Degradation Of Aromatic Compounds Research Articles

Effect of Palmitoylethanolamide Compared to a Placebo on the Gut Microbiome and Biochemistry in an Overweight Adult Population: A Randomised, Placebo Controlled, Double-Blind Study.

This study investigates the effects of palmitoylethanolamide (PEA) on the gut microbiome of overweight adults. Fifty-eight participants (twenty males, thirty-eight females) aged 18-65 years with a BMI range of 30-40 kg/m2 were recruited. Participants were randomised to receive PEA (n = 36) or a placebo (n = 22) for 12 weeks. Microbiota composition, richness, diversity, and metabolic functions, faecal short chain fatty acids and calprotectin, pathology markers, and health-related questionnaires were analysed throughout the 12 weeks of supplementation. PEA supplementation significantly reduced triglyceride levels and IL-2 concentrations. No significant differences were found in the overall microbiota composition between the groups, and microbiota richness and diversity remained consistent for both groups. Functional analysis demonstrated no differences in functional richness and diversity, but specific pathways were modified. PEA supplementation resulted in a decrease in the abundance of pathways related to aromatic compound degradation, NAD interconversion, and L-glutamate degradation, while pathways associated with molybdopterin biosynthesis and O-antigen building blocks exhibited increased abundance. Increased production of O-antigen results in smooth LPS associated with reduced pathogenic stealth and persistence. PEA supplementation may influence specific microbial species, metabolic pathways, and reduce serum triglyceride and IL-2 concentration, shedding light on the intricate relationship between PEA, the microbiome, and host health.

Total RNA analysis of the active microbiome on moving bed biofilm reactor carriers under incrementally increasing micropollutant concentrations.

Micropollutants are increasingly prevalent in the aquatic environment. A major part of these originates from wastewater treatment plants since traditional treatment technologies do not remove micropollutants sufficiently. Moving bed biofilm reactors (MBBRs), however, have been shown to aid in micropollutant removal when applied to conventional wastewater treatment as a polishing step. Here, we used Total RNA sequencing to investigate both the active microbial community and functional dynamics of MBBR biofilms when these were exposed to increasing micropollutant concentrations over time. Concurrently, we conducted batch culture experiments using biofilm carriers from the MBBRs to assess micropollutant degradation potential. Our study showed that biofilm eukaryotes, in particular protozoa, were negatively influenced by micropollutant exposure, in contrast to prokaryotes that increased in relative abundance. Further, we found several functional genes that were differentially expressed between the MBBR with added micropollutants and the control. These include genes involved in aromatic and xenobiotic compound degradation. Moreover, the biofilm carrier batch experiment showed vastly different alterations in benzotriazole and diclofenac degradation following the increased micropollutant concentrations in the MBBR. Ultimately, this study provides essential insights into the microbial community and functional dynamics of MBBRs and how an increased load of micropollutants influences these dynamics.

Effects of Bacillus altitudinis inoculants on cigar tobacco leaf fermentation.

Microbial succession and metabolic adjustment during cigar tobacco leaf (CTL) fermentation are key factors to improve the quality and flavor of CTLs. However, the interactions in the above processes remain to be further elucidated. Bacillus altitudinis inoculants were added to the CTLs, and metagenomics and metabolomics were used to analyze the effects of the inoculants on regulating microbial succession, metabolic shift, and aroma production during fermentation. The addition of the inoculants reinforced the CTL macromolecule transformation and facilitated the aroma production efficiently, and the total aroma production was increased by 43% compared with natural fermentation. The omics analysis showed that Staphylococcus was a main contributor to fatty acid degradation, inositol phosphate metabolism, energy supply (oxidative phosphorylation), nutrient transport (ABC transporter and phosphotransferase system [PTS]), and aroma production (terpenoid backbone biosynthesis, phenylalanine metabolism, and degradation of aromatic compounds). Furthermore, Staphylococcus was positively correlated with TCA cycle intermediates (citric acid, fumaric acid, and aconitic acid), cell wall components, peptidoglycan intermediates (GlcNAc-1-P and UDP-GlcNAc), and phytic acid degradation products (inositol). The characteristics collectively showed Staphylococcus to be the most dominant in the microbial community at the genus level during microflora succession. The addition of the inoculants supplemented the nutritional components of the CTLs, enhanced the metabolic activity and diversity of bacteria such as Corynebacterium, improved their competitive advantages in the microflora succession, and facilitated the richness of microbial communities. Additionally, a metabolic shift in nicotine degradation and NAD + anabolism from Staphylococcus to Corynebacterium in fermentation with inoculants was first observed. Meanwhile, the significantly correlative differential metabolites with Staphylococcus and Corynebacterium were a metabolic complement, thus forming a completely dynamic fermentation ecosystem. The results provided evidence for CTL fermentation optimization.

