Effect of Dissolved Oxygen on the Growth, Sporulation and Larvicidal Activity of Bacillus sphaericus 2362

• Main Author: Abdul Karim, Mohamed Ismail
• Format: Article
• Language: English; English
• Published: Universiti Putra Malaysia Press 1996
• Online Access: http://psasir.upm.edu.my/id/eprint/3217/1/Effect_of_Dissolved_Oxygen_on_the_Growth%2C_Sporulation.pdf; http://psasir.upm.edu.my/id/eprint/3217/
• Institution: Universiti Putra Malaysia

Bacillus sphaericus produces bacterial protein toxin capable of killing larvae of mosquitoes which spread diseases such as filariasis, encephalitis and malaria. In batch culture, a maximum spore count of 2.9 x 109/ml media was obtained after 48 h cultivation. In continuous culture, a dilution rate of 0.10 hr- I was found to give a higher spore count than 0.15 h- 1 and 0.2 h- I dilution rates. Kinetic studies on dissolved oxygen (DO) levels showed that 20,50 and 100% gave rapid formation of free spores, whilst 5% DO gave poor results. Cells grown at 5, 20 and 50% DO levels gave comparable values of mosquito-larvicidal activity while those grown at 100% DO were significantly less toxic.