White rot fungi capable of decolourising textile dyes under alkaline conditions

Four different white rot fungi were screened to study the decolourisation of the textile dyes Reactive Black 5 (RB5) and Poly R-478 on plates under alkaline condition. Three strains of Trametes versicolor (MUM 94.04 MUM 04.100 MUM 04.101) and one strain of Phanerochaete chrysosporium (MUM 94.15), showed better decolourisation results. The strains were used for decolourisation study in liquid culture medium (LCM). All four strains presented more efficient decolourisation on dye RB5, but they differed in decolourisation capacity depending on the analised pH value. In LCM the decolouration of dye reached 100% for the two strains of WRF studied

Utilization of white rot fungi for textile dye decolourisation under alkaline condition and high salt concentration in solid medium

A large amount of azo dyes are used for dyeing textiles. However, the dyes contaminate wastewaters and need to be treated. This is important because of the aesthetic, toxic and carcinogenic effects of the affected waters. Recently there has been an increase in interest in using white rot fungi (wrf) which degrade xenobiotic compounds including azo dyes. Wrf degrade lignin and others recalcitrant molecules using nonspecific extracellular enzymes. Four white rot fungi obtained from the Micoteca da Universidade do Minho (MUM) culture collection were used to screen for degradability capabilities. Reactice Black 5 (RB5) was selected in the present work because these dyes are most commonly used in the textile dyeing. Screening for RB5 decolourisation was carried out on solid medium in plates. Two wrf showed good growth and decolourisation abilities. These are now under study to determine which ligninolytic enzymes are produced

White-rot fungi capable of decolourising textile dyes under alkaline conditions

Twelve white-rot fungal strains belonging to seven different species were screened on plates under alkaline condition to study the decolourisation of the textile dyes Reactive Black 5 and Poly R-478. Three strains of Trametes versicolor (Micoteca da Universidade do Minho (MUM) 94.04, 04.100 and 04.101) and one strain of Phanerochaete chrysosporium (MUM 94.15) showed better decolourisation results. These four strains were used for decolourisation studies in liquid culture medium. All four selected strains presented more efficient decolourisation rates on Reactive Black 5 than on Poly R-478. For both dyes on solid and liquid culture media, the decolourisation capability exhibited by these strains depended on dye concentration and pH values of the media. Finally, the decolourisation of Reactive Black 5 by T. versicolor strains MUM 94.04 and 04.100 reached 100 %. In addition, the highest white-rot fungi ligninolytic enzyme activities were found for these two strains

Descoloração de corantes têxteis por fungos ligninolíticos em condições de pH e salinidade elevada

Tese de doutoramento em Engenharia Quimica e BiológicaO principal objetivo deste trabalho consistiu em selecionar e avaliar diferentes estirpes de fungos da podridão branca da madeira (Fpb) quanto à capacidade de descoloração, em condições similares às apresentadas na indústria têxtil, utilizando o corante azo Reativo Preto 5 (RP5). O corante Poly R-478 (PR478) foi utilizado como parâmetro comparativo por ser considerado um indicador da atividade de enzimas existentes no sistema ligninolítico dos Fpb. O trabalho inicial foi realizado com doze estirpes de Fbp em meio de cultura sólido e permitiu a seleção das estirpes aptas em descolorir estes corantes em condições restritivas. A extensão da descoloração dos dois corantes e a atividade das enzimas ligninolíticas envolvidas neste processo foram avaliadas, utilizando-se as estirpes Trametes versicolor MUM 94.04, 04.100 e 04.101 para além da estirpe modelo de estudo Phanerochaete chrysoporium MUM 94.15 (ATCC 24725), em meio de cultura líquido (MCL) alcalino sob agitação. As estirpes T. versicolor MUM 94.04 e MUM 04.100 apