Ho-San Kim

Bacillus thuringiensis: a common member of microflora in activated sludges of a sewage treatment plant.

Bacillus thuringiensis was recovered at a high frequency from activated-sludge system environments in an urban sewage-digestive plant. All of the test materials, sampled at several digesting steps, contained the organism. Of 515 colonies belonging to the B. cereus/B. thuringiensis group, 45 (8.7%) were assigned to B. thuringiensis. The highest density of this bacterium was 1.6 × 103 cfu/ml in a scum sample of the first aeration basin. Among the 45 isolates, 7 were assigned to the known H serovars. Two isolates of the serovar kenyae isolates exhibited Lepidoptera-specific toxicity. Diptera-specific toxicity was shown by an isolate of serovar israelensis and a serologically undefined isolate. Lectin activity was associated with 12 isolates.

Specificity of lectin activity of Bacillus thuringiensis parasporal inclusion proteins

Sheep erythrocyte‐agglutinating parasporal inclusion proteins from four Bacillus thuringiensis strains (FITC‐20, FITC‐73, FITC‐ 76 and IBC‐1456) were examined for lectin activity against erythrocytes from four mammalian (rabbit, horse, cow and guinea pig) and an avian (chicken) species. Of the five erythrocyte species, only rabbit cells were agglutinated with the protein of the human cancer cell‐killing strain IBC‐1456. No haemagglutination (HA) activities were shown in other protein‐erythrocyte combinations. The lectin activity of the strain IBC‐1456 against rabbit cells was strongly inhibited by preincubation with D‐galactose. Overall results revealed that the B. thuringiensis lectins have a preference for sheep erythrocytes.