RESUMO
Fungal-bacterial consortia enhance organic pollutant removal, but the underlying mechanisms are unclear. We used stable isotope probing (SIP) to explore the mechanism of bioaugmentation involved in polycyclic aromatic hydrocarbon (PAH) biodegradation in petroleum-contaminated soil by introducing the indigenous fungal strain Aspergillus sp. LJD-29 and the bacterial strain Pseudomonas XH-1. While each strain alone increased phenanthrene (PHE) degradation, the simultaneous addition of both strains showed no significant enhancement compared to treatment with XH-1 alone. Nonetheless, the assimilation effect of microorganisms on PHE was significantly enhanced. SIP revealed a role of XH-1 in PHE degradation, while the absence of LJD-29 in 13C-DNA indicated a supporting role. The correlations between fungal abundance, degradation efficiency, and soil extracellular enzyme activity indicated that LJD-29, while not directly involved in PHE assimilation, played a crucial role in the breakdown of PHE through extracellular enzymes, facilitating the assimilation of metabolites by bacteria. This observation was substantiated by the results of metabolite analysis. Furthermore, the combination of fungus and bacterium significantly influenced the diversity of PHE degraders. Taken together, this study highlighted the synergistic effects of fungi and bacteria in PAH degradation, revealed a new fungal-bacterial bioaugmentation mechanism and diversity of PAH-degrading microorganisms, and provided insights for in situ bioremediation of PAH-contaminated soil.IMPORTANCEThis study was performed to explore the mechanism of bioaugmentation by a fungal-bacterial consortium for phenanthrene (PHE) degradation in petroleum-contaminated soil. Using the indigenous fungal strain Aspergillus sp. LJD-29 and bacterial strain Pseudomonas XH-1, we performed stable isotope probing (SIP) to trace active PHE-degrading microorganisms. While inoculation of either organism alone significantly enhanced PHE degradation, the simultaneous addition of both strains revealed complex interactions. The efficiency plateaued, highlighting the nuanced microbial interactions. SIP identified XH-1 as the primary contributor to in situ PHE degradation, in contrast to the limited role of LJD-29. Correlations between fungal abundance, degradation efficiency, and extracellular enzyme activity underscored the pivotal role of LJD-29 in enzymatically facilitating PHE breakdown and enriching bacterial assimilation. Metabolite analysis validated this synergy, unveiling distinct biodegradation mechanisms. Furthermore, this fungal-bacterial alliance significantly impacted PHE-degrading microorganism diversity. These findings advance our understanding of fungal-bacterial bioaugmentation and microorganism diversity in polycyclic aromatic hydrocarbon (PAH) degradation as well as providing insights for theoretical guidance in the in situ bioremediation of PAH-contaminated soil.
Assuntos
Aspergillus , Biodegradação Ambiental , Consórcios Microbianos , Fenantrenos , Microbiologia do Solo , Poluentes do Solo , Fenantrenos/metabolismo , Poluentes do Solo/metabolismo , Aspergillus/metabolismo , Pseudomonas/metabolismo , Pseudomonas/genética , Bactérias/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Fungos/metabolismo , Fungos/genética , Fungos/classificaçãoRESUMO
Every year, a huge amount of lethal compounds, such as synthetic dyes, pesticides, pharmaceuticals, hydrocarbons, etc. are mass produced worldwide, which negatively affect soil, air, and water quality. At present, pesticides are used very frequently to meet the requirements of modernized agriculture. The Food and Agriculture Organization of the United Nations (FAO) estimates that food production will increase by 80% by 2050 to keep up with the growing population, consequently pesticides will continue to play a role in agriculture. However, improper handling of these highly persistent chemicals leads to pollution of the environment and accumulation in food chain. These effects necessitate the development of technologies to eliminate or degrade these pollutants. Degradation of these compounds by physical and chemical processes is expensive and usually results in secondary compounds with higher toxicity. The biological strategies proposed for the degradation of these compounds are both cost-effective and eco-friendly. Microbes play an imperative role in the degradation of xenobiotic compounds that have toxic effects on the environment. This review on the fate of xenobiotic compounds in the environment presents cutting-edge insights and novel contributions in different fields. Microbial community dynamics in water bodies, genetic modification for enhanced pesticide degradation and the use of fungi for pharmaceutical removal, white-rot fungi's versatile ligninolytic enzymes and biodegradation potential are highlighted. Here we emphasize the factors influencing bioremediation, such as microbial interactions and carbon catabolism repression, along with a nuanced view of challenges and limitations. Overall, this review provides a comprehensive perspective on the bioremediation strategies.
