Elucidating the significant roles of root exudates in organic pollutant biotransformation within the rhizosphere.

Biotransformation of organic pollutants is crucial for the dissipation of environmental pollutants. While the roles of microorganisms have been extensively studied, the significant contribution of various root exudates are still not very well understood. Through plant growth experiment, coupled with gas and liquid chromatography-mass spectrometry methods, this study examined the effect of the presence of M. sativa on microbial-associated biochemical transformation of petroleum hydrocarbons. The results of this study revealed that the concentration of exudates within the soil matrix is a function of proximity to root surfaces. Similarly, biodegradation was found to correlate with distance from roots, ranging from ≥ 90% within the rhizosphere to < 50% in bulk soil and unplanted control soil. Most importantly, for the first time in a study of an entire petroleum distillate, this study revealed a statistically significant negative correlation between root exudate concentration and residual total petroleum hydrocarbons. While not all the compounds that may influence biodegradation are derived from roots, the results of this study show that the presence of plant can significantly influence biodegradation of hydrocarbon pollutants through such root exudation as organic acids, amino acids, soluble sugars and terpenoids. Therefore, root exudates, including secondary metabolites, offer great prospects for biotechnological applications in the remediation of organic pollutants, including recalcitrant ones.

A Metabolomics Assay to Diagnose Citrus Huanglongbing Disease and to Aid in Assessment of Treatments to Prevent or Cure Infection.

Citrus greening disease, or Huanglongbing (HLB), has devastated citrus crops globally in recent years. The causal bacterium, 'Candidatus Liberibacter asiaticus', presents a sampling issue for qPCR diagnostics and results in a high false negative rate. In this work, we compared six metabolomics assays to identify HLB-infected citrus trees from leaf tissue extracted from 30 control and 30 HLB-infected trees. A liquid chromatography-mass spectrometry-based assay was most accurate. A final partial least squares-discriminant analysis (PLS-DA) model was trained and validated on 690 leaf samples with corresponding qPCR measures from three citrus varieties (Rio Red grapefruit, Hamlin sweet orange, and Valencia sweet orange) from orchards in Florida and Texas. Trees were naturally infected with HLB transmitted by the insect vector Diaphorina citri. In a randomized validation set, the assay was 99.9% accurate to classify diseased from nondiseased samples. This model was applied to samples from trees receiving plant defense-inducer compounds or biological treatments to prevent or cure HLB infection. From two trials, HLB-related metabolite abundances and PLS-DA scores were tracked longitudinally and compared with those of control trees. We demonstrate how our assay can assess tree health and the efficacy of HLB treatments and conclude that no trialed treatment was efficacious.

Biostimulation of Petroleum-Contaminated Soil Using Organic and Inorganic Amendments.

The most common approaches for the in-situ bioremediation of contaminated sites worldwide are bioaugmentation and biostimulation. Biostimulation has often proved more effective for chronically contaminated sites. This study examined the effectiveness of optimized water hyacinth compost in comparison with other organic and inorganic amendments for the remediation of crude oil-polluted soils. Water hyacinth was found to be rich in nutrients necessary to stimulate microbial growth and activity. An organic geochemical analysis revealed that all amendments in this study increased total petroleum hydrocarbon (TPH) biodegradation by ≥75% within 56 days, with the greatest biodegradation (93%) occurring in sterilized soil inoculated with optimized water hyacinth compost. This was followed by polluted soil amended with a combination of spent mushroom and water hyacinth composts (SMC + WH), which recorded a TPH biodegradation of 89%. Soil amendment using the inorganic fertilizer NPK (20:10:10) resulted in 86% TPH biodegradation. On the other hand, control samples (natural attenuation) recorded only 4% degradation. A molecular analysis of residual polycyclic aromatic hydrocarbons (PAHs) showed that the 16 PAHs designated by the US EPA as priority pollutants were either completely or highly degraded in the combined treatment (SMC + WH), indicating the potential of this amendment for the environmental remediation of soils contaminated with recalcitrant organic pollutants.

Anti-COVID-19 potential of Azadirachta indica (Neem) leaf extract.

