Comparative evaluation of the microbial community in biological processes treating industrial and domestic wastewaters

Aims: Comparison of the microbial composition and process performance between laboratory scale processes treating domestic and vegetable oil wastewaters. Methods and Results: Two laboratory scale modified Ludzack–Ettinger processes were operated under similar operating conditions. One process was fed domestic wastewater and the other an industrial wastewater, vegetable oil effluent. Nitrogen removal capacities of the processes were similar. The industrial process exhibited a lower COD removal capacity and oxygen utilization rate, although a greater mixed liquor volatile suspended solids concentration was observed in the industrial process. Fluorescent in situ hybridization (FISH) with probes EUBmix, ALF1b, BET42a, GAM42a and HGC69a revealed that 81% and 72% of total cells stained with 4′, 6‐diamidino‐2‐phenylindole (DAPI) within the domestic and industrial processes respectively bound to EUBmix. This indicated a slightly lower Eubacterial population within the industrial process. The alpha‐proteobacteria was the dominant community in the industrial process (31% of EUBmix), while the beta‐proteobacteria dominated the domestic process (33% of EUBmix). Conclusions: The findings served to establish a difference in the microbial population between the processes. Therefore, the class alpha‐proteobacteria could play a primary role in the degradation of vegetable oil effluent. Significance and Impact of the Study: This research will aid in process design and retrofitting of biological processes treating vegetable oil effluent.     

Microbial response to single‐cell protein production and brewery wastewater treatment

As global fisheries decline, microbial single‐cell protein (SCP) produced from brewery process water has been highlighted as a potential source of protein for sustainable animal feed. However, biotechnological investigation of SCP is difficult because of the natural variation and complexity of microbial ecology in wastewater bioreactors. In this study, we investigate microbial response across a full‐scale brewery wastewater treatment plant and a parallel pilot bioreactor modified to produce an SCP product. A pyrosequencing survey of the brewery treatment plant showed that each unit process selected for a unique microbial community. Notably, flow equalization basins were dominated by Prevotella, methanogenesis effluent had the highest levels of diversity, and clarifier wet‐well samples were sources of sequences for the candidate bacterial phyla of TM7 and BD1‐5. Next, the microbial response of a pilot bioreactor producing SCP was tracked over 1 year, showing that two different production trials produced two different communities originating from the same starting influent. However, SCP production resulted generally in enrichment of several clades of rhizospheric diazotrophs of Alphaproteobacteria and Betaproteobacteria in the bioreactor and even more so in the final product. These diazotrophs are potentially useful as the basis of a SCP product for commercial feed production.     

A meta‐analysis of temperature sensitivity as a microbial trait

Traits‐based approaches in microbial ecology provide a valuable way to abstract organismal interaction with the environment and to generate hypotheses about community function. Using macromolecular rate theory (MMRT), we recently identified that temperature sensitivity can be characterized as a distinct microbial trait. As temperature is fundamental in controlling biological reactions, variation in temperature sensitivity across communities, organisms, and processes has the potential to vastly improve understanding of microbial response to climate change. These microbial temperature sensitivity traits include the heat capacity (), temperature optimum (T_opt), and point of maximum temperature sensitivity (TS_max), each of which provide unique insights about organismal response to changes in temperature. In this meta‐analysis, we analyzed the distribution of these temperature sensitivity traits from bacteria, fungi, and mixed communities across a variety of biological systems (e.g., soils, oceans, foods, wastewater treatment plants) in order to identify commonalities in temperature responses across these diverse organisms and reaction rates. Our analysis of temperature sensitivity traits from over 350 temperature response curves reveals a wide distribution of temperature sensitivity traits, with T_opt and TS_max well within biological relevant temperatures. We find that traits vary significantly depending on organism type, microbial diversity, source environment, and biological process, with higher temperature sensitivity found in fungi than bacteria and in less diverse systems. Carbon dioxide production was found to be less temperature sensitive than denitrification, suggesting that changes in temperature will have a potentially larger impact on nitrogen‐related processes. As climate changes, these results have important implications for basic understanding of the temperature sensitivity of biological reactions and for ecological understanding of species’ trait distributions, as well as for improved treatment of temperature sensitivity in models.     

Microbial Production of Hydrogen by Mixed Culture Technologies: A Review

With its high energy content and clean combustion, hydrogen is recognized as a renewable clean energy source with enormous potential. Biological hydrogen production is a promising alternative with significant advantages over conventional petroleum‐derived chemical processes. Sustainable hydrogen production from renewable resources such as cassava, wastewater, and other agricultural waste is economically feasible for industrial applications. So far, the major bottlenecks in large‐scale biological hydrogen production are the low production rate and yield. This review discusses the various factors that affect the metabolic pathways of dark hydrogen production, and highlights the state‐of‐the‐art development of mixed culture technology. The aim of this review is to provide suggestions for the future directions of mixed culture technology, as well as by‐product valorization in dark fermentation.     

