P. Khampang et al., Efficient expression of mosquito-larvicidal proteins in a gram-negative bacterium capable of recolonization in the guts of Anopheles dirus larva, APPL MICR B, 51(1), 1999, pp. 79-84
The gram-negative bacterium, An11/2 G1, isolated from the guts of Anopheles
dirus mosquito larvae, was identified as Enterobacter amnigenus. The E. am
nigenus was able to recolonize in the gut of An. dirus larva but not in tho
se of Aedes aegypti and Culex quinquefasciatus larvae. It was able to float
in water for a longer period than Bacillus thuringiensis subsp. israelensi
s and Bacillus sphaericus. These are desirable characteristics for a delive
ry vehicle of mosquito-larvicidal toxins for the control of mosquito larvae
, and E. amnigenus was therefore used as a host to express the cryIVB gene
of B. thuringiensis subsp. israelensis and the binary toxin genes of B. sph
aericus. The recombinant E. amnigenus produced a high level of CryIVB prote
in, which was toxic to larvae of Ae. aegypti and An. dirus. Another E. amni
genus producing the 51-kDa protein of B. sphaericus was toxic to larvae of
An. dirus and Cx. quinquefasciatus. The recombinant plasmids were stable in
E. amnigenus without the presence of selective pressure for at least 23 ge
nerations. The recombinant E. amnigenus should represent a desirable biolog
ical agent for controlling mosquito larvae.