4 research outputs found

    Effect of potassium and potting-bag size on foliar biomass and related attributes and oil composition of rose geranium (Pelargonium graveolens)

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    Published ArticleThis study was conducted to evaluate the effect of four concentrations of potassium (K; 1.3, 3.3, 5.3 and 7.3 mmol L−1) and two potting-bag sizes (5 and 10 L) on foliar biomass and related attributes and oil composition of rose geranium (Pelargonium graveolens). Plants were grown in a climate-controlled greenhouse at the University of the Free State and treatments were arranged in a split plot design. Potassium concentrations were allocated to the main plots and potting-bag size to the subplots replicated three times. Plant height, K tissue content, linalool, geraniol, geranyl formate and citronellol:geraniol ratio were affected by the K application. Plant height, number of branches, branch:height ratio, foliage fresh mass, K tissue content and oil yield were affected by the potting-bag size. Foliar fresh mass was significantly increased by the interaction between K concentration and potting-bag size. Growers may use a 5.3 mmol L−1 K concentration and a 5 L potting bag for optimum production of rose geranium under soil-less cultivation

    The biobleaching potential of laccase produced from mandarin peelings : impetus for a circular bio-based economy in textile biofinishing

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    The quest for circular bioeconomy has been on the rise in recent years, and it is anticipated to fulfil the environmental sustainability aspect of the sustainable development goals (SDG 2030). In this regard, our investigation attempted the biotechnological appraisal of an enzymatic derivative of bacterial (Pseudomonas sp. HRJ16) mandarin peelings (MP) fermentation as a vehicle for an environmentally benign and sustainable textile bioscouring. Production of the bacterial exudate (HRJ16 laccase) was optimized by response surface methodology (RSM), using the common low-cost agroindustrial waste (MP). HRJ16 laccase was further assessed for its advantageous biochemical and catalytic properties, and then applied in synthetic dye decolorization and denim bleaching. Results emphasized the extremotolerance of the exudate to temperature, pH, salts, cations and surfactants, when at least ca. 80 % residual activity was recollected after exposure to the different extreme operating conditions. The interesting capabilities of the HRJ16 in this study culminated in its successful bioscouring of denim fabric over 6 h and the spontaneous decolorization of the resultant effluent. This constitutive properties of HRJ16 might make it a crucial catalyst for achieving a circular bioeconomy in the textile industry.The South Africa Medical Research Council (SAMRC), the National Research Foundation and Central University of Technology, Free State.https://www.journals.elsevier.com/arabian-journal-of-chemistryhj2023Chemical Engineerin

    Metagenomic assessment of nitrate-contaminated mine wastewaters and optimization of complete denitrification by indigenous enriched bacteria

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    Nitrate contamination in water remains to be on the rise globally due to continuous anthropogenic activities, such as mining and farming, which utilize high amounts of ammonium nitrate explosives and chemical-NPK-fertilizers, respectively. This study presents insights into the development of a bioremediation strategy to remove nitrates (NO3−) using consortia enriched from wastewater collected from a diamond mine in Lesotho and a platinum mine in South Africa. A biogeochemical analysis was conducted on the water samples which aided in comparing and elucidating their unique physicochemical parameters. The chemical analysis uncovered that both wastewater samples contained over 120 mg/L of NO3− and over 250 mg/L of sulfates (SO42-), which were both beyond the acceptable limit of the environmental surface water standards of South Africa. The samples were atypical of mine wastewaters as they had low concentrations of dissolved heavy metals and a pH of over 5. A metagenomic analysis applied to study microbial diversities revealed that both samples were dominated by the phyla Proteobacteria and Bacteroidetes, which accounted for over 40% and 15%, respectively. Three consortia were enriched to target denitrifying bacteria using selective media and then subjected to complete denitrification experiments. Denitrification dynamics and denitrifying capacities of the consortia were determined by monitoring dissolved and gaseous nitrogen species over time. Denitrification optimization was carried out by changing environmental conditions, including supplementing the cultures with metal enzyme co-factors (iron and copper) that were observed to promote different stages of denitrification. Copper supplemented at 50 mg/L was observed to be promoting complete denitrification of over 500 mg/L of NO3−, evidenced by the emission of nitrogen gas (N2) that was more than nitrous oxide gas (N2O) emitted as the terminal by-product. Modification and manipulation of growth conditions based on the microbial diversity enriched proved that it is possible to optimize a bioremediation system that can reduce high concentrations of NO3−, while emitting an environmentally-friendly N2 instead of N2O, that is, a greenhouse gas. Data collected and discussed in this research study can be used to model an upscale NO3− bioremediation system aimed to remove nitrogenous and other contaminants without secondary contamination

    Nitrate Water Contamination from Industrial Activities and Complete Denitrification as a Remediation Option

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    Freshwater is a scarce resource that continues to be at high risk of pollution from anthropogenic activities, requiring remediation in such cases for its continuous use. The agricultural and mining industries extensively use water and nitrogen (N)-dependent products, mainly in fertilizers and explosives, respectively, with their excess accumulating in different water bodies. Although removal of NO3 from water and soil through the application of chemical, physical, and biological methods has been studied globally, these methods seldom yield N2 gas as a desired byproduct for nitrogen cycling. These methods predominantly cause secondary contamination with deposits of chemical waste such as slurry brine, nitrite (NO2), ammonia (NH3), and nitrous oxide (N2O), which are also harmful and fastidious to remove. This review focuses on complete denitrification facilitated by bacteria as a remedial option aimed at producing nitrogen gas as a terminal byproduct. Synergistic interaction of different nitrogen metabolisms from different bacteria is highlighted, with detailed attention to the optimization of their enzymatic activities. A biotechnological approach to mitigating industrial NO3 contamination using indigenous bacteria from wastewater is proposed, holding the prospect of optimizing to the point of complete denitrification. The approach was reviewed and found to be durable, sustainable, cost effective, and environmentally friendly, as opposed to current chemical and physical water remediation technologies