RESUMO
Anthropogenic organohalide pollutants pose a severe threat to public health and ecosystems. In situ bioremediation using organohalide respiring bacteria (OHRB) offers an environmentally friendly and cost-efficient strategy for decontaminating organohalide-polluted sites. The genomic structures of many OHRB suggest that dehalogenation traits can be horizontally transferred among microbial populations, but their occurrence among anaerobic OHRB has not yet been demonstrated experimentally. This study isolates and characterizes a novel tetrachloroethene (PCE)-dechlorinating Sulfurospirillum sp. strain SP, distinguishing itself among anaerobic OHRB by showcasing a mechanism essential for horizontal dissemination of reductive dehalogenation capabilities within microbial populations. Its genetic characterization identifies a unique plasmid (pSULSP), harboring reductive dehalogenase and de novo corrinoid biosynthesis operons, functions critical to organohalide respiration, flanked by mobile elements. The active mobility of these elements was demonstrated through genetic analyses of spontaneously emerging nondehalogenating variants of strain SP. More importantly, bioaugmentation of nondehalogenating microcosms with pSULSP DNA triggered anaerobic PCE dechlorination in taxonomically diverse bacterial populations. Our results directly support the hypothesis that exposure to anthropogenic organohalide pollutants can drive the emergence of dehalogenating microbial populations via horizontal gene transfer and demonstrate a mechanism by which genetic bioaugmentation for remediation of organohalide pollutants could be achieved in anaerobic environments.
Assuntos
Chloroflexi , Poluentes Ambientais , Ecossistema , Bactérias/genética , Respiração , Família Multigênica , Biodegradação AmbientalRESUMO
AIMS: Microbial enhanced oil recovery (MEOR) is cost-effective and eco-friendly for oil exploitation. Genetically modified biosurfactants-producing high-yield strains are promising for ex-situ MEOR. However, can they survive and produce biosurfactants in petroleum reservoirs for in-situ MEOR? What is their effect on the native bacterial community? METHODS AND RESULTS: A genetically modified indigenous biosurfactants-producing strain Pseudomonas aeruginosa PrhlAB was bioaugmented in simulated reservoir environments. Pseudomonas aeruginosa PrhlAB could stably colonize in simulated reservoirs. Biosurfactants (200 mg l-1) were produced in simulated reservoirs after bio-augmenting strain PrhlAB. The surface tension of fluid was reduced to 32.1 mN m-1. Crude oil was emulsified with an emulsification index of 60.1%. Bio-augmenting strain PrhlAB stimulated the MEOR-related microbial activities. Hydrocarbon-degrading bacteria and biosurfactants-producing bacteria were activated, while the hydrogen sulfide-producing bacteria were inhibited. Bio-augmenting P. aeruginosa PrhlAB reduced the diversity of bacterial community, and gradually simplified the species composition. Bacteria with oil displacement potential became dominant genera, such as Shewanella, Pseudomonas, and Arcobacter. CONCLUSIONS: Culture-based and sequence-based analyses reveal that genetically modified biosurfactants-producing strain P. aeruginosa PrhlAB are promising for in-situ MEOR as well.