COVID-19 is caused by infection with the "severe acute respiratory syndrome coronavirus-2″ (i.e., SARS-CoV-2). This is an enveloped virus having a positive sense, single-stranded RNA genome; like the two earlier viruses SARS-CoV and the Middle East respiratory syndrome (MERS) virus. COVID-19 is unique in that, in the severe case, it has the propensity to affect multiple organs, leading to multiple organ distress syndrome (MODS), and causing high morbidity and mortality in the extreme case. In addition, comorbidities like age, cardiovascular disease, diabetes and its complications, obesity, are risk factors for severe COVID-19. It turns out that a most plausible, simple, single explanation for this propensity for MODS is the pivotal involvement of the vascular endothelium (VE). This is a consequence of the fact that the VE seamlessly connects all the entire vascular bed in the body, thus linking all the target organs (heart, lungs, kidney, liver, brain) and systems. Infection with SARS-CoV-2 leads to hyper-inflammation yielding uncontrolled production of a mixture of cytokines, chemokines, reactive oxygen species, nitric oxide, oxidative stress, acute phase proteins (e.g., C-reactive protein), and other pro-inflammatory substances. In the extreme case, a cytokine storm is created. Displacement of the virus bound to the VE, and/or inhibition of binding of the virus, would constitute an effective strategy for preventing COVID-19. In this regard, the acetone-water extract of the leaf of the Neem (Azadirachta indica) plant has been known to prevent the adherence of malaria parasitized red blood cells (pRBCs) to VE; prevent cytoadherence of cancer cells in metastasis; and prevent HIV from invading target T lymphocytes. We therefore hypothesize that this Neem leaf acetone-water extract will prevent the binding of SARS-CoV-2 to the VE, and therefore be an effective therapeutic formulation against COVID-19. It is therefore advocated herein that this extract be investigated through rigorous clinical trials for this purpose. It has the advantages of being (i) readily available, and renewable in favor of the populations positioned to benefit from it; (ii) simple to prepare; and (iii) devoid of any detectable toxicity.

Enhancing rhizoremediation of petroleum hydrocarbons through bioaugmentation with a plant growth-promoting bacterial consortium.

The slow rate of natural attenuation of organic pollutants, together with unwanted environmental impacts of traditional remediation strategies, has necessitated the exploration of plant-microbe systems for enhanced bioremediation applications. The identification of microorganisms capable of promoting rhizoremediation through both plant growth-promoting and hydrocarbon-degrading processes is crucial to the success and adoption of plant-based remediation techniques. In this study, through successive enrichments of soil samples from a historic oil-contaminated site in Wietze, Germany, we isolated a plant growth-promoting and hydrocarbon-degrading bacterial consortium dominated by Alphaproteobacteria. In microcosm experiments involving Medicago sativa L. and the isolated bacterial consortium, we examined the ability of the consortium to enhance rhizoremediation of petroleum hydrocarbons. The inoculation of M. sativa with the consortium resulted in 66% increase in plant biomass, and achieved a 91% reduction in diesel fuel hydrocarbon concentrations in the soil within 60 days. Metagenome analysis led to the identification of genes and taxa putatively involved in these processes. The majority of the coding DNA sequences associated with plant growth promotion and hydrocarbon degradation in this study were affiliated to Acidocella aminolytica and Acidobacterium capsulatum indicating their potential for biotechnological applications in the rhizoremediation of sites contaminated by petroleum-derived organic pollutants.

Mutual Pan-African support paradigm to produce scientific evidence of traditional medical practices for use against COVID-19 and emerging pandemics.

Africa is endowed with a profoundly rich and diverse system of plants and other bio-resources out of which, by traditional medicine practice, the people have satisfied their healthcare needs right from antiquity. In contemporary times, it has become necessary to modernize this traditional medical care system via scientific studies. Validation of the efficacy of health-enhancement products and drugs from plants and other bio-resources is predicated on diligent and intensive research accompanied by rigorous and conclusive clinical trials. Africa has eminently qualified human resources but due to the finance-intensive nature of medical research, individual African states on their own cannot fund the level of research desired for dealing with such serious issues as the COVID-19 pandemic. A collaboration among African states guided by a Mutual Pan-African support paradigm (MPASP) is a unique strategy for achieving success in any such a high-impact global project as the use of traditional medicine against COVID-19 and emerging pandemics; and this is hereby advocated.

Diversity and metagenome analysis of a hydrocarbon-degrading bacterial consortium from asphalt lakes located in Wietze, Germany.

