587 research outputs found

    Biodegradation of paracetamol and its intermediate metabolite hydroquinone by bacterial strains isolated from two mines of the iberian pyrite belt

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    The main objective of the current study was to isolate bacterial strains able to biodegrade the emerging pollutants paracetamol (APAP) and hydroquinone (HQ), amongst the most worldwide prescribed drugs, also frequently detected in wastewater treatment plants influents and effluents and the environment. The most promising microbial consortia of Poderosa and Lousal mines for APAP removal were selected based on the previous reports of PROBIOMA project (European Regional Development Fund ERDF - Interreg V-A Spain-Portugal program (POCTEP)). The ability of the selected microbial consortia to remove APAP from the Mineral Salt Medium (MSM) at an initial concentration of about 500 mgL-1 (MSM-APAP (500 mgL-1)), under dark shaking conditions of 160 rpm at 25 °C, was confirmed using UV-vis molecular spectroscopy. Subsequently, the isolation step from selected samples proceeded from three successive enrichment cultures using MSM-drug (500 mgL-1) under the aforementioned conditions by spreading first on LB-drug and then on MSM-drug (500 mgL-1) agar plates and resulted in seven isolates able to utilize APAP as sole carbon source, and identified according to 16S rRNA gene sequence analysis as members of genera Aeromonas, Bacillus (two isolates), Niallia, Paraburkholderia, Rhizobium, and Variovorax, as well as one HQ utilizing isolate (Mycolicibacterium sp.). The HPLC analysis of APAP removal, in MSM-APAP (500 mgL-1) under the same culture conditions, by the two putative APAP biodegrading Bacillus sp. isolates revealed that Bacillus sp. (PDE3.1) showed maximal APAP %removal of 63+3 after 18 days, while Bacillus. sp. (PLC2.1) showed %removal of only 8+1 at the end of the experiment after 21 days. The key metabolites of APAP degradation (4-aminophenol and HQ) were detected through GC-MS analysis in the experiment with Bacillus sp. (PDE3.1) at very low concentrations. Then, the seven potential APAP biodegrading bacterial isolates were tested for APAP removal in MSM at a lower concentration of 50 mgL-1. Rhizobium sp. (PDE3.3) and Paraburkholderia sp. (PLA3.3) seemed the most promising where APAP %removal was 49±4 and 47.9±0.9, respectively. Later, the co-culture of the three most promising isolates (Rhizobium sp. (PDE3.3), Paraburkholderia sp. (PLA3.3), and Bacillus sp. (PDE3.1) didn’t improve the %removal compared with the pure cultures, while the co-culture with the seven potential APAP biodegrading isolates did not show removal capacity. Mycolicibacterium sp. (HPB1.1) showed at least 88% removal of HQ from MSM-HQ (50 mgL-1) after four days; hence, was checked for APAP removal in MSM-APAP (50 mgL-1) and showed APAP %removal of 41.6±0.1. Overall, some bacterial strains isolated from Poderosa and Lousal mines showed removal capacity; hence, more efforts should be directed at investigating if biodegradation is the main removal mechanism involved, and at exploring the biodegradation potentials of The Iberian Pyrite Belt mines associated bacteria.As crescentes preocupações ambientais sobre a incapacidade das estações de tratamento de águas residuais (ETARs) para remover completamente os produtos farmacêuticos e outros poluentes das águas residuais, são apoiadas por estudos que reportam as ETAR como a principal fonte de poluentes emergentes no ambiente aquático. Desde a década de 80 que a aplicação da tecnologia de bioaumentação em sistemas de ETAR convencionais usando estirpes bacterianas com as capacidades de biodegradação desejadas tem recebido atenção com o objetivo da remoção completa dos medicamentos contaminantes das águas residuais antes da liberação no meio ambiente. Por outro lado, ambientes extremos sempre foram considerados como uma fonte valiosa de estirpes microbianos com extraordinários potenciais metabólicos considerados como mecanismos de adaptação às condições circundantes de habitats tão extremos, permitindo que esses micróbios extremófilos dominem e se sobreponham a outras comunidades microbianas. O principal objetivo do presente estudo foi isolar e identificar estirpes bacterianas com potencial metabólico para biodegradar o poluente emergente paracetamol (APAP) e seu metabólito hidroquinona (HQ) em ETARs. A escolha do APAP como modelo de estudo deve-se à sua classificação entre os medicamentos mais prescritos no mundo, à sua deteção frequente em afluentes e efluentes de ETARs e no meio ambiente, bem como sua inclusão na Lista Modelo da Organização Mundial da Saúde de Medicamentos Essenciais. Para monitorização da remoção de APAP e HQ foram utilizados diferentes métodos de análise em diferentes fases do trabalho: absorvância de UV-vis em leitor de placas, HPLC com