Spore toxin complex recovery from solid-state fermentation of some mosquitocidal Bacilli

The efficiency of different methods for recovery of spore toxin complex (STC) from solid-state fermentation (SSF) extracts of Bacillus thuringiensis israelensis (Bti) and Lysinibacillus sphaericus 14N1(Ls14N1) was studied. Drying at 30-50 degrees C, lyophilisation, flocculation by ferric chloride at 0.1-0.2% and encapsulation by entrapment in calcium alginate beads, agar, or polyacrylamide gel were efficient methods for recovery of STC of Ls14N1 and Bti from SSF extracts. Also, STC was precipitated with remained the mosquitocidal activity through adjusting the pH of the SSF liquid extract before centrifugation at pH 2-5 or after addition of acetone (200-400%), ethanol (400%) or acetic acid (2.5-4%) to SSF liquid extract of Ls14N1. On the other hand, STC of Bti showed a good recovery by centrifugation after adjusting SSF liquid extract at pH 4 followed by pH 3 and pH 5 or after the addition of ethanol (300%) or acetone (200-300%). This study contains simple and multiple methods for efficient recovery of STC of Bti and Ls14N1 grown under SSF. The choice of the best method depends on the availability of the necessary equipment as well as the cost of the treatment.