An official website of the United States government
Anaerobic digestion (AD), microalgae cultivation, and microbial fuel cells (MFCs) are the major biological processes to convert organic solid wastes and wastewater in the agricultural industry into biofuels, biopower, various biochemical and fertilizer products, and meanwhile, recycle water. Various nanomaterials including nano zero valent irons (nZVIs), metal oxide nanoparticles (NPs), carbon-based and multicompound nanomaterials have been studied to improve the economics and environmental sustainability of those biological processes by increasing their conversion efficiency and the quality of products, and minimizing the negative impacts of hazardous materials in the wastes. This review article presented the structures, functionalities and applications of various nanomaterials that have been studied to improve the performance of AD, microalgae cultivation, and MFCs for recycling and valorizing agricultural solid wastes and wastewater. The review also discussed the methods that have been studied to improve the performance of those nanomaterials for their applications in those biological processes.
more »
« less
Harvesting Microalgae for Food and Energy Products
Abstract Microalgae are promising biological factories for diverse natural products. Microalgae tout high productivity, and their biomass has value in industrial products ranging from biofuels, feedstocks, food additives, cosmetics, pharmaceuticals, and as alternatives to synthetic or animal‐derived products. However, harvesting microalgae to extract bioproducts is challenging given their small size and suspension in liquid growth media. In response, technologic developments have relied upon mechanical, chemical, thermal, and biological means to dewater microalgal suspensions and further extract bioproducts. In this review, the effectiveness and considerations were evaluated for the implementation of microalgae harvesting techniques. Nonbiological methods—filtration, chemical, electrical, and magnetic nanoparticle flocculation, centrifugation, hydrothermal liquefaction, and solvent‐based extraction, as well as biological coculture‐based methods are included. Recent advances in coculture algae‐flocculation technologies that involve bacteria and fungi are summarized. These produce a variety of natural bioproducts, which show promise in fuel and food additive applications. Furthermore, this review addresses the developments of genetic tools and resources to optimize the productivity and harvesting of microalgae or to provide new bioproducts via heterologous expression. Finally, a glimpse of future biotechnologies that will converge to produce, harvest, and process microalgae using sustainable and cost‐effective methods is offered.
more »
« less
- Award ID(s):
- 1737898
- PAR ID:
- 10456789
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small Methods
- Volume:
- 4
- Issue:
- 10
- ISSN:
- 2366-9608
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Microalgae biofilms have been demonstrated to recover nutrients from wastewater and serve as biomass feedstock for bioproducts. However, there is a need to develop a platform to quantitatively describe microalgae biofilm production, which can provide guidance and insights for improving biomass areal productivity and nutrient uptake efficiency. This paper proposes a unified experimental and theoretical framework to investigate algae biofilm growth on a rotating algae biofilm reactor (RABR). Experimental laboratory setups are used to conduct controlled experiments on testing environmental and operational factors for RABRs. We propose a differential–integral equation‐based mathematical model for microalgae biofilm cultivation guided by laboratory experimental findings. The predictive mathematical model development is coordinated with laboratory experiments of biofilm areal productivity associated with ammonia and inorganic phosphorus uptake by RABRs. The unified experimental and theoretical tool is used to investigate the effects of RABR rotating velocity, duty cycle (DC), and light intensity on algae biofilm growth, areal productivity, nutrient uptake efficiency, and energy efficiency in wastewater treatment. Our framework indicates that maintaining a reasonable light intensity range improves biomass areal productivity and nutrient uptake efficiency. Our framework also indicates that faster RABR rotation benefits biomass areal productivity. However, maximizing the nutrient uptake efficiency requires a reasonably low RABR rotating speed. Energy efficiency is strongly correlated with RABR rotating speed and DC.more » « less
-
Background: Although microalgal biofuels have potential advantages over conventional fossil fuels, high production costs limit their application in the market. We developed bio-flocculation and incubation methods for the marine alga Nannochloropsis oceanica CCMP1779 and the oleaginous fungus Mortierella elongata AG77 resulting in increased oil productivity. Results: Grown separately and then combining the cells the M. elongata mycelium could efficiently capture N. oceanica due to an intricate cellular interaction between the two species leading to bio-flocculation. Use of a high-salt culture medium induced accumulation of triacylglycerol (TAG) and enhanced the content of polyunsaturated fatty acids (PUFAs) including arachidonic acid (ARA) and docosahexaenoic acid (DHA) in M. elongata. To increase TAG productivity in the alga, we developed an effective reduced nitrogen supply regime based on ammonium in environmental photobioreactors (ePBRs). Under optimized conditions, N. oceanica produced high levels of TAG that could be indirectly monitored by following chlorophyll content. Combining N. oceanica and M. elongata to initiate bio-flocculation yielded high levels of TAG and total fatty acids, ~15% and 22% of total dry weight (DW), respectively, as well as high levels of PUFAs. Genetic engineering N. oceanica for higher TAG content in nutrient-replete medium was accomplished by overexpressing DGTT5, a gene encoding the type II acyl-CoA:diacylglycerol acyltransferase 5. Combined with bioflocculation this approach led to increased production of TAG under nutrient replete conditions (~10% of DW) compared to the wild type (~6% of DW). Conclusions: The combined use of M. elongata and N. oceanica with available genomes and genetic engineering tools for both species opens up new avenues to improve bio-fuel productivity and allows the engineering of polyunsaturated fatty acids. Keywords: Microalgae, Filamentous fungi, Flocculation, Cell wall interaction, Biofuel, Nitrogen starvation, Polyunsaturated fatty acid, Triacylglycerolmore » « less
-
All chemical processes exhibit two main universal features. They are stochastic because chemical reactions might happen only after random successful collisions of reacting species, and they are dynamic because the amount of reactants and products change with time. Since biological processes rely heavily on specific chemical reactions, stochasticity and dynamics are also crucial features for all living systems. To understand the molecular mechanisms of chemical and biological processes, it is important to develop and apply theoretical methods that fully incorporate the randomness and dynamic nature of these systems. In recent years, there have been significant advances in formulating and exploring such theoretical methods. As an illustration of such developments, in this review, the recent applications of stochastic kinetic models for various biological processes are discussed. Specifically, we focus on applying these theoretical approaches to investigate the biological signaling, clearance of bacteria under antibiotics, T cells activation in the immune system, and cancer initiation dynamics. The main advantage of the presented stochastic kinetic models is that they generally can be solved analytically, allowing to clarify the underlying microscopic picture, as well as explain the existing experimental observations and make new testable predictions. This theoretical approach becomes a powerful tool in uncovering the molecular mechanisms of complex natural phenomena.more » « less
-
Abstract Actinobacteria are a large and diverse group of bacteria that are known to produce a wide range of secondary metabolites, many of which have important biological activities, including antibiotics, anti-cancer agents, and immunosuppressants. The biosynthesis of these compounds is often highly regulated with many natural products (NPs) being produced at very low levels in laboratory settings. Environmental factors, such as small molecule elicitors, can induce the production of secondary metabolites. Specifically, they can increase titers of known NPs as well as enabling discovery of novel NPs typically produced at undetectable levels. These elicitors can be NPs, including antibiotics or hormones, or synthetic compounds. In recent years, there has been a growing interest in the use of small molecule elicitors to induce the production of secondary metabolites from actinobacteria, especially for the discovery of NPs from “silent” biosynthetic gene clusters. This review aims to highlight classes of molecules that induce secondary metabolite production in actinobacteria and to describe the potential mechanisms of induction. One-Sentence SummaryThis review describes chemical elicitors of actinobacteria natural products described to date and the proposed mechanisms of induction.more » « less
