ABSTRACT
Here, we present a new lux-biosensor based on Bacillus subtilis for detecting of DNA-tropic and oxidative stress-causing agents. Hybrid plasmids pNK-DinC, pNK-AlkA, and pNK-MrgA have been constructed, in which the Photorhabdus luminescens reporter genes luxABCDE are transcribed from the stress-inducible promoters of B. subtilis: the SOS promoter PdinC, the methylation-specific response promoter PalkA, and the oxidative stress promoter PmrgA. The luminescence of B. subtilis-based biosensors specifically increases in response to the appearance in the environment of such common toxicants as mitomycin C, methyl methanesulfonate, and H2O2. Comparison with Escherichia coli-based lux-biosensors, where the promoters PdinI, PalkA, and Pdps were used, showed generally similar characteristics. However, for B. subtilis PdinC, a higher response amplitude was observed, and for B. subtilis PalkA, on the contrary, both the amplitude and the range of detectable toxicant concentrations were decreased. B. subtilis PdinC and B. subtilis PmrgA showed increased sensitivity to the genotoxic effects of the 2,2'-bis(bicyclo [2.2.1] heptane) compound, which is a promising propellant, compared to E. coli-based lux-biosensors. The obtained biosensors are applicable for detection of toxicants introduced into soil. Such bacillary biosensors can be used to study the differences in the mechanisms of toxicity against Gram-positive and Gram-negative bacteria.
Subject(s)
Bacillus subtilis , Bacterial Proteins , Biosensing Techniques , Microorganisms, Genetically-Modified , Plasmids , Promoter Regions, Genetic , Bacillus subtilis/genetics , Bacillus subtilis/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Microorganisms, Genetically-Modified/genetics , Microorganisms, Genetically-Modified/metabolism , Plasmids/genetics , Plasmids/metabolismABSTRACT
The mercury-resistance transposon Tn5053 inhibits restriction activity of the type I restriction-modification endonuclease EcoKI in Escherichia coli K12 cells. This is the first report of antirestriction activity of a non-conjugative transposon. The gene (ardD) coding for the antirestriction protein has been cloned. The ardD gene is located within the tniA gene, coding for transposase, on the complementary strand. The direction of transcription is opposite to transcription of the tniA gene.