Assuntos
Petróleo , Pseudomonas aeruginosa , Tensoativos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Petróleo/metabolismo , Tensoativos/metabolismo , Biodegradação Ambiental , Bactérias/genética , Bactérias/metabolismo , Bactérias/classificação , Hidrocarbonetos/metabolismo , MicrobiotaRESUMO
The Persian Gulf is a transit point for a lot of crude oil at the international level. The purpose of this research is to compare two methods of biostimulation and bioaugmentation for degradation of sediments contaminated with crude oil in the Persian Gulf. In this research, six types of microcosms were designed (Sediments from Khark Island). Some indicators such as: the quantity of marine bacteria, enzyme activity (Catalase, Polyphenol oxidase, Dehydrogenase), biodiversity indices and the percentage of crude oil degradation were analyzed during different days (0, 20, 40, 60, 80, 100 and 120). The results of this research showed that the highest quantity of heterotrophic and crude oil-degrading bacteria was found in the sixth microcosm (SB). This microcosm represents a combination of two methods: bioaugmentation and biostimulation (3.9 × 106 CFU g-1). Following crude oil pollution, the activity of catalase and polyphenol oxidase increased and the dehydrogenase enzyme decreased. The bioaugmentation microcosm exhibited the highest activity of enzymes among all the microcosms studied. Predominant bacteria in each microcosm belonged to: Cellulosimicrobium, Shewanella, Alcanivorax and Cobetia. The highest degradation of crude oil is related to the Stimulation-Bioaugmentation microcosm (SB). The statistical results of this research proved that there is a significant relationship between the type of method chosen for biodegradation with the sampling time and the quantity of marine bacteria. The results of this research confirm that crude oil pollution in the Persian Gulf sediments can be reduced by choosing the proper bioremediation method.
Assuntos
Bactérias , Biodegradação Ambiental , Sedimentos Geológicos , Petróleo , Sedimentos Geológicos/microbiologia , Petróleo/metabolismo , Oceano Índico , Bactérias/metabolismo , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/análise , MicrobiotaRESUMO
Persistent, aged hydrocarbons in soil hinder remediation, posing a significant environmental threat. While bioremediation offers an environmentally friendly and cost-effective approach, its efficacy for complex contaminants relies on enhancing pollutant bioavailability. This study explores the potential of immobilized bacterial consortia combined with biochar and rhamnolipids to accelerate bioremediation of aged total petroleum hydrocarbon (TPH)-contaminated soil. Previous research indicates that biochar and biosurfactants can increase bioremediation rates, while mixed consortia offer sequential degradation and higher hydrocarbon mineralization. The present investigation aimed to assess whether combining these strategies could further enhance degradation in aged, complex soil matrices. The bioaugmentation (BA) with bacterial consortium increased the TPHs degradation in aged soil (over 20% compared to natural attenuation - NA). However, co-application of BA with biochar and rhamnolipid higher did not show a statistically prominent synergistic effect. While biochar application facilitated the maintenance of hydrocarbon degrading bacterial consortium in soil, the present study did not identify a direct influence in TPHs degradation. The biochar application in contaminated soil contributed to TPHs adsorption. Rhamnolipid alone slightly increased the TPHs biodegradation with NA, while the combined bioaugmentation treatment with rhamnolipid and biochar increased the degradation between 27.5 and 29.8%. These findings encourage further exploration of combining bioaugmentation with amendment, like biochar and rhamnolipid, for remediating diverse environmental matrices contaminated with complex and aged hydrocarbons.
Assuntos
Biodegradação Ambiental , Carvão Vegetal , Glicolipídeos , Hidrocarbonetos , Poluentes do Solo , Poluentes do Solo/metabolismo , Glicolipídeos/metabolismo , Carvão Vegetal/química , Hidrocarbonetos/metabolismo , Microbiologia do Solo , Petróleo/metabolismo , Solo/químicaRESUMO
Bioaugmentation technology for improving the performance of thermophilic anaerobic digestion (TAD) of food waste (FW) treatment is gaining more attention. In this study, four thermophilic strains (Ureibacillus suwonensis E11, Clostridium thermopalmarium HK1, Bacillus thermoamylovorans Y25 and Caldibacillus thermoamylovorans QK5) were inoculated in the TAD of FW system, and the biochemical methane potential (BMP) batch study was conducted to assess the potential of different bioaugmented strains to enhance methane production. The results showed that the cumulative methane production in groups inoculated with E11, HK1, Y25 and QK5 improved by 2.05%, 14.54%, 19.79% and 9.17%, respectively, compared with the control group with no inoculation. Moreover, microbial community composition analysis indicated that the relative abundance of the main hydrolytic bacteria and/or methanogenic archaea was increased after bioaugmentation, and the four strains successfully became representative bacterial biomarkers in each group. The four strains enhanced methane production by strengthening starch, sucrose, galactose, pyruvate and methane metabolism functions. Further, the correlation networks demonstrated that the representative bacterial genera had positive correlations with the differential metabolic functions in each bioaugmentation group. This study provides new insights into the TAD of FW with bioaugmented strains.
