Degradation Of Microorganisms Research Articles

Efficiency of Microorganisms and Effectiveness of Biodegradation Techniques on LDPE Plastics: A Systematic Review.

The aim of the research was to demonstrate the efficiency of microorganisms and the effectiveness of biodegradation techniques on Low-density polyethylene (LDPE) plastics. The research question was: What is the efficiency of LDPE-degrading microorganisms and the effectiveness of biodegradation techniques? The systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles were obtained from Scopus, Web of Science (WOS), Embase, and Google Scholar. The DeCS/Mesh search terms were: Low-density polyethylene, efficiency, biodegradation, microbial consortia, fungi, bacteria. Inclusion criteria were: scientific articles that included bacteria, fungi, and microbial consortia reported as LDPE degraders that report the percentage of weight loss; articles published from January 2010 to October 2022, and publications in Spanish and English with open access. Exclusion criteria were: studies that do not report gravimetry, the biodegradation time of LDPE, and the genus or species of the polyethylene-degrading microorganism. Out of 483 studies found, 50 were included in this Systematic Review (SR). The most frequent study techniques were scanning electron microscopy (SEM), gravimetry, and fourier transform infrared spectroscopy (FTIR), and in the case of microorganisms, the most studied belonged to the genus Pseudomonas, Bacillus, and Aspergillus. Regarding the isolation place, the most frequent mentioned in the reviewed articles were landfill soil and sanitary landfill soil. The efficiency of LDPE-degrading microorganisms was higher in bacteria such as Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp., which obtained a range of DE of 9.00-70.00%, 24.00-64%, 1.15 - 61.00%, 45.00%, and 1.5-40% with DT of 4-150, 120, 4-150, 30, and 30-120 days, respectively; in the case of fungi, the main microorganisms are Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii with efficiencies of 54.34, 48.78, and 46.34%, in 90 days, respectively; and the most efficient microbial consortia were from Enterobacter spp. and Pantoea sp. with 38.00 - 81.00%, in 120 days; and, Pseudomonas protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp. with 55. 00 - 75.00% in 120 days. The most efficient microorganisms in LDPE degradation are Enterobacter spp., Pantoea spp., Pseudomonas spp., Escherichia coli, and Bacillus spp.; in fungi Neopestalotiopsis phangngaensis, Colletotrichum fructicola, and Thyrostroma jaczewskii; and in microbial consortia, those formed by Enterobacter spp. and Pantoea sp., and that of P. protegens, Stenotrophomonas sp., B. vallismortis and Paenibacillus sp.; and the most effective techniques used in LDPE biodegradation are SEM, gravimetry, and FTIR.

Opaline silica precipitations in the Permian Fengcheng Formation indicate hot spring environments in north Mahu Sag, NW China

The Permian Fengcheng Formation represents a series of deposits formed in an alkaline saline lake, characterized by high proportions of cherts, located in the Northwestern Junggar Basin in China. While discussions on silica-rich hot springs as sources of silica for brine and subsequent chert deposition have been extensively conducted for Quaternary and Mesozoic-Cenozoic alkaline saline lakes worldwide, investigations into Paleozoic alkaline saline lakes are scarce due to challenges associated with identifying evidences of hot spring environments. In this study, we present detailed SEM-EDS analyses and examine silica isotope compositions as well as oxygen isotope compositions to discuss hydrothermal-associated silica precipitation processes. Our findings suggest that migrating silica-rich hot springs along deep-rooted faults released silica into the brine, leading to chert deposition during cooling periods and induction of thermophilic microorganism degradation. Microorganism-associated siliceous precipitates primarily consist of opal-A spheres adhered by extracellular polymeric substances (EPS), while numerous microorganism spheres have undergone silicification. Opal-A spheres within these structures were partially transformed into well-crystallized quartz through multiple stages of dissolution-precipitation processes during prolonged burial history. Furthermore, our results indicate that deep-rooted fault-related hot springs can occur both in marginal and subaqueous areas within alkaline saline lakes, with chert formations observed in shallow-marginal saline lake settings as well as deeper regions. The findings of this study provide valuable insights into the paleoenvironmental conditions, which can be further explored in investigating the accumulation of organic matter in chert-rich successions formed within an alkaline saline lake.

