Growth & toxicity of Bacillus thuringiensis var israelensis.

ABSTRACT

Chemically defined media containing glutamic acid, glutamine and aspartic acid at a 20 mM concentration individually supported abundant growth and sporulation of Bacillus thuringiensis var israelensis. The parasporal crystals produced in these media were toxic to fourth instar larvae of Culex pipiens quinquefasciatus Say. The medium containing 20 mM of glutamine induced early sporulation of B. thuringiensis var israelensis. An LC50 value of 3.92 micrograms/l was obtained. Calcium alginate and agar agar immobilized formulations of Bacillus thuringiensis var israelensis exhibited toxicity of 90 per cent and above to C. pipiens quinquefasciatus Say larvae, over a period of 90 days.