Cloning and Heterologous Expression of Insecticidal-Protein-Encoding Genes from Photorhabdus luminescens TT01 in Enterobacter cloacae for Termite Control

Abstract

Enterobacter cloacae, one of the indigenous gut bacteria of the Formosan subterranean termite (Coptotermes formosanus), was genetically modified with a transposon Tn5 vector containing genes (tcdA1 and tcdB1) encoding orally insecticidal proteins from the entomopathogenic bacterium Photorhabdus luminescens subsp. laumondii TT01, a symbiont of the entomopathogenic nematode Heterorhabditis bacteriophora, for termite control. In the laboratory, termites were fed filter paper inoculated with the recombinant bacteria. The chromosomal expression of the introduced genes showed that there were insecticidal activities against termite workers and soldiers challenged with the transformed bacteria. After termites were fed recombinant bacteria, the termite mortality was 3.3% at day 5, and it increased from 8.7% at day 9 to 93.3% at day 29. All the dead termites contained the recombinant bacteria in their guts. Transfer of the recombinant bacteria occurred between donor workers (initially fed recombinant bacteria) and recipient workers (not fed). More than 20% of the recipient termites ingested recombinant bacteria within 2 h, and 73.3% of them had ingested recombinant bacteria after 12 h. The method described here provides a useful alternative for sustainable control of the Formosan subterranean termite (C. formosanus) and other social insects, such as the imported red fire ant (Solenopsis invicta).

Pdl1 Is a Putative Lipase that Enhances Photorhabdus Toxin Complex Secretion

“…In addition TC toxins have also been heterologously expressed in Enterobacteria species which associate with termites as a control strategy [16]. Most recently Lang et al demonstrated the mode of action of certain C-subunit C-terminal domains in the ADP-ribosylation of actin and RhoA [9].…”

Overview of the Basic Biology of Bacillus thuringiensis with Emphasis on Genetic Engineering of Bacterial Larvicides for Mosquito Control

“…Since then no other reports of transgenic plants expressing the "Toxin complexes" have been forthcoming. Interestingly a different method of pest control by the "Toxin complexes" has been reported, namely the control of termites using a transgenic indigenous gut bacterium [129]. This ingenious scheme involves generating an Enterobacter cloacae strain expressing both TcdA and TcdB which is then fed to the termites.…”

Microbes as tools and targets for termite control

“…In a previous study, genetically engineered Enterobacter cloacae expressing an insecticidal toxin from Photorhabdus luminescens was shown to kill termites in lab experiments (Zhao et al, 2008). Enterobacter cloacae is frequently found in the termite gut and genetically engineered strains have been shown to be introduced effectively into termite colonies and survive long enough to express foreign gene product and be transferred among nest mates .…”