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Applied Microbiology and Biotechnology Feb 2022Due to mounting impacts of climate change, particularly increased incidence of drought, hence water scarcity, it has become imperative to develop new technologies for... (Review)
Review
Due to mounting impacts of climate change, particularly increased incidence of drought, hence water scarcity, it has become imperative to develop new technologies for recovering water from nutrient-rich, water-replete effluents other than sewage. Notably, anaerobic digestate could be harnessed for the purpose of water recovery by repurposing digestate-borne minerals as nutrients in fermentative processes. The high concentrations of ammonium, phosphate, sulfate, and metals in anaerobic digestate are veritable microbial nutrients that could be harnessed for bio-production of bulk and specialty chemicals. Tethering nutrient sequestration from anaerobic digestate to bio-product accumulation offers promise for concomitant water recovery, bio-chemical production, and possible phosphate recovery. In this review, we explore the potential of anaerobic digestate as a nutrient source and as a buffering agent in fermentative production of glutamine, glutamate, fumarate, lactate, and succinate. Additionally, we discuss the potential of synthetic biology as a tool for enhancing nutrient removal from anaerobic digestate and for expanding the range of products derivable from digestate-based fermentations. Strategies that harness the nutrients in anaerobic digestate with bio-product accumulation and water recovery could have far-reaching implications on sustainable management of nutrient-rich manure, tannery, and fish processing effluents that also contain high amounts of water. KEY POINTS: • Anaerobic digestate may serve as a source of nutrients in fermentation. • Use of digestate in fermentation would lead to the recovery of valuable water.
Topics: Anaerobiosis; Manure; Nutrients; Sewage; Water
PubMed: 35122155
DOI: 10.1007/s00253-022-11804-6 -
Journal of Environmental Management Oct 2023In recent years, anaerobic digestion (AD) has gained popularity as a practical method for generating clean energy and efficiently managing organic waste. However, the... (Review)
Review
In recent years, anaerobic digestion (AD) has gained popularity as a practical method for generating clean energy and efficiently managing organic waste. However, the effectiveness of the reactor is compromised by the accumulation of ammonia, acids, and nutrients, leading to inhibition and instability. Because of its adaptability, biochar (BC) has sparked a substantial interest in biogas production and can be created by charring biomass and waste materials. Adding BC to the AD process could yield the following benefits: mitigating toxic inhibition, reducing the duration of the methanogenic lag phase, immobilising functional bacteria, and enhancing the rate of electron transfer between methanogenic and acetogenic microorganisms. Nonetheless, there remains to be more comprehensive knowledge regarding the multifaceted function of BC and its intricate mechanisms in the generation of biogas in AD. The research summarises scattered information from the literature on BC production from various feedstocks and factors affecting its characteristics. Additionally, a comprehensive analysis of the utilisation of BC as an additive within AD is presented here, emphasising how BC characteristics impact AD processes and how they effectively engage key challenges.
Topics: Bioreactors; Anaerobiosis; Biofuels; Symbiosis; Methane
PubMed: 37572403
DOI: 10.1016/j.jenvman.2023.118743 -
FEMS Microbiology Ecology Oct 2022
Topics: Anaerobiosis; Biodegradation, Environmental
PubMed: 36308759
DOI: 10.1093/femsec/fiac108 -
Applied and Environmental Microbiology Dec 2023Many parameters affect phage-bacteria interaction. Some of these parameters depend on the environment in which the bacteria are present. Anaerobiosis effect on phage...
Many parameters affect phage-bacteria interaction. Some of these parameters depend on the environment in which the bacteria are present. Anaerobiosis effect on phage infection in facultative anaerobic bacteria has not yet been studied. The absence of oxygen triggers metabolic changes in facultative bacteria and this affects phage infection and viral life cycle. Understanding how an anaerobic environment can alter the behavior of phages during infection is relevant for the phage therapy success.