The pollution of terrestrial and aquatic environments by petroleum contaminants, especially diesel fuel, is a persistent environmental threat requiring cost-effective and environmentally sensitive remediation approaches. Bioremediation is one such approach, but is dependent on the availability of microorganisms with the necessary metabolic abilities and environmental adaptability. The aim of this study was to examine the microbial community in a petroleum contaminated site, and isolate organisms potentially able to degrade hydrocarbons. Through successive enrichment of soil microorganisms from samples of an historic petroleum contaminated site in Wietze, Germany, we isolated a bacterial consortium using diesel fuel hydrocarbons as sole carbon and energy source. The 16S rRNA gene analysis revealed the dominance of Alphaproteobacteria. We further reconstructed a total of 18 genomes from both the original soil sample and the isolated consortium. The analysis of both the metagenome of the consortium and the reconstructed metagenome-assembled genomes show that the most abundant bacterial genus in the consortium, Acidocella, possess many of the genes required for the degradation of diesel fuel aromatic hydrocarbons, which are often the most toxic component. This can explain why this genus proliferated in all the enrichment cultures. Therefore, this study reveals that the microbial consortium isolated in this study and its dominant genus, Acidocella, could potentially serve as an effective inoculum for the bioremediation of sites polluted with diesel fuel or other organic contaminants.

Metagenome Analysis of a Hydrocarbon-Degrading Bacterial Consortium Reveals the Specific Roles of BTEX Biodegraders.

Environmental contamination by petroleum hydrocarbons is of concern due to the carcinogenicity and neurotoxicity of these compounds. Successful bioremediation of organic contaminants requires bacterial populations with degradative capacity for these contaminants. Through successive enrichment of microorganisms from a petroleum-contaminated soil using diesel fuel as the sole carbon and energy source, we successfully isolated a bacterial consortium that can degrade diesel fuel hydrocarbons. Metagenome analysis revealed the specific roles of different microbial populations involved in the degradation of benzene, toluene, ethylbenzene and xylene (BTEX), and the metabolic pathways involved in these reactions. One hundred and five putative coding DNA sequences were identified as responsible for both the activation of BTEX and central metabolism (ring-cleavage) of catechol and alkylcatechols during BTEX degradation. The majority of the Coding DNA sequences (CDSs) were affiliated to Acidocella, which was also the dominant bacterial genus in the consortium. The inoculation of diesel fuel contaminated soils with the consortium resulted in approximately 70% hydrocarbon biodegradation, indicating the potential of the consortium for environmental remediation of petroleum hydrocarbons.

Dose-response analysis of diesel fuel phytotoxicity on selected plant species.

As an ecotoxicological tool, bioassays are an effective screening tool to eliminate plants sensitive to the contaminant of interest, and thereby reduce the number of plant species requiring further study. We conducted a bioassay analysis of fifteen plant species to determine their tolerance to diesel fuel toxicity. Dose-response analysis revealed that increasing diesel fuel concentrations in the soil generally led to a monotonically decreasing biomass in 13 species (P < 0.001), with EC10 values (±SE) ranging from 0.36 ± 0.18 g/kg to 12.67 ± 2.13 g/kg. On the other hand, hydrocarbons had a statistically significant hormetic influence on Medicago sativa (f = 3.90 ± 1.08; P < 0.01). The EC10 and EC50 values (±SE) from the fitted hormetic model were 15.33 ± 1.47 g/kg and 26.89 ± 2.00 g/kg, respectively. While previous studies have shown M. sativa's tolerance of hydrocarbon toxicity, this is the first attempt to describe diesel fuel-induced hormesis in M. sativa using the Cedergreen-Ritz-Streibig model. This study thus shows that hormesis cannot be ignored in plant toxicology research, and that when present, an appropriate statistical model is necessary to avoid drawing wrong conclusions.

Assessing the Effect of Diesel Fuel on the Seed Viability and Germination of Medicago sativa Using the Event-Time Model.