Sphaerotilus uruguayifluvii sp. nov., a novel filamentous bacterium isolated from river water.

Strain C29T, a Gram-staining-negative, straight rod occurring singly, in pairs or short chains, was isolated from floating filamentous biomass of the Uruguay River. The strain was catalase and oxidase positive, chemoorganotrophic, strictly aerobic, non-motile, and grew at pH 6.0-9.0, 15-45°C, and 0-0.5% (w/v) NaCl. Polyhydroxybutyrate was accumulated in nutrient-limited conditions. Phylogenetic analysis based on the 16S rRNA gene revealed that strain C29T had the highest sequence similarity with Leptothrix discophora SS-1T (97.82%), Ideonella livida TBM-1T (97.82%), Vitreoscilla filiformis L1401-2T (97.52%), Sphaerotilus sulfidivorans D-501T (97.50%) and Sphaerotilus natans DSM6575T(97.46%). Other type strains with validly published names had similarities below 97.46%. Further phylogenomic analysis showed that strain C29T was affiliated to the family Sphaerotilaceae. Average nucleotide identity (ANI) and in silico DNA-DNA hybridization (dDDH) values with its phylogenetic relatives were lower than 91 and 41%, respectively, revealing that strain C29T represented a new species. The DNA G + C content of strain C29T was 70.9%. The annotation of the genome of the novel strain shows it possessed genes for the degradation of aromatic compounds. It also contained genes that encode sigma factors involved in response regulation of stress resistance, which is an important function for adaptation and survival in natural niches. Based on the results of the phylogenetic and phenotypic analyses, we propose that strain C29T represents a novel species, for which the name Sphaerotilus uruguayifluvii sp. nov. is proposed. The type strain is C29T (= CCM 9043T = DSM 113250T).

In Silico Analysis of the Phylogenetic and Physiological Characteristics of Sphingobium indicum B90A: A Hexachlorocyclohexane-Degrading Bacterium.

The study focuses on the in silico genomic characterization of Sphingobium indicum B90A, revealing a wealth of genes involved in stress response, carbon monoxide oxidation, β-carotene biosynthesis, heavy metal resistance, and aromatic compound degradation, suggesting its potential as a bioremediation agent. Furthermore, genomic adaptations among nine Sphingomonad strains were explored, highlighting shared core genes via pangenome analysis, including those related to the shikimate pathway and heavy metal resistance. The majority of genes associated with aromatic compound degradation, heavy metal resistance, and stress response were found within genomic islands across all strains. Sphingobium indicum UT26S exhibited the highest number of genomic islands, while Sphingopyxis alaskensis RB2256 had the maximum fraction of its genome covered by genomic islands. The distribution of lin genes varied among the strains, indicating diverse genetic responses to environmental pressures. Additionally, in silico evidence of horizontal gene transfer (HGT) between plasmids pSRL3 and pISP3 of the Sphingobium and Sphingomonas genera, respectively, has been provided. The manuscript offers novel insights into strain B90A, highlighting its role in horizontal gene transfer and refining evolutionary relationships among Sphingomonad strains. The discovery of stress response genes and the czcABCD operon emphasizes the potential of Sphingomonads in consortia development, supported by genomic island analysis.

