scholarly journals Microbial ecological mechanism for long-term production of high concentrations of n-caproate via lactate-driven chain elongation

2021 ◽  
Author(s):  
Xiaoyu Zhu ◽  
Xin Feng ◽  
Cheng Liang ◽  
Jiabao Li ◽  
Jia Jia ◽  
...  
Keyword(s):  
Organic Waste ◽  
Metagenomic Data ◽  
Chain Elongation ◽  
Human Society ◽  
Waste Streams ◽  
Term Operation ◽  
The Core ◽  
Microbial Network ◽  
High Concentrations

Lactate-driven chain elongation (LCE) has emerged as a new biotechnology to upgrade organic waste streams into valuable biochemical and fuel precursor, medium chain carboxylate, n-caproate. Considering that a low cost of downstream extraction is critical for biorefinery technology, a high concentration of n-caproate production is very important to improve the scale-up of the LCE process. We report here that in a nonsterile open environment, the n-caproate concentration was increased from the previous record of 25.7 g·L−1 to a new high level of 33.7 g·L−1 (76.8 g COD·L−1), with the highest production rate of 11.5 g·L−1·d−1 (26.2 g COD·L−1·d−1). In addition, the LCE process remained stable with an average concentration of n-caproate production of 20.2 ± 5.62 g·L−1 (46.1 ± 12.8 g COD·L−1) for 780 days. Dynamic changes in taxonomic composition integrated with metagenomic data reveal the microbial ecology for long-term production of high concentrations of n-caproate: 1) the core microbiome is related to efficient functional groups, such as Ruminococcaceae (with functional strain CPB6); 2) the core bacteria can maintain stability for long-term operation; 3) the microbial network has relatively low microbe-microbe interaction strength; and 4) low relative abundance and variety of competitors. The network structure could be shaped by hydraulic retention time (HRT) over time, and long-term operation at an HRT of 8 days displayed higher efficacy. IMPORTANCE Our research revealed the microbial network of LCE reactor microbiome for n-caproate production at high concentrations, which will provide a foundation for designing or engineering the LCE reactor microbiome to recover n-caproate from organic waste streams in the future. In addition, the hypothetical model of the reactor microbiome that we proposed may offer guidance for researchers to find the underlying microbial mechanism when they encounter low-efficiency n-caproate production from the LCE process. We anticipate that our research will rapidly advance LCE biotechnology with the goal of promoting the sustainable development of human society.

scholarly journals Fermentation of Organic Residues to Beneficial Chemicals: A Review of Medium-Chain Fatty Acid Production

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1571
Author(s):  
Panagiota Stamatopoulou ◽  
Juliet Malkowski ◽  
Leandro Conrado ◽  
Kennedy Brown ◽  
Matthew Scarborough
Keyword(s):  
Organic Waste ◽  
Chain Elongation ◽  
Organic Substrates ◽  
Industrial Chemicals ◽  
Waste Streams ◽  
Fatty Acid Production ◽  
Medium Chain ◽  
Renewable Feedstocks ◽  
History Of ◽  
Complex Organic

Medium-chain fatty acids (MCFAs) have a variety of uses in the production of industrial chemicals, food, and personal care products. These compounds are often produced through palm refining, but recent work has demonstrated that MCFAs can also be produced through the fermentation of complex organic substrates, including organic waste streams. While “chain elongation” offers a renewable platform for producing MCFAs, there are several limitations that need to be addressed before full-scale implementation becomes widespread. Here, we review the history of work on MCFA production by both pure and mixed cultures of fermenting organisms, and the unique metabolic features that lead to MCFA production. We also offer approaches to address the remaining challenges and increase MCFA production from renewable feedstocks.

scholarly journals Development Within a Religious Ontology? The Argument from Islamic Dharma

2019 ◽  
Vol 32 (4) ◽  
pp. 1038-1056
Author(s):  
Fernande W. Pool
Keyword(s):  
Life Experiences ◽  
Religious Life ◽  
Ethnographic Research ◽  
Human Society ◽  
Research Participants ◽  
The Core ◽  
Development Framework

AbstractDrawing on long-term ethnographic research with Muslims in India, this article suggests that religion should not (only) be understood as a sub-category of development but as an integral part of the meta-ontology based on which one should engage with development initially. Value-driven development implies a normative view of society, and a ‘more human’ society is at the core of worthwhile development. For the research participants, their ontological conceptions (notions of what being human means) and the ethical autonomy to deliberate on a normative view of life and society are embedded in the Islamic dharma. To approach religion as only a sub-category in an otherwise secular development framework marginalises these, and probably many other, religious life experiences and ontological notions from the outset. Instead, secular and religious ontologies should be considered at par in an inclusive dialogue on worthwhile development.

