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Carvalho VCF, Gan AZM, Shon A, Kolakovic S, Freitas EB, Reis MAM, Fradinho JC, Oehmen A. The phototrophic metabolic behaviour of Candidatus accumulibacter. WATER RESEARCH 2024; 259:121865. [PMID: 38851111 DOI: 10.1016/j.watres.2024.121865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/10/2024]
Abstract
The phototrophic capability of Candidatus Accumulibacter (Accumulibacter), a common polyphosphate accumulating organism (PAO) in enhanced biological phosphorus removal (EBPR) systems, was investigated in this study. Accumulibacter is phylogenetically related to the purple bacteria Rhodocyclus from the family Rhodocyclaceae, which belongs to the class Betaproteobacteria. Rhodocyclus typically exhibits both chemoheterotrophic and phototrophic growth, however, limited studies have evaluated the phototrophic potential of Accumulibacter. To address this gap, short and extended light cycle tests were conducted using a highly enriched Accumulibacter culture (95%) to evaluate its responses to illumination. Results showed that, after an initial period of adaptation to light conditions (approximately 4-5 h), Accumulibacter exhibited complete phosphorus (P) uptake by utilising polyhydroxyalkanoates (PHA), and additionally by consuming glycogen, which contrasted with its typical aerobic metabolism. Mass, energy, and redox balance analyses demonstrated that Accumulibacter needed to employ phototrophic metabolism to meet its energy requirements. Calculations revealed that the light reactions contributed to the generation of, at least more than 67% of the ATP necessary for P uptake and growth. Extended light tests, spanning 21 days with dark/light cycles, suggested that Accumulibacter generated ATP through light during initial operation, however, it likely reverted to conventional anaerobic/aerobic metabolism under dark/light conditions due to microalgal growth in the mixed culture, contributing to oxygen production. In contrast, extended light tests with an enriched Tetrasphaera culture, lacking phototrophic genes in its genome, clearly demonstrated that phototrophic P uptake did not occur. These findings highlight the adaptive metabolic capabilities of Accumulibacter, enabling it to utilise phototrophic pathways for energy generation during oxygen deprivation, which holds the potential to advance phototrophic-EBPR technology development.
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Affiliation(s)
- V C F Carvalho
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - A Z M Gan
- School of Chemical Engineering, University of Queensland, Brisbane, QLD, 4072, Australia
| | - A Shon
- School of Chemical Engineering, University of Queensland, Brisbane, QLD, 4072, Australia
| | - S Kolakovic
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - E B Freitas
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - M A M Reis
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - J C Fradinho
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - A Oehmen
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal; School of Chemical Engineering, University of Queensland, Brisbane, QLD, 4072, Australia.
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Effects of Nutritional Mode on the Physiological and Biochemical Characteristics of the Mixotrophic Flagellate Poterioochromonas malhamensis and the Potential Ecological Implications. Microorganisms 2022; 10:microorganisms10050852. [PMID: 35630297 PMCID: PMC9147812 DOI: 10.3390/microorganisms10050852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 01/27/2023] Open
Abstract
Mixotrophic flagellates play an important role in connecting the classical food chain and microbial food loop. The feeding characteristics of the mixotrophic flagellate Poterioochromonasmalhamensis have been well studied, but its role as a food source for other large zooplankton is less studied. This study focuses on the physiological and biochemical changes in P. malhamensis when using autotrophy, chemoheterotrophy, and phagotrophy, and the effect of these changes on the feeding ability of one of its predators, the ciliate Paramecium caudatum. The results showed that chemoheterotrophic P. malhamensis had a higher growth rate and larger cell size than autotrophic and phagotrophic P. malhamensis. The biochemical composition of P. malhamensis also varied greatly between the three nutritional modes. The protein, total absolute amino acid, and fucoxanthin contents were highest for autotrophic P. malhamensis, while chemoheterotrophic P. malhamensis had the highest contents of total sugar and total absolute fatty acid. The contents of most biochemical components in phagotrophic P. malhamensis fell between those in autotrophic and chemoheterotrophic P. malhamensis. A feeding experiment showed that the grazing ability of P. caudatum on chemoheterotrophic P. malhamensis was significantly higher than that on phagotrophic P. malhamensis and autotrophic P. malhamensis. This study showed that the transformation of nutritional modes can alter the biochemical composition of the mixotrophic flagellate P. malhamensis and, as a result, affect the grazing ability of its predator P. caudatum.