Exploring the potential of Canavalia ensiformis for phytoremediation of B10 biodiesel-contaminated soil: insights on aromatic compound degradation and soil fertility

The widespread use of petroleum-based fuels poses a significant environmental problem due to the risks associated with accidental spills. Among the treatments available, phytoremediation is increasingly accepted as an effective and low-cost solution. This study aimed to evaluate the degradation of the aromatic fraction of biodiesel B10 and the soil fertility analysis in artificially contaminated soils treated with phytoremediation. The experimental design consisted of a 3x3 factorial, with three types of soil treatment: control, autoclaved, and planted with C. ensiformis L, and three levels of B10 biodiesel contamination: 0, 1, and 2%, to simulate spills of 30,000 and 60,000 L ha−1. The soil was analyzed at three depths: 0–10, 10–20, and 20–30 cm. The results indicated that aromatic compound degradation after phytoremediation was superior to 92,76% and 88,65% for 1% and 2% B10 soil contamination, respectively. The fuel contamination affected soil fertility, reducing the availability of phosphorus and zinc while increasing the Total Organic Carbon (TOC), pH, and the availability of manganese and iron for plants.

Fulvic acid and fermentation agent optimize in situ composting by reducing antibiotic resistance genes abundances and altering succession of bacterial communities

The use of biostimulants to enhance microbial activity has been extensively reported. However, their regulatory properties on the ecological security of in situ composting have not yet been fully elucidated. Here, the effects of two biostimulants (fermentation agent [FM] and fulvic acid [FA]) on in situ composting were investigated under field conditions. The abundances of antibiotic resistance genes (ARGs), as well as those of the microbial communities and the activities of enzymes, were comprehensively investigated. The addition of biostimulants significantly reduced the abundances of streptomycin and sulfonamide resistance genes by 79%–97% and decreased the abundance of Gammaproteobacteria. This was particularly true for species that are members of the Enterobacteriaceae and contain many ARGs. The addition of biostimulants promoted the succession of bacterial communities toward enhancing the solubility of phosphorus, promoting the degradation of aromatic compounds, and reducing the emissions of NOx gas. The application of FA and FM resulted in distinct bacterial network structures, and many negative correlations were associated with ARGs in the temperature subnetwork in the FM treatment. This study provides an effective strategy for the in situ treatment of agricultural waste and underscores the significance of biostimulants in improving the biological safety of medium-temperature in-situ composting.

Evaluation of a hybrid advanced oxidation process for removal of pirimicarb insecticide in aqueous media: Statistical optimization and estimation of electrical energy consumption

AbstractIn this paper, the role of periodate and persulfate as inorganic oxidants were studied in presence of ultraviolet radiation and titanium dioxide nanoparticles as a hybrid advanced oxidation photocatalytic processes for degradation and mineralization of the pirimicarb insecticide in aqueous media. The effects of several factors such as the ultraviolet irradiation, initial oxidant concentration, titanium dioxide nanoparticles dosage, and pH on the process performance were investigated. The process optimization was performed by the central composite design as a tools of response surface methodology for 30 mg L−1 of the insecticide initial concentration at 25°C and 10 min of degradation process. A degradation efficiency of about 86% and 85% have been obtained for the persulfate and periodate processes, respectively, in the optimum conditions. The mineralization efficiency of the process using persulfate and periodate were about 35% and 46% after 60 min, respectively. The kinetic studies show that both processes follow a pseudo‐first‐order kinetic model and the rate constants were 0.1483 min−1 for the persulfate and 0.1152 min−1 for the periodate process. Generally, it can be concluded that this method is suitable for the degradation and mineralization of toxic aromatic compounds.

Genomic, Phylogenetic and Physiological Characterization of the PAH-Degrading Strain Gordonia polyisoprenivorans 135.

The strain Gordonia polyisoprenivorans 135 is able to utilize a wide range of aromatic compounds. The aim of this work was to study the features of genetic organization and biotechnological potential of the strain G. polyisoprenivorans 135 as a degrader of aromatic compounds. The study of the genome of the strain 135 and the pangenome of the G. polyisoprenivorans species revealed that some genes, presumably involved in PAH catabolism, are atypical for Gordonia and belong to the pangenome of Actinobacteria. Analyzing the intergenic regions of strain 135 alongside the "panIGRome" of G. polyisoprenivorans showed that some intergenic regions in strain 135 also differ from those located between the same pairs of genes in related strains. The strain G. polyisoprenivorans 135 in our work utilized naphthalene (degradation degree 39.43%) and grew actively on salicylate. At present, this is the only known strain of G. polyisoprenivorans with experimentally confirmed ability to utilize these compounds.

Transcriptome Sequencing and Analysis of Trichoderma polysporum Infection in Avena fatua L. Leaves before and after Infection.

Biological control is a scientific management method used in modern agricultural production, and microbially derived biopesticides are one effective method with which to control weeds in agricultural fields. In order to determine the key genes for weed control by Trichoderma polysporum, transcriptome sequencing was carried out by high-throughput sequencing technology, and the strains of T. polysporum HZ-31 infesting Avena fatua L. at 24, 48, and 72 h were used as the experimental group, with 0 h as the control group. A total of 690,713,176 clean reads were obtained, and the sequencing results for each experimental group and the control group (0 h) were analyzed. In total, 3464 differentially expressed genes were found after 24 h of infection with the pathogen, including 1283 down-regulated genes and 2181 up-regulated genes. After 48 h of infection, the number of differentially expressed genes was 3885, of which 2242 were up-regulated and 1643 were down-regulated. The number of differentially expressed genes after 72 h of infection was the highest among all the groups, with 4594 differentially expressed genes, of which 2648 were up-regulated and 1946 were down-regulated. The up-regulated genes were analyzed by GO and KEGG, and the results showed that the up-regulated differentially expressed genes were mainly enriched in the biosynthesis of phenylalanine, tyrosine, and tryptophan; the degradation of aromatic compounds; methane metabolism; and other pathways. Among them, the PHA2, GDH, ADH2, and AROF genes were significantly enriched in the above-mentioned pathways, so they were hypothesized to play an important role in the synthesis of the herbicidally active substances of T. polysporum HZ-31. The results of this study can provide a theoretical basis for further studies on the pathogenicity of T. polysporum to A. fatua L., and accelerate the development and utilization of new and efficient bioherbicides.

Insights into the distribution characteristic of microbiota in alkaline–sandy soil with inorganic and organic fertiliser treatments: contrasting abundance, structure and functionality

ABSTRACT Fertiliser amendment is the most direct method for improving soil properties of ecologically vulnerable areas (e.g. desertification soil area), and then, understanding the response of microbial community activities and growth to different fertilisation treatments is of great significance in sandy soil restoration. Here, a field experiment with different fertiliser treatments in typical alkaline–sandy soil was conducted. In this study, the difference of physicochemical property, microbial communities and functions in different treatments of no fertiliser (CK), (ii) fly ash chemical fertilisers (CF), (iii) humic straw organic fertiliser (OF), (iv) functional microbial fertiliser (FMF), (v) sulphate-reducing bacterial (SRB) fertiliser (MF) and (vi) humic straw organic fertiliser + functional microbial fertiliser + SRB fertiliser (CMF) were evaluated. The result showed that the contents of soil total organic carbon, NO3-N, P and K in the FMF were highest. The abundance of keystone taxa (Gemmatimonadetes and Thaumarchaeota) increased significantly in the treatments of microbial fertiliser. Microbial fertiliser boosted genes for aerobic nitrite oxidation, nitrogen fixation, ammonia oxidation and aromatic compound degradation. The number of methylotrophy and dark sulphur oxidation genes was reduced. The bbove results indicated that the treatments with the inoculation of functional microbes are better than the others for the restoration of alkaline–sandy soil.

Development of an internal two-stage upflow anaerobic reactor integrating biostimulation strategies to enhance the degradation of aromatic compounds in wastewater from purified terephthalic acid and dimethyl terephthalate manufacturing processes

In this study, we aimed to establish high-rate biological treatment of purified terephthalic acid (PTA) and dimethyl terephthalate (DMT) wastewater that minimizes the inhibitory effects of high concentration benzoate and acetate. To achieve this, we developed a novel bioreactor system and biostimulation strategy. An internal two-stage upflow anaerobic (ITUA) reactor was operated with (i) a packed bed containing green tuff medium underlying (ii) a compartment seeded with anaerobic granular sludge. Ethylene glycol was amended to stimulate syntrophic interactions. Continuous operation of the system for 1,026 days achieve an organic removal rate of 11.0 ± 0.6 kg COD/m3/d. The abundance of aromatic degraders significantly increased during operation. Thus, we successfully developed a high-rate treatment system to treat wastewater from the PTA/DMT manufacturing processes by activating syntrophs in an ITUA reactor.

Paenarthrobacter aromaticivorans sp. nov., a paraoxon-degrading bacterium isolated from red pepper cultivation soil.