Failure Analysis and Transformation of Hydrogen Compressor Dry Gas Seal

2013 ◽  
Vol 331 ◽  
pp. 98-101 ◽  
Author(s):  
Hui Cao ◽  
Yan Liu ◽  
Chang Ji Lin
Keyword(s):  
Labyrinth Seal ◽  
Supply System ◽  
Gas Oil ◽  
Dry Gas Seal ◽  
Term Operation ◽  
The Core ◽  
Coker Gas Oil ◽  
Tandem Structure ◽  
Gas Supply

Recycle hydrogen compressor group is the core equipment of heavy coker gas oil hydrotreater unit of refinery. This compressor adopts tandem structure with intermediate labyrinth seal as its dry gas seal type. The compressor dry gas seal has officially been put into operation for six months, it damaged twice and caused the device to unplanned shutdown, seriously affected the long term operation of the device. During research and analysis on the seal of the unit, a series of problems were found, such as gas anti-channeling, sealing gas with oil etc. After transformation on the sealed gas supply system, the compressor achieved the purpose of long term stable running.

scholarly journals Application of mechanical filters for purification of electrolyte from solid products of the air and aluminum chemical cell reaction

2020 ◽  
Vol 18 (4) ◽  
pp. 713-718
Author(s):  
Nadezhda Okorokova ◽  
Aleksandr Perchenok ◽  
Stanislav Sevruk ◽  
Elena Suvorova ◽  
Ariadna Farmakovskaya ◽  
...  
Keyword(s):  
Aluminum Hydroxide ◽  
Power Plants ◽  
Solid Phase ◽  
Small Mass ◽  
Alkaline Electrolyte ◽  
Term Operation ◽  
High Concentrations ◽  
Filtration Unit ◽  
Term Performance

This work presents the results of the development and application of a filtration unit - a cartridge filter with a throttle (discharge) hole - for separating the solid phase - crystalline aluminum hydroxide Al(OH)3, formed during long-term operation of an air and aluminum chemical cell with alkaline electrolyte and power plants based on them. The main theoretical provisions on the filtration mechanism using the discharge hole are formulated, according to which the filtration process consists of two types of filtration - blowout piping and particle coupling. The developed method made it possible to: purify electrolyte with low friction to electrolyte flow at high concentrations of the solid phase; ensure long-term performance of the purification system with large masses of the solid phase formed; be able to quickly regenerate the electrolyte; have a small mass and volume; leave a sufficient amount of solid phase in the electrolyte so that the crystals of aluminum hydroxide passing through the filter are a seed for the crystallization of dissolved aluminum in the circuit. The studies carried out allowed us to conclude that the use of mechanical cartridge filters with an orifice hole is an effective and reliable method for cleaning the electrolyte of a power plant with an air and aluminum chemical cell.

Russia’s Development Strategy: Guidelines and Restrictions

2008 ◽  
pp. 119-130 ◽  
Author(s):  
V. Senchagov
Keyword(s):  
Economic Development ◽  
Development Strategy ◽  
Conceptual Basis ◽  
The Core ◽  
Economic Development Strategy ◽  
Socio Economic Development ◽  
Rates Of Growth

The core of Russia’s long-term socio-economic development strategy is represented by its conceptual basis. Having considered debating points about the essence and priority of the strategy, the author analyzes the logic and stages of its development as well as possibilities, restrictions and risks of high GDP rates of growth.

Unravelling a microbial synergy to boost caproate production via carboxylates chain elongation with ethanol

2019 ◽  
Vol 26 (2) ◽  
pp. 63-71
Author(s):  
Ling Leng ◽  
Ying Wang ◽  
Peixian Yang ◽  
Takashi Narihiro ◽  
Masaru Konishi Nobu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Microbial Consortia ◽  
Chain Elongation ◽  
Desulfovibrio Vulgaris ◽  
Rrna Gene ◽  
Selective Enrichment ◽  
Microbial Network ◽  
Cost Efficient ◽  
Rrna Gene Sequencing

Chain elongation of volatile fatty acids for medium chain fatty acids production (e.g. caproate) is an attractive approach to treat wastewater anaerobically and recover resource simultaneously. Undefined microbial consortia can be tailored to achieve chain elongation process with selective enrichment from anaerobic digestion sludge, which has advantages over pure culture approach for cost-efficient application. Whilst the metabolic pathway of the dominant caproate producer, Clostridium kluyveri, has been annotated, the role of other coexisting abundant microbiomes remained unclear. To this end, an ethanol-acetate fermentation inoculated with fresh digestion sludge at optimal conditions was conducted. Also, physiological study, thermodynamics and 16 S rRNA gene sequencing to elucidate the biological process by linking the system performance and dominant microbiomes were integrated. Results revealed a possible synergistic network in which C. kluyveri and three co-dominant species, Desulfovibrio vulgaris, Fusobacterium varium and Acetoanaerobium sticklandii coexisted. D. vulgaris and A. sticklandii (F. varium) were likely to boost the carboxylates chain elongation by stimulating ethanol oxidation and butyrate production through a syntrophic partnership with hydrogen (H2) serving as an electron messenger. This study unveils a synergistic microbial network to boost caproate production in mixed culture carboxylates chain elongation.

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