Designed bacteria based on natural pbr operons for detecting and detoxifying environmental lead: A mini-review.

Lead (Pb), a naturally occurring element, is redistributed in the environment mainly due to anthropogenic activities. Pb pollution is a crucial public health problem worldwide due to its adverse effects. Environmental bacteria have evolved various protective mechanisms against high levels of Pb. The pbr operon, first identified in Cupriavidus metallidurans CH34, encodes a unique Pb(II) resistance mechanism involving transport, efflux, sequestration, biomineralization, and precipitation. Similar pbr operons are gradually found in diverse bacterial strains. This review focuses on the pbr-encoded Pb(II) resistance system. It summarizes various whole-cell biosensors harboring artificially designed pbr operons for Pb(II) biomonitoring with fluorescent, luminescent, and colorimetric signal output. Optimization of genetic circuits, employment of pigment-based reporters, and screening of host cells are promising in improving the sensitivity, selectivity, and response range of whole-cell biosensors. Engineered bacteria displaying Pb(II) binding and sequestration proteins, including PbrR and its derivatives, PbrR2 and PbrD, for adsorption are involved. Although synthetic bacteria show great potential in determining and removing Pb at the nanomolar level for environmental protection and food safety, some challenges must be addressed to meet demanding application requirements.

[Detecting the isoflurane in the air of workplaces with chromatographic method].

OBJECTIVE: To establish a solvent desorption Gas chromatographic method for detecting the isoflurane in air of workplaces. METHODS: This method is based on "Standardization of methods for determination of toxic substances in workplace air". RESULTS: This method presents the linear relation with the minimum detectable limit 1.0 µg/ml and the minimum detectable concentration 0.07 mg/m(3). The precision (RSD) was 0.5% ∼ 5.0%, the mean dsorption efficiencies were 96.7% ∼ 98.9%, the absorption efficiencies were 92.1% ∼ 100%, the breakthrough volume was 3.7 mg isoflurane/100 mg active carbon. Other volatile organic solvents (Sevoflurane, Enflurane and Ethyl Alcohol) did not interfere the detection. The sample could be stored in the active carbon tube at least for 10 days. CONCLUSION: This method is meet the requirement of GBZ/T 210.4-2008 "Guide for establishing occupational health standards-Part4: Determination methods of air chemicals in workplace" and is feasible for determining the isoflurane in the air of workplaces.

[Determination of phosphoric acid in the air of workplace by ion chromatography].

OBJECTIVE: To develop a method to determine phosphoric acid in the air of workplace by ion chromatography. METHODS: Phosphoric acid was collected by millipore filter and washed by deionized water then detected by ion chromatography. RESULTS: Linearity range of test was 0 ∼ 20 µg/ml, relative standard deviation (RSD) was 1.95% ∼ 3.31%, the elution efficiency was 103.0% ∼ 109.6%, determination limit was 0.1 µg/ml (when sample size was 20.01) concentration limit was 0.01 mg/m(3) (when the collected air was 75 L). CONCLUSION: This method is convenient for air collection, simple, with high sensitivity and good precision, is a good method for determination of phosphoric acid in the air of workplace.