The remediation of contaminated sites using plant-based techniques has gained increasing attention in recent decades. However, information on the effects of contaminant imbibition on seed viability and germination rates are often lacking in the literature. To this end, our research investigated, by means of an event-time model, the effect of diesel fuel imbibition on the seed viability and germination rate of Medicago sativa, a plant species with great potential for remediation of organic contaminants. The event-time model provided an accurate and biologically relevant method for analysing germination data. Our results reveal that the direct imbibition of diesel fuel by M. sativa seeds for ≤48 h, or their exposure to soil diesel fuel concentrations of 0-10 g/kg diesel fuel, affects their germination rates, as shown by increasing t50 values from 90.6 (±2.78) to 114.2 (±2.67) hours, without significantly affecting seed viability. On the other hand, diesel fuel imbibition of longer duration, or the exposure of M. sativa seeds to ≥20 g/kg diesel fuel-contaminated soils, leads to no further effect on time to seed emergence. Instead, these conditions compromise seed viability, resulting in a decrease in the proportion of germinated seeds from 0.91 (±0.03) in 10 g/kg diesel fuel contaminated soil to 0.84 (±0.04) and 0.70 (±0.05) in 20 and 30 g/kg diesel fuel-contaminated soils, respectively. The fact that low concentrations of diesel fuel and 0-48 h of direct imbibition delayed seed emergence without adversely affecting the percentage of viable seeds suggests that this inhibitory effect on germination at low diesel fuel exposure could be attributed more to physical constraints rather than biological damage on the seeds. The models used in this study provide an accurate and biologically relevant method for the analyses of germination data. This is vital since expensive germination experiments, be it in the field of toxicology or agriculture, deserve to be accurately analysed.

Metagenome Assembly and Metagenome-Assembled Genome Sequences from a Historical Oil Field Located in Wietze, Germany.

Crude oil-polluted sites are a global threat, raising the demand for remediation worldwide. Here, we investigated a crude oil metagenome from a former borehole in Wietze, Germany, and reconstructed 42 metagenome-assembled genomes, many of which contained genes involved in crude oil degradation with a high potential for bioremediation purposes.

Ethanol-blended petroleum fuels: implications of co-solvency for phytotechnologies.

In recent decades, there has been increasing interest in the use of ethanol-blended fuels as alternatives to unblended fossil fuels. These initiatives are targeted at combating CO2 and particulate matter emissions, as these oxygenates leave behind a lesser carbon footprint. Noble as it may appear, this innovation is not without attendant ugly consequences. One major implication is the effect of co-solvency on the applicability of various forms of phytotechnologies for contaminant removal. By means of gas chromatography-mass spectrometry, this research investigated the effect of diesel fuel ethanol addition on the leaching potentials of petroleum hydrocarbons. Since phytoremediation of hydrocarbons depends largely on rhizodegradation of contaminants by the root-associated microbiome, the leaching of petroleum hydrocarbons beyond the rooting zones of plants may limit the effectiveness of this process as a reclamation strategy for ethanol-blended fuel spills. The analyses presented in this paper highlight the need for energy scientists to carefully consider the environmental impacts of ethanol-blended innovations holistically.

Chemical constituents of Nauclea latifolia and their anti-GST and anti-fungal activities.

The crude ethanolic extract of Nauclea latifolia yielded five known compounds, strictosamide (1), naucleamides A (2), naucleamide F (3), quinovic acid-3-O-beta-rhamnosylpyranoside (4), and quinovic acid 3-O-beta-fucosylpyranoside (5). Microbial reactions, using a whole cell culture of Rhizopus circinans on compound (1), yielded three analogues, 10-hydroxystrictosamide (6), 10-beta-glucosyloxyvincoside lactam (7) and 16,17-dihydro-10-beta-glucosyloxyvincoside lactam (8). Compounds 1-8 were identified with the aid of extensive NMR spectral studies. Compound 8 was found to be a new metabolite. Compounds 1-8 exhibited different levels of anti-GST and anti-fungal activities.

New bioactive natural products from Coprinus micaceus.

Chemical studies on the crude methanolic extract of Coprinus micaceus, collected from the Canadian Prairie region, have resulted in the isolation of two new natural products, micaceol (1), a sterol and (Z,Z)-4-oxo-2,5-hetpadienedioic acid (2). Compound 2 was isolated for the first time as a natural product. Structures of these new compounds were established with the aid of extensive NMR spectroscopic studies. Compound 1 has shown anti-bacterial activity against Corynebacterium xerosis and Staphylococcus aureus, whereas compound 2 exhibited glutathione S-transferase inhibition.