Cocultivating aerobic heterotrophs and purple bacteria for microbial protein in sequential photo- and chemotrophic reactors

Alloul, Abbas; Muys, Maarten; Hertoghs, Nick; Kerckhof, Frederiek‐Maarten; Vlaeminck, Siegfried E.

doi:10.1016/j.biortech.2020.124192

Cited by 32 publications

(25 citation statements)

References 45 publications

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“…Low pigmentation was also visually observed for aerobically grown Rhodobacter sphaeroides, Rhodopseudomonas palustris, and R. rubrum in our previous study. 13 It was, thus, likely that the overall bacteriochlorophyll a content of the biomass produced in a raceway reactor was lower compared to strict anaerobic conditions due to the contribution of aerobic heterotrophic growth to biomass production.…”

Section: Methodsmentioning

confidence: 99%

“…In the case of our previous study on synthetic wastewater, PNSB were able to be selectively produced with an abundance of Rhodobacter capsulatus between 93 and 97% and low microbial diversity (exponent Shannon index between 1.2 and 1.5). 13 For microalgae, a review of nine techno-economic analyses on biodiesel production indicated that raceway reactors are more interesting from a cost perspective compared to closed PBRs. 23 This is mainly due to the higher investment cost of a vertical tubular PBR, which is between €1100−5000 m −3 compared to €14−56 m −3 for a raceway reactor.…”

Section: Introductionmentioning

confidence: 99%

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Operational Strategies to Selectively Produce Purple Bacteria for Microbial Protein in Raceway Reactors

Alloul

Cerruti

Adamczyk

et al. 2021

Environ. Sci. Technol.

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Purple non-sulfur bacteria (PNSB) show potential for microbial protein production on wastewater as animal feed. They offer good selectivity (i.e., low microbial diversity and high abundance of one species) when grown anaerobically in the light. However, the cost of closed anaerobic photobioreactors is prohibitive for protein production. Although open raceway reactors are cheaper, their feasibility to selectively grow PNSB is thus far unexplored. This study developed operational strategies to boost PNSB abundance in the biomass of a raceway reactor fed with volatile fatty acids. For a flask reactor run at a 2 day sludge retention time (SRT), matching the chemical oxygen demand (COD) loading rate to the removal rate in the light period prevented substrate availability during the dark period and increased the PNSB abundance from 50–67 to 88–94%. A raceway reactor run at a 2 day SRT showed an increased PNSB abundance from 14 to 56% when oxygen supply was reduced (no stirring at night). The best performance was achieved at the highest surface-to-volume ratio (10 m2 m–3 increased light availability) showing productivities up to 0.2 g protein L–1 day–1 and a PNSB abundance of 78%. This study pioneered in PNSB-based microbial protein production in raceway reactors, yielding high selectivity while avoiding the combined availability of oxygen, COD, and darkness.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Operational Strategies to Selectively Produce Purple Bacteria for Microbial Protein in Raceway Reactors

Alloul

Cerruti

Adamczyk

et al. 2021

Environ. Sci. Technol.

Self Cite

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“…In one study, Aspergillus niger H3 and Bacillus licheniformis were used to produce bacterial protein from potato starch wastewater in a dual-step process: (1) A. niger H3 metabolized the fiber in the potato wastewater through the action of cellulases; (2) B. licheniformis utilized the released sugars from the fermentation of potato fibers to produce bacterial protein [198]. Others used a hybrid system of purple non-sulfur bacteria and aerobic heterotrophic bacteria to improve the production efficiency and nutritional quality of the bacterial protein produced, including higher protein content and more favorable amino acid/fatty acid profiles, as compared with when either of the bacteria was cultured alone [199].…”

Section: White Leg Shrimp (Penaeus Vannamei)mentioning

confidence: 99%

Safety of Alternative Proteins: Technological, Environmental and Regulatory Aspects of Cultured Meat, Plant-Based Meat, Insect Protein and Single-Cell Protein

Hadi

Brightwell

2021

Foods

157

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Food security and environmental issues have become global crises that need transformative solutions. As livestock production is becoming less sustainable, alternative sources of proteins are urgently required. These include cultured meat, plant-based meat, insect protein and single-cell protein. Here, we describe the food safety aspects of these novel protein sources, in terms of their technological backgrounds, environmental impacts and the necessary regulatory framework for future mass-scale production. Briefly, cultured meat grown in fetal bovine serum-based media can be exposed to viruses or infectious prion, in addition to other safety risks associated with the use of genetic engineering. Plant-based meat may contain allergens, anti-nutrients and thermally induced carcinogens. Microbiological risks and allergens are the primary concerns associated with insect protein. Single-cell protein sources are divided into microalgae, fungi and bacteria, all of which have specific food safety risks that include toxins, allergens and high ribonucleic acid (RNA) contents. The environmental impacts of these alternative proteins can mainly be attributed to the production of growth substrates or during cultivation. Legislations related to novel food or genetic modification are the relevant regulatory framework to ensure the safety of alternative proteins. Lastly, additional studies on the food safety aspects of alternative proteins are urgently needed for providing relevant food governing authorities with sufficient data to oversee that the technological progress in this area is balanced with robust safety standards.

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“…In the same article, we also showed that mixtures of volatile fatty acids improve the growth performance of several pure and mixed PNSB cultures relative to individual volatile fatty acids. In another paper, we observed that fructose as a carbon source enhanced the protein content of several PNSB species compared to growth on volatile fatty acids, alcohols or other sugars (Alloul et al ., 2021a).…”

Section: Purple Bacteria For Hydrogenotrophy Methylotrophy and Acetotrophy?mentioning

confidence: 99%

Unlocking the genomic potential of aerobes and phototrophs for the production of nutritious and palatable microbial food without arable land or fossil fuels

Alloul

Spanoghe

Machado

et al. 2021

Microbial Biotechnology

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Renewable H 2 -and CO 2 -derived compounds as novel resource framework for microbial biomass production Food production and the planetary boundaries are already beyond the limits of sustainability (Steffen et al., 2015), yet even more pressure on Earth's carrying capacity is expected with the global population projected to reach 9.2-12.3 billion people by the turn of the century and the rise in living standards (Gerland et al., 2014). Structural changes of the agricultural-based food chain are required to increase food production and simultaneously reduce the environmental footprint (Horton, 2017). An alternative route to conventional food is the production of microorganisms as a source of human food also known as microbial protein or single-cell protein (Pikaar et al., 2018). The cultivation of microorganisms for food has many environmental benefits compared to agricultural crop production such as a reduction in arable land expansion, greenhouse gas

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Cocultivating aerobic heterotrophs and purple bacteria for microbial protein in sequential photo- and chemotrophic reactors

Cited by 32 publications

References 45 publications

Operational Strategies to Selectively Produce Purple Bacteria for Microbial Protein in Raceway Reactors

Operational Strategies to Selectively Produce Purple Bacteria for Microbial Protein in Raceway Reactors

Safety of Alternative Proteins: Technological, Environmental and Regulatory Aspects of Cultured Meat, Plant-Based Meat, Insect Protein and Single-Cell Protein

Unlocking the genomic potential of aerobes and phototrophs for the production of nutritious and palatable microbial food without arable land or fossil fuels

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