and delta-endotoxin concentration exhibited a semi-log linear relationship. Based on these findings, delta-endotoxin concentration can be determined rapidly to monitor the progress of the biopesticide production process. [Copyright &y& Elsevier]

Abstract: Starch industry wastewater was investigated to assess and improve its potential as a raw material for the conidia production of biocontrol fungi, Trichoderma viride. The wastewater was tested with and without supplements of glucose, soluble starch, meat peptone and probable conidiation inducer chemicals in shake flask culture. Addition of complex carbon source (soluble starch, 1% and 2% w/v) produced maximum conidia (≈3.02 and 4.2×1010 CFU/mL, respectively). On the other hand, glucose addition as a simpler carbon source was either ineffective or, reduced conidia production (from 1.6×108 in control to 3.0×107 CFU/mL in 5% w/v glucose supplement). Supplement of nitrogen source showed a small increase of conidia concentration. Propionic, maleic and humic acids, EDTA, pyridine, glycerol and CaCO3 were examined as probable conidiation inducers and showed effect only on initial rate of conidiation with no increase in final conidia concentration. Intra and extracellular ATP correlation with spore production showed dependence on growth media used and conidia concentration at the end of fermentation. Addition of carbon and nitrogen sources showed an increase in protease activity (from 0.4985 to 2.43IU/mL) and entomotoxicity (from 10448 to 12335 spruce budworm unit (SBU)/μL). Entomotoxicity was improved by 11% in fermenter over shake flask when starch industry wastewater was supplemented with meat peptone. [Copyright &y& Elsevier]

Abstract: Starch industry wastewater (SWW), slaughterhouse wastewater (SHWW) and secondary sludges from three different wastewater treatment plants (Jonquière—JQS, Communauté Urbaine de Québec—CUQS and Black lake—BLS) were used as raw materials for the production of Bacillus thuringiensis (Bt) based biopesticides in a pilot scale fermentor (100L working volume). The slaughterhouse wastewater exhibited the lowest Bt growth and entomotoxcity (Tx) potential (measured against spruce budworm) due to low availability of carbon, nitrogen and other nutrients. Performance variation (growth, sporulation, proteolytic activity and Tx potential) within the three types of sludges was directly related to the availability of nitrogen and carbohydrates, which could change with sludge origin and methods employed for its generation. The Tx potential of Bt obtained in different secondary sludges (JQS: 12×109 SBU/L; CUQS: 13×109 SBU/L and BLS: 16×109 SBU/L) and SWW (18×109 SBU/L) was higher than the soybean based synthetic medium (10×109 SBU/L). The maximum protease activity was obtained in CUQ secondary sludge (4.1IU/mL) due to its high complex protein concentration. Nevertheless, high carbohydrate concentration in SWW repressed enzyme production. The secondary sludges and SWW were found to be suitable raw materials for high potency Bt biopesticide production. [Copyright &y& Elsevier]