Assuntos
Bacillus , Perda e Desperdício de Alimentos , Eliminação de Resíduos , Anaerobiose , Alimentos , Bactérias/metabolismo , Metano , Reatores Biológicos , Esgotos/microbiologiaRESUMO
For better understanding the mechanism of microbial strains promoting methane production, four strains Hungatella xylanolytica A5, Bacillus licheniformis B1, Paraclostridium benzoelyticum C2 and Advenella faeciporci E1 were inoculated into anaerobic digestion systems. After bioaugmentation, the cumulative methane production of A5, B1, C2 and E1 groups elevated by 11.68%, 8.20%, 18.21% and 15.67% compared to CK group, respectively. The metagenomic analysis revealed that the species diversity and uniformity of the experimental groups was improved, and hydrolytic acidifying bacteria, represented by Clostridiaceae, Anaerolineaceae and Oscillospiraceae, and methanogens, such as Methanotrichaceae and Methanobacteriaceae, were enriched. Meanwhile, the abundance of key genes in carbohydrate, pyruvate and methane metabolism was increased in the inoculated groups, providing reasonable reasons for more methane production. The strengthening mechanism of microbial strains in this study offered a theoretical foundation for selecting a suitable bioaugmentation strategy to solve the problems of slow start-up and low methane production in anaerobic digestion.
Assuntos
Metagenoma , Metano , Metano/metabolismo , Anaerobiose , Bactérias/metabolismo , Bactérias/genética , Bactérias/classificação , Reatores Biológicos/microbiologia , Perda e Desperdício de AlimentosRESUMO
Aquaculture farming generates a significant amount of wastewater, which has prompted the development of creative bioprocesses to improve wastewater treatment and bioresource recovery. One promising method of achieving these aims is to directly recycle pollutants into microbe-rice bran complexes, which is an economical and efficient technique for wastewater treatment that uses synergetic interactions between algae and bacteria. This study explores novel bioaugmentation as a promising strategy for efficiently forming microbial-rice bran complexes in unsterilized aquaculture wastewater enriched with agricultural residues (molasses and rice bran). Results found that rice bran serves a dual role, acting as both an alternative nutrient source and a biomass support for microalgae and bacteria. Co-bioaugmentation, involving the addition of probiotic bacteria (Bacillus syntrophic consortia) and microalgae consortiums (Tetradesmus dimorphus and Chlorella sp.) to an existing microbial community, led to a remarkable 5-fold increase in microbial-rice bran complex yields compared to the non-bioaugmentation approach. This method provided the most compact biofloc structure (0.50 g/L) and a large particle diameter (404 µm). Co-bioaugmentation significantly boosts the synthesis of extracellular polymeric substances, comprising proteins at 6.5 g/L and polysaccharides at 0.28 g/L. Chlorophyta, comprising 80% of the total algal phylum, and Proteobacteria, comprising 51% of the total bacterial phylum, are emerging as dominant species. These microorganisms play a crucial role in waste and wastewater treatment, as well as in the formation of microbial-rice bran complexes that could serve as an alternative aquaculture feed. This approach prompted changes in both microbial community structure and nutrient cycling processes, as well as water quality. These findings provide valuable insights into the transformative effects of bioaugmentation on the development of microbial-rice bran complexes, offering potential applications in bioprocesses for waste and wastewater management.
RESUMO
Magnetic fields (MF) have been proven efficient in bioaugmentation, and the internal MFs have become competitive because they require no configuration, despite their application in waste gas treatment remaining largely unexplored. In this study, we firstly developed an intensity-regulable bioaugmentation with internal MF for gaseous chlorobenzene (CB) treatment with modified packing in batch bioreactors, and the elimination capacity increased by up to 26%, surpassing that of the external MF. Additionally, the microbial affinity to CB and the packing surface was enhanced, which was correlated with the ninefold increased secreted ratio of proteins/polysaccharides, 43% promoted cell surface hydrophobicity, and half reduced zeta potential. Furthermore, the dehydrogenase content was promoted over 3 times, and CB removal steadily increased with the rising intensity indicating enhanced biofilm activity and reduced CB bioimpedance; this was further supported by kinetic analysis, which resulted in improved cell adhesive ability and biological utilisation of CB. The results introduced a novel concept of adjustable magnetic bioaugmentation and provided technical support for industrial waste gas treatments. KEY POINTS: ⢠Regulable magnetic bioaugmentation was developed to promote 26% chlorobenzene removal ⢠Chlorobenzene mineralisation was enhanced under the magnetic field ⢠Microbial adhesion was promoted through weakening repulsive forces.