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Wu XX, Li JW, Xing SF, Chen HT, Song C, Wang SG, Yan Z. Establishment of a resource recycling strategy by optimizing isobutanol production in engineered cyanobacteria using high salinity stress. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:174. [PMID: 34461979 PMCID: PMC8404291 DOI: 10.1186/s13068-021-02023-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 08/21/2021] [Indexed: 06/07/2023]
Abstract
BACKGROUND Isobutanol is an attractive biofuel with many advantages. Third-generation biorefineries that convert CO2 into bio-based fuels have drawn considerable attention due to their lower feedstock cost and more ecofriendly refining process. Although autotrophic cyanobacteria have been genetically modified for isobutanol biosynthesis, there is a lack of stable and convenient strategies to improve their production. RESULTS In this study, we first engineered Synechococcus elongatus for isobutanol biosynthesis by introducing five exogenous enzymes, reaching a production titer of 0.126 g/L at day 20. It was then discovered that high salinity stress could result in a whopping fivefold increase in isobutanol production, with a maximal in-flask titer of 0.637 g/L at day 20. Metabolomics analysis revealed that high salinity stress substantially altered the metabolic profiles of the engineered S. elongatus. A major reason for the enhanced isobutanol production is the acceleration of lipid degradation under high salinity stress, which increases NADH. The NADH then participates in the engineered isobutanol-producing pathway. In addition, increased membrane permeability also contributed to the isobutanol production titer. A cultivation system was subsequently developed by mixing synthetic wastewater with seawater to grow the engineered cyanobacteria, reaching a similar isobutanol production titer as cultivation in the medium. CONCLUSIONS High salinity stress on engineered cyanobacteria is a practical and feasible biotechnology to optimize isobutanol production. This biotechnology provides a cost-effective approach to biofuel production, and simultaneously recycles chemical nutrients from wastewater and seawater.
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Affiliation(s)
- Xiao-Xi Wu
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Jian-Wei Li
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Su-Fang Xing
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Hui-Ting Chen
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Chao Song
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Shu-Guang Wang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China
| | - Zhen Yan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China.
- Suzhou Research Institute, Shandong University, Suzhou, 215123, Jiangsu, China.
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Foladori P, Petrini S, Andreottola G. How suspended solids concentration affects nitrification rate in microalgal-bacterial photobioreactors without external aeration. Heliyon 2020; 6:e03088. [PMID: 31909261 PMCID: PMC6939075 DOI: 10.1016/j.heliyon.2019.e03088] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/02/2019] [Accepted: 12/17/2019] [Indexed: 11/27/2022] Open
Abstract
The use of microalgae for the treatment of municipal wastewater makes possible to supply oxygen and save energy, but must be coupled with bacterial nitrification to obtain nitrogen removal efficiency above 90%. This paper explores how the concentration of Total Suspended Solids (TSS, from 0.2 to 3.9 g TSS/L) affects the nitrification kinetic in three microalgal-bacterial consortia treating real municipal wastewater. Two different behaviors were observed: (1) solid-limited kinetic at low TSS concentrations, (2) light-limited kinetic at higher concentrations. For each consortium, an optimal TSS concentration that produced the maximum volumetric ammonium removal rate (around 1.8–2.0 mg N L−1 h−1), was found. The relationship between ammonium removal rate and TSS concentration was then modelled considering bacteria growth, microalgae growth and limitation by dissolved oxygen and light intensity. Assessment of the optimal TSS concentrations makes possible to concentrate the microbial biomass in a photobioreactor while ensuring high kinetics and a low footprint.
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Affiliation(s)
- Paola Foladori
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Trento, Italy
| | - Serena Petrini
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Trento, Italy
| | - Gianni Andreottola
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123, Trento, Italy
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Wang L, Chen L, Wu SX, Ye J. Non-airtight fermentation of sugar beet pulp with anaerobically digested dairy manure to provide acid-rich hydrolysate for mixotrophic microalgae cultivation. BIORESOURCE TECHNOLOGY 2019; 278:175-179. [PMID: 30690260 DOI: 10.1016/j.biortech.2019.01.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 01/14/2019] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
Non-airtight fermentation of lignocellulosic agricultural residues with animal wastes is an emerging pretreatment method to produce acid-rich substrates in two-phase anaerobic digestion. Acid-rich hydrolysate could be an excellent feedstock for cultivating microalgae, therefore, the feasibility of a two-step process combining non-airtight fermentation of sugar beet pulp with anaerobically digested dairy manure and mixotrophic microalgae species Chlorella cultivation in the hydrolysate was explored in this study. The hydrolysis and acidification process of 8-day non-airtight fermentation produced up to 8.1 g/L volatile fatty acids under mesophilic condition. Microalgal growths in diluted hydrolysates were compared with that in diluted digested dairy manure (DDM) as a control using experimental data and fitted logistic models. Chlorella grown in the 10-fold diluted DDM showed an exponential decay, while Chlorella cultured in the 3-fold diluted hydrolysate demonstrated the best performance in terms of biomass density, which reached 2.17 g/L within a short period of time.
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Affiliation(s)
- Liang Wang
- Department of Soil and Water Systems, Twin Falls Research & Extension Center, University of Idaho, 315 Falls Ave, Twin Falls, ID 83301, United States
| | - Lide Chen
- Department of Soil and Water Systems, Twin Falls Research & Extension Center, University of Idaho, 315 Falls Ave, Twin Falls, ID 83301, United States.
| | - Sarah Xiao Wu
- Department of Biological Engineering, University of Idaho, 875 Perimeter Drive, Moscow, ID 83844, United States
| | - Jianfeng Ye
- Water Research Institute, Shanghai Academy of Environmental Sciences, 508 Qinzhou Rd, 200233 Shanghai, China
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