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Bioresource Technology Jul 2024This study assessed the impact of nine mixed ferrous sulfates and biochars on electric field-assisted aerobic composting (EAC), focusing on the spectroscopy of dissolved...
This study assessed the impact of nine mixed ferrous sulfates and biochars on electric field-assisted aerobic composting (EAC), focusing on the spectroscopy of dissolved organic matter (DOM) and microbial communities. Adding 1.05% ferrous sulfate and 5.25% biochar to EAC increased the specific ultraviolet absorbances at 254 and 280 nm by 142.3% and 133.9% on day 35, respectively. This ratio accelerated the early response of carboxyl groups (-COOH) and lignin (CꘌC), enhancing the relative abundance of Thermobifida (4.0%) and Thermopolyspora (4.3%). The condition contributed to humus precursor formation on day 5, increasing the maximum fluorescence intensity of the humus-like component by 74.2% compared to the control on day 35. This study is the first to develop a combined and efficient organic and inorganic additive by multiple-variable experimentation for DOM humification. Consequently, it optimizes EAC for solid waste recycling.
Topics: Charcoal; Composting; Ferrous Compounds; Aerobiosis; Humic Substances; Bacteria; Electricity; Soil; Soil Microbiology
PubMed: 38801959
DOI: 10.1016/j.biortech.2024.130901 -
Carbohydrate Research Jul 2024Aim of the study was to optimize and produce beta-mannanase at fermenter scale by using cheaper minimal media. Increased production of beta-mannanase from Microbacterium...
Aim of the study was to optimize and produce beta-mannanase at fermenter scale by using cheaper minimal media. Increased production of beta-mannanase from Microbacterium camelliasinensis CIAB417 was achieved by heterologous expression in E. coli BL21 (DE3). The scale-up production of beta-mannanase was optimized from shake flask to 5-L fermenter. The cost-effective minimal media (M9+e) without any vitamins was found to be most effective and optimized for culturing the cells. The same media displayed no significant fluctuation in the pH while culturing the cells for the production of beta-mannanase both at shake flask and fermenter level. Additionally, E. coli cells were able to produce similar amount of dry cell weight and recombinant beta-mannanase both in the presence of micro and macro-oxygen environment. The optimized media was demonstrated to show no significant drop in pH throughout the recombinant protein production process. In one litre medium, 2.0314 g dry weight of E. coli cells yielded 1.8 g of purified recombinant beta-mannanase. The purified enzyme was lyophilized and demonstrated to hydrolyse locust bean gum to release mannooligosaccharides.
Topics: beta-Mannosidase; Escherichia coli; Recombinant Proteins; Fermentation; Mannans; Bioreactors; Hydrogen-Ion Concentration; Aerobiosis; Galactans; Culture Media; Plant Gums; Actinobacteria; Hydrolysis
PubMed: 38788560
DOI: 10.1016/j.carres.2024.109150 -
Bioprocess and Biosystems Engineering Jul 2024With the anoxic-aerobic membrane bioreactor (AO-MBR, CP) as a reference, high-throughput sequencing technology was used to reveal the characteristics of the microbial...
With the anoxic-aerobic membrane bioreactor (AO-MBR, CP) as a reference, high-throughput sequencing technology was used to reveal the characteristics of the microbial community structure in the anaerobic side-stream anoxic-aerobic membrane bioreactor sludge reduction process (AOMBR-ASSR, SRP). After the stable operation of two processes for 120 days, the average removal efficiencies of TN and TP in the effluent of SRP were increased by 5.6% and 29.8%, respectively. The observed sludge yields (Y) of the two processes were 0.14 and 0.17 gMLSS/(gCOD), respectively, and the sludge reduction rate of the SRP was 19.5%. Compared to the CP, the microbial richness and diversity index of SRP increased significantly. Chloroflexi, which is responsible for the degradation of organic substances under an anaerobic condition, seemed to be reduced in the SRP. Meanwhile, other phyla that involved in the nitrogen cycle, such as Nitrospirae and Planctomycetes, were found to be more abundant in the SRP than in the CP. A total of 21 identified classes were observed, and primarily hydrolyzed fermented bacteria (Sphingobacteriia, Betaproteobacteria, Actinobacteria and Deltaproteobacteria) and slow-growing microorganisms (Bacilli) were accumulated in the SRP. At the genus level, the inserted anaerobic side-stream reactor favored the hydrolyzed bacteria (Saprospiraceae, Rhodobacter and Candidatus_Competibacter), fermented bacteria (Lactococcus and Trichococcus), and slow-growing microorganisms (Dechloromonas and Haliangium), which play a crucial role in the sludge reduction. Furthermore, the enrichment of bacterial species related to nitrogen (Nitrospir and Azospira) provided the potential for nitrogen removal, while the anaerobic environment of the side-stream reactor promoted the enrichment of phosphorus-accumulating organisms.
