ACTIVITY OF THE MICROSOMAL OXIDATION SYSTEM IN RAT LIVER UNDER THE INFLUENCE OF SODIUM FLUORIDE

Summary. The pathogenesis of fluoride intoxication at the molecular, cellular and functional levels has not been sufficiently studied. There are very few modern data on these issues, so they are contradictory, since the effects of this trace element are multifaceted and cannot be characterized unambiguously. The aim of the study – to learn the state of the monooxygenase system of rat hepatocytes under conditions of the formation of fluoride intoxication. Materials and Methods. In the experiment, we used 30 sexually mature rats (N=30) of the Wistar population weighing 200–210 g for 1.5 months. Sodium fluoride solution was administered orally at doses of 1/10 DL50, which was 20 mg/kg of animal body weight. Results. The results of experiments on the study of oxygen consumption by rat liver microsomes under fluoride intoxication indicated that the rate of endogenous respiration of microsomes, the rate of NADPH oxidation, the rate of NADH oxidation in the presence of EDTA, and the rate of lipid peroxidation increase under the influence of fluorides. Sodium fluoride stimulated an increase in all parameters of microsomal oxidation, except for cytochrome b5. It should be assumed that in this case there is an increase in the generation of reactive oxygen species, free radicals, which stimulate the development of free radical processes in the body and are, most likely, the leading link in oxidative stress. Conclusions. These changes indicate a violation of the bioenergetics of hepatocytes associated with the mitochondrial apparatus and the development of hypoxic processes, which lead to a decrease in the activity of redox reactions occurring at the level of intracellular membranes and organelles.

ABACO: A New Model of Microalgae-Bacteria Consortia for Biological Treatment of Wastewaters

Microalgae-bacteria consortia have been proposed as alternatives to conventional biological processes to treat different types of wastewaters, including animal slurry. In this work, a microalgae-bacteria consortia (ABACO) model for wastewater treatment is proposed, it being calibrated and validated using pig slurry. The model includes the most relevant features of microalgae, such as light dependence, endogenous respiration, and growth and nutrient consumption as a function of nutrient availability (especially inorganic carbon), in addition to the already reported features of heterotrophic and nitrifying bacteria. The interrelation between the different populations is also included in the model, in addition to the simultaneous release and consumption of the most relevant compounds, such as oxygen and carbon dioxide. The implementation of the model has been performed in MATLAB software; the calibration of model parameters was carried out using genetic algorithms. The ABACO model allows one to simulate the dynamics of different components in the system, and the relative proportions of microalgae, heterotrophic bacteria, and nitrifying bacteria. The percentage of each microbial population obtained with the model was confirmed by respirometric techniques. The proposed model is a powerful tool for the development of microalgae-related wastewater treatment processes, both to maximize the production of microalgal biomass and to optimize the wastewater treatment capacity.

Wastewater COD characterization: RBCOD and SBCOD characterization analysis methods

Wastewater characterization is the basis for process design and operation optimization of wastewater treatment plants (WWTPs). In this work, a comprehensive study of the respirometry method has been performed to evaluate the biodegradable organic matters of wastewater. First, the optimal initial substrate to biomass ratio (S0/X0) was confirmed. Second, under the optimal S0/X0, the degradation curves of wastewater carbon oxygen demand (COD) components rapidly biodegradable COD (RBCOD) and slowly biodegradable COD (SBCOD) were obtained. Third, the Mann–Kendall test was performed to confirm the time point (t2) when endogenous respiration levels were reached, and the hydrolysis model was used to determine the time point (t1) of the SBCOD degradation stage. Considering the results, an adequate wastewater COD characterization method for RBCOD and SBCOD has been proposed. This study provides strong support to carry out effective and feasible process design, process diagnosis and optimization capability, can help achieve refined and stable operational management of WWTPs.

