Comparative study of semi-specific Aeromonas hydrophila and universal Pseudomonas fluorescens biosensors for BOD measurements in meat industry wastewaters

Aeromonas hydrophila P69.1 (A. hydrophila) was used to construct a semi-specific biosensor to estimate biochemical oxygen demand (BOD) in high fat and grease content wastewaters. A. hydrophila cells were grown in fat containing medium to induce necessary enzymes for transport and degradation of fatty substances. Universal biosensor based on non-specific Pseudomonas fluorescens P75 (P. fluorescens) was used to conduct comparison experiments. Biosensors were calibrated using OECD synthetic wastewater and steady-state method, subsequently several experiments with synthetic and industrial wastewaters were conducted. A linear range up to 45 mg l(-1) BOD(7) was gained using A. hydrophila biosensor, in comparison to 40 mg l(-1) BOD(7) obtained using P. fluorescens biosensors. The lower limit of detection was 5 mg l(-1) BOD(7). Service life of A. hydrophila and P. fluorescens biosensors were 110 and 115 days, respectively. The response time of the biosensors depended on the BOD(7) of measuring solution and was up to 20 min when analyzing different wastewaters. Both biosensors underestimated BOD in meat industry wastewater from 43% up to 71%, but more accurate results could be obtained with A. hydrophila biosensor. Semi-specific A. hydrophila biosensor was able to measure proportion of fat found in wastewater sample, while other refractory compounds remained undetectable to both biosensors.     

Novel BOD (biological oxygen demand) sensor using mediator-less microbial fuel cell

A microbial fuel cell type of biosensor was used to determine the biochemical oxygen demand (BOD) of wastewater. The biosensor gave a good correlation between the BOD value and the coulomb produced. The BOD sensor has been operated for over 5 years in a stable manner without any servicing. This is much longer that that of previously reported BOD biosensors.     

Characterization of two novel yeast strains used in mediated biosensors for wastewater

After isolation from a pulp mill wastewater treatment facility, two yeast strains, designated SPT1 and SPT2, were characterized and used in the development of mediated biochemical oxygen demand (BOD) biosensors for wastewater. 18S rRNA gene sequence analysis revealed a one nucleotide difference between the sequence of SPT1 and those of Candida sojae and Candida viswanthii. While SPT2 had the highest overall homology to Pichia norvegensis, at only 73.5%, it is clearly an ascomycete, based on BLAST comparisons and phylogenetic analyses. Neighbor-joining dendrograms indicated that SPT1 clustered with several Candida spp., and that SPT2 clustered with Starmera spp., albeit as a very deep branch. Physiological tests, microscopic observations, and fatty acid analysis confirmed that SPT1 and SPT2 are novel yeast strains. Physiological tests also indicated that both strains had potential for use in mediated biosensors for estimation of BOD in wastewater. The lower detection limits of SPT1- and SPT2-based K3Fe(CN)6-mediated biosensors for a pulp-mill effluent were 2 and 1 mg BOD/L, respectively. Biosensor-response times for effluents from eight different pulp mills were in the range of 5 min. Reliability and sensitivity of the SPT1- and SPT2-based biosensors were good, but varied with the wastewater.     

生物传感器快速测定BOD的研究

生化需氧量(biochemicaloxygendemand,BOD)是一种表征水体有机污染程度的综合指标,广泛应用于水体监测和废水处理厂的运行控制。由于BOD的标准测定方法需时5天,不能及时地反映水质状况和反馈处理信息,因此快速测定BOD的方法和仪器化研究近年来得到广泛的重视。利用生物传感器测定BOD是一种有效地快速测定废水中可生化降解有机物的方法。介绍生物传感器的工作原理及其生物敏感材料,讨论BOD传感器的性能参数以及BOD快速测定值(BODst)与标准BOD5值的一致性问题。对现阶段市场上常见的几种BOD快速测定仪进行简单的介绍,并对它们的性能进行比较 。     

Application of biochemical oxygen demand (BOD) biosensor for optimization of biological carbon and nitrogen removal from synthetic wastewater in a sequencing batch reactor system