A bacterial strain designated MMS21-TAE1-1T, capable of degrading paraoxon, was isolated from red pepper soil (36° 25' 26.0″ N, 126° 25' 47.0″ E) and subjected to polyphasic taxonomic characterisation. MMS21-TAE1-1T was an aerobic, non-motile and Gram-stain-positive bacterium. MMS21-TAE1-1T showed growth at 10-37 °C (optimum, 30 °C), at pH 4-10 (optimum, pH 7) and in the presence of 0-6 % NaCl (optimum, 0 %). On the basis of the results of 16S rRNA gene sequence analysis, MMS21-TAE1-1T could be assigned to the genus Paenarthrobacter and shared the highest sequence similarities with Paenarthrobacter aurescens NBRC 12136T (99.72 %), then with Paenarthrobacter nitroguajacolicus G2-1T (99.65 %) and Paenarthrobacter ilicis DSM 20138T (99.17 %). However, the results of genome-based comparison using orthologous average nucleotide identity (orthoANI) and digital DNA-DNA hybridisation indicated that MMS21-TAE1-1T could be readily distinguished from all species of the genus with validly published names. The predominant menaquinone of MMS21-TAE1-1T was MK-9(H2). The diagnostic polar lipids were diphosphatidylglycerol and phosphatidylinositol, and unidentified glycolipids were also present. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and iso-C15 : 0. The chemotaxonomic properties of MMS21-TAE1-1T were generally consistent with those of members of the genus Paenarthrobacter. The genome of MMS21-TAE1-1T contained genes related to degradation of aromatic compounds. It is evident from the results of this study that strain MMS21-TAE1-1T merits recognition as representing a novel species of the genus Paenarthrobacter, for which the name Paenarthrobacter aromaticivorans sp. nov. is proposed. The type strain is MMS21-TAE1-1T (=KCTC 49652T = LMG 32368T).

Metagenomic analysis of soil microbial communities associated with Poa alpigena Lindm in Haixin Mountain, Qinghai Lake.

To investigate the impact of Poa alpigena Lindm on rhizosphere and bulk soil microorganisms in Haixin Mountain, Qinghai Lake, this study employed metagenomics technology to analyze the microbial communities of the samples. Results showed that 65 phyla, 139 classes, 278 orders, 596 families, 2376 genera, and 5545 species of soil microorganisms were identified from rhizosphere and bulk soil samples. Additionally, a microbial gene library specific to Poa alpigena Lindm was established for Qinghai Lake. Through α-diversity analysis, the richness and diversity of bulk microorganisms both significantly had a higher value than that in rhizosphere soil. The indicator microorganisms of rhizosphere and bulk soil at class level were Actinobacteria and Alphaproteobacteria, respectively. KEGG pathway analysis indicated that Carotenoid biosynthesis, Starch and sucrose metabolism, Bacterial chemotaxis, MAPK signaling pathway, Terpenoid backbone biosynthesis, and vancomycin resistance were the key differential metabolic pathways of rhizosphere soil microorganisms; in contrast, in bulk soil, the key differential metabolic were Benzoate degradation, Glycolysis gluconeogenesis, Aminobenzoate degradation, ABC transporters, Glyoxylate and dicarboxylate metabolism, oxidative phosphorylation, Degradation of aromatic compounds, Methane metabolism, Pyruvate metabolism and Microbial metabolism diverse environments. Our results indicated that Poa alpigena Lindm rhizosphere soil possessed selectivity for microorganisms in Qinghai Lake Haixin Mountain, and the rhizosphere soil also provided a suitable survival environment for microorganisms.