Topics: Bacteriophages; Anaerobiosis; Bacteria
PubMed: 37966212
DOI: 10.1128/aem.01491-23 -
The Science of the Total Environment Apr 2023Stringent discharge phosphorus limits and rising urge to reach very low effluent total phosphorus concentrations have challenged the available technologies to further... (Review)
Review
Stringent discharge phosphorus limits and rising urge to reach very low effluent total phosphorus concentrations have challenged the available technologies to further remove phosphorus. The significance of Enhanced Biological Phosphorus Removal (EBPR) process may have been overshadowed by the design and operation limitations. These scarcities mainly root back to the lack of knowledge and understanding of fundamental mechanisms, design standards, and operational guidance. Anaerobic biomass fraction design and operation as a primary driving force for biological phosphorus removal process is commonly outweighed by aerobic and total plant sludge retention operation and design criteria. This paper tends to critically review the different perspectives of mainstream and side-stream EBPR processes and to particularly target contrasting views on hydrolysis and fermentation rates as well as anaerobic condition implementation and magnitude. Subsequently, from distinct point of views, knowledge gaps are comprehensively discussed to eventually recognize the advances and drawbacks aimed to reach a sustainable EBPR process.
Topics: Phosphorus; Anaerobiosis; Bioreactors; Biological Products; Sewage
PubMed: 36740070
DOI: 10.1016/j.scitotenv.2023.162018 -
Biotechnology Advances 2023Nowadays, anaerobic digestion (AD) is being increasingly encouraged to increase the production of biogas and thus of biomethane. Due to the high diversity among... (Review)
Review
Nowadays, anaerobic digestion (AD) is being increasingly encouraged to increase the production of biogas and thus of biomethane. Due to the high diversity among feedstocks used, the variability of operating parameters and the size of collective biogas plants, different incidents and limitations may occur (e.g., inhibitions, foaming, complex rheology). To improve performance and overcome these limitations, several additives can be used. This literature review aims to summarize the effects of the addition of various additives in co-digestion continuous or semi-continuous reactors to fit as much as possible with collective biogas plant challenges. The addition of (i) microbial strains or consortia, (ii) enzymes and (iii) inorganic additives (trace elements, carbon-based materials) in digester is analyzed and discussed. Several challenges associated with the use of additives for AD process at collective biogas plant scale requiring further research work are highlighted: elucidation of mechanisms, dosage and combination of additives, environmental assessment, economic feasibility, etc.
Topics: Anaerobiosis; Bioreactors; Biofuels; Methane
PubMed: 36933869
DOI: 10.1016/j.biotechadv.2023.108129 -
Bulletin of Mathematical Biology Nov 2021A multiscale mathematical model is presented to describe de novo granulation, and the evolution of multispecies granular biofilms, in a continuously fed bioreactor. The...
A multiscale mathematical model is presented to describe de novo granulation, and the evolution of multispecies granular biofilms, in a continuously fed bioreactor. The granule is modelled as a spherical free boundary domain with radial symmetry. The equation governing the free boundary is derived from global mass balance considerations and takes into account the growth of sessile biomass as well as exchange fluxes with the bulk liquid. Starting from a vanishing initial value, the expansion of the free boundary is initiated by the attachment process, which depends on the microbial species concentrations within the bulk liquid and their specific attachment velocity. Nonlinear hyperbolic PDEs model the growth of the sessile microbial species, while quasi-linear parabolic PDEs govern the dynamics of substrates and invading species within the granular biofilm. Nonlinear ODEs govern the evolution of soluble substrates and planktonic biomass within the bulk liquid. The model is applied to an anaerobic, granular-based bioreactor system, and solved numerically to test its qualitative behaviour and explore the main aspects of de novo anaerobic granulation: ecology, biomass distribution, relative abundance, dimensional evolution of the granules and soluble substrates, and planktonic biomass dynamics within the bioreactor. The numerical results confirm that the model accurately describes the ecology and the concentrically layered structure of anaerobic granules observed experimentally, and that it can predict the effects on the process of significant factors, such as influent wastewater composition; granulation properties of planktonic biomass; biomass density; detachment intensity; and number of granules.
Topics: Anaerobiosis; Biofilms; Biomass; Bioreactors; Mathematical Concepts; Models, Biological
PubMed: 34741191
DOI: 10.1007/s11538-021-00951-y -
Bioresource Technology Jan 2022Anaerobic digestion (AD) is a technique that can be used to treat high concentrations of various organic wastes using a consortium of functionally diverse microorganisms... (Review)
Review
Anaerobic digestion (AD) is a technique that can be used to treat high concentrations of various organic wastes using a consortium of functionally diverse microorganisms under anaerobic conditions. Methane gas, a beneficial by-product of the AD process, is a renewable energy source that can replace fossil fuels following purification. However, detailed functional roles and metabolic interactions between microbial populations involved in organic waste removal and methanogenesis are yet to be known. Recent metagenomic approaches based on advanced high-throughput sequencing techniques have enabled the exploration of holistic microbial taxonomy and functionality of complex microbial populations involved in the AD process. Gene-centric and genome-centric analyses based on metagenome-assembled genomes are a platform that can be used to study the composition of microbial communities and their roles during AD. This review looks at how these up-to-date metagenomic analyses can be applied to promote our understanding and improved the development of the AD process.