A bench scale reactor using a sequencing batch reactor process was used to evaluate the applicability of biosensors for the process optimization of biological carbon and nitrogen removal. A commercial biochemical oxygen demand (BOD) biosensor with a novel microbial membrane was used to determine the duration of each phase by measuring samples in real time in an SBR cycle with filling/anoxic-anaerobic/aerobic/sludge wasting/settling/withdrawal periods. Possible strategies to increase the efficiency for the biological removal of carbon and nitrogen from synthetic wastewater have been developed. The results show that application of a BOD biosensor enables estimation of organic carbon, in real time, allowing the optimization or reduction the SBR cycle time. Some typical consumption patterns for organic carbon in the non-aeration phase of a typical SBR operation were identified. The rate of decrease of BOD measured using a sensor BOD, was the highest in the initial glucose breakdown period and during denitrification. It then slowed down until a 'quiescent period' was observed, which may be considered as the commencement of the aeration period. Monitoring the BOD curve with a BOD biosensor allowed the reduction of the SBR cycle time, which leads to an increase in the removal efficiency. By reducing the cycle time from 8 to 4 h cycle, the removal efficiencies of nitrate, glucose, and phosphorus in a given time interval, were increased to nearly double, while the removal of nitrogen ammonium was increased by one-third.     

A yeast co-culture-based biosensor for determination of waste water contamination levels

Artificial microbial co-cultures were formed to develop the receptor element of a biosensor for assessment of biological oxygen demand (BOD). The co-cultures possessed broad substrate specificities and enabled assays of water and fermentation products within a broad BOD range (2.4–80 mg/dm³) with a high correlation to the standard method (R = 0.9988). The use of the co-cultures of the yeasts Pichia angusta, Arxula adeninivorans and Debaryomyces hansenii immobilized in N-vinylpyrrolidone-modified poly(vinyl alcohol) enabled developing a BOD biosensor possessing the characteristics not inferior to those in the known biosensors. The results are indicative of a potential of using these co-cultures as the receptor element base in prototype models of instruments for broad application.     

Bilirubin oxidase from Bacillus pumilus: a promising enzyme for the elaboration of efficient cathodes in biofuel cells

A CotA multicopper oxidase (MCO) from Bacillus pumilus, previously identified as a laccase, has been studied and characterized as a new bacterial bilirubin oxidase (BOD). The 59 kDa protein containing four coppers, was successfully over-expressed in Escherichia coli and purified to homogeneity in one step. This 509 amino-acid enzyme, having 67% and 26% sequence identity with CotA from Bacillus subtilis and BOD from Myrothecium verrucaria, respectively, shows higher turnover activity towards bilirubin compared to other bacterial MCOs. The current density for O(2) reduction, when immobilized in a redox hydrogel, is only 12% smaller than the current obtained with Trachyderma tsunodae BOD. Under continuous electrocatalysis, an electrode modified with the new BOD is more stable, and has a higher tolerance towards NaCl, than a T. tsunodae BOD modified electrode. This makes BOD from B. pumilus an attractive new candidate for application in biofuel cells (BFCs) and biosensors.     

Biosensor analyzer for BOD index express control on the basis of the yeast microorganisms Candida maltosa, Candida blankii, and Debaryomyces hansenii

The parameters of biosensors based on the yeast strains Candida maltosa VKM Y-2359, Candida blankii VKM Y-2675, and Debaryomyces hansenii VKM Y-2482 for biochemical oxygen demand (BOD) detection are compared. The catalytic activity of the strains was analyzed in relation to the growth phase. The possibility of using D. hansenii as a basis for receptor element of a biosensor for BOD detection in municipal and biotechnological wastewaters was shown.     

Mediated microbial biosensor using a novel yeast strain for wastewater BOD measurement

Two new yeast strains (SPT1 and SPT2) were isolated and immobilized on glassy carbon electrodes to form microbial biosensors for estimation of biochemical oxygen demand (BOD). Ferricyanide was proven to be the most efficient mediator to shuttle electrons from the redox center of reduced microbial enzymes to the electrode in the presence of excess glucose/glutamic acid (GGA). With a 3-fold greater metabolic assimilation capability and greater responses to various effluent samples, SPT1 was selected for sensor-BOD measurements. BOD estimations for the GGA standard resulted in an extended linear range: 2-100 mg/l. Response reproducibility was +/-10% for a GGA standard containing 10 mg BOD/l. For analysis of pulp mill effluents, the BOD detection limit was 2 mg/l with a response time of 5 min.     