Rains, drains and active strains: towards online assessment of wastewater bacterial communities

Wastewater treatment is one of the largest scale and arguably the most commercially important biotechnological process in the world. Bacterial breakdown of waste materials facilitates the safe disposal of effluents into receiving water bodies. Given this significance, research has focused on identifying the keystone species on which efficient treatment is based. However, unravelling the microbial diversity within such systems has proven difficult. This is highlighted by our lack of detailed knowledge of the microbial interactions within these complex populations, limiting our ability to fully exploit bacterial degradative abilities. Even with the incorporation of new emerging molecular techniques, there have been no investigations linking genetic sequence to microbial function and successful treatment operation. To reach this goal, researchers need the ability to identify, enumerate and monitor the metabolic functions of subpopulations within these complex bacterial communities. Flow cytometry (FCM) combined with fluorescence-based molecular identification techniques provides a method for such studies. Moreover, single-cell sorting provides a unique opportunity to identify and remove individual cells of interest. Laboratory culture of sorted cells is often possible and permits the use of more traditional microbiological techniques to backup molecular investigations. Utilising this approach will advance our understanding of wastewater treatment processes and help maintain and enhance plant operation to improve efficiency.     

Dunaliella biotechnology: methods and applications

The microalga Dunaliella salina is the best commercial source of natural β-carotene. Additionally, different species of Dunaliella can accumulate significant amounts of valuable fine chemicals such as carotenoids, glycerol, lipids, vitamins, minerals and proteins. They also have a large potential for biotechnological processes such as expressing of foreign proteins and treatment of wastewater. In this review, we discussed several biotechnological aspects of the mass cultivation of D. salina like strain selection, carotenoid induction, culture conditions, culture systems and downstream processes. We also discuss several traditional and new applications of the genus.     

rRNA-targeted寡核苷酸探针识别活性污泥微生物群落结构与功能研究进展

活性污泥中微生物群落内部关系非常复杂 ,及时对活性污泥中优势菌群和群落内部关系进行监测是污水处理中采取正确措施的关键。历史研究表明传统培养方法经常导致活性污泥优势菌群检测的失败 ,而r RNA- targeted寡核苷酸探针作为一种快速原位监测活性污泥微生物群落结构和功能的新工具被引入 ,使我们对参与污水净化的微生物群落结构和优势菌群能有较全面的了解。就该方法在识别除磷污泥、脱氮污泥、污泥泡沫和膨胀污泥中微生物群落结构和功能的典型应用进行综述 ,分析了该方法存在的优点和缺点 ,并对目前已建立且应用于活性污泥微生物检测的 r RNA- targeted寡核苷酸探针进行了详细总结     

Harnessing a methane‐fueled,sediment‐free mixed microbial community for utilization of distributed sources of natural gas

Harnessing the metabolic potential of uncultured microbial communities is a compelling opportunity for the biotechnology industry, an approach that would vastly expand the portfolio of usable feedstocks. Methane is particularly promising because it is abundant and energy‐rich, yet the most efficient methane‐activating metabolic pathways involve mixed communities of anaerobic methanotrophic archaea and sulfate reducing bacteria. These communities oxidize methane at high catabolic efficiency and produce chemically reduced by‐products at a comparable rate and in near‐stoichiometric proportion to methane consumption. These reduced compounds can be used for feedstock and downstream chemical production, and at the production rates observed in situ they are an appealing, cost‐effective prospect. Notably, the microbial constituents responsible for this bioconversion are most prominent in select deep‐sea sediments, and while they can be kept active at surface pressures, they have not yet been cultured in the lab. In an industrial capacity, deep‐sea sediments could be periodically recovered and replenished, but the associated technical challenges and substantial costs make this an untenable approach for full‐scale operations. In this study, we present a novel method for incorporating methanotrophic communities into bioindustrial processes through abstraction onto low mass, easily transportable carbon cloth artificial substrates. Using Gulf of Mexico methane seep sediment as inoculum, optimal physicochemical parameters were established for methane‐oxidizing, sulfide‐generating mesocosm incubations. Metabolic activity required >～40% seawater salinity, peaking at 100% salinity and 35 °C. Microbial communities were successfully transferred to a carbon cloth substrate, and rates of methane‐dependent sulfide production increased more than threefold per unit volume. Phylogenetic analyses indicated that carbon cloth‐based communities were substantially streamlined and were dominated by Desulfotomaculum geothermicum. Fluorescence in situ hybridization microscopy with carbon cloth fibers revealed a novel spatial arrangement of anaerobic methanotrophs and sulfate reducing bacteria suggestive of an electronic coupling enabled by the artificial substrate. This system: 1) enables a more targeted manipulation of methane‐activating microbial communities using a low‐mass and sediment‐free substrate; 2) holds promise for the simultaneous consumption of a strong greenhouse gas and the generation of usable downstream products; and 3) furthers the broader adoption of uncultured, mixed microbial communities for biotechnological use.     

