ISSN 1002-1027  CN 11-2952/G2

Acta scientiarum naturalium Universitatis Pekinensis

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Utilization of Sewage Sludge and Waste Molasses for Production of Bacillus thuringiensis Based Biopesticide

CHANG Ming1ZHOU Shungui1,2LU Na1NI Jinren1,3   

  1. 1Department of Environmental Engineering, Peking University,and the Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871; 2Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Con
  • Received:2006-09-01 Online:2007-11-20 Published:2007-11-20

Abstract: Feasibility of combined fermentation of sewage sludge and waste molasses to ?Bacillus thuringiensis? based biopesticide was studied. As a kind of useful supplemental carbon sources, waste molassesproved to be effective in promoting the growth and metabolism of ?Bacillus thuringiensis? when the additive proportion was lower than 2.0%. Excessive molasses delayed the fermentation process and restrained the spores or crystals from maturing. The best combined medium was found to be sewage sludge (3% total solid) supplemented with 1.5 % molasses (w/w). In this medium, the highest viable cells count (VC) and viable spores count (VS) could rise up to 4.17×108CFU?mL-1and 3.60×108CFU?mL-1, respectively. Both crystal protein concentration and entomotoxicity of this medium were also superior to other combined media at the end of fermentation, with the highest crystal protein yield of 1.96 mg?mL-1 and entomotoxicity of 788 IU?μL-1, respectively. Moreover, significant correlation can be seen between the crystal protein yield and the entomotoxicity. Therefore, crystal protein yield can be used as a simple but reliable index for assessing the Bt fermentation process.