Topics: Anaerobiosis; Bioreactors; Metagenome; Metagenomics; Methane
PubMed: 34813924
DOI: 10.1016/j.biortech.2021.126350 -
Free Radical Biology & Medicine Aug 2019Oxygen is a major metabolic driving force that enabled the expansion of metabolic networks including new metabolites and new enzymes. It had a dramatic impact on the... (Review)
Review
Oxygen is a major metabolic driving force that enabled the expansion of metabolic networks including new metabolites and new enzymes. It had a dramatic impact on the primary electron transport chain where it serves as terminal electron acceptor, but oxygen is also used by many enzymes as electron acceptor for a variety of reactions. The organismal oxygen phenotype, aerobic vs. anaerobic, should be manifested in its O-utilizing enzymes. Traditionally, enzymes involved in primary oxygen metabolism such as cytochrome c, and reactive oxygen species (ROS)-neutralizing enzymes (e.g. catalase), were used as identifiers of oxygen phenotype. However, these enzymes are often found in strict anaerobes. We aimed to identify the O-utilizing enzymes that may distinguish between aerobes and anaerobes. To this end, we annotated the O-utilizing enzymes across the prokaryotic tree of life. We recovered over 700 enzymes and mapped their presence/absence in 272 representative genomes. As seen before, enzymes mediating primary oxygen metabolism, and ROS neutralizing enzymes, could be found in both aerobes and anaerobes. However, there exists a subset of enzymes, primarily oxidases that catabolyze various substrates, including amino acids and xenobiotics, that are preferentially enriched in aerobes. Overall it appears that the total number of oxygen-utilizing enzymes, and the presence of enzymes involved in 'peripheral', secondary oxygen metabolism, can reliably distinguish aerobes from anaerobes based solely on genome sequences. These criteria can also indicate the oxygen phenotype in metagenomic samples.
Topics: Amino Acids; Anaerobiosis; Catalase; Electrons; Metagenome; Oxidation-Reduction; Oxygen; Reactive Oxygen Species; Xenobiotics
PubMed: 30935870
DOI: 10.1016/j.freeradbiomed.2019.03.031 -
Water Research Oct 2020Hydroxylamine is a key intermediate in several biological reactions of the global nitrogen cycle. However, the role of hydroxylamine in anammox is still not fully...
Hydroxylamine is a key intermediate in several biological reactions of the global nitrogen cycle. However, the role of hydroxylamine in anammox is still not fully understood. In this work, the impact of hydroxylamine (also in combination with other substrates) on the metabolism of a planktonic enrichment culture of the anammox species Ca. Kuenenia stuttgartiensis was studied. Anammox bacteria were observed to produce ammonium both from hydroxylamine and hydrazine, and hydroxylamine was consumed simultaneously with nitrite. Hydrazine accumulation - signature for the presence of anammox bacteria - strongly depended on the available substrates, being higher with ammonium and lower with nitrite. Furthermore, the results presented here indicate that hydrazine accumulation is not the result of the inhibition of hydrazine dehydrogenase, as commonly assumed, but the product of hydroxylamine disproportionation. All kinetic parameters for the identified reactions were estimated by mathematical modelling. Moreover, the simultaneous consumption and growth on ammonium, nitrite and hydroxylamine of anammox bacteria was demonstrated, this was accompanied by a reduction in the nitrate production. Ultimately, this study advances the fundamental understanding of the metabolic versatility of anammox bacteria, and highlights the potential role played by metabolic intermediates (i.e. hydroxylamine, hydrazine) in shaping natural and engineered microbial communities.
Topics: Anaerobiosis; Bacteria; Hydroxylamine; Hydroxylamines; Nitrites; Oxidation-Reduction
PubMed: 32739592
DOI: 10.1016/j.watres.2020.116188