Assuntos
Biofilmes , Clorobenzenos , Adesão Celular , Cinética , Membrana Celular , GasesRESUMO
To evaluate the effects of bioaugmentation fermentation inoculated with one ester-producing strain (Wickerhamomyces anomalus ZX-1) and two strains of lactic acid bacteria (Lactobacillus plantarum CGMCC 24035 and Lactobacillus acidophilus R2) for improving the flavor of persimmon vinegar, microbial community, flavor compounds and metabolites were analyzed. The results of microbial diversity analysis showed that bioaugmentation fermentation significantly increased the abundance of Lactobacillus, Saccharomyces, Pichia and Wickerhamomyces, while the abundance of Acetobacter, Apiotrichum, Delftia, Komagataeibacter, Kregervanrija and Aspergillus significantly decreased. After bioaugmentation fermentation, the taste was softer, and the sensory irritancy of acetic acid was significantly reduced. The analysis of HS-SPME-GC-MS and untargeted metabolomics based on LC-MS/MS showed that the contents of citric acid, lactic acid, malic acid, ethyl lactate, methyl acetate, isocitrate, acetoin and 2,3-butanediol were significantly increased. By multivariate analysis, 33 differential metabolites were screened out to construct the correlation between the differential metabolites and microorganisms. Pearson correlation analysis showed that methyl acetate, ethyl lactate, betaine, aconitic acid, acetoin, 2,3-butanediol and isocitrate positively associated with Wickerhamomyces and Lactobacillus. The results confirmed that the quality of persimmon vinegar was improved by bioaugmentation fermentation.
Assuntos
Ácido Acético , Diospyros , Fermentação , Microbiota , Ácido Acético/metabolismo , Diospyros/microbiologia , Diospyros/metabolismo , Saccharomycetales/metabolismo , Paladar , Aromatizantes/metabolismo , Lactobacillus plantarum/metabolismo , Microbiologia de Alimentos , Lactobacillus acidophilus/metabolismo , Lactobacillus acidophilus/crescimento & desenvolvimento , Bactérias/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/genéticaRESUMO
Single-use facial masks which are predominantly made out of polypropylene is being used and littered in large quantities during post COVID-19 situation. Extensive researches on bioremediation of plastic pollution on soil led to the identification of numerous plastic degrading microorganisms. These organisms assimilate plastic polymers as their carbon source for synthesizing energy. Pseudomonas fluorescens (PF) is one among such microorganism which is being identified to biodegrade plastic polymers in controlled environment. The natural biodegradation of facial mask in soil-like fraction collected from municipal waste management site, bioaugmentation of the degradation process with Pseudomonas fluorescens, biostimulation of the soil with carbonless nutritional supplements and combined bioaugmentation with biostimulation process were studied in the present work. The study has been conducted both in controlled and in natural condition for a period of 12 months. The efficiency of the degradation was verified through FTIR analyses using carbonyl index, bond energy change, Loss in ignition (LOI) measurement along with CHNS analyses of residual substances. The analysis of results reported that carbonyl index (in terms of transmittance) was reduced to 46% of the control batch through the inclusion of PF in natural condition. The bioaugmented batch maintained in natural condition showed 33% reduction of LOI with respect to the control batch. The unburnt carbon content of the residual matter obtained from the furnace were analysed using CHNS analyser and indicated the lowest carbon content in the same bioaugmented batch. In this study, an attempt is made to verify the feasibility of enhancing biodegradation of single-use facial mask by bioaugmentation of soil-like fraction available in solid waste management park with Pseudomonas fluorescens under natural condition. CHNS and FTIR analysis assures the biodegradation of plastic waste in the soil-like fraction using Pseudomonas fluorescens under both controlled and natural environmental condition.
