High rate selection of PHA accumulating mixed cultures in sequencing batch reactors with uncoupled carbon and nitrogen feeding

Lorini, Laura; Re, Francesco Lo; Majone, Mauro; Francesco, Valentino

doi:10.1016/j.nbt.2020.01.006

Cited by 50 publications

(48 citation statements)

References 39 publications

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“…In the third operational period (NII and SII, for SBR-N and SBR-S, respectively), a double growth limitation (DGL) strategy was imposed, in which carbon (added in the feast phase) and nitrogen (added in the famine phase) feedings were uncoupled. Thus, nitrogen availability was limited during the feast phase, establishing an additional selective pressure advantageous for PHA-storing microorganisms [ 41 , 42 ]. In the last operational period (NIII and SIII, for SBR-N and SBR-S, respectively), the extent of the impact of pH control on the PHAs’ accumulation yields was tested by operating both SBRs under the same DGL strategy combined with a reduction of the NaHCO 3 supply during the famine phase.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of PHA-Accumulating Bacterial Communities Fed with Lipid-Rich Liquid Effluents from Fish-Canning Industries

et al. 2022

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The biosynthesis of polyhydroxyalkanoates (PHAs) from industrial wastes by mixed microbial cultures (MMCs) enriched in PHA-accumulating bacteria is a promising technology to replace petroleum-based plastics. However, the populations’ dynamics in the PHA-accumulating MMCs are not well known. Therefore, the main objective of this study was to address the shifts in the size and structure of the bacterial communities in two lab-scale sequencing batch reactors (SBRs) fed with fish-canning effluents and operated under non-saline (SBR-N, 0.5 g NaCl/L) or saline (SBR-S, 10 g NaCl/L) conditions, by using a combination of quantitative PCR and Illumina sequencing of bacterial 16S rRNA genes. A double growth limitation (DGL) strategy, in which nitrogen availability was limited and uncoupled to carbon addition, strongly modulated the relative abundances of the PHA-accumulating bacteria, leading to an increase in the accumulation of PHAs, independently of the saline conditions (average 9.04 wt% and 11.69 wt%, maximum yields 22.03 wt% and 26.33% SBR-N and SBR-S, respectively). On the other hand, no correlations were found among the PHAs accumulation yields and the absolute abundances of total Bacteria, which decreased through time in the SBR-N and did not present statistical differences in the SBR-S. Acinetobacter, Calothrix, Dyella, Flavobacterium, Novosphingobium, Qipengyuania, and Tsukamurella were key PHA-accumulating genera in both SBRs under the DGL strategy, which was revealed as a successful tool to obtain a PHA-enriched MMC using fish-canning effluents.

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Section: Methodsmentioning

confidence: 99%

Dynamics of PHA-Accumulating Bacterial Communities Fed with Lipid-Rich Liquid Effluents from Fish-Canning Industries

et al. 2022

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“…A reactor SBR-A with a 2 L working volume was initially seeded with activated sludge from the aeration tank of the Gaobeidian wastewater treatment plant (Beijing, China). The feast and famine regime was adapted for PHA-accumulating bacteria selection, in which carbon and nitrogen feeding were uncoupled . During the feast phase, the ammonia-deficient fermentative liquid was added into the selecting reactor to set an initial concentration of 2000 mg COD/L, and the details of the inlet water quality are listed in Table S1.…”

Section: Methodsmentioning

confidence: 99%

“…The feast and famine regime was adapted for PHA-accumulating bacteria selection, in which carbon and nitrogen feeding were uncoupled. 14 During the feast phase, the ammonia-deficient fermentative liquid was added into the selecting reactor to set an initial concentration of 2000 mg COD/L, and the details of the inlet water quality are listed in Table S1. At the end of the feast, nitrate was added as the main nitrogen source over the famine phase.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…With a deeper understanding of mixed culture PHA storage systems, several optimized selection regimes have been developed based on feast and famine modes to improve selection efficiency. The uncoupled carbon and nitrogen feeding regime is one of the best studied strategies for culture selection. − Under uncoupled carbon and nitrogen conditions, a nitrogen-free feast phase is created to enhance PHA storage, and the addition of nitrogen is delayed to the beginning of the famine phase to induce PHA-based growth. In comparison to traditional feast and famine regimes, uncoupled substrate strategies enhance selective pressure and accelerate the progress of PHA-storing microorganisms, gaining advantages over non-storing microorganisms.…”

Section: Introductionmentioning

confidence: 99%

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Polyhydroxyalkanoate Production from Food Waste Coupled with Aerobic Nitrate Reduction

Liu

Xiong

et al. 2021

ACS Sustainable Chem. Eng.

