Rhodococcus aetherivorans BCP1 as cell factory for the production of intracellular tellurium nanorods under aerobic conditions

Background: Tellurite (TeO32-) is recognized as a toxic oxyanion to living organisms. However, mainly anaerobic or facultative-anaerobic microorganisms are able to tolerate and convert TeO32- into the less toxic and available form of elemental Tellurium (Te0), producing Te-deposits or Te-nanostructures. The use of TeO32--reducing bacteria can lead to the decontamination of polluted environments and the development of "green-synthesis" methods for the production of nanomaterials. In this study, the tolerance and the consumption of TeO32- have been investigated, along with the production and characterization of Te-nanorods by Rhodococcus aetherivorans BCP1 grown under aerobic conditions. Results: Aerobically grown BCP1 cells showed high tolerance towards TeO32- with a minimal inhibitory concentration (MIC) of 2800μg/mL (11.2mM). TeO32- consumption has been evaluated exposing the BCP1 strain to either 100 or 500μg/mL of K2TeO3 (unconditioned growth) or after re-inoculation in fresh medium with new addition of K2TeO3 (conditioned growth). A complete consumption of TeO32- at 100μg/mL was observed under both growth conditions, although conditioned cells showed higher consumption rate. Unconditioned and conditioned BCP1 cells partially consumed TeO32- at 500μg/mL. However, a greater TeO32- consumption was observed with conditioned cells. The production of intracellular, not aggregated and rod-shaped Te-nanostructures (TeNRs) was observed as a consequence of TeO32- reduction. Extracted TeNRs appear to be embedded in an organic surrounding material, as suggested by the chemical-physical characterization. Moreover, we observed longer TeNRs depending on either the concentration of precursor (100 or 500μg/mL of K2TeO3) or the growth conditions (unconditioned or conditioned grown cells). Conclusions:Rhodococcus aetherivorans BCP1 is able to tolerate high concentrations of TeO32- during its growth under aerobic conditions. Moreover, compared to unconditioned BCP1 cells, TeO32- conditioned cells showed a higher oxyanion consumption rate (for 100μg/mL of K2TeO3) or to consume greater amount of TeO32- (for 500μg/mL of K2TeO3). TeO32- consumption by BCP1 cells led to the production of intracellular and not aggregated TeNRs embedded in an organic surrounding material. The high resistance of BCP1 to TeO32- along with its ability to produce Te-nanostructures supports the application of this microorganism as a possible eco-friendly nanofactory

Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: New metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes

Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD-coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation-were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria-Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step

A hidden integral structure endows absolute concentration robust systems with resilience to dynamical concentration disturbances: A hidden integral structure endows absolute concentration robust systems with resilience to dynamical concentration disturbances

Biochemical systems that express certain chemical species of interest at the same level at any positive steady state are called 'absolute concentration robust' (ACR). These species behave in a stable, predictable way, in the sense that their expression is robust with respect to sudden changes in the species concentration, provided that the system reaches a (potentially new) positive steady state. Such a property has been proven to be of importance in certain gene regulatory networks and signaling systems. In the present paper, we mathematically prove that a well-known class of ACR systems studied by Shinar and Feinberg in 2010 hides an internal integral structure. This structure confers these systems with a higher degree of robustness than was previously known. In particular, disturbances much more general than sudden changes in the species concentrations can be rejected, and robust perfect adaptation is achieved. Significantly, we show that these properties are maintained when the system is interconnected with other chemical reaction networks. This key feature enables the design of insulator devices that are able to buffer the loading effect from downstream systems - a crucial requirement for modular circuit design in synthetic biology. We further note that while the best performance of the insulators are achieved when these act at a faster timescale than the upstream module (as typically required), it is not necessary for them to act on a faster timescale than the downstream module in our construction

Potential impact of dreissenids species in relation to the first report of quagga mussel (Dreissena bugensis) at the end of winter 2022 in Lake Garda (Northern Italy)