Mikroben unter Strom

Microbes wired up – From wastewater treatment to bioelectrotechnology Electron conducting microbes – this still sounds like science fiction or at least like an exotic natural phenomenon. Groundbreaking research in this area, however, indicates that this process seems to be widely spread within anaerobic microbial ecology. Microbes “wire up” with their living and non‐living surrounding to construct energetic networks. With microbial bioelectrochemical systems, we try to utilize this knowledge for environmental and biotechnological applications. While initially, the recovery of energy as electric current in microbial fuel cells was the main R&D target, our new scientific insights of microbial extracellular electron transfer allow us to make controlled use of this phenomenon for a multitude of further applications.     

Microbial alkaline pectinases and their industrial applications: a review

The biotechnological potential of pectinolytic enzymes from microorganisms has drawn a great deal of attention from various researchers worldwide as likely biological catalysts in a variety of industrial processes. Alkaline pectinases are among the most important industrial enzymes and are of great significance in the current biotechnological arena with wide-ranging applications in textile processing, degumming of plant bast fibers, treatment of pectic wastewaters, paper making, and coffee and tea fermentations. The present review features the potential applications and uses of microbial alkaline pectinases, the nature of pectin, and the vast range of pectinolytic enzymes that function to mineralize pectic substances present in the environment. It also emphasizes the environmentally friendly applications of microbial alkaline pectinases thereby revealing their underestimated potential. The review intends to explore the potential of these enzymes and to encourage new alkaline pectinase-based industrial technology. Electronic Publication     

Recombinant microbial lipases for biotechnological applications

Lipases, mainly of microbial origin, represent the most widely used class of enzymes in biotechnological applications and organic chemistry. Modern methods of genetic engineering combined with an increasing knowledge of structure and function will allow further adaptation to industrial needs and exploration of novel applications. Production of such tailored lipases requires their functional overexpression in a suitable host. Hence, this article describes the functional heterologous production of commercially important microbial lipases. Based on the knowledge of different lipases' substrate binding sites, the most suitable lipase for a particular application may be selected.     

Comparative bioelectrochemical analysis of Pseudomonas aeruginosa and Escherichia coli with anaerobic consortia as anodic biocatalyst for biofuel cell application

Aims: To study the bioelectrochemical behaviour of Pseudomonas aeruginosa (MTCC 17702) and Escherichia coli (MTCC 10436) and to assess their potential to act as anodic biocatalyst with the function of anaerobic consortia for microbial (bio) fuel cell (BFC) application. Methods and Results: Three BFCs (single chamber; open‐air cathode; noncatalysed electrodes) were operated simultaneously in acidophilic microenvironments. Pseudomonas aeruginosa (BFC_P) showed higher current density (264 mA m^?2) followed by mixed culture (BFC_M; 166 mA m^?2) and E. coli (BFC_E; 147 mA m^?2). However, total operating period and substrate degradation were relatively found to be effective with mixed culture (58%; 72 h) followed by BFC_P (39%; 60 h) and BFC_E (31%; 48 h). Higher electron discharge (ED) was observed with Ps. aeruginosa while mixed culture showed the involvement of redox mediators in the ED process. Conclusions: Mixed culture showed to sustain biopotential for longer periods along with a stable ED. The presence of redox signals and high substrate degradation was also evidencing its performance compared to the pure strains studied. This supports the practical utility of mixed culture over the pure cultures for real‐field BFC applications especially while operating with wastewater. Significance and Impact of the Study: This study revealed the efficiency and viability of mixed consortia in comparison with pure strains for microbial (bio) fuel cell applications.     

污水生物处理中的噬菌体及其功能研究进展

污水生物处理是一种利用微生物分解污水中的污染物、实现污水净化的方法。噬菌体是侵染细菌的病毒,在污水生物处理系统中广泛存在,它们能够特异性地控制微生物菌群,影响污水处理效果和调控污泥性状。因此,研究污水生物处理中噬菌体的分布及其功能具有重要意义。本文介绍了不同污水生物处理中噬菌体的分布,简要分析了噬菌体分离、培养与鉴定方法及其优缺点,详细总结了噬菌体在污水生物处理中的功能,包括:(1)调节微生物群落结构,影响污水处理效果;(2)作为环境监测的指示生物;(3)控制病原菌、污泥膨胀、污泥发泡和膜污染;(4)减少污泥产量,重点分析了影响噬菌体功能的因素,探讨了污水生物处理中噬菌体功能应用存在的问题及其解决方法,最后对噬菌体未来应用的发展方向进行了展望,以期为污水生物处理技术和工艺的开发与应用提供参考,促进污水处理健康发展。     

