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Chacon-Aparicio S, Villamil JA, Martinez F, Melero JA, Molina R, Puyol D. Achieving Discharge Limits in Single-Stage Domestic Wastewater Treatment by Combining Urban Waste Sources and Phototrophic Mixed Cultures. Microorganisms 2023; 11:2324. [PMID: 37764168 PMCID: PMC10536668 DOI: 10.3390/microorganisms11092324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/09/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
This work shows the potential of a new way of co-treatment of domestic wastewater (DWW) and a liquid stream coming from the thermal hydrolysis of the organic fraction of municipal solid waste (OFMSW) mediated by a mixed culture of purple phototrophic bacteria (PPB) capable of assimilating carbon and nutrients from the medium. The biological system is an open single-step process operated under microaerophilic conditions at an oxidative reduction potential (ORP) < 0 mV with a photoperiod of 12/24 h and fed during the light stage only so the results can be extrapolated to outdoor open pond operations by monitoring the ORP. The effluent mostly complies with the discharge values of the Spanish legislation in COD and p-values (<125 mg/L; <2 mg/L), respectively, and punctually on values in N (<15 mg/L). Applying an HRT of 3 d and a ratio of 100:7 (COD:N), the presence of PPB in the mixed culture surpassed 50% of 16S rRNA gene copies, removing 78% of COD, 53% of N, and 66% of P. Furthermore, by increasing the HRT to 5 d, removal efficiencies of 83% of COD, 65% of N, and 91% of P were achieved. In addition, the reactors were further operated in a membrane bioreactor, thus separating the HRT from the SRT to increase the specific loading rate. Very satisfactory removal efficiencies were achieved by applying an HRT and SRT of 2.3 and 3 d, respectively: 84% of COD, 49% of N, and 93% of P despite the low presence of PPB due to more oxidative conditions, which step-by-step re-colonized the mixed culture until reaching >20% of 16S rRNA gene copies after 49 d of operation. These results open the door to scaling up the process in open photobioreactors capable of treating urban wastewater and municipal solid waste in a single stage and under microaerophilic conditions by controlling the ORP of the system.
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Affiliation(s)
| | | | | | | | | | - Daniel Puyol
- Chemical and Environmental Engineering Group, University Rey Juan Carlos, 28933 Madrid, Spain; (S.C.-A.); (F.M.); (J.A.M.); (R.M.)
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Alloul A, Blansaer N, Cabecas Segura P, Wattiez R, Vlaeminck SE, Leroy B. Dehazing redox homeostasis to foster purple bacteria biotechnology. Trends Biotechnol 2023; 41:106-119. [PMID: 35843758 DOI: 10.1016/j.tibtech.2022.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/14/2022] [Accepted: 06/17/2022] [Indexed: 12/27/2022]
Abstract
Purple non-sulfur bacteria (PNSB) show great potential for environmental and industrial biotechnology, producing microbial protein, biohydrogen, polyhydroxyalkanoates (PHAs), pigments, etc. When grown photoheterotrophically, the carbon source is typically more reduced than the PNSB biomass, which leads to a redox imbalance. To mitigate the excess of electrons, PNSB can exhibit several 'electron sinking' strategies, such as CO2 fixation, N2 fixation, and H2 and PHA production. The lack of a comprehensive (over)view of these redox strategies is hindering the implementation of PNSB for biotechnology applications. This review aims to present the state of the art of redox homeostasis in phototrophically grown PNSB, presenting known and theoretically expected strategies, and discussing them from stoichiometric, thermodynamic, metabolic, and economic points of view.
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Affiliation(s)
- Abbas Alloul
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Antwerpen, Belgium.