Assuntos
Biodegradação Ambiental , Plásticos , Pseudomonas fluorescens , Resíduos Sólidos , Pseudomonas fluorescens/metabolismo , Plásticos/metabolismo , Solo/química , Microbiologia do Solo , Gerenciamento de Resíduos/métodos , Poluentes do Solo/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos/métodosRESUMO
Understanding the developmental characteristics of microbial communities in biofilms is crucial for designing targeted functional microbial enhancements for the remediation of complex contamination scenarios. The strong prioritization effect of microorganisms confers the ability to colonize strains that arrive first dominantly. In this study, the auto-aggregating denitrifying bacterial Pseudomonas stutzeri strain YC-34, which has both nitrogen and chromium removal characteristics, was used as a biological material to form a stable biofilm system based on the principle of dominant colonization and biofortification. The effect of the biofilm system on nitrogen and chromium removal was characterized by measuring the changes in the quality of influent and effluent water. The pattern of biofilm changes was analyzed by measuring biofilm content and thickness and characterizing extracellular polymer substances (EPS). Further analysis of the biofilm microbiota characteristics and potential functions revealed the mechanism of strain YC-34 biofortified biofilm. The results revealed that the biofilm system formed could achieve 90.56% nitrate-nitrogen removal with an average initial nitrate-nitrogen concentration of 51.9â¯mg/L and 40% chromium removal with an average initial hexavalent chromium Cr(VI) concentration of 7.12â¯mg/L. The biofilm properties of the system were comparatively analyzed during the biofilm formation period, the fluctuation period of Cr(VI)-stressed water quality, and the stabilization period of Cr(VI)-stressed water quality. The biofilm system may be able to increase the structure of hydrogen bonds, the type of protein secondary structure, and the abundance of amino acid-like components in the EPS, which may confer biofilm tolerance to Cr(VI) stress and allow the system to maintain a stable biofilm structure. Furthermore, microbial characterization indicated an increase in microbial diversity in the face of chromium stress, with an increase in the abundance of nitrogen removal-associated functional microbiota and an increasing trend in the abundance of nitrogen transfer pathways. These results demonstrate that the biofilm system is stable in nitrogen and chromium removal. This bioaugmentation method may provide a new way for the remediation of heavy metal-polluted water bodies and also provides theoretical and application parameters for the popularization and application of biofilm systems.
Assuntos
Desnitrificação , Nitratos , Nitratos/metabolismo , Nitrogênio/metabolismo , Cromo/metabolismo , Biofilmes , Bactérias/metabolismoRESUMO
Thauera is the most widely found dominant denitrifying genus in wastewater. In earlier study, MBBR augmented with a specially developed denitrifying five-membered bacterial consortium (DC5) where Thauera was found to be the most abundant and persistent genus. Therefore, to check the functional potential of Thauera in the removal of nitrate-containing wastewater in the present study Thauera sp.V14 one of the member of the consortium DC5 was used as the model organism. Thauera sp.V14 exhibited strong hydrophobicity, auto-aggregation ability, biofilm formation and denitrification ability, which indicated its robust adaptability short colonization and nitrate removal efficiency. Continuous reactor studies with Thauera sp.V14 in 10 L dMBBR showed 91% of denitrification efficiency with an initial nitrate concentration of 620 mg L-1 within 3 h of HRT. Thus, it revealed that Thauera can be employed as an effective microorganism for nitrate removal from wastewater based on its performance in the present studies.
Assuntos
Nitratos , Águas Residuárias , Thauera , Biofilmes , Desnitrificação , Reatores Biológicos/microbiologia , NitrogênioRESUMO
Bioaugmentation of soils can increase the mobilization of metal(loid)s from the soil-bearing phases. However, once desorbed, these metal(loid)s are mostly complexed to the dissolved organic matter (DOM) in the soil solution, which can restrict their availability to plants (roots mainly taking up the free forms) and then the phytoextraction performances. Firstly the main drivers influencing phytoextraction are reminded, then the review focuses on the DOM role. After having reminding the origin, the chemical structure and the lability of DOM, the pool of stable DOM (the most abundant in the soil) most involved in the complexation of metal(loid)s is addressed in particular by focusing on carboxylic and/or phenolic groups and factors controlling metal(loid) complexation with DOM. Finally, this review addresses the ability of microorganisms to degrade metal(loid)-DOM complexes as an additional lever for increasing the pool of free metal(loid) ions, and then phytoextraction performances, and details the origin of microorganisms and how they are selected. The development of innovative processes including the use of these DOM-degrading microorganisms is proposed in perspectives.
