Similarities between crystal protein subunits of Bacillus thuringiensis strain 1884 serotype H14 and strain PG14 serotype H8a,8b, and their relationship with mosquitocidal activity.

Bacillus thuringiensis subsp. israelensis strain 1884 and B. thuringiensis subsp. morrisoni strain PG14 have the same toxicity toward mosquito larvae. Their protein crystal contents were compared either on native electrophoretic systems or on gel filtration. Analysis of electroeluted native proteins in SDS-PAGE showed that the 28-Kd protein alone, without the 68- or 130-Kd protein, was not larvicidal; however, toxicity was recorded as soon as 28- and 68-Kd proteins were associated. After gel filtration of 1884 soluble crystal, the 68-Kd protein alone, without 28 or 130 Kd, was not toxic; toxicity was also recorded when 28- and 68-Kd proteins and higher molecular weight proteins were associated. A comparable pattern was observed with PG14 soluble crystals.