Topics: Bioreactors; Sewage; Anaerobiosis; Membranes, Artificial; Microbiota; Bacteria; Aerobiosis
PubMed: 38777954
DOI: 10.1007/s00449-024-03019-y -
Bioresource Technology Jul 2024In this study, the possibility of an auto-aggregating bacterium Pseudomonas strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity for improving...
Evaluation of aerobic granulation performance bioaugmented with the auto-aggregating bacterium Pseudomonas stutzeri strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity.
In this study, the possibility of an auto-aggregating bacterium Pseudomonas strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity for improving granulation and nitrogen removal was evaluated. The results showed that the supplementation of strain XL-2 promoted granulation, making R1 (experimental group with strain XL-2) dominated by granules at 14 d, which was 12 days earlier than R2 (control group without strain XL-2). This was attributed to the promotion of extracellular polymeric substances (EPS) secretion, particularly proteins by adding strain XL-2, thereby improving the hydrophobicity of sludge and altering the proteins secondary structures to facilitate aggregation. Meanwhile, adding strain XL-2 improved simultaneous nitrification and denitrification efficiency of R1. Microbial community analysis indicated that strain XL-2 successfully proliferated in aerobic granule sludge and might induce the enrichment of genera such as Flavobacterium and Paracoccus that were favorable for EPS secretion and denitrification, jointly promoting granulation and enhancing nitrogen removal efficiency.
Topics: Denitrification; Nitrification; Pseudomonas stutzeri; Aerobiosis; Sewage; Nitrogen; Heterotrophic Processes; Extracellular Polymeric Substance Matrix; Bioreactors
PubMed: 38777236
DOI: 10.1016/j.biortech.2024.130869 -
Chemosphere Jul 2024Three sequential batch reactors (SBR) were operated to evaluate salt addition's impact on granulation, performance, and biopolymer production in aerobic granular sludge...
Three sequential batch reactors (SBR) were operated to evaluate salt addition's impact on granulation, performance, and biopolymer production in aerobic granular sludge (AGS) systems. System R1 was fed without adding salt (control); system R2 operated with saline pulses, i.e., one cycle with salt (2.5 g NaCl/L) addition followed by another without salt; and R3 received continuous supplementation of 2.5 g NaCl/L. The results indicated that the reactors supplemented with salt presented higher concentrations of mixed liquor volatile suspended solids (MLVSS) and better settleability than R1, showing that osmotic pressure contributed to biomass growth, accelerated granulation, and improved physical characteristics. The faster granulation occurred in R2, thus proving the beneficial effects of intermittent salt addition through alternating pulses. Salt addition did not impair the simultaneous removal of carbon, nitrogen, and phosphorus. In fact, R2 showed better carbon removals. In conclusion, continuous or intermittent (pulsed) supplementation of 2.5 g NaCl/L did not lead to increased production of extracellular polymeric substances (EPS) and alginate-like exopolymers (ALE). This outcome could be attributed to the low saline concentration employed, a higher food-to-microorganism (F/M) ratio observed in R1, and possibly greater endogenous consumption of biopolymers in the famine period in R2 and R3 due to the greater solids retention time (SRT). Therefore, this study brings important results that contribute to a better understanding of the effect of salt in continuous dosing or in pulses as a selection pressure strategy to accelerate granulation, as well as the behavior of the AGS systems for saline effluents.
Topics: Bioreactors; Sewage; Waste Disposal, Fluid; Phosphorus; Aerobiosis; Biomass; Nitrogen; Biopolymers; Carbon; Salt Stress; Sodium Chloride
PubMed: 38777193
DOI: 10.1016/j.chemosphere.2024.142402 -
Chemosphere Jul 2024This study re-evaluated the role of anoxic and anaerobic zones during the enhanced biological phosphorus (P) removal process by investigating the potential effect of...
