Abstract: Seasonal isolation of Sphaerotilus from activated sludge has been made for three years. It is shown that the appearance of Sphaerotilus varies considerably with environmental conditions, especlally with temperature and water quality.Sphaerotilus can't be isolated from activated sludge at 30—36℃ but grows well at 20—28℃. 7 strains of Sphaerotilus are isolated from mixture of domestic sewage and industrial effluents and dye waste water.

Key words: Nilaparvata lugens, Heat shock response, Endogenous enzymes of protective system, Lipid peroxides