Regularized S-Map Reveals Varying Bacterial Interactions

ABSTRACT There is a growing awareness that bacterial interactions follow a highly nonlinear pattern in reality. However, it is challenging to track the varying bacterial interactions using pairwise correlation analysis, which fails to explore their potential effects on the behavior of microbes. Here, we utilized a regularized sequential locally weighted global linear map (S-map) to capture the varying interspecific interactions from the time series data of a bacterial community under exposure to nitrite. Our results show that bacterial interactions are highly variable and that asymmetric interactions dominate the interaction pattern in a community. Furthermore, we propose a Jacobian coefficient-based statistical method to predict the harmony level of a bacterial community at each successive ecosystem state. The results show that the bacterial community exhibits a higher harmony level in nitrite-treated samples than in the control group. We show that the community harmony level is positively associated with the specific endogenous respiration rates and biofilm formation of the culture. In addition, the community tends to process lower diversity and structural stability under zero- and high-nitrite stresses. We demonstrate that the harmony level, rather than structural stability, is a useful index for unveiling the underlying mechanism of bacterial performance. Overall, the regularized S-map can help us to understand bacterial interactions in ecosystems more accurately than previous approaches. IMPORTANCE It has long been acknowledged that bacterial interactions play important roles in community structure and function. Revealing the interaction variability can allow an understanding of how bacteria respond to perturbation and why bacterial community performance changes. Such information should improve our skills in engineering bacterial communities (e.g., in a wastewater treatment plant) and achieve better removal performance and lower energy consumption.

Analyzing transient respirometric data by analytical algorithm for Monod kinetic parameters

This study aims to develop an analytical algorithm with oxygen update (Ou) data obtained from transient respirometric measurement. Based on Monod kinetics, this study formulates a novel two-phase analytical model for an oxygen uptake rate plot (OUR vs. Ou) obtained by respirometric techniques. The first phase is a hyperbolic equation relating to exogenous and endogenous respiration, while the second phase is a linear equation for endogenous respiration only. An algorithm was therefore developed to analyze four Monod parameters by locating the best phase-separating point at which the absolute average relative error (ARE) of OUR is minimized. An analysis using test data on acetate verified that the algorithm is capable of transient kinetic parameter estimation with an ARE below 5–10%. A sensitivity analysis on domestic wastewater coupled with a Monte Carlo simulation concluded that the kinetic test must be conducted at a relatively high initial substrate level (So/Xo ≧ 1 and So/Ks ≧ 10) for reliable parameter estimation. Moreover, it is crucial to conduct the kinetic test with sufficient and acclimated seed culture for the degradation of substrate. The results of this study can be used to develop an automatic transient kinetic analyzer with modern programmable respirometers.

Proliferation of biomass and its impact on the operation of a submerged membrane bioreactor

The aim of this work was to investigate the biomass proliferation and its impact on the operation of a submerged membrane bioreactor (sMBR). A programmable logic controller (PLC) was used to control the process of the sMBR with no discharge of sludge. When MLSS was 9670 mg/L and the solid retention times (SRT) ranged from 20 to 40 days, the optimal removal efficiencies of COD, NH3-N, TP were 93.89%, 93.02%, 80.57%, respectively. Accompanying with the decreasing of the sludge loading, the substrate and nutrition were insufficient in the sMBR, leading to endogenous respiration of the activated sludge, which decreased the activity of sludge and resulted in the death of more microorganisms.

Cellular mechanisms of hypoxia development in the tissues of experimental animals under varying characteristics of vibration exposure