Appraising bacterial strains for rapid BOD sensing—an empirical test to identify bacterial strains capable of reliably predicting real effluent BODs

The measured response of rapid biochemical oxygen demand (BOD) biosensors is often not identical to those measured using the conventional 5-day BOD assay. This paper highlights the efficacy of using both glucose–glutamic acid (GGA) and Organisation for Economic Cooperation and Development (OECD) BOD standards as a rapid screen for microorganisms most likely to reliably predict real effluent BODs when used in rapid BOD devices. Using these two synthetic BOD standards, a microorganism was identified that produced comparable BOD response profiles for two assays, the MICREDOX® assay and the conventional 5-day BOD₅ test. A factorial experimental design systematically evaluated the impact of four factors (microbial strain, growth media composition, media strength, and microbial growth phase) on the BOD response profiles using GGA and OECD synthetic standard substrates. An outlier was identified that showed an improved correlation between the MICREDOX® BOD (BOD_sens) and BOD₅ assays for both the synthetic standards and for real wastewater samples. Microbial strain was the dominant factor influencing BOD_sens values, with Arthrobacter globiformis single cultures clearly demonstrating superior rapid BOD_sens response profiles for both synthetic and real waste samples. It was the only microorganism to approach the BOD₅ response for the OECD substrate (171 mg O₂?L^?1), and also reported BOD values for real waste samples that were comparable to those produced by the BOD₅ test, including discriminating between filtered and unfiltered samples.     

生物废水处理系统的细胞自动机模型

建立了活性污泥处理生物废水的细胞自动机模型,对活性污泥生物量与有机物浓度动态进行了研究,提出了计算活性污泥回流循环比的方法.结果表明,在Moore邻居模型下废水达标排放所需时间较Von. Neumann邻居模型少,不同生长阶段的微生物浓度波动具有时滞性.稳定期有机物浓度和生物量不受活性污泥初始浓度的影响.活性污泥处理生物废水的细胞自动机模型有助于为污水处理提供理论依据.     

生物芯片、生物传感器和生物信息学

近年来,在生物技术和医学研究领域涌现出了许多新技术平台,其中就包括生物芯片技术和生物传感器技术。生物芯片和生物传感器的构建都必须以生物信息学为基础,而两种技术平台应用所得出的数据和结果又反过来大大丰富和充实了生物信息学本身。本分析概述了生物芯片和生物传感器两种技术平台以及生物信息学,对三之间的相互关系进行了讨论。     

Study of Biological Activity and Process Stability in Submerged Membrane Bioreactors

Synthetic wastewater was treated in a bench scale submerged membrane bioreactor (SMBR). A long‐term experiment was conducted by varying the sludge residence time (SRT) (10–500 d) and BOD loading (1.3–0.25 kg/m³·d). The biological activity was observed in terms of the oxygen utilization rate (OUR) and adenosine triphosphate (ATP) profile; the process stability was analyzed based on the extent of organic degradation and suction pressure. The microbial population in the SMBR was dependent on the SRT and BOD loading, and its biological activity was increased with an increase in the SRT or BOD loading. At a low feed to microorganism (F/M) ratio (0.06 kg BOD/kg MLSS·d), the sludge production of the reactor was reduced to 0.04 kg MLSS/kg BOD, which is much less than in the conventional activated sludge process (0.4–0.6 kg MLSS/kg BOD). The F/M ratio influenced the biological activity (via ATP and the OUR) significantly at a short SRT (≤90 d). However, the effect of the F/M ratio ceased at a low F/M ratio (≤ 0.07 kg BOD/kg MLSS·d). The accumulation of organics in the SMBR was accompanied with an increase in the supernatant TOC, which caused a high suction pressure and an abrupt change in the operating conditions to process instability. However, the process stability of the SMBR increased with an increase in the SRT and a decrease in the BOD loading along with a concomitant decrease in the biological activity and sludge production.     

Distribution and movement of toxaphene in anaerobic saline marsh soils

The biological oxygen demand (BOD) of filtered water from Lake Wingra, Wisconsin is significantly higher in the littoral zone than in the pelagial zone. Laboratory experiments indicate that BOD is not influenced by water temperature at the time of sampling or by enrichment with nitrate or ammonia. Rather, enrichment with macrophyte leachate sharply increases BOD, and enrichment with phosphate produces a small but significant increase in BOD. We conclude that high BOD in littoral waters of the lake is an indication of production of labile organic matter in the water by dense beds of the macrophyte Myriophyllum spicatum.     