Understanding visible light and microbe-driven degradation mechanisms of polyurethane plastics: Pathways, property changes, and product analysis

The accumulation of polyurethane plastics (PU-PS) in the environment is on the rise, posing potential risks to the health and function of ecosystems. However, little is known about the degradation behavior of PU-PS in the environment, especially water environment. To address this knowledge gap, we investigated and isolated a degrading strain of Streptomyces sp. B2 from the surface of polyurethane coatings. Subsequently, a photoreactor was employed to simulate the degradation process of bio-based polyurethane (BPU) and petroleum-based polyurethane (PPU) under three conditions, including single microorganism (SM), single light exposure (SL), and combined light exposure/microorganism action (ML) in aqueous solution. The results indicated that PU-PS mainly relies on biodegradation, with the highest degradation rate observed after 28 d under SM condition (BPU 5.69 %; PPU 5.25 %). SL inhibited microbial growth and degradation, with the least impact on plastic degradation. Microorganisms colonized the plastic surface, secreting relevant hydrolytic enzymes and organic acids into the culture medium, providing a negative charge. The carbon chains were broken and aged through hydrogen peroxide induction or attack by oxygen free radicals. This process promoted the formation of oxidized functional groups such as OH and CO, disrupting the polymer's structure. Consequently, localized fragmentation and erosion of the microstructure occurred, resulting in the generation of secondary microplastic (MPs) particles, weight loss of the original plastic, increased surface roughness, and enhanced hydrophilicity. Additionally, BPU exhibited greater degradability than PPU, as microorganisms could utilize the produced fatty acids, which promoted their reproduction. In contrast, PPU degradation generated a large amount of isocyanate, potentially toxic to cells and inhibiting biodegradation. This study unveils the significant role of microorganisms in plastic degradation and the underlying degradation mechanisms of BPU, providing a novel strategy for polyurethane degradation and valuable information for comprehensive assessment of the behavior and fate of MPs in the environment.

Impaired reprogramming of the autophagy flux in maturing dendritic cells from crohn disease patients with core autophagy gene-related polymorphisms

ABSTRACT Crohn disease (CD) is an inflammatory bowel disease whose pathogenesis involves inappropriate immune responses toward gut microbiota on genetically predisposed backgrounds. Notably, CD is associated with single-nucleotide polymorphisms affecting several genes involved in macroautophagy/autophagy, the catabolic process that ensures the degradation and recycling of cytosolic components and microorganisms. In a clinical translation perspective, monitoring the autophagic activity of CD patients will require some knowledge on the intrinsic functional status of autophagy. Here, we focused on monocyte-derived dendritic cells (DCs) to characterize the intrinsic quantitative features of the autophagy flux. Starting with DCs from healthy donors, we documented a reprogramming of the steady state flux during the transition from the immature to mature status: both the autophagosome pool size and the flux were diminished at the mature stage while the autophagosome turnover remained stable. At the cohort level, DCs from CD patients were comparable to control in term of autophagy flux reprogramming capacity. However, the homozygous presence of ATG16L1 rs2241880 A>G (T300A) and ULK1 rs12303764 (G/T) polymorphisms abolished the capacity of CD patient DCs to reprogram their autophagy flux during maturation. This effect was not seen in the case of CD patients heterozygous for these polymorphisms, revealing a gene dose dependency effect. In contrast, the NOD2 rs2066844 c.2104C>T (R702W) polymorphism did not alter the flux reprogramming capacity of DCs. The data, opening new clinical translation perspectives, indicate that polymorphisms affecting autophagy-related genes can differentially influence the capacity of DCs to reprogram their steady state autophagy flux when exposed to proinflammatory challenges. Abbreviation: BAFA1: bafilomycin A1, CD: Crohn disease; DC: dendritic cells; HD: healthy donor; iDCs: immature DCs; IL: interleukin; J: autophagosome flux; LPS: lipopolysaccharide; MHC: major histocompatibility complex; nA: autophagosome pool size; SNPs: single-nucleotide polymorphisms; PCA: principal component analysis; TLR: toll like receptor; τ: transition time; TNF: tumor necrosis factor.

