Bioremediation of polyaromatic hydrocarbons (PAHs) using rhizosphere technology

The remediation of polluted sites has become a priority for society because of increase in quality of life standards and the awareness of environmental issues. Over the past few decades there has been avid interest in developing in situ strategies for remediation of environmental contaminants, because of the high economic cost of physicochemical strategies, the biological tools for remediation of these persistent pollutants is the better option. Major foci have been considered on persistent organic chemicals i.e. polyaromatic hydrocarbons (PAHs) due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity. Rhizoremediation, a specific type of phytoremediation that involves both plants and their associated rhizospheric microbes is the creative biotechnological approach that has been explored in this review. Moreover, in this review we showed the significance of rhizoremediation of PAHs from other bioremediation strategies i.e. natural attenuation, bioaugmentation and phytoremediation and also analyze certain environmental factor that may influence the rhizoremediation technique. Numerous bacterial species were reported to degrade variety of PAHs and most of them are isolated from contaminated soil, however few reports are available from non contaminated soil. Pseudomonas aeruginosa, Pseudomons fluoresens, Mycobacterium spp., Haemophilus spp., Rhodococcus spp., Paenibacillus spp. are some of the commonly studied PAH-degrading bacteria. Finally, exploring the molecular communication between plants and microbes, and exploiting this communication to achieve better results in the elimination of contaminants, is a fascinating area of research for future perspective.(AU)

Growth of tropical tree species and absorption of copper in soil artificially contaminated / Crescimento de espécies arbóreas tropicais e absorção de cobre em solo artificialmente contaminado

Reclamation of copper contaminated sites using forest species may be an efficient alternative to reduce the negative impact. The aim of this study was to quantify the growth and evaluate the quality of seedlings of native species at different doses of copper in the soil. The experimental design was completely randomized, with seven replications in a factorial arrangement (3×9), using three indigenous species of plants (Anadenanthera macrocarpa, Mimosa scabrella and Apuleia leiocarpa) and nine doses of copper in the soil (0, 60, 120, 180, 240, 300, 360, 420 and 480 mg kg–1).The experiment was carried out in a greenhouse which the seedlings were grown for 180 days. The experimental units were plastic pots of 125 cm3 filled with Oxisol. The results indicated that the levels of copper applied to the soil decreased the quality of seedlings and growth of Apuleia leiocarpato a lesser extent compared with Mimosa scabrella and Anadenanthera macrocarpa. Anadenanthera macrocarpa was the forest species that resulted in the lowest copper translocation from roots to shoots. In addition, the Apuleia leiocarpa exhibited high resistance and tolerance for copper in the soil and also, it is highlighted an ability for copper phytoremediation.(AU)

A recuperação de áreas contaminadas com cobre utilizando espécies florestais pode ser uma alternativa eficiente para reduzir o impacto negativo deste elemento nestas áreas. O objetivo deste estudo foi quantificar o crescimento e avaliar a qualidade de mudas de espécies nativas em diferentes doses de cobre no solo. O delineamento experimental foi inteiramente casualizado, com sete repetições, em um esquema fatorial (3×9), utilizando-se três espécies nativas de plantas (Anadenanthera macrocarpa, Mimosa scabrella e Apuleia leiocarpa) e nove doses de cobre no solo (0, 60, 120, 180, 240, 300, 360, 420 e 480 mg kg–1). O experimento foi realizado em casa de vegetação, onde as plantas foram cultivadas por 180 dias. As unidades experimentais foram vasos de plástico de 125 cm3, preenchidos com Latossolo Vermelho distrófico. Os resultados indicaram que o nível de cobre aplicado ao solo reduziu a qualidade de plântulas e crescimento de Apuleia leiocarpa para um menor grau comparado com bracatinga e angico. Anadenanthera macrocarpa foi a espécie florestal que apresentou menor translocação de cobre a parte aérea das mudas. Além disso, a Apuleia leiocarpa exibiu elevada tolerância para o cobre no solo e também destaca-se mostrando uma capacidade para fitoremediação de áreas contaminadas com cobre.(AU)

Evaluation of two Brazilian indigenous plants for phytostabilization and phytoremediation of copper-contaminated soils / Avaliação de duas plantas nativas brasileiras para fitoestabilização e fitorremediação de solos contaminados com cobre

Indigenous plants have been grown naturally and vigorously in copper contaminated soils. Thus, the aim of this study was to evaluate the phytoremediation ability of two indigenous plants naturally grown in two vineyard soils copper contaminated, and in a copper mining waste. However, it was evaluated the macro and micronutrient uptake and the potential of phytoremediation. So, a greenhouse study was carried out with Bidens pilosa and Plantago lanceolata in samples of vineyard soils (Inceptisol and Mollisol) copper contaminated, and in a copper mining waste. Plant growth, macro and micronutrient up take, tolerance index (TI), translocation factor (TF), metal extraction ratio (MER), bioaccumulation factor (BCF), plant effective number of the shoots (PENs), and plant effective number of the total plant (PENt) were analyzed. Both plants grown in vineyard soils showed high phytomass production and TI. P. lanceolata plants cultivated in the Inceptisol showed the highest copper concentrations in the shoots (142 mg kg–1), roots (964 mg kg–1) and entire plants (1,106 mg kg–1). High levels of copper were phytoaccumulated from the Inceptisol by B. pilosa and P. lanceolata with 3,500 and 2,200 g ha–1 respectively. Both B. pilosa and P. lanceolata plants showed characteristics of high copper hyperaccumulator. Results showed that both species play an important role in the natural copper phytoaccumulation in both vineyard soils contaminated with copper, being important to its phytoremediation.(AU)