Community history affects the predictability of microbial ecosystem development

Microbial communities mediate crucial biogeochemical, biomedical and biotechnological processes, yet our understanding of their assembly, and our ability to control its outcome, remain poor. Existing evidence presents conflicting views on whether microbial ecosystem assembly is predictable, or inherently unpredictable. We address this issue using a well-controlled laboratory model system, in which source microbial communities colonize a pristine environment to form complex, nutrient-cycling ecosystems. When the source communities colonize a novel environment, final community composition and function (as measured by redox potential) are unpredictable, although a signature of the community''s previous history is maintained. However, when the source communities are pre-conditioned to their new habitat, community development is more reproducible. This situation contrasts with some studies of communities of macro-organisms, where strong selection under novel environmental conditions leads to reproducible community structure, whereas communities under weaker selection show more variability. Our results suggest that the microbial rare biosphere may have an important role in the predictability of microbial community development, and that pre-conditioning may help to reduce unpredictability in the design of microbial communities for biotechnological applications.     

New Aspects of Microbial Nitrogen Transformations in the Context of Wastewater Treatment – A Review

Over the past few years, new technologies for nitrogen removal have been developed mainly because of the increasing financial costs of the traditional wastewater treatment technologies. Newly discovered pathways, like the anaerobic oxidation of ammonium (ANAMMOX), and uses for nitrogen removal technologies are under discussion. Processes and technologies such as: Partial nitrification; Single reactor systems for High Ammonium Removal Over Nitrite (SHARON); Anammox; Aerobic/anoxic deammonification; Oxygen Limited Autotrophic Nitrification‐Denitrification (OLAND); Completely Autotrophic Nitrogen Removal Over Nitrite (CANON); wetland based systems, all have a high potential for nitrogen removal. However, the pathways of nitrogen transformation processes are very complex. An understanding of how various environmental factors affect these processes and a sound knowledge of existing, worldwide experience pertaining to these novel technologies are the key if the nitrogen removal rates are to be improved and success is to be realized in full‐scale applications. This review describes the present knowledge of the new treatment technologies for wastewater with high nitrogen loads. Special emphasis is given to the influence of environmental factors and the reactor configuration on the nitrogen transformation process and microbial activity.     

Wastewater treatment: a model system for microbial ecology

Biological wastewater treatment is among the most important biotechnological applications and, as drivers of the key processes, microorganisms are central to its success. Therefore, the study of wastewater microorganisms has obvious applied significance; however, the importance of wastewater treatment reactors as model systems for microbial ecology is often overlooked. Modern molecular techniques, including environmental genomics, have identified unexpected microbial key players for nutrient removal and sludge bulking and/or foaming, and provided many exciting insights into the diversity, functions and niche differentiations of these predominantly uncultivated microorganisms. It is now time for wastewater microbiology to be recognized as a mature and dynamic discipline in its own right, offering much toward a deeper understanding of life in complex microbial communities. Here, we consider selected key findings to illustrate the past and future roles of molecular ecophysiology and genomics in the development of wastewater microbiology as an important subdiscipline of microbial ecology.     

Application of rRNA-targeted oligonucleotide probes in biotechnology

Ribosomal RNA-targeted oligonucleotide probes have become valuable tools for the detection of microorganisms involved in important biotechnological processes. Microorganisms which are of major importance for processes such as wastewater treatment, microbial leaching or methane production can be detected and quantified in situ within a complex microbial community. For certain processes, such as nitrification or biological phosphate removal, new microorganisms have become the focus of interest and have led to an improved understanding of these bioremediation techniques. Hybridization techniques have become fast and reliable alternatives to conventional cultivation techniques in the food industry as a control method for starter cultures for fermentation processes or product control. Recent analytical tools such as flow cytometry and digital image processing have improved the efficiency of these techniques. This review is intended to present a summary of methodological aspects of rRNA-based hybridization techniques and their application in biotechnology.     

光照混菌培养应用研究进展

光合细菌与其他微生物在光照条件下混合培养是近年来的研究热点。综述了光照混菌培养的特点和目前光照混菌培养在水体净化、生物制氢和高价值物质生产方面的应用,并对影响混合菌株生长代谢与繁殖的因素做了总结。分析表明菌株之间存在的相互协同共生作用能促进微生物的生长繁殖,使底物被充分利用,提高物质产率。光照混菌培养工艺简单、成本较低,在水体净化、生物制氢、高价值物质生产方面的应用具有相当好的效果。在影响因素中对混合培养影响最大的因素是菌株接种量、接种比和培养基pH。在总结光照混菌培养应用现存不足的基础上,对其发展前景作出展望。