This study re-evaluated the role of anoxic and anaerobic zones during the enhanced biological phosphorus (P) removal process by investigating the potential effect of introducing an anoxic zone into a high-rate microaerobic activated sludge (MAS) system (1.60-1.70 kg chemical oxygen demand (COD) m d), i.e., a high-rate anoxic/microaerobic (A/M) system for sewage treatment. In the absence of a pre-anaerobic zone, introducing an anoxic zone considerably reduced effluent NO-N concentrations (7.2 vs. 1.5 mg L) and remarkably enhanced total nitrogen (75% vs. 89%) and total P (18% vs. 60%) removal and sludge P content (1.48% vs. 1.77% (dry weight)) due to further anoxic denitrifying P removal in the anoxic zone (besides simultaneous nitrification and denitrification in the microaerobic zone). High-throughput pyrosequencing demonstrated the niche differentiation of different polyphosphate accumulating organism (PAO) clades (including denitrifying PAO [DPAO] and non-DPAO) in both systems. Introducing an anoxic zone considerably reduced the total PAO abundance in sludge samples by 42% and modified the PAO community structure, including 17-19 detected genera. The change was solely confined to non-DPAOs, as no obvious change in total abundance or community structure of DPAOs including 7 detected genera was observed. Additionally, introducing an anoxic zone increased the abundance of ammonia-oxidizing bacteria by 39%. The high-rate A/M process provided less aeration, higher treatment capacity, a lower COD requirement, and a 75% decrease in the production of waste sludge than the conventional biological nutrient removal process.
Topics: Phosphorus; Sewage; Denitrification; Waste Disposal, Fluid; Bioreactors; Nitrogen; Anaerobiosis; Nitrification; Bacteria; Aerobiosis; Biological Oxygen Demand Analysis
PubMed: 38768781
DOI: 10.1016/j.chemosphere.2024.142377 -
Microbiome May 2024During the bloom season, the colonial cyanobacterium Microcystis forms complex aggregates which include a diverse microbiome within an exopolymer matrix. Early research...
BACKGROUND
During the bloom season, the colonial cyanobacterium Microcystis forms complex aggregates which include a diverse microbiome within an exopolymer matrix. Early research postulated a simple mutualism existing with bacteria benefitting from the rich source of fixed carbon and Microcystis receiving recycled nutrients. Researchers have since hypothesized that Microcystis aggregates represent a community of synergistic and interacting species, an interactome, each with unique metabolic capabilities that are critical to the growth, maintenance, and demise of Microcystis blooms. Research has also shown that aggregate-associated bacteria are taxonomically different from free-living bacteria in the surrounding water. Moreover, research has identified little overlap in functional potential between Microcystis and members of its microbiome, further supporting the interactome concept. However, we still lack verification of general interaction and know little about the taxa and metabolic pathways supporting nutrient and metabolite cycling within Microcystis aggregates.
RESULTS
During a 7-month study of bacterial communities comparing free-living and aggregate-associated bacteria in Lake Taihu, China, we found that aerobic anoxygenic phototrophic (AAP) bacteria were significantly more abundant within Microcystis aggregates than in free-living samples, suggesting a possible functional role for AAP bacteria in overall aggregate community function. We then analyzed gene composition in 102 high-quality metagenome-assembled genomes (MAGs) of bloom-microbiome bacteria from 10 lakes spanning four continents, compared with 12 complete Microcystis genomes which revealed that microbiome bacteria and Microcystis possessed complementary biochemical pathways that could serve in C, N, S, and P cycling. Mapping published transcripts from Microcystis blooms onto a comprehensive AAP and non-AAP bacteria MAG database (226 MAGs) indicated that observed high levels of expression of genes involved in nutrient cycling pathways were in AAP bacteria.
CONCLUSIONS
Our results provide strong corroboration of the hypothesized Microcystis interactome and the first evidence that AAP bacteria may play an important role in nutrient cycling within Microcystis aggregate microbiomes. Video Abstract.
Topics: Microcystis; Microbiota; China; Lakes; Nutrients; Phototrophic Processes; Aerobiosis; Eutrophication; Bacteria; Nitrogen; Carbon
PubMed: 38741135
DOI: 10.1186/s40168-024-01801-4 -
Applied Microbiology and Biotechnology May 2024Aerobic granular sludge (AGS) and conventional activated sludge (CAS) are two different biological wastewater treatment processes. AGS consists of self-immobilised...