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Polyhydroxyalkanoate (PHA) production from wastes by mixed microbial cultures has been developed into an integrated process to couple with nitrate removal due to its economic and environmental benefits. However, the anoxic conditions for denitrification result in low productivity of PHA production due to the limited energy supply. In this work, the fully aerobic feeding regime uncoupling carbon and nitrogen supply was applied to enhance the culture enrichment and productivity while being accompanied by nitrate removal. The enriched cultures showed a nitrate assimilation rate of 2.35 ± 1.10 mg of NO 3 − −N per gram of active biomass (X a ) per hour; meanwhile, the specific growth rate (μ X a , 0.019 ± 0.002 h −1 ) and biomass yield on PHA (Y X a /PHA , 0.68 ± 0.15 g X a /g PHA) were higher than those of a classic anoxic process (μ X a , 0.011 ± 0.001 h −1 and Y X a /PHA , 0.38 ± 0.09 g X a /g PHA). Furthermore, ammonia and oxygen were confirmed to have significant impacts on regulating nitrate utilization by directing nitrate flow to assimilatory nitrate use, aerobic denitrification, or anoxic denitrification. Metagenome analysis revealed that the overall function was mostly undertaken by Thauera aminoaromatica, and a nitrate metabolic model driven by PHAs was proposed. In summary, these findings widened application scenarios for PHA production coupled with nitrate removal.

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“…Lorini et al, reported on application of sequencing batch reactors for cultivation of mixed culture with uncoupled carbon and nitrogen feeding. The different organic load rates studied (4.25 to 12.72 g COD/L·d) results in PHA productivity of 0.1 g PHA/L/h at optimum conditions [ 197 ]. Silva et al, explored how nitrogen feeding would influence PHA formation by MMCs.…”

Section: Pha Production Using Mixed Culturesmentioning

confidence: 99%

Emergent Approaches to Efficient and Sustainable Polyhydroxyalkanoate Production

2021

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Petroleum-derived plastics dominate currently used plastic materials. These plastics are derived from finite fossil carbon sources and were not designed for recycling or biodegradation. With the ever-increasing quantities of plastic wastes entering landfills and polluting our environment, there is an urgent need for fundamental change. One component to that change is developing cost-effective plastics derived from readily renewable resources that offer chemical or biological recycling and can be designed to have properties that not only allow the replacement of current plastics but also offer new application opportunities. Polyhydroxyalkanoates (PHAs) remain a promising candidate for commodity bioplastic production, despite the many decades of efforts by academicians and industrial scientists that have not yet achieved that goal. This article focuses on defining obstacles and solutions to overcome cost-performance metrics that are not sufficiently competitive with current commodity thermoplastics. To that end, this review describes various process innovations that build on fed-batch and semi-continuous modes of operation as well as methods that lead to high cell density cultivations. Also, we discuss work to move from costly to lower cost substrates such as lignocellulose-derived hydrolysates, metabolic engineering of organisms that provide higher substrate conversion rates, the potential of halophiles to provide low-cost platforms in non-sterile environments for PHA formation, and work that uses mixed culture strategies to overcome obstacles of using waste substrates. We also describe historical problems and potential solutions to downstream processing for PHA isolation that, along with feedstock costs, have been an Achilles heel towards the realization of cost-efficient processes. Finally, future directions for efficient PHA production and relevant structural variations are discussed.

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High rate selection of PHA accumulating mixed cultures in sequencing batch reactors with uncoupled carbon and nitrogen feeding

Cited by 50 publications

References 39 publications

Dynamics of PHA-Accumulating Bacterial Communities Fed with Lipid-Rich Liquid Effluents from Fish-Canning Industries

Dynamics of PHA-Accumulating Bacterial Communities Fed with Lipid-Rich Liquid Effluents from Fish-Canning Industries

Polyhydroxyalkanoate Production from Food Waste Coupled with Aerobic Nitrate Reduction

Emergent Approaches to Efficient and Sustainable Polyhydroxyalkanoate Production

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