Application of electric potential and Fe(Ⅲ) to stimulate perfluorooctanoic acid (PFOA) degradation using mixed culture anammox granules

Pollution by perfluorooctanoic acid (PFOA), a highly persistent and toxic substance, is commonly addressed with several approaches, but the need for post-treatment affects their environmental and economic sustainability. Biodegradation, which can efficiently degrade micropollutants in water under optimal conditions, offers a promising solution, but faces challenges from the persistence of the C-F bond and the high reactivity of F-. Despite recent use of various microorganisms for PFOA degradation, performance issues persist. In this study, we aimed to simulate PFOA degradation while mixed culture anammox granules oxidize NH4+ and to confirm the effects of electric potential and Fe(Ⅲ) applications on PFOA degradation. A control reactor containing only anammox granules exhibited NH4+ and PFOA removal efficiencies of 11.52% and 19.2%, respectively, with traceable biodegradation at 3.7%. In contrast, a reactor that applied both electric potential and Fe(Ⅲ) demonstrated enhanced removal efficiencies of 41.98% and 50.93%, with traceable biodegradation at 35.03%. Bio-electrochemical properties also improved, showing an average current generation of 331.95 μA and Coulombic efficiency of 141.79 ± 7.6%. This study shows that mixed-culture anammox granules with electric potential and Fe(Ⅲ) can be introduced for efficient PFOA biodegradation and provides the basis for further studies on overcoming the limitations of PFOA biodegradation.

Highly effective removal of 4-chloroaniline in water by nano zero-valent iron cooperated with microbial degradation

The misuse of aromatic amines like 4-chloroaniline (4-CA) has led to severe environmental and health issues. However, it’s difficult to be utilized by microorganisms for degradation. Nano-zero-valent iron (nZVI) is a promising material for the remediation of chloroaniline pollution, however, the synergistic effect and mechanism of nZVI with microorganisms for the degradation of 4-CA are still unclear. This study investigated the potential of 4-CA removal by the synergistic system involving nZVI and 4-CA degrading microbial flora. The results indicate that the addition of nZVI significantly enhanced the bio-degradation rate of 4-CA from 43.13 % to 62.26 %. Under conditions involving 0.1 % nZVI addition at a 24-hour interval, pH maintained at 7, and glucose as an external carbon source, the microbial biomass, antioxidant enzymes, and dehydrogenase were significantly increased, and the optimal 4-CA degradation rate achieved 68.79 %. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis of intermediates indicated that the addition of nZVI reduced compounds containing benzene rings and enhanced the dechlorination efficiency. The microbial community remained stable during the 4-CA degradation process. This study illustrates the potential of nZVI in co-microbial remediation of 4-CA compounds in the environment.

The comparative plastisphere microbial community profile at Kung Wiman beach unveils potential plastic-specific degrading microorganisms.

Plastic waste is a global environmental issue that impacts the well-being of humans, animals, plants, and microorganisms. Microplastic contamination has been previously reported at Kung Wiman Beach, located in Chanthaburi province along with the Eastern Gulf of Thailand. Our research aimed to study the microbial population of the sand and plastisphere and isolate microorganisms with potential plastic degradation activity. Plastic and sand samples were collected from Kung Wiman Beach for microbial isolation on agar plates. The plastic samples were identified by Fourier-transform infrared spectroscopy. Plastic degradation properties were evaluated by observing the halo zone on mineral salts medium (MSM) supplemented with emulsified plastics, including polystyrene (PS), polylactic acid (PLA), polyvinyl chloride (PVC), and bis (2-hydroxyethyl) terephthalate (BHET). Bacteria and fungi were identified by analyzing nucleotide sequence analysis of the 16S rRNA and internal transcribed spacer (ITS) regions, respectively. 16S and ITS microbiomes analysis was conducted on the total DNA extracted from each sample to assess the microbial communities. Of 16 plastic samples, five were identified as polypropylene (PP), four as polystyrene (PS), four as polyethylene terephthalate (PET), two as high-density polyethylene (HDPE), and one sample remained unidentified. Only 27 bacterial and 38 fungal isolates were found to have the ability to degrade PLA or BHET on MSM agar. However, none showed degradation capabilities for PS or PVC on MSM agar. Notably, Planococcus sp. PP5 showed the highest hydrolysis capacity of 1.64 ± 0.12. The 16S rRNA analysis revealed 13 bacterial genera, with seven showing plastic degradation abilities: Salipiger, Planococcus, Psychrobacter, Shewanella, Jonesia, Bacillus, and Kocuria. This study reports, for the first time of the BHET-degrading properties of the genera Planococcus and Jonesia. Additionally, The ITS analysis identified nine fungal genera, five of which demonstrated plastic degradation abilities: Aspergillus, Penicillium, Peacilomyces, Absidia, and Cochliobolus. Microbial community composition analysis and linear discriminant analysis effect size revealed certain dominant microbial groups in the plastic and sand samples that were absent under culture-dependent conditions. Furthermore, 16S and ITS amplicon microbiome analysis revealed microbial groups were significantly different in the plastic and sand samples collected. We reported on the microbial communities found on the plastisphere at Kung Wiman Beach and isolated and identified microbes with the capacity to degrade PLA and BHET.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%–95.70% and 13.32%–97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3− indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Three-Dimensional Model for Bioventing: Mathematical Solution, Calibration and Validation