Plantas nativas crescem naturalmente e vigorosamente em solos contaminados com cobre. Assim, o objetivo deste estudo foi avaliar a capacidade de fitorremediação de duas plantas nativas, naturalmente encontradas em dois solos de vitivinicultura contaminados com cobre, e em rejeito de mineração de cobre. Foram avaliados os teores de macro e micronutrientes nos tecidos das plantas, e o potencial de fitorremediação. Assim, um estudo em casa de vegetação foi realizado com plantas de Bidens pilosa e Plantago lanceolata, com amostras de dois solos de vitivinicultura (Neossolos e Cambissolos) contaminados com cobre, e com rejeito de mineração de cobre. O crescimento das plantas, teores de macro e micronutrientes nos tecidos, índice de tolerância (TI), fator de translocação (TF), taxa de extração do metal (MER), fator de bioacumulação (BCF), número efetivo dos plantas da parte aérea (PENs) e número efetivo de plantas inteiras (PENt) foram analisados. Ambas as espécies cultivadas em solos vitivinicultura mostraram elevada produção de fitomassa e os TI. P. lanceolata cultivadas no Neossolo mostraram as concentrações de cobre mais elevados na parte aérea (142 mg kg–1), nas raízes (964 mg kg–1) e nas plantas inteiras (1.106 mg kg–1). Altos níveis de cobre foram fitoacumulados pelas plantas B. pilosa e P. lanceolata com 3.500 e 2.200 g ha–1, respectivamente, quando cultivadas em Neossolo. Ambas as espécies apresentaram características hiperacumuladoras de cobre. Os resultados mostraram que estas espécies desempenham um papel importante na fitoacumulação de cobre naturalmente em ambos os solos de vitivinicultura contaminados com cobre, sendo importantes para a fitorremediação.(AU)

Biodegradation of kerosene: Study of growth optimization and metabolic fate of P. janthinellum SDX7

Penicillum janthinellum SDX7 was isolated from aged petroleum hydrocarbon-affected soil at the site of Anand, Gujarat, India, and was tested for different pH, temperature, agitation and concentrations for optimal growth of the isolate that was capable of degrading upto 95%, 63% and 58% of 1%, 3% and 5% kerosene, respectively, after a period of 16 days, at optimal growth conditions of pH 6.0, 30 °C and 180 rpm agitation. The GC/MS chromatograms revealed that then-alkane fractions are easily degraded; however, the rate might be lower for branched alkanes, n-alkylaromatics, cyclic alkanes and polynuclear aromatics. The test doses caused a concentration-dependent depletion of carbohydrates of P. janthinellum SDX7 by 3% to 80%, proteins by 4% to 81% and amino acids by 8% to 95% upto 16 days of treatment. The optimal concentration of 3% kerosene resulted in the least reduction of the metabolites of P. janthinellum such as carbohydrates, proteins and amino acids with optimal growth compared to 5% and 1% (v/v) kerosene doses on the 12th and 16th day of exposure. Phenols were found to be mounted by 43% to 66% at lower and higher concentrations during the experimental period. Fungal isolate P. janthinellum SDX7 was also tested for growth on various xenobiotic compounds.(AU)

Effect of arbuscular mycorrhizal fungi on young vines in copper-contaminated soil

Abstract High copper (Cu) levels in uprooted old vineyard soils may cause toxicity in transplanted young vines, although such toxicity may be reduced by inoculating plants with arbuscular mycorrhizal fungi (AMF). The objective of this study was to evaluate the effects of AMF on the plant growth, chlorophyll contents, mycorrhizal colonization, and Cu and phosphorus (P) absorption in young vines cultivated in a vineyard soil contaminated by Cu. Commercial vineyard soil with high Cu levels was placed in plastic tubes and transplanted with young vines, which were inoculated with six AMF species (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus, R. irregularis) and a control treatment on randomized blocks with 12 replicates. After 130 days, the mycorrhizal colonization, root and shoot dry matter (DM), height increment, P and Cu absorption, and chlorophyll contents were evaluated. The height increment, shoot DM and chlorophyll contents were not promoted by AMF, although the root DM was increased by R. clarus and R. irregularis, which had the greatest mycorrhizal colonization and P uptake. AMF increased Cu absorption but decreased its transport to shoots. Thus, AMF species, particularly R. clarus and R. irregularis, contribute to the establishment of young vines exposed to high Cu levels.(AU)