detetor de UV-vis e GC-MS. A análise espectral de UV-vis em leitor de placas foi usada para monitorizar APAP e HQ nas culturas de enriquecimento dos consórcios microbianos utilizados para os isolamentos, o HPLC foi utilizado nos estudos de remoção com os isolados selecionados e o GC-MS para detetar produtos da degradação do APAP. Para a construção de retas de calibração a usar nas análises das amostras fizeram-se os seguintes testes e/ou afinações: no leitor de placas foram selecionados comprimentos de onda com picos de absorbância em soluções padrão dos compostos APAP e HQ; no HPLC determinaram-se os tempos de retenção destes compostos e também do metabolito 4-aminofenol com um método previamente utilizado para estes compostos em trabalhos anteriores já publicados pelo grupo onde o trabalho foi efetuado, no GC-MS testou-se um método previamente utilizado pelo grupo para análises de outro fármaco (17α-etinilestradiol) e determinaram-se os tempos de retenção dos compostos em estudo neste trabalho. Os consórcios microbianos mais promissores das minas Poderosa e do Lousal para biodegradação de APAP foram selecionados com base nos relatórios anteriores do projeto PROMIOMA. A capacidade dos consórcios microbianos selecionados de biodegradar APAP em meio mineral MSM suplementado com uma concentração de 500 mgL-1 (MSM-APAP (500 mgL-1)), no escuro sob condições de agitação de 160 rpm a 25 °C, foi confirmada por análise de absorbância de UV-vis. Subsequentemente, a etapa de isolamento fez-se a partir de três culturas de enriquecimento sucessivas em MSM-APAP (500 mgL-1) nas condições descritas, por espalhando primeiro em placas de LB-agar e depois em placas de MSM-agar-APAP (500 mgL-1), e resultou em sete isolados potencialmente degradadores de APAP identificados de acordo com análises das sequências do gene ARNr 16S como membros dos géneros Aeromonas, Bacillus (dois isolados), Niallia, Paraburkholderia, Rhizobium e Variovorax. Foi também selecionado um isolado degradador de HQ identificado como Mycolicibacterium sp.. Estes géneros, exceto o Bacillus, são relatados pela primeira vez para a biodegradação de APAP. As análises por HPLC da biodegradação do APAP, em MSM-APAP (500 mgL-1) nas mesmas condições de cultivo, pelos dois Bacillus sp. revelaram que o isolado Bacillus sp. (PDE3.1) mostrou uma percentagem máxima de remoção de APAP de 63±3 após 18 dias, enquanto o isolado Bacillus. sp. (PLC2.1) mostrou apenas 8±1% de remoção no final da experiência. Nenhum dos principais metabólitos da degradação do APAP (HQ e 4-aminofenol) foi detetado por análise de HPLC, no entanto eles foram detetados na análise por GC-MS, ainda que em concentrações baixas, na experiência com o Bacillus sp. PDE3.1, sugerindo que a biodegradação do APAP pode ter ocorrido através da descarboxilação inicial do APAP em 4-aminofenol no qual o grupo amina é depois substituído pelo grupo hidroxilo produzindo-se HQ. Os sete isolados bacterianos potencialmente biodegradadores de APAP foram também testados quanto à biodegradação de APAP em MSM numa concentração mais baixa: 50 mgL-1. Nestes testes, os isolados Rhizobium sp. (PDE3.3) e Paraburkholderia sp.(PLA3.3) pareceram os mais promissores, com com % de remoção de APAP de 49±4 and 47,9±0,9, respectivamente. Posteriormente, uma co-cultura dos três isolados mais promissores (Rhizobium sp. (PDE3.3), Paraburkholderia sp. (PLA3.3) e Bacillus sp. PDE3.1) não melhorou a remoção de APAP em comparação com as culturas de isolados puros, enquanto uma co-cultura com todos os sete isolados potencialmente biodegradadores de APAP não apresentou capacidade degradadora. Por outro lado, o isolado Mycolicbacterium sp. (HPB1.1) revelou pelos menos 88% de remoção de HQ após quatro dias numa experiência em MSM-HQ (50 mgL-1). Portanto, este promissor isolado foi também testado para biodegradação em MSM-APAP (50 mgL-1), tendo sido comprovada a remoção de 41,6±0,1% do APAP inicial com uma concentração residual de 29,34±0,05 mgL-1. Por fim, o isolado Mycolicibacterium sp. (HPB1.1) foi selecionado para trabalhos futuros e foi cultivado em meio LB (pH 7) a 25°C sob condições de agitação (160 rpm) para estudo da cinética de crescimento da cultura ao longo de 68 h, com base na densidade ótica a 600 nm (OD600) de amostras em intervalo de 2 h. As células cresceram exponencialmente sem fase lag visível e o crescimento exponencial, associado ao crescimento mais rápido com coeficiente de determinação R2 de 0,99, estendeu-se até 36 h onde foi alcançado uma OD600 máxima de 1,27. A taxa de crescimento específico μ durante o crescimento exponencial foi calculada como 0,047 h-1. Depois, uma fase de desaceleração ou aceleração negativa de crescimento parece seguir-se ao crescimento exponencial e estender-se das 36 h até às 42 h, onde a fase estacionária parece começar e durar até às 68 h, havendo depois uma diminuição da OD600