The aim of the work was to study the primary bioenergetic mechanisms of hypoxia formation in the myocardial tissue of experimental animals depending on the differentiated physical characteristics of vibration (frequency and duration) and their combination. The study of the functional states of native mitochondria in the composition of the tissue homogenate was carried out using the polarographic method and a galvanic-type closed-oxygen sensor in a 1-ml thermostatic cuvette in a salt incubation medium. The metabolic states of the mitochondria of the myocardium of experimental animals were modeled in vitro during the oxidation of endogenous substrates (before and after the administration of inhibitors of different links of the respiratory chain), with varying exogenous energy substrates (before and after the introduction of 2,4-DNP into the cell). In order to ensure synchronism of measurements in a short time, an incomplete cycle of metabolic states “endogenous respiration → rest → activity” was used. The results of multiple comparisons of variations in kinetic parameters revealed a reliable but multidirectional effect of the frequency of vibration on the rate of oxidation of substrates of the mitochondria of the heart of rabbits in different metabolic states. A change in the duration of exposure to vibration showed an increase in the oxidation rate of endogenous substrates and succinic acid at rest to 21–56 sessions by 17% and 24. 4%, respectively, while the oxidation rate of glutamate decreased to 56 sessions by 24. 5%. Comparison of the general variability of kinetic parameters with a combination of frequency and duration of vibration at different levels of variation showed that it was the interaction of factors that made the most important and significant contribution to the intergroup variability of oxidation rates of endogenous and exogenous substrates, identifying signs of the formation of bioenergetic hypoxia and allowing analysis of the primary physical transformation phenomena in the biological effect.

Endogenous respiration process analysis between aMBR and UV/O3-aMBR for polluted surface water treatment

The microbial endogenous respiration process is very important in biological water treatment processes. This study analyzed and compared the endogenous respiration process in an attached growth membrane bioreactor (aMBR) system and a UV/O3 integrated aMBR system (UV/O3-aMBR) in treating polluted surface water with CODMn around 10 mg/L. The endogenous respiration activity of heterotrophic microbes and autotrophic nitrifiers activity in both systems was analyzed and compared. Results show that heterotrophic bacteria and autotrophic nitrifiers enter endogenous respiration at 6 h aeration in an aMBR and 0 h in a UV/O3-aMBR system. Biomass amount on PVA-gel in aMBR was higher than in UV/O3-aMBR in terms of specific respiration rates SOURt, SOURH, and SOURA. Substrate remained on PVA-gel in the aMBR system, but no substrate remained on PVA-gel in the UV/O3-aMBR system. Higher species of microbes, including recoverable and irrecoverable components, existed in the aMBR system as compared to the UV/O3-aMBR system. The UV/O3-aMBR system could make full use of the advanced oxidation process (AOP) and biological process, leading to a higher treatment performance, and has the potential to mitigate total energy demand. Thus, the UV/O3-aMBR system can be used as a new technology for treating polluted surface water with the co-contribution of biological process and AOP treatment.

Alteration of Pseudomonas aeruginosa respiration by 4-(1-adamantyl)-phenol derivative

Derivatives of 4-(1-adamantyl)-phenol are a promising class of antimicrobials affecting the structural integrity and functions of the bacterial cell membrane. The functioning of Pseudomonas aeruginosa respiratory chain and related system of oxidative phosphorylation was investigated before and after treatment with a derivative of 4-(1-adamantyl)-phenol (compound KVM-97). Oxygen consumption was measured polarographically with a Clark-type oxygen electrode. KVM-97 was tested at 0.5× and 1.0× MIC (minimum inhibitory concentration). Specific substrates of the respiratory chain (either 3.0 mM glutamate with 2.0 mM malonate or 3.0 mM succinate with 5.0 μM rotenone) were used. All reactions were stimulated by addition of ADP (0.2 mmol). It was found that at tested concentrations, KVM-97 inhibited the endogenous respiration and substrate oxidation in P. aeruginosa cells. The inhibiting effect was dose-dependent and more pronounced with succinate oxidation rather than glutamate oxidation. The respiratory control index value (RCI) in compound-treated cells was in average 1.5 times lower compared to the intact cells. The decrease in the RCI was related to changing the oxygen uptake rates in state 3 and state 4, which indicate the uncoupling of respiration and oxidative phosphorylation. The data obtained showed that 4-(1-adamantyl)-phenol derivative inhibits oxygen consumption and has uncoupling effects in P. aeruginosa cells.