Despite its proven high toxicity, unsymmetrical dimethylhydrazine (UDMH) continues to be used in rocket technology and some other areas of human activity. In this work, the ability of plant-bacterial consortia to reduce the genotoxicity of UDMH and its incomplete oxidation products was investigated. Genotoxicity was assessed using a specific lux-biosensor, Escherichia coli MG1655 pAlkA-lux, which emits stronger light when cellular DNA is alkylated. For microbiological biodegradation, the Bacillus subtilis KK1112 strain was isolated from the soil via a two-stage selection process for resistance to high UDMH concentrations exceeding 5000 MAC. This strain's ability to biodegrade UDMH was demonstrated, as treatment of UDMH-polluted medium with KK1112 resulted in reduced DNA alkylation. A synergistic reduction in the DNA-alkylating potency of UDMH oxidation products was studied under the combined application of bacteria KK1112 and plant seedlings: Bromus inermis Leyss, Medicago varia Mart. and Phleum pratense L. The greatest effect was achieved when bacteria were used in combination with B. inermis. KK1112 cells accelerated seedling development and mitigated UDMH-induced growth inhibition. The findings suggest that the consortium of KK1112 and B. inermis has a great potential for remediation of UDMH-polluted soils in arid climatic zones.

The YhaJ transcription factor responds to dinitrophenol (DNT) and its metabolic products. The YhaJ-involving cells have been exploited for whole-cell biosensors of soil-buried landmines. Such biosensors would decrease the damage to personnel who approach landmine fields. By the structure determination of the DNA-binding domain (DBD) of YhaJ and the structure-guided mutagenesis, we found that the mutation increasing the DNA binding affinity decreases the signal leakage in the absence of an effector, resulting in a significant enhancement of the response ratio for the DNT metabolite detection. The decrease in signal leakage explains the LysR-type transcriptional regulators' (LTTRs') unique mechanism of signal absence repression by choosing between two different activation binding sites. We showed that the biosensor performance enhancement by the decrease in signal leakage could combine with the previous signal-enhancing mutations. The novel mechanism of performance enhancement of YhaJ shed light on bacterial transcription regulation and the optimization of biosensors that involve the large family of LTTRs.

Phosphonates (PHTs), organic compounds with a stable C-P bond, are widely distributed in nature. Glyphosate (GP), a synthetic PHT, is extensively used in agriculture and has been linked to various human health issues and environmental damage. Given the prevalence of GP, developing cost-effective, on-site methods for GP detection is key for assessing pollution and reducing exposure risks. We adopted Agrobacterium tumefaciens CHLDO, a natural GP degrader, as a host and the source of genetic parts for constructing PHT biosensors. In this bacterial species, the phn gene cluster, encoding the C-P lyase pathway, is regulated by the PhnF transcriptional repressor. We selected the phnG promoter, which displays a dose-dependent response to GP, to build a set of whole-cell biosensors. Through stepwise genetic optimization of the transcriptional cascade, we created a whole-cell biosensor capable of detecting GP in the 0.25-50 mu M range in various samples, including soil and water.

Buprofezin (BUP) is an effective insecticide against Homopteran and Thysanoptera pests. However, exposure to BUP may result in several harmful effects on the non-target organism including human body, such as hepatotoxicity and DNA damage. Therefore, development of a reliable analytical method for BUP holds paramount importance. This study presents a novel albumin-based supramolecular biosensor, DPP@ALB, designed for the sensitive detection of BUP in environmental matrices, including water, soil, and real food samples. The features of this biosensor include a fast response, high sensitivity, and visually detectable fluorescence color change, enabling on-site detection of BUP based on the portable paper strips and 3D-printed miniaturized testing system. Overcoming challenges associated with the low chemical reactivity of BUP, this supramolecular biosensor emerges as the very first fluorescent sensor for efficient and reliable monitoring of BUP with applications in broader areas of environmental analysis and food safety.

Pesticides and fertilizers used in agriculture can negatively affect the soil, increasing its toxicity. In this work, a battery of whole-cell bacterial lux-biosensors based on the E. coli MG1655 strain with various inducible promoters, as well as the natural luminous Vibrio aquamarinus VKPM B-11245 strain, were used to assess the effects of agrochemical soil treatments. The advantages of using biosensors are sensitivity, specificity, low cost of analysis, and the ability to assess the total effect of toxicants on a living cell and the type of their toxic effect. Using the V. aquamarinus VKPM B-11245 strain, the synergistic effect of combined soil treatment with pesticides and mineral fertilizers was shown, which led to an increase in the overall (integral) toxicity of soils higher than that of the individual application of substances. Several probable implementation mechanisms of agrochemical toxic effects have been discovered. DNA damage caused by both SOS response induction and alkylation, oxidative stress due to increased superoxide levels, and damage to cellular proteins and membranes are among them. Thus, the usage of biosensors makes it possible to assess the cumulative effect of various toxicants on living organisms without using expensive chemical analyses.

Biocementation consists in using urease enzyme and a solution rich in urea and in calcium to precipitate calcium carbonate (biocement). When applying this treatment in soils, the biocement minerals bond the grains improving overall soil's hydro-mechanical properties. For the practical use of this technique, it is necessary to be able to predict the properties of the treated soil after following specific protocols, by preference avoiding non-destructive testing such as those performed on samples extracted after the treatment. The amount of biocement precipitated depends on the amount of urease enzyme, urea and calcium. This idea has inspired the development of one magnetoresistive biosensor to detect urease, to be used as a non-destructive monitoring tool during the treatment. A magnetoresistive platform was used to quantify the signal, which is related to the urease concentration through a calibration curve. The sensor was tested to measure the enzyme present in the inflow and outflow fluids used to treat cylindrical soil samples (2.5 cm diameter and 2.0 cm height), prepared with a uniform grading size sand (D-50=0.3 mm). Purified urease from Canavalia ensiformis, was used. The improvement of the biocemented sand samples was quantified through measuring the calcium carbonate content of the soil after the treatment and the values were related with the amount of enzyme retained by the soil, determined using the sensor readings. This work found, for the first time, the relationship between the measured concentration of urease retained by soil and the calcium carbonate content precipitated. This relationship is an important tool for monitoring the treatment, without the need to use destructive tests or even stop the treatment.