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RESUMO As leveduras vêm apresentando bons resultados na biodegradação de corantes, tornando-se uma alternativa ambientalmente segura e de custo mais baixo para o tratamento de efluentes contendo corantes industriais. Assim, o objetivo deste trabalho foi estudar a descoloração do azo corante Preto Reativo 5 (PR5) pela levedura Pichia kudriavzevii SD5. Para otimização dos parâmetros de descoloração do Preto Reativo 5 foram realizados dois planejamentos experimentais do tipo Delineamento Composto Central Rotacional (DCCR) 23, sendo cada planejamento composto por 17 ensaios, a 150 rpm durante 24 h. As variáveis estudadas foram pH, temperatura e concentração do corante e tiveram como resposta a porcentagem de descoloração. Também foram realizados testes de toxicidade do sobrenadante após 16 h e 24 h de cultivo, utilizando-se sementes de alface (Lactuca sativa) e o microcrustáceo Artemia salina. Os resultados mostraram que a P. kudriavzevii SD5 é uma levedura tolerante a vários tipos de estresse, uma vez que apresentou capacidade de degradar elevadas concentrações do corante PR5 a 45° C. Entretanto, apenas a temperatura apresentou influência estatisticamente significativa (p < 0,05) na descoloração do PR5. Os bioensaios de toxicidade demonstraram que ocorreu diminuição da toxicidade após 24 h de cultivo, e o perfil de absorbância do sobrenadante apontou para um mecanismo degradativo de descoloração.
ABSTRACT Yeasts have been showing good results in the biodegradation of industrial dyes, becoming an environmentally safe and cost-effective alternative for the treatment of effluents containing industrial dyes. Thus, the objective of this work was to study the discoloration of the Reactive Black 5 (RB5) azo dye by the yeast Pichia kudriavzevii SD5. Two experimental designs were employed to optimize the discoloration parameters by means of Central Composite Design (CCD) 23, totalizing 17 trials each, at 150 rpm for 24 h. The studied independent variables were pH, temperature, and concentration of the dye and the outcome parameter was the rate of decolorization (%). Furthermore, the toxicity bioassays of the supernatant after 16 and 24 h of the culture were carried out using lettuce seeds (Lactuca sativa) and the microcrustacean Artemia salina. Results showed that P. kudriavzevii SD5 is a multi-stress tolerant yeast, being capable to degrade high concentrations of RB5 at 45° C. However, only the temperature showed statistical significance (p < 0.05) for dye discoloration. Toxicity bioassays demonstrated that toxicity decreased after 24 h of culture and the absorbance profile of the supernatant pointed to a degradative mechanism of discoloration.
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Objective To establish a rapid diagnosis method for the biological toxicity of soil, accurately and rapidly evaluate the toxicity of contaminated sites and identify the dominant pollutants. Methods Take the soil pollution of a galvanized factory as an example, while the metal concentration level was analyzed and detected, a rapid biological toxicity detection method based on the acute toxicity test of luminescent bacteria （Vibrio qinghaiensis sp.-Q67） was established, and the dominant pollutants were identified by stepwise multiple regression. Results The pollutants came from wastewater and metal plating fragments directly discharged from the manufacturing line of the factory. The concentration of those pollutants was correlated with the acute toxicity of Vibrio qinghaiensis sp.-Q67. The dominant pollutants in the study were zinc （Zn）, aluminum （Al） and copper （Cu）. Conclusion The luminescent bacteria toxicity test method based on Vibrio qinghaiensis sp.-Q67 can conveniently and rapidly assess the degree of toxic damage of polluted soil and identify the dominant pollutants and can be applied to the acute toxicity evaluation of polluted soil.
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Luminescence , Vibrio , WastewaterABSTRACT
Objective: To investigate the removal effect of 5 kinds of common flocculants on 6 kinds of toxic alkaloids in processing wastewater of Aconiti Radix. Method: HPLC was employed to determine contents of 6 kinds of alkaloids in the processing wastewater of Aconiti Radix before and after flocculation.The mobile phase consisted of acetonitrile-tetrahydrofuran(25:15)-0.1 mol·L-1 ammonium acetate solution(each 1 L contains 0.5 mL of glacial acetic acid) for gradient elution, volume flow rate was 1.0 mL·min-1, detection wavelength was 235 nm.The removal characteristics and effects of five common flocculants of ferric chloride, aluminum sulfate, polymeric ferric sulfate, polyaluminum chloride/polyacrylamide(PAC/PAM) and sodium polyacrylate were compared and preliminarily optimized. Result: The 5 kinds of flocculants had certain selectivity for different types of alkaloids, and the removal of 6 kinds of alkaloids showed obvious differences.Among them, the PAC/PAM attenuated relative superiority, when the pH 6, adding amount of 0.25 g·L-1 and PAC-PAM dosing ratio of 30:1, comprehensive removal effect was relatively good, removal rates of mesaconitine and hypaconitine was 85.4%and 58.3%, respectively. Conclusion: The flocculation method can be used as a pretreatment process to reduce the toxicity of processing wastewater of Aconiti Radix.
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The impact of environmental pollution, especially chronic low exposures of heavy metals (Pb, Cd, Hg, As, Cr, etc.) on nutritional status and health of human and livestock, has become a cause of concern. It is established that malnutrition inhibits enzyme system, alters neurotransmitter levels, degenerate myelin, glial and neural elements, lowering of IQ scores as well as impairment of fine and gross motor coordination. Chronic low-level exposure to heavy metals also results in similar type of deformities at sub-clinical level. However, additive impact of undernutrition and adverse effects of heavy metal exposure is emerging as a serious threat to health in developing countries. High blood Pb/Cd levels and low nutrient levels cause subclinical damage of organ system such as haemopoietic, renal, nervous systems in neonates, children, post-partum women, and occupationally exposed population. This could be due to chronic low-level heavy metal exposures and vis-à-vis interaction between pollutants and nutrients. Our studies are focused on the utility of biomarkers for early subclinical detection of haemopoietic and rental toxicity. Lead exposure from non-conventional sources such as toys, pet/glass bottles, etc. suggest long-term investigation. The present review compiles result of studies conducted in this area highlighting the importance of pollution-nutrition interaction. This may facilitate policymakers on developing the strategies to counter the heavy metal exposure of humans/livestock and their consequences.
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Objective To evaluate the biological toxicity of heavy metals by using Caenorhabditis elegans. Methods The C. elegans at L4 stage were exposed to CdCl2 CrCl3 As2O3 PbCl2 HgCl2 with low concentrations and M9 buffer the control group for 72 h respectively and the effects of heavy metals with different concentrations on the survival time and reproduction of C. elegans were evaluated. Results After exposure to 2.5 10μmol/L HgCl2 and PbCl2 10μmol/L CdCl2 and 50μmol/L CrCl3 for 72 h respectively the life spans and survival curves of the C. elegans were different from those in the control group the differences were statistically significant all P<0.05 . After exposure to CdCl2 CrCl3 As2O3 PbCl2 and HgCl2 with the con?centrations of 2.5 50 100μmol/L for 72 h respectively the generational time and brood size of C. elegans were all different from those in the control group all P<0.01 . Among the 5 heavy metals at low concentrations the reproduction toxicity of Hg was bigger than Pb Cd Cr and the toxicity of As was the weakest. Conclusion Heavy metal exposure can affect the life span and reproductive toxicity of C. elegans.