Impacts of o-cresol spill on composition and function of river sediment and soil microbial communities.

o-Cresol is a toxic substance with strong irritating and corrosive effects on skin and mucous membranes. To date, information on the effects of o-cresol on microbial communities in the natural environment is very limited. In the present study, 16S rRNA sequencing and metagenomic technique were carried out to elucidate the effects of the o-cresol spill on microbial communities in river sediments and nearby soils. o-Cresol spill induced the increase in the relative abundance of phyla Planctomycetes and Gemmatimonadetes, suggesting their resilience to o-cresol-induced stress. Uncultured Gemmatimonadetes genera and the MND1 genus exhibited enrichment, while the Pseudomonas genus dominated across all samples, indicating their potential pivotal roles in adapting to the o-cresol spill. Moreover, o-cresol spill impaired the metabolic functions of microbes but triggered their defense mechanisms. Under o-cresol pressure, microbial functions related to carbon fixation were upregulated and functions associated with sulfur metabolism were downregulated. In addition, the o-cresol spill led to an increase in functional genes related to the conversion of o-cresol to 3-methylcatechol. Several genes involved in the degradation of aromatic compounds were also identified, potentially contributing to the biodegradation of o-cresol. This study provides fresh insights into the repercussions of an abrupt o-cresol spill on microbial communities in natural environments, shedding light on their adaptability, defense mechanisms, and biodegradation potential.

Correlation between insulin resistance and coronary collateral circulation in patients with chronic total coronary occlusion

To explore the impact of diabetes on collateral circulation (CC) development in patients with chronic total coronary occlusion (CTO) and the underlying regulatory mechanism. This study was conducted among 87 patients with coronary heart disease (CHD), who had CTO in at least one vessel as confirmed by coronary angiography. Among them 42 patients were found to have a low CC level (Cohen-Rentrop grades 0-1) and 45 had a high CC level (grades 2-3). In the 39 patients with comorbid diabetes mellitus and 48 non-diabetic patients, insulin resistance (IR) levels were compared between the subgroups with different CC levels. The steady-state mode evaluation method was employed for calculating the homeostatic model assessment for insulin resistance index (HOMA-IR) using a mathematical model. During the interventional procedures, collateral and peripheral blood samples were collected from 22 patients for comparison of the metabolites using non-targeted metabolomics analysis. NT-proBNP levels and LVEF differed significantly between the patients with different CC levels (P<0.05). In non-diabetic patients, HOMA-IR was higher in low CC level group than in high CC level groups. Compared with the non-diabetic patients, the diabetic patients showed 63 upregulated and 48 downregulated metabolites in the collateral blood and 23 upregulated and 14 downregulated metabolites in the peripheral blood. The differential metabolites in the collateral blood were involved in aromatic compound degradation, fatty acid biosynthesis, and steroid degradation pathways; those in the peripheral blood were related with pentose phosphate metabolism, bacterial chemotaxis, hexanoyl-CoA degradation, glycerophospholipid metabolism, and lysine degradation pathways. The non-diabetic patients with a low level of CC had significant insulin resistance. The degradation pathways of aromatic compounds, fatty acid biosynthesis, and steroid degradation are closely correlated with the development of CC.

Anaerobic co-metabolic biodegradation of pharmaceuticals and personal care products driven by glycerol fermentation

Anaerobic digestion in two sequential phases, acidogenesis and methanogenesis, has been shown to be beneficial for enhancing the biomethane generation from wastewater. In this work, the application of glycerol (GOH) as a fermentation co-substrate during the wastewater treatment was evaluated on the biodegradation of different pharmaceuticals and personal care products (PPCPs). GOH co-digestion during acidogenesis led to a significant increase in the biodegradation of acetaminophen (from 78 to 89%), ciprofloxacin (from 25 to 46%), naproxen (from 73 to 86%), diclofenac (from 36 to 48%), ibuprofen (from 65 to 88%), metoprolol (from 45 to 59%), methylparaben (from 64 to 78%) and propylparaben (from 68 to 74%). The heterotrophic co-metabolism of PPCPs driven by glycerol was confirmed by the biodegradation kinetics, in which kbio (biodegradation kinetics constant) values increased from 0.18 to 2.11 to 0.27–3.60 L g−1-VSS d−1, for the operational phases without and with GOH, respectively. The assessment of metabolic pathways in each phase revealed that the prevalence of aromatic compounds degradation, metabolism of xenobiotics by cytochrome P450, and benzoate degradation routes during acidogenesis are key factors for the enzymatic mechanisms linked to the PPCPs co-metabolism. The phase separation of anaerobic digestion was effective in the PPCPs biodegradation, and the co-fermentation of glycerol provided an increase in the generation potential of biomethane in the system (energetic potential of 5.0 and 6.3 kJ g−1-CODremoved, without and with GOH, respectively). This study showed evidence that glycerol co-fermentation can exert a synergistic effect on the PPCPs removal during anaerobic digestion mediated by heterotrophic co-metabolism.