Bioventing is an established technique extensively employed in the remediation of soil contaminated with petroleum hydrocarbons. In this study, the objective was to develop an improved foundational bioventing model that characterizes gas flow in vadose zones where aqueous and non-aqueous phase liquid (NAPL) are present and immobile, accounting for interphase mass transfer and first order biodegradation kinetics. By incorporating a correlation for the biodegradation rate constant, which is a function of soil properties including initial population of petroleum degrader microorganisms in soil, sand content, clay content, water content, and soil organic matter content, this model offers the ability to integrate a specific biodegradation rate constant tailored to the soil properties for each site. The governing equations were solved using the finite volume method in OpenFOAM employing the “porousMultiphaseFoam v2107” (PMF) toolbox. The equation describing gas flow in unsaturated soil was solved using a mixed pressure-saturation method, where calculated values were employed to solve the component transport equations. Calibration was done against a set of experimental data for a meso-scale reactor considering contaminant volatilization rate as the pre-calibration parameter and the mass transfer coefficient between aqueous and NAPL phase as the main calibration parameter. The calibrated model then was validated by simulating a large-scale reactor. The modelling results showed an error of 2.9% for calibrated case and 4.7% error for validation case which present the fitness to the experimental data, proving that the enhanced bioventing model holds the potential to improve predictions of bioventing and facilitate the development of efficient strategies to remediate soil contaminated with petroleum hydrocarbons.

The Phylogeny and Metabolic Potentials of a Lignocellulosic Material-Degrading Aliiglaciecola Bacterium Isolated from Intertidal Seawater in East China Sea.

Lignocellulosic materials are composed of cellulose, hemicellulose and lignin and are one of the most abundant biopolymers in marine environments. The extent of the involvement of marine microorganisms in lignin degradation and their contribution to the oceanic carbon cycle remains elusive. In this study, a novel lignin-degrading bacterial strain, LCG003, was isolated from intertidal seawater in Lu Chao Harbor, East China Sea. Phylogenetically, strain LCG003 was affiliated with the genus Aliiglaciecola within the family Alteromonadaceae. Metabolically, strain LCG003 contains various extracellular (signal-fused) glycoside hydrolase genes and carbohydrate transporter genes and can grow with various carbohydrates as the sole carbon source, including glucose, fructose, sucrose, rhamnose, maltose, stachyose and cellulose. Moreover, strain LCG003 contains many genes of amino acid and oligopeptide transporters and extracellular peptidases and can grow with peptone as the sole carbon and nitrogen source, indicating a proteolytic lifestyle. Notably, strain LCG003 contains a gene of dyp-type peroxidase and strain-specific genes involved in the degradation of 4-hydroxy-benzoate and vanillate. We further confirmed that it can decolorize aniline blue and grow with lignin as the sole carbon source. Our results indicate that the Aliiglaciecola species can depolymerize and mineralize lignocellulosic materials and potentially play an important role in the marine carbon cycle.