Aerobic granular sludge (AGS) and conventional activated sludge (CAS) are two different biological wastewater treatment processes. AGS consists of self-immobilised microorganisms that are transformed into spherical biofilms, whereas CAS has floccular sludge of lower density. In this study, we investigated the treatment performance and microbiome dynamics of two full-scale AGS reactors and a parallel CAS system at a municipal WWTP in Sweden. Both systems produced low effluent concentrations, with some fluctuations in phosphate and nitrate mainly due to variations in organic substrate availability. The microbial diversity was slightly higher in the AGS, with different dynamics in the microbiome over time. Seasonal periodicity was observed in both sludge types, with a larger shift in the CAS microbiome compared to the AGS. Groups important for reactor function, such as ammonia-oxidising bacteria (AOB), nitrite-oxidising bacteria (NOB), polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs), followed similar trends in both systems, with higher relative abundances of PAOs and GAOs in the AGS. However, microbial composition and dynamics differed between the two systems at the genus level. For instance, among PAOs, Tetrasphaera was more prevalent in the AGS, while Dechloromonas was more common in the CAS. Among NOB, Ca. Nitrotoga had a higher relative abundance in the AGS, while Nitrospira was the main nitrifier in the CAS. Furthermore, network analysis revealed the clustering of the various genera within the guilds to modules with different temporal patterns, suggesting functional redundancy in both AGS and CAS. KEY POINTS: • Microbial community succession in parallel full-scale aerobic granular sludge (AGS) and conventional activated sludge (CAS) processes. • Higher periodicity in microbial community structure in CAS compared to in AGS. • Similar functional groups between AGS and CAS but different composition and dynamics at genus level.
Topics: Sewage; Microbiota; Bacteria; Bioreactors; Aerobiosis; Sweden; Glycogen; Ammonia; Nitrites; Nitrates; Phosphates; Water Purification
PubMed: 38739161
DOI: 10.1007/s00253-024-13165-8 -
Bioresource Technology Jun 2024Mercury (Hg), particularly organic mercury, poses a global concern due to its pronounced toxicity and bioaccumulation. Bioremediation of organic mercury in high-salt...
Mercury (Hg), particularly organic mercury, poses a global concern due to its pronounced toxicity and bioaccumulation. Bioremediation of organic mercury in high-salt wastewater faces challenges due to the growth limitations imposed by elevated Cl and Na concentrations on microorganisms. In this study, an isolated marine bacterium Alteromonas macleodii KD01 was demonstrated to degrade methylmercury (MeHg) efficiently in seawater and then was applied to degrade organic mercury (MeHg, ethylmercury, and thimerosal) in simulated high-salt wastewater. Results showed that A. macleodii KD01 can rapidly degrade organic mercury (within 20 min) even at high concentrations (>10 ng/mL), volatilizing a portion of Hg from the wastewater. Further analysis revealed an increased transcription of organomercury lyase (merB) with rising organic mercury concentrations during the exposure process, suggesting the involvement of mer operon (merA and merB). These findings highlight A. macleodii KD01 as a promising candidate for addressing organic mercury pollution in high-salt wastewater.
Topics: Biodegradation, Environmental; Mercury; Alteromonas; Wastewater; Water Pollutants, Chemical; Seawater; Aerobiosis; Methylmercury Compounds
PubMed: 38734262
DOI: 10.1016/j.biortech.2024.130831 -
ACS Synthetic Biology Jun 2024NAD is a redox coenzyme and is the center of energy metabolism. In metabolic engineering modifications, an insufficient NAD(H) supply often limits the accumulation of...
NAD is a redox coenzyme and is the center of energy metabolism. In metabolic engineering modifications, an insufficient NAD(H) supply often limits the accumulation of target products. In this study, was found to be able to supply NAD(H) in large fluxes, up to 7.6 times more than in aerobic fermentation. Aerobic fermentation in a medium without amino nitrogen sources demonstrated that NAD synthesis was not dependent on NAD precursors in the medium. Inhibition by antisense RNA and the detection of transcript levels indicated that the main NAD supply pathway is the de novo biosynthesis pathway. It was further demonstrated that NAD(H) supply was unaffected by changes in metabolic flow through Δ aerobic fermentation (80 g/L ethanol). In conclusion, the ability of to supply NAD(H) in large fluxes provides a new approach to solving the NAD(H) supply problem in synthetic biology.
Topics: NAD; Candida; Aerobiosis; Fermentation; Metabolic Engineering; Saccharomyces cerevisiae; Ethanol; RNA, Antisense
PubMed: 38733342
DOI: 10.1021/acssynbio.4c00030