    An efficient algorithm for discrete modelling of tracer kinetics

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    AbstractEffective study of certain health care problems and biomedical systems requires development and utilization of duly validated models for characterization of tracer kinetics in compartmental systems. This report presents an efficient algorithm for evaluation of discrete-time models in this context, starting from real patient data. The procedure evolved is systematic and involves parameter identification, model order determination and ascertaining the validity of the model: mathematical techniques proposed for this three-tier approach are robust as well as simple. A method for deriving state-space representations for multicompartmental systems directly from observations vector is also outlined. An illustrative example is given which demonstrates the effectiveness of the algorithm when applied to tracer analysis of the hepatobiliary system. The methodology proposed is recursive in nature such that it can be implemented very conveniently utilizing a microcomputer or even a programmable pocket calculator

    An improved neuroendocrine–proportional–integral–derivative controller with sigmoid-based secretion rate for nonlinear multi-input–multi-output crane systems

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    This paper proposes an improved neuroendocrine–proportional–integral–derivative controller for nonlinear multi-input–multi-output crane systems using a sigmoid-based secretion rate of the hormone regulation. The main advantage of the sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative is that the hormone secretion rate of neuroendocrine–proportional–integral–derivative can be varied according to the change of error. As a result, it can provide high accuracy control performance, especially in nonlinear multi-input–multi-output crane systems. In particular, the hormone secretion rate is designed to adapt with the changes of error using a sigmoid function, thus contributing to enhanced control accuracy. The parameters of the sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative controller are tuned using the safe experimentation dynamics algorithm. The performance of the proposed sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative controller-based safe experimentation dynamics algorithm is evaluated by tracking the error and the control input. In addition, the performances of proportional–integral–derivative and neuroendocrine–proportional–integral–derivative controllers are compared with the proposed sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative performance. From the simulation work, it is discovered that the sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative design provides better control performances in terms of the objective function, the total norm of error and the total norm of input compared to proportional–integral–derivative and neuroendocrine–proportional–integral–derivative controllers. In particular, it is shown the proposed sigmoid-based secretion rate neuroendocrine–proportional–integral–derivative controller contributes 5.12% of control accuracy improvement by changing the fixed hormone secretion rate into a variable hormone secretion rate based on the change of error

    The effect of glufosinate ammonium in three different textured soil types under Malaysian tropical environment