| | - Naïm Blansaer
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Antwerpen, Belgium
| | | | - Ruddy Wattiez
- Laboratory of Proteomics and Microbiology, University of Mons, Mons, Belgium
| | - Siegfried E Vlaeminck
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Antwerpen, Belgium
| | - Baptiste Leroy
- Laboratory of Proteomics and Microbiology, University of Mons, Mons, Belgium
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Alloul A, Van Kampen W, Cerruti M, Wittouck S, Pabst M, Weissbrodt D. Exploring the role of antimicrobials in the selective growth of purple phototrophic bacteria through genome mining and agar spot assays. Lett Appl Microbiol 2022; 75:1275-1285. [PMID: 35938312 PMCID: PMC9804395 DOI: 10.1111/lam.13795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 01/05/2023]
Abstract
Purple non-sulphur bacteria (PNSB) are an emerging group of microbes attractive for applied microbiology applications such as wastewater treatment, plant biostimulants, microbial protein, polyhydroxyalkanoates and H2 production. These photoorganoheterotrophic microbes have the unique ability to grow selectively on organic carbon in anaerobic photobioreactors. This so-called selectivity implies that the microbial community will have a low diversity and a high abundance of a particular PNSB species. Recently, it has been shown that certain PNSB strains can produce antimicrobials, yet it remains unclear whether these contribute to competitive inhibition. This research aimed to understand which type of antimicrobial PNSB produce and identify whether these compounds contribute to their selective growth. Mining 166 publicly-available PNSB genomes using the computational tool BAGEL showed that 59% contained antimicrobial encoding regions, more specifically biosynthetic clusters of bacteriocins and non-ribosomal peptide synthetases. Inter- and intra-species inhibition was observed in agar spot assays for Rhodobacter blasticus EBR2 and Rhodopseudomonas palustris EBE1 with inhibition zones of, respectively, 5.1 and 1.5-5.7 mm. Peptidomic analysis detected a peptide fragment in the supernatant (SVLQLLR) that had a 100% percentage identity match with a known non-ribosomal peptide synthetase with antimicrobial activity.
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Affiliation(s)
- A. Alloul
- Department of BiotechnologyDelft University of TechnologyDelftthe Netherlands,Department of Bioscience EngineeringUniversity of AntwerpAntwerpenBelgium
| | - W. Van Kampen
- Department of BiotechnologyDelft University of TechnologyDelftthe Netherlands
| | - M. Cerruti
- Department of BiotechnologyDelft University of TechnologyDelftthe Netherlands
| | - S. Wittouck
- Department of Bioscience EngineeringUniversity of AntwerpAntwerpenBelgium
| | - M. Pabst
- Department of BiotechnologyDelft University of TechnologyDelftthe Netherlands
| | - D.G. Weissbrodt
- Department of BiotechnologyDelft University of TechnologyDelftthe Netherlands
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Alloul A, Cerruti M, Adamczyk D, Weissbrodt DG, Vlaeminck SE. Operational Strategies to Selectively Produce Purple Bacteria for Microbial Protein in Raceway Reactors. Environ Sci Technol 2021; 55:8278-8286. [PMID: 34085818 DOI: 10.1021/acs.est.0c08204] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
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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Affiliation(s)
- Abbas Alloul
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Marta Cerruti
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Damian Adamczyk
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - David G Weissbrodt
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Siegfried E Vlaeminck
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
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Cerruti M, Stevens B, Ebrahimi S, Alloul A, Vlaeminck SE, Weissbrodt DG. Enrichment and Aggregation of Purple Non-sulfur Bacteria in a Mixed-Culture Sequencing-Batch Photobioreactor for Biological Nutrient Removal From Wastewater. Front Bioeng Biotechnol 2021; 8:557234. [PMID: 33392158 PMCID: PMC7773948 DOI: 10.3389/fbioe.2020.557234] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 11/23/2020] [Indexed: 12/13/2022] Open
Abstract
Mixed-culture biotechnologies are widely used to capture nutrients from wastewater. Purple non-sulfur bacteria (PNSB), a guild of anoxygenic photomixotrophic organisms, rise interest for their ability to directly assimilate nutrients in the biomass. One challenge targets the aggregation and accumulation of PNSB biomass to separate it from the treated water. Our aim was to enrich and produce a concentrated, fast-settling PNSB biomass with high nutrient removal capacity in a 1.5-L, stirred-tank, anaerobic sequencing-batch photobioreactor (SBR). PNSB were rapidly enriched after inoculation with activated sludge at 0.1 gVSS L-1 in a first batch of 24 h under continuous irradiance of infrared (IR) light (>700 nm) at 375 W m-2, with Rhodobacter reaching 54% of amplicon sequencing read counts. SBR operations with decreasing hydraulic retention times (48 to 16 h, i.e., 1-3 cycles d-1) and increasing volumetric organic loading rates (0.2-1.3 kg COD d-1 m-3) stimulated biomass aggregation, settling, and accumulation in the system, reaching as high as 3.8 g VSS L-1. The sludge retention time (SRT) increased freely from 2.5 to 11 days. Acetate, ammonium, and orthophosphate were removed up to 96% at a rate of 1.1 kg COD d-1 m-3, 77% at 113 g N d-1 m-3, and 73% at 15 g P d-1 m-3, respectively, with COD:N:P assimilation ratio of 100:6.7:0.9 m/m/m. SBR regime shifts sequentially selected for Rhodobacter (90%) under shorter SRT and non-limiting concentration of acetate during reaction phases, for Rhodopseudomonas (70%) under longer SRT and acetate limitation during reaction, and Blastochloris (10%) under higher biomass concentrations, underlying competition for substrate and photons in the PNSB guild. With SBR operations we produced a fast-settling biomass, highly (>90%) enriched in PNSB. A high nutrient removal was achieved by biomass assimilation, reaching the European nutrient discharge limits. We opened further insights on the microbial ecology of PNSB-based processes for water resource recovery.