Earthworm-assisted bioremediation in a clayey soil contaminated by biodiesel

The Success in bioremediation techniques depends on factors such as site characteristics, environmental factors, contaminant nature (temperature, pH, nutrients), presence of suitable biodegradable genes, the contamination nature, etc. Earthworms can aid in these on these factors, through their biological, chemical and physical characteristics, they aerate the soil, improve the nutritional status and help to release the contaminants binding in the soil particles, besides, they help the degrading microorganisms’ dispersion. Biodiesel is a contaminant widely used in the fuel industry, and its production is encouraged. Thus, the aim of this study is analyzed the efficiency of an earthworm species (Eudrilus eugeniae) to remediated a residual clayey soil contaminated with biodiesel, with and without assistance for biostimulated native microorganisms. Therefore, a clay soil was contaminated with biodiesel (24 g / kg) and the ability of the earthworms of the species (Eudrilus eugeniae) to degrade biodiesel with or without biostimulation (cattle manure) for a period of 90 days was analyzed. Earthworms and cow dung have proved to be efficient for remediation processes, providing 100% degradation at the end of 90 days for "biostimulation and earthworm" and "biostimulation, microorganisms and earthworm" samples. Thus, the use of earthworms contributes to a faster remediation process and, together with microorganisms, they are a more sustainable solution for application in areas contaminated with fuels.

Exploration and application of microbial method to enhance the effect of hydraulic fracturing on coal seam permeability enhancement and gas extraction

The efficient extraction of gas from low-permeability coal seams is an urgent problem in coal mine safety production. The traditional gas extraction technology generally suffers from problems that limited penetration enhancement or extraction effect, low construction efficiency, large workload, etc. Thus, it is especially urgent and important to explore the new technology applicable to efficient underground gas extraction. In this paper, based on the principle of hydraulic fracturing to increase permeability, we innovatively propose a technique to enhance the effect of hydraulic fracturing to increase permeability and further improve the efficiency of gas extraction using the gas desorption activity of native microorganisms in coal seams. Herein, the composition of the primary microbial community of a coal seam in Xinji No.2 mine was analyzed by bacterial and archaeal 16SrDNA amplicon sequencing, the community structure of the main functional microorganisms was clarified, the optimal combination of functional microorganisms for organic matter degradation in coal seam under anaerobic culture conditions was obtained. Besides the Biolog microplate technology was used to screen the nutrients of the excitation carbon source to stimulate the rapid decomposition of coal organic matter by microorganisms and to define the optimal ratio of the excitation carbon source to microorganisms. Finally, the effect of this technology on the application of coal seam fracturing and gas extraction was tested through field industrial tests, revealing that the extraction effect of this technology was more significant than that of the common coal seam perforation extraction technology. The results of this paper provide a new technical idea for gas extraction from low permeability coal seams, which is an important reference value for subsequent similar studies.

Characterization of DNA Degrading Microorganisms from Dewar Creek Hot Springs in Western Canada

