Unusual envelopes associated with parasporal inclusions of a mosquitocidal Bacillus thuringiensis serovar fukuokaensis isolate.

A mosquitocidal soil isolate of Bacillus thuringiensis serovar fukuokaensis (H3ade) produced spherical parasporal inclusions measuring 0.6-0.7 microm in diameter. Inclusion matrix was homogeneous substance surrounded by a thick, highly electron-dense envelope 30-50 nm in thickness. The envelopes were associated with both intracellular and extracellular inclusions. Densely woven network was the inner structure of the envelope. Often, inclusions had round-shaped, enveloped small protrusions on the surface.