Along with Dreissena polymorpha (zebra mussel), Dreissena bugensis (quagga mussel) is considered one of the most widespread and successful invasive species in Europe, Russia, and North America. The quagga mussel is a bivalve mollusc of the dreissenids family originating from the estuarine region of the rivers Dnieper and Southern Bug (Black Sea). The spread in Europe began after the 1940s and was associated with construction of canal-river systems. D. polymorpha was observed in Lake Garda since the end of the 1960s. In the last years, D. bugensis was found in the northern perialpine region and in late winter 2022 it was identified along the eastern shores of Lake Garda. Both species are defined as ecosystems engineers because they can strongly change the substrate structure, causing great economic damage in water pipes, potable water treatment plants, and port constructions. Moreover, they can affect resource availability for the other species. A few significant ecological differences between the two species suggest that the impact of quagga mussel could be even larger compared to that caused by zebra mussel. In this poster we will discuss the main expected ecological impacts following the introduction of quagga mussel into new aquatic habitats

Low temperature/uv-assisted composites as gas sensors for medical applications

The sensing of gas molecules is of fundamental importance for environmental monitoring, control of chemical processes, medical applications, and so on [1]. Furthermore, recent success in non-invasive medical diagnostics, based on human breath analysis, is pushing forward the development of extremely sensitive gas sensors for ppb detection of specific analytes (e.g. acetone) in a complex gas mixture [1,2]. In recent years, graphene-based gas sensors have attracted much attention and different structures have been developed showing high sensing performances and room temperature working conditions [2]. However, they still suffer from several problems, which could be overcome by covering the graphene surface with metal oxide semiconductors. Furthermore, studies regarding the detection of Volatile Organic Compounds (VOCs) are still at the beginning [3]. Hence, the present work will be aimed at: i) optimizing the synthetic routes of ad hoc composite VOCs sensing materials (based on graphene oxide/SnO2 hybrids); ii) engineering the gas sensor device; and iii) evaluating the sensing performances at both high and mild temperatures (also exploiting the UV light) towards gaseous ethanol, acetone and ethylbenzene. Starting from pure graphite, graphene oxide (GO) powder was synthesized by adopting the Hummer\u2019s modified method, in which the synthetic route was deeply investigated, and several parameters (such as H2O2 concentration) were modulated. Once optimized this step, SnO2 were grown on its surface by hydrothermal method, varying the starting salt precursor/GO weight ratio between 4 and 32. For comparison, pure commercial and home-made SnO2 were also tested. Several physico-chemical analyses were performed to characterize all the as-prepared nanopowders. Subsequently, a homogeneous film was deposited by spraying technique onto Pt-Interdigitated Electrodes (Pt-IDEs). Then, gaseous ethanol (Figure 1) and acetone were sensed, obtaining very promising results for both pure and hybrid materials at 350\ub0C, and at lower temperatures (150\ub0C to 30\ub0C, by exploiting the UV light) for the graphene-based samples

Multi-stage calibration of the simulation model of a school building through short-term monitoring

The increasing attention on the improvement of new and existing buildings' performance is emphasizing the importance of the reliability of the simulation models in predicting the complexity of the building behaviour and, consequently, in some advanced applications of building simulation, such as the optimization of the choice of different Energy Efficiency Measures (EEMs) or the adoption of model predictive control strategies. The reliability of the energy model does not depend only on the quality and details of the model itself, but also on the uncertainty related to many input values, such as the physical properties of materials and components, the information on the building management and occupation, and the boundary conditions considered for the simulation. Especially for the existing buildings, this kind of data is often missing or characterized by high uncertainty, and only very simplified behavioural models of occupancy are available. This could compromise the optimization process and undermine the potential of building simulation. In this context, the calibration of the simulation model by means of on-site monitoring is of crucial importance to increase the reliability of the predictions, and to take better decisions, even though this process can be time consuming. This work presents a multi-stage methodology to calibrate the building energy simulation by means of low-cost monitoring and short-term measurements. This approach is applied to a Primary School in the North-East of Italy, which has been monitored from December 2012 to April 2014. Four monitoring periods have been selected to calibrate different sets of variables at a time, while the validation has been carried out on two different periods. The results show that even if less than 8 weeks have been considered in the proposed calibration approach, the maximum error in the estimation of the temperature is less than ±0.5 in 77.3% of the timesteps in the validation period

Estimation of the sugar cane cultivated area from LANDSAT images using the two phase sampling method

A two phase sampling method and the optimal sampling segment dimensions for the estimation of sugar cane cultivated area were developed. This technique employs visual interpretations of LANDSAT images and panchromatic aerial photographs considered as the ground truth. The estimates, as a mean value of 100 simulated samples, represent 99.3% of the true value with a CV of approximately 1%; the relative efficiency of the two phase design was 157% when compared with a one phase aerial photographs sample