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    Glufosinate ammonium is a broad spectrum, non-selective, contact and organophosphate herbicide which is commonly used in Malaysian oil palm plantations. Research area was one of the oil palm growing areas of Malaysia is located adjacent to the Tasik Chini, Pahang. Farmers use this herbicide to control several types of unwanted plants which could compete with the oil palm for nutrients. Rain water and the sprayed solution are easily adsorbed by soil particles. The glufosinate ammonium sorption was determined by the batch equilibrium technique. The collected soil samples (0-50 cm depth) divided into five groups at 10 cm depth intervals. Glufosinate ammonium adsorption coefficients were correlated with the soil pH, organic matter (OM), clay content, and cation exchange capacity (CEC). Series of glufosinate ammonium standard were as 0.01, 0.1, 0.25, 0.5, 1, 3, 5, and 10 μm/mL. The Linear and Freundlich equations were fitted for obtaining the adsorption and desorption isotherms. The result of the analyses showed that adsorption of glufosinate ammonium was correlated to the clay content. The clay fraction of the soil is the main absorbent of the glufosinate ammonium. Desorption from the soil was indicated by the high binding strength of the adsorbed glufosinate ammonium

    Rice varieties with multiple traits for intensive cropping in the coastal zones of the Ganges

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    EFFECT OF PERMEABLE VESSEL CLOSURE AND GELLING AGENT ON REDUCTION OF HYPERHYDRICITY IN IN VITRO CULTURE OF CARNATION

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    Hyperhydricity, an abnormal morphological appearance and physiologicalfunction, is an important problem in carnation tissue culture. The problem causes premature flowering, high occurrence of abnormal shoots, difficulty in transferring hyperhydric plantlets to soil, and low survival rate of plantlets. High relative humidity and the water potential are considered as the key factors involved in the abnormality. Furthermore, permeable culture vessel and gelling agent were assured to be high potential treatment to eliminate it. Objective of this research was to reduce  hyperhydricity in regenerants of carnation using different permeable vessel closures and gelling agents and to assess the multiplication and  acclimatization abilities of recovered shoots. Experiment was arranged in randomized complete block design with four replications. First factor was different types of closure, i.e. cotton wool, plastic wrap, parafilm and aluminium foil, while second one was gelling agents, i.e. bacto agar, phytagel, swallow agar, and Type 900 agar. The recovered shoots were then multiplied, rooted, and acclimatized. The results showed that hyperhydricity was successfully reduced by applying permeable closure (cotton wool and plastic wrap) in combination with Type 900 agar. The combination of plastic wrap and Type 900 agar was the most appropriate treatment in reducing hyperhydricity and producing good quality shoots. The treatment reduced the problem down to 23% of total condition of hyperhydricity (100%) and increased leaf chlorophyll content from 0.0883 to 0.1288 mg mg-1. The plastic wrap was easily applied and cheaper material compared to cotton wool. The recovered shoots were able to produce 1-3 healthy axillary shoots and easily rooted on half-strength MS. The recovered plantlets were simply acclimatized with survival rate up to 100% on kossas peat + soil (1:1, v/v) and flowered 4-5 months after acclimatization with decreasing in number and size of flower

    Dissipation of chlorpyrifos in a Malaysian agricultural soil: a comparison between a field experiment and simulation by the VARLEACH and PERSIST models

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    A comparison of the dissipation of chlorpyrifos in a Malaysian agricultural soil was undertaken using data from a field experiment and simulation by the PERSIST model. The study was carried out at an oil palm estate located close to the Kuala Lumpur International Airport (KLIA), Sepang, Selangor (for field experiment). The plots were treated with chlorpyrifos at the manufacturer’s recommended dosage. Soil samples were collected according to the sampling schedule at intervals of 0, 1, 3, 7, 14, 21, 30, 60 and 90 days. Residues of chlorpyrifos in soil from the field trial were analyzed in the laboratory. Simulation of chlorpyrifos leaching and persistency was done using two computer-run software VARLEACH and PERSIST. Generally, predicted data for chlorpyrifos residue obtained using the VARLEACH and PERSIST models was found to be well matched with the observed data from the field trial. The PERSIST Prediction for chlorpyrifos residue in soils planted with oil palm trees was found to be accurate and conformed to the results observed in the field trial
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