This review focuses on the available drivers to increase the pool of free (i.e. phytoavailable) metal(loid)s in the soil solution, with a specific focus on the ability of microorganisms to degrade dissolved organic matter for enriching this pool, and then to substantially improve phytoextraction performance.
Assuntos
Poluentes do Solo , Solo , Solo/química , Matéria Orgânica Dissolvida , Biodegradação Ambiental , Metais , Poluentes do Solo/metabolismoRESUMO
BACKGROUND: Bacillus velezensis DQA21 is a functional strain used in the fermentation process of strong-aroma baijiu; however, its specific role in the process is still unclear. RESULTS: In this study, specific roles of B. velezensis DQA21 in the fermentation process were explored. Bioaugmentation of B. velezensis DQA21 increased the diversity and abundance of the bacterial community during the first 32 days of fermentation and significantly inhibited the diversity and richness of the fungal community during days 12 to 32. According to cluster analysis, changes in the microbial community structure were observed during fermentation, and the fermentation process could be divided into two stages: stage I, days 0-12; and stage II, days 12-45. Additionally, the microbial community structures during the two fermentation stages were significantly different. Co-occurrence analysis showed that bioaugmentation with Bacillus increased the correlation between microorganisms in jiupei and had a significant impact on the overall network structure of the microbial community. In addition, Bacillus significantly increased the production of flavor substances in jiupei, causing the total esters, total alcohols, and total acids contents to increase by 19.1%, 81.1%, and 25.9% respectively. CONCLUSION: The results suggested that bioaugmentation with B. velezensis DQA21 had a strong impact on the microbial community structure in strong-aroma baijiu, enhancing the volatile flavor components. Additionally, the work also provides a better understanding on the effect of augmentation on the microbial community in jiupei, which could help better regulation of solid-state fermentation in strong-aroma baijiu. © 2024 Society of Chemical Industry.
Assuntos
Bacillus , Fermentação , Aromatizantes , Microbiota , Paladar , Bacillus/metabolismo , Aromatizantes/metabolismo , Aromatizantes/química , Bactérias/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/genética , Fungos/metabolismo , Odorantes/análiseRESUMO
To assess the possibility of using aerobic denitrification (AD) bacteria with high NO2--N accumulation for nitrogen removal in wastewater treatment, conditional optimization, as well as sole and mixed nitrogen source tests involving AD bacterium, Comamonas sp. pw-6 was performed. The results showed that the optimal carbon source, pH, C/N ratio, rotational speed, and salinity for this strain were determined to be succinate, 7, 20, 160 rpm, and 0%, respectively. Further, this strain preferentially utilized NH4+-N, NO3--N, and NO2--N, and when NO3--N was its sole nitrogen source, 92.28% of the NO3--N (150 mg·L-1) was converted to NO2--N. However, when NH4+-N and NO3--N constituted the mixed nitrogen source, NO3--N utilization by this strain was significantly lower (p < 0.05). Therefore, a strategy was proposed to combine pw-6 bacteria with traditional autotrophic nitrification to achieve the application of pw-6 bacteria in NH4+-N-containing wastewater treatment. Bioaugmented application experiments showed significantly higher NH4+-N removal (5.96 ± 0.94 mg·L-1·h-1) and lower NO3--N accumulation (2.52 ± 0.18 mg·L-1·h-1) rates (p < 0.05) than those observed for the control test. Thus, AD bacteria with high NO2--N accumulation can also be used for practical applications, providing a basis for expanding the selection range of AD strains for wastewater treatment.