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Affiliation(s)
- Marta Cerruti
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Berber Stevens
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Sirous Ebrahimi
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands.,Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran
| | - Abbas Alloul
- Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium
| | | | - David G Weissbrodt
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
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Zarezadeh S, Moheimani NR, Jenkins SN, Hülsen T, Riahi H, Mickan BS. Microalgae and Phototrophic Purple Bacteria for Nutrient Recovery From Agri-Industrial Effluents: Influences on Plant Growth, Rhizosphere Bacteria, and Putative Carbon- and Nitrogen-Cycling Genes. Front Plant Sci 2019; 10:1193. [PMID: 31632425 PMCID: PMC6779020 DOI: 10.3389/fpls.2019.01193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 08/29/2019] [Indexed: 05/27/2023]
Abstract
Microalgae (MA) and purple phototrophic bacteria (PPB) have the ability to remove and recover nutrients from digestate (anaerobic digestion effluent) and pre-settled pig manure that can be Utilized as bio-fertilizer and organic fertilizer. The objective of this study was to compare the effectiveness of MA and PPB as organic fertilizers and soil conditioners in relation to plant growth and the soil biological processes involved in nitrogen (N) and carbon (C) cycling. To this end, a glasshouse experiment was conducted using MA and PPB as bio-fertilizers to grow a common pasture ryegrass (Lolium rigidum Gaudin) with two destructive harvests (45 and 60 days after emergence). To evaluate the rhizosphere bacterial community, we used barcoded PCR-amplified bacterial 16S rRNA genes for paired-end sequencing on the Illumina Mi-Seq. Additionally, we used phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis for the detection of putative functional genes associated with N and soil-C cycling. There was a significant increase in plant growth when the soil was amended with PPB, which almost performed as well as the chemical fertilizers. Analysis of the rhizosphere bacteria after the second harvest revealed a greater abundance of Firmicutes than in the first harvest. Members of this phylum have been identified as a biostimulant for plant growth. In contrast, the MA released nutrients more slowly and had a profound effect on N cycling by modulating N mineralization and N retention pathways. Thus, MA could be developed as a slow-release fertilizer with better N retention, which could improve crop performance and soil function, despite nutrient losses from leaching, runoff, and atmospheric emissions. These data indicate that biologically recovered nutrients from waste resources can be effective as a fertilizer, resulting in enhanced C- and N-cycling capacities in the rhizosphere.
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Affiliation(s)
- Somayeh Zarezadeh
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Navid R. Moheimani
- Algae R and D Centre, Murdoch University, Perth, WA, Australia
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, Perth, WA, Australia
| | - Sasha N. Jenkins
- UWA School of Agriculture and Environment (M079), The University of Western Australia, Perth, WA, Australia
- The UWA Institute of Agriculture (M082), The University of Western Australia, Perth, WA, Australia
| | - Tim Hülsen
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Hossein Riahi
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Bede S. Mickan
- UWA School of Agriculture and Environment (M079), The University of Western Australia, Perth, WA, Australia
- The UWA Institute of Agriculture (M082), The University of Western Australia, Perth, WA, Australia
- Richgro Garden Products, Jandakot, WA, Australia
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