Microbiota characterization of the green mussel Perna viridis at the tissue scale and its relationship with the environment.

Research on the microbiota associated with marine invertebrates is important for understanding host physiology and the relationship between the host and the environment. In this study, the microbiota of the green mussel Perna viridis was characterized at the tissue scale using 16S rRNA gene high-throughput sequencing and compared with the microbiota of the surrounding environment. Different mussel tissues were sampled, along with two environmental samples (the mussel's attachment substratum and seawater). The results showed that the phyla Proteobacteria, Bacteroidetes, and Spirochaetae were dominant in mussel tissues. The bacterial community composition at the family level varied among the tissues of P. viridis. Although the microbiota of P. viridis clearly differed from that of the surrounding seawater, the composition and diversity of the microbial community of the foot and outer shell surface were similar to those of the substratum, indicating their close relationship with the substratum. KEGG prediction analysis indicated that the bacteria harbored by P. viridis were enriched in the degradation of aromatic compounds, osmoregulation, and carbohydrate oxidation and fermentation, processes that may be important in P. viridis physiology. Our study provides new insights into the tissue-scale characteristics of mussel microbiomes and the intricate connection between mussels and their environment.

Spatial distribution of volatile organic compounds in contaminated soil and distinct microbial effect driven by aerobic and anaerobic conditions

The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total concentrations of ΣVOCs in surface soils (0–20 cm) were 134–1664 ng g−1. Contamination of VOCs in surface soil exhibited remarkable variability, closely related to previous production activities at the sampling sites. Additionally, the concentrations of ΣVOCs varied with increasing soil depth from 0 to 10 m. Soils at depth of 2 m showed ΣVOCs concentrations of 127–47,389 ng g−1. Among the studied VOCs, xylene was the predominant contaminant in subsoils (2 m), with concentrations ranging from n.d. to 45,400 ng g−1. Chlorinated alkanes and olefins demonstrated a greater downward migration ability compared to monoaromatic hydrocarbons, likely due to their lower hydrophobicity. As a result, this vertical distribution of VOCs led to a high ecological risk in both the surface and deep soil. Notably, the risk quotient (RQ) of xylene in subsoil (2 m, RQ up to 319) was much higher than that in surface soil. Furthermore, distinct effects of VOCs on soil microbes were observed under aerobic and anaerobic conditions. Specifically, after the 30-d incubation of xylene-contaminated soil, Ilumatobacter was enriched under aerobic condition, whereas Anaerolineaceae was enriched under anaerobic condition. Moreover, xylene contamination significantly affected methylotrophy and methanol oxidation functions for aerobic soil (t-test, p < 0.05). However, aromatic compound degradation and ammonification were significantly enhanced by xylene in anaerobic soil (t-test, p < 0.05). These findings suggest that specific VOC compound has distinct microbial ecological effects under different oxygen content conditions in soil. Therefore, when conducting soil risk assessments of VOCs, it is crucial to consider their ecological effects at different soil depths.

Insights into the degradation of diesel-contaminated seawater through natural microbiota and culturable microorganisms: The overlook role of extracellular polymeric substances (EPS)

The role of EPS produced during biodegradation diesel-contaminated seawater, as well as the effect of EPS on natural microbiota and culturable microorganisms, remains unknown. Here, natural microbiota (pre and post enrichment with diesel) from 5 islands’ seawater in Jiaozhou Bay were explored through metagenomic and culture-dependent approaches. EPS response degradation was mainly characterized by the following aspects: 1) The post-enrichment samples contained significantly fewer dominant bacterial genera than the pre-enrichment samples, and EPS or PS (polysaccharides) promoted degradation of C16-C24 hydrocarbon fractions; 2) EPS caused higher increases in aromatic compound degradation functional genes copies; 3) EPS enhanced the enzymatic activity of alkane hydroxylase and ethanol dehydrogenase; 4) Diesel degradation by mono and mixed cultures of culturable bacteria (B1 and B2) with extracted EPS showed a higher biomass, biosurfactant production, expression of PAH-RHDα GN and cytochrome P450 genes, degradability and emulsification capacity. The above innovations provided new perspectives for oil-spill bioremediation.