Biological and technical challenges for implementation of yeast-based biosensors

Biosensors are low-cost and low-maintenance alternatives to conventional analytical techniques for biomedical, industrial and environmental applications. Biosensors based on whole microorganisms can be genetically engineered to attain high sensitivity and specificity for the detection of selected analytes. While bacteria-based biosensors have been extensively reported, there is a recent interest in yeast-based biosensors, combining the microbial with the eukaryotic advantages, including possession of specific receptors, stability and high robustness. Here, we describe recently reported yeast-based biosensors highlighting their biological and technical features together with their status of development, that is, laboratory or prototype. Notably, most yeast-based biosensors are still in the early developmental stage, with only a few prototypes tested for real applications. Open challenges, including systematic use of advanced molecular and biotechnological tools, bioprospecting, and implementation of yeast-based biosensors in electrochemical setup, are discussed to find possible solutions for overcoming bottlenecks and promote real-world application of yeast-based biosensors.     

Modeling of rotating biological contactor systems

An investigation of the rotating biological contractor (RBC) process variables to determine the efficiency of biological oxygen demand (BOD) removal is presented. Operating parameters including influent BOD content (<355 mg/liter), flow rate, disk surface area, hydraulic loading, disk rotational speed, liquid retention time, stage number, and wastewater temperature were evaluated. The BOD predictive model was developed using literature data with multiple regression analysis. This study shows that influent BOD concentration, hydraulic loading, stage number, and wastewater temperature are the most significant variables in predicting the RBC system performance. The model presently developed was verified by field data concerned with the treatment of both domestic and low-strength industrial wastewaters. Also, the results calculated by this model were compared to those obtained from Weng's model.     

Covalent enzyme immobilization by poly(ethylene glycol) diglycidyl ether (PEGDE) for microelectrode biosensor preparation

Poly(ethylene glycol) diglycidyl ether (PEGDE) is widely used as an additive for cross-linking polymers bearing amine, hydroxyl, or carboxyl groups. However, the idea of using PEGDE alone for immobilizing proteins on biosensors has never been thoroughly explored. We report the successful fabrication of microelectrode biosensors based on glucose oxidase, d-amino acid oxidase, and glutamate oxidase immobilized using PEGDE. We found that biosensors made with PEGDE exhibited high sensitivity and a response time on the order of seconds, which is sufficient for observing biological processes in vivo. The enzymatic activity on these biosensors was highly stable over several months when they were stored at 4 °C, and over at least 3d at 37 °C. Glucose microelectrode biosensors implanted in the central nervous system of anesthetized rats reliably monitored changes in brain glucose levels induced by sequential administration of insulin and glucose. PEGDE provides a simple, low cost, non-toxic alternative for the preparation of in vivo microelectrode biosensors.     

Illuminating the kinome: Visualizing real-time kinase activity in biological systems using genetically encoded fluorescent protein-based biosensors

Genetically encoded fluorescent protein-based kinase biosensors are a central tool for illumination of the kinome. The adaptability and versatility of biosensors have allowed for spatiotemporal observation of real-time kinase activity in living cells and organisms. In this review, we highlight various types of kinase biosensors, along with their burgeoning applications in complex biological systems. Specifically, we focus on kinase activity reporters used in neuronal systems and whole animal settings. Genetically encoded kinase biosensors are key for elucidation of the spatiotemporal regulation of protein kinases, with broader applications beyond the Petri dish.     

Biosensors for the evaluation of lipase activity

In the review a comprehensive analysis is given of instrumental analytical approaches to control the activity of lipolytic enzymes and their substrates. A special attention is attached to the methods based on the biosensor technology. A number of electrochemical, optical and mechanical biosensors that were developed in several laboratories are analyzed in detail. In addition, perspectives are evaluated for the development of these biosensors and their practical application. It was concluded that biosensors may provide all practical demands which are in enzymology field at the express determination of lipase activity and triacylglycerol levels in biological objects.     

An integrated physical and biological model for anaerobic lagoons

A computational fluid dynamics (CFD) model that integrates physical and biological processes for anaerobic lagoons is presented. In the model development, turbulence is represented using a transition k-ω model, heat conduction and solar radiation are included in the thermal model, biological oxygen demand (BOD) reduction is characterized by first-order kinetics, and methane yield rate is expressed as a linear function of temperature. A test of the model applicability is conducted in a covered lagoon digester operated under tropical climate conditions. The commercial CFD software, ANSYS-Fluent, is employed to solve the integrated model. The simulation procedures include solving fluid flow and heat transfer, predicting local resident time based on the converged flow fields, and calculating the BOD reduction and methane production. The simulated results show that monthly methane production varies insignificantly, but the time to achieve a 99% BOD reduction in January is much longer than that in July.