Assuntos
Comamonas , Desnitrificação , Nitrogênio , Eliminação de Resíduos Líquidos , Águas Residuárias , Nitrogênio/metabolismo , Comamonas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Aerobiose , Purificação da Água/métodos , Poluentes Químicos da Água/metabolismoRESUMO
Soil contamination by petroleum, including crude oil from various sources, is increasingly becoming a pressing global environmental concern, necessitating the exploration of innovative and sustainable remediation strategies. The present field-scale study developed a simple, cost-effective microbial remediation process for treating petroleum-contaminated soil. The soil treatment involves adding microbial activators to stimulate indigenous petroleum-degrading microorganisms, thereby enhancing the total petroleum hydrocarbons (TPH) degradation rate. The formulated microbial activator provided a growth-enhancing complex of nitrogen and phosphorus, trace elements, growth factors, biosurfactants, and soil pH regulators. The field trials, involving two 500 m3 soil samples with the initial TPH content of 5.01% and 2.15%, were reduced to 0.41% and 0.02% in 50 days, respectively, reaching the national standard for cultivated land category II. The treatment period was notably shorter than the commonly used composting and bioaugmentation methods (typically from 8 to 12 weeks). The results indicated that the activator could stimulate the functional microorganisms in the soil and reduce the phytotoxicity of the contaminated soil. After 40 days of treatment, the germination rate of rye seeds increased from 20 to 90%, indicating that the microbial activator could be effectively used for rapid on-site remediation of oil-contaminated soils.
Assuntos
Biodegradação Ambiental , Petróleo , Microbiologia do Solo , Poluentes do Solo , Poluentes do Solo/metabolismo , Projetos Piloto , Hidrocarbonetos/metabolismo , Poluição por Petróleo , Solo/química , Recuperação e Remediação Ambiental/métodos , Germinação/efeitos dos fármacos , Bactérias/metabolismo , Nitrogênio/metabolismoRESUMO
The feasibility of a simultaneous nitrification, denitrification and fermentation process (SNDF) under electric stirrer agitation conditions was verified in a single reactor. Enhanced activated sludge for phenol degradation and denitrification in pharmaceutical phenol-containing wastewater under low dissolved oxygen conditions, additional inoculation with Comamonas sp. BGH and optimisation of co-metabolites were investigated. At a hydraulic residence time (HRT) of 28 h, 15 mg/L of substrate as strain BGH co-metabolised substrate degraded 650 ± 50 mg/L phenol almost completely and was accompanied by an incremental increase in the quantity of strain BGH. Strain BGH showed enhanced phenol degradation. Under trisodium citrate co-metabolism, strain BGH combined with activated sludge treated phenol wastewater and degraded NO2--N from 50 ± 5 to 0 mg/L in only 7 h. The removal efficiency of this group for phenol, chemical oxygen demand (COD) and TN was 99.67%, 90.25% and 98.71%, respectively, at an HRT of 32 h. The bioaugmentation effect not only promotes the degradation of pollutants, but also increases the abundance of dominant bacteria in activated sludge. Illumina MiSeq sequencing research showed that strain BGH promoted the growth of dominant genera (Acidaminobacter, Raineyella, Pseudarcobacter) and increased their relative abundance in the activated sludge system. These genera are resistant to toxicity and organic matter degradation. This paper provides some reference for the activated sludge to degrade high phenol pharmaceutical wastewater under the action of biological enhancement.
Assuntos
Reatores Biológicos , Desnitrificação , Fermentação , Nitrificação , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água , Reatores Biológicos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/análise , Águas Residuárias/química , Fenol/metabolismo , Esgotos/microbiologia , Biodegradação AmbientalRESUMO
Bioaugmentation is an efficient method for improving the efficiency of coking wastewater removal. Nevertheless, how different immobilization approaches affect the efficiency of bioaugmentation remains unclear, as does the corresponding mechanism. With the assistance of immobilized bioaugmentation strain Rhodococcus biphenylivorans B403, the removal of synthetic coking wastewater was investigated (drying agent, alginate agent, and absorption agent). The reactor containing the absorption agent exhibited the highest average removal efficiency of phenol (99.74 %), chemical oxygen demand (93.09 %), and NH4+-N (98.18 %). Compared to other agents, the covered extracellular polymeric substance on the absorption agent surface enhanced electron transfer and quorum sensing, and the promoted quorum sensing benefited the activated sludge stability and microbial regulation. The phytotoxicity test revealed that the wastewater's toxicity was greatly decreased in the reactor with the absorption agent, especially under high phenol concentrations. These findings showed that the absorption agent was the most suitable for wastewater treatment bioaugmentation.