Historically, discovery and subsequent characterization of microbial species relied on pure cultures. Some challenges associated with creating pure cultures have been overcome with advances in culture independent and DNA-based molecular methods such as single-cell genomics, metagenomics, or large scale amplicon sequencing. With these advances, the rate of discovery of new species from genomic data has quickly outpaced the number of organisms with cultured representatives. As description and characterization still rely on cultures, our understanding of yet uncultured species is greatly lacking. Major lineages in the bacterial domain equivalent to phyla that lack any cultured representatives are termed “candidate phyla.” Candidate phyla are found across the bacterial tree of life, and many uncultured organisms are found to be dominant in understudied environments. Extreme environments such as thermal springs are an example of understudied environments, making them excellent environments for studying novel microbial lineages. The objective of this research is to characterize uncultured bacterial lineages from Dewar Creek hot spring in Western Canada, with a focus on DNA and protein metabolizing bacteria. Based on previous genomic data from organisms in this hot spring, we hypothesize that the candidate phylum S2R-29, with extremely low GC content, metabolizes extracellular DNA or protein Dewar Creek is a thermal spring located in the Purcell Wilderness Conservancy in British Colombia, Western Canada. It is one of Canada’s hottest springs, reaching temperatures of up to 83˚C. Samples of DNA extracted from the Dewar Creek hot spring were PCR-amplified with primers for the v3v4 region of the 16S rRNA gene to detect S2R-29, and then sequenced on an Illumina Miseq. S2R-29 was found in samples ranging in temperature from 60˚C to 77 ˚C. In addition to samples from Dewar Creek, samples from other thermal springs in Canada, as well as samples from springs in New Zealand are also being sequenced with the same primers to determine the prevalence of this candidate phylum in other similar environments. This will give a better idea of the growth conditions and range of this organism. Previously, S2R-29 single amplified genomes (SAGs) were generated from Dewar Creek samples. Analysis of these SAGs suggests that S2R-29 has the potential to use peptides and DNA as carbon sources (Fig. 1). To test the potential to metabolize DNA and protein, enrichments of samples with 13C labelled dNTPs or 13C labelled protein have been started. These enrichments will be used for stable isotope probing (SIP) to determine if any organisms in Dewar Creek are metabolizing dNTPs or protein. In addition to SIP, primers specific for S2R-29 for quantitative PCR (qPCR) have been designed and will be run on the enrichments to determine if there are any changes in the abundance of S2R-29 over time in these enrichments, further testing the metabolic potential of these organisms. Finally, probes for fluorescence in situ hybridization (FISH) will be designed for S2R-29. These will be used to perform FISH with samples from Dewar Creek in order to visualize this candidate phylum. With this research, we hope to characterize this novel phylum, and possibly discover other novel lineages of DNA- and protein- metabolizing bacteria in Dewar Creek. This research will help better understand these processes in understudied environments as well as aid our understanding of the roles that bacterial metabolisms might play in biogeochemical cycles such as biodegradation of organic matter. In all, we hope that this research gives insight into the kinds of lifestyles bacteria have evolved in order to thrive in high temperature environments.

Screening and degradation characteristics of plastic-degrading microorganisms in film-mulched vegetable soil

In recent years, the incomplete recycle of residual mulch film (RMF) leads to the increasing richness of plastic fragment in soil, which poses a serious threat to the soil ecological environment. Therefore, the degradation of RMF in soil has aroused the interest of researchers. In this study, the degradation microorganisms were screened from film-mulched vegetable field, the results showed that seven potential plastic-degradation microorganisms were screened and identified, including four bacteria (Burkholderia cepacia, Burkholderia diffusa, Burkholderia aenigmatica, Chrysebacterium nepalense) and three fungi (Geotrichum candidum, Fusarium oxysporum and Trichoderma sp.). The results of degradation ability experiments showed that the weight loss rate of single strains ranges from 1.58 to 2.44% after 90 d. The loss rate of weight-average molecular weight (Mw) and number-average molecular weight (Mn) for single strains after 30 d were 2.61–22.40% and 17.92–39.18%, respectively. In addition, the weight loss rate of the mixed strains ranges from 1.34 to 1.62% after 90 d. The loss rate of Mw and Mn for mixed strains after 30 d were 8.04–10.06% and 20.06–39.25%, respectively. The comparing results showed that there may be inhibitory interactions between microorganisms in mixed strains are culture. This research can provide theoretical basis and data support for the control and disposal measures of RMF pollution.

Assessment of the efficiency of immobilized degrading microorganisms in removing the organochlorine pesticide residues from agricultural soils.

To investigate the removal of organochlorine pesticide residues by immobilized degrading microbe, indigenous microorganisms from organochlorine pesticide (OCP)-contaminated soils in Chengdu plain, pot experiments were carried out to evaluate the potential of the immobilized complex microbial specific degrading microbe treated with sodium alginate (SA) composite carrier in decontaminating OCP-contaminated soils, and field experiments were also conducted to investigate the enhanced efficiency of immobilized microbial agents on the dissipation of OCPs in the contaminated plots for different cultivation usage. The results showed that the dissipation rate of OCPs in contaminated soils with initial concentrations of 122.24μg/kg was 89.94% after the addition of 25mg of immobilized microbial agents at the end of the 90days of experiment, which was 6.1% higher than that of the compound microbial agents under the same environmental conditions, and the control group without the addition of microbial agents was only 1.18%, while the concentration of OCPs in contaminated soils with initial concentrations of 203.64μg/kg only decreased to 65.29μg/kg after the addition of 20mg of compound microbial agents. In contrast, the soil concentration of immobilized microbial agent treatment group under the same conditions decreased to 52.15μg/kg. During the field experiment, the enhanced efficiency of immobilized microbial agents on the degradation of OCPs in different cultivation usage was evidently different, showed that the concentration of OCPs in paddy fields (18.60%) > tea gardens (12.17%) ≥ orchards (11.41%) > vegetable fields (6.21%) ≥ dryland (4.79%), which was especially significant in stress environment. Overall, the immobilization treatment obviously improved the degradation potential of OCPs-specific degrading microbe, and the degree of improvement was related to the metabolic activity of the degrading microbe, the addition amount, remediation time, and habitat conditions.

Bioremediation of an industrial soil contaminated by hydrocarbons in microcosm system, involving bioprocesses utilizing co-products and agro-industrial wastes.

The present study describes practical implication of bioaugmentation and biostimulation processes for bioremediation of an industrial soil chronically contaminated by hydrocarbons. For this purpose, biomass production of six autochthonous hydrocarbon-degrading bacteria were evaluated as inoculum of bioaugmentation strategy, by testing carbon and nitrogen sources included co-products and agro-industrial waste as sustainable and low-cost components of the growth medium. Otherwise, biostimulation was approached by the addition of optimized concentration of nitrogen and phosphorus. Microcosm assays showed that total hydrocarbons (TH) were significantly removed from chronically contaminated soil undergoing bioremediation treatment. Systems Mix (bioaugmentation); N,P (biostimulation) and Mix + N,P (bioaugmentation and biostimulation) reached higher TH removal, being 89.85%, 91.00%, 93.04%, respectively, comparing to 77.83% of system C (natural attenuation) at 90days. The increased heterotrophic aerobic bacteria and hydrocarbon degrading bacteria counts were according to TH biodegrading process during the experiments. Our results showed that biostimulation with nutrients represent a valuable alternative tool to treat a chronically hydrocarbon-contaminated industrial soil, while bioaugmentation with a consortium of hydrocarbon degrading bacteria would be justified when the soil has a low amount of endogenous degrading microorganisms. Furthermore, the production of inoculum for application in bioaugmentation using low-cost substrates, such as industrial waste, would lead to the development of an environmentally friendly and attractive process in terms of cost-benefit.

Biodegradation of septic tank fecal sludge using Priestia aryabhattai

AbstractThe significant potential of microorganisms for fecal sludge degradation is an interesting area for investigation, primarily due to its current lack of attention. This study involved the identification of indigenous bacteria in septic tank fecal waste with the Polymerase Chain Reaction (PCR) 16S rRNA gene. Subsequently, selected bacteria strains were subjected to a potential assessment using a single method. Variables in this experiment included the addition of 2% (v/v) bacteria and sample sterilization. The results showed that the use of PCR 16S rRNA analysis led to the identification of Priestia aryabhattai, a member of the phylum Firmicutes, as the dominant species in the samples. This bacteria exhibited adaptability to both aerobic and anaerobic conditions. Sterile samples with the addition of P. aryabhattai 2% (v/v), showed the best removal efficiency percentages of 79.77%, 79.62%, 62.91%, and 70.48% for Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), and Volatile Suspended Solids (VSS). Meanwhile, the total carbon and nitrogen decreased to 2895 mg/L C and 794.12 mg/L NH3‐N, respectively. Based on the results, Priestia aryabhattai has the potential to degrade organic waste but is not suitable for fecal sludge.

Experimental study on the water purification performance of carbonated recycled aggregate pervious concrete

By carbonation treatment, the disadvantages of recycled aggregates (RAs), such as a high porosity, high crushing index and weak interface transition zone, can be improved to some extent. However, the purification performance of carbonated recycled aggregate pervious concrete (CRAPC) remains unknown. In this study, the purification performance of three types of pervious concrete prepared from natural aggregates (NAs), RAs and carbonated recycled aggregates (CRAs) was investigated. High-throughput sequencing of microorganisms was carried out as well. The results reveal that pervious concrete has a significant purification capacity, and the pervious concrete prepared by RAs and CRAs can further improve the ability to remove pollutants. Compared with natural aggregate pervious concrete (NAPC), recycled aggregate pervious concrete (RAPC) and CRAPC were more favourable for pollutant adsorption and microorganism growth due to their special pore structure. Furthermore, although the purification capacity of CRAPC was slightly inferior to that of RAPC, its mechanical properties and alkalinity were improved. In addition, the purification mechanism of pervious concrete mainly includes adsorption and microorganism degradation. The total COD removal amounts of NAPC, CRAPC and RAPC were 87.00 mg/L, 104.00 mg/L and 108.00 mg/L, respectively. The adsorption amounts were 10.00, 12.50, and 16.75 mg/L, and the microorganism degradation amounts were 77.00, 91.50 and 91.25 mg/L, respectively. Compared with adsorption, microorganism degradation plays a major role in total pollutant removal. Furthermore, a water purification model for pervious concrete is proposed.

A strategy to promote the convenient storage and direct use of polyhydroxybutyrate-degrading Bacillus sp. JY14 by lyophilization with protective reagents

BackgroundBioplastics are attracting considerable attention, owing to the increase in non-degradable waste. Using microorganisms to degrade bioplastics is a promising strategy for reducing non-degradable plastic waste. However, maintaining bacterial viability and activity during culture and storage remains challenging. With the use of conventional methods, cell viability and activity was lost; therefore, these conditions need to be optimized for the practical application of microorganisms in bioplastic degradation. Therefore, we aimed to optimize the feasibility of the lyophilization method for convenient storage and direct use. In addition, we incoporated protective reagents to increase the viability and activity of lyophilized microorganisms. By selecting and applying the best protective reagents for the lyophilization process and the effects of additives on the growth and PHB-degrading activity of strains were analyzed after lyophilization. For developing the lyophilization method for protecting degradation activity, it may promote practical applications of bioplastic-degrading bacteria.ResultsIn this study, the polyhydroxybutyrate (PHB)-degrading strain, Bacillus sp. JY14 was lyophilized with the use of various sugars as protective reagents. Among the carbon sources tested, raffinose was associated with the highest cell survival rate (12.1%). Moreover, 7% of raffionose showed the highest PHB degradation yield (92.1%). Therefore, raffinose was selected as the most effective protective reagent. Also, bacterial activity was successfully maintained, with raffinose, under different storage temperatures and period.ConclusionsThis study highlights lyophilization as an efficient microorganism storage method to enhance the applicability of bioplastic-degrading bacterial strains. The approach developed herein can be further studied and used to promote the application of microorganisms in bioplastic degradation.

Metagenome-assembled genomes reveal carbohydrate degradation and element metabolism of microorganisms inhabiting Tengchong hot springs, China

A hot spring is a distinctive aquatic environment that provides an excellent system to investigate microorganisms and their function in elemental cycling processes. Previous studies of terrestrial hot springs have been mostly focused on the microbial community, one special phylum or category, or genes involved in a particular metabolic step, while little is known about the overall functional metabolic profiles of microorganisms inhabiting the terrestrial hot springs. Here, we analyzed the microbial community structure and their functional genes based on metagenomic sequencing of six selected hot springs with different temperature and pH conditions. We sequenced a total of 11 samples from six hot springs and constructed 162 metagenome-assembled genomes (MAGs) with completeness above 70% and contamination lower than 10%. Crenarchaeota, Euryarchaeota and Aquificae were found to be the dominant phyla. Functional annotation revealed that bacteria encode versatile carbohydrate-active enzymes (CAZYmes) for the degradation of complex polysaccharides, while archaea tend to assimilate C1 compounds through carbon fixation. Under nitrogen-deficient conditions, there were correspondingly fewer genes involved in nitrogen metabolism, while abundant and diverse set of genes participating in sulfur metabolism, particularly those associated with sulfide oxidation and thiosulfate disproportionation. In summary, archaea and bacteria residing in the hot springs display distinct carbon metabolism fate, while sharing the common energy preference through sulfur metabolism. Overall, this research contributes to a better comprehension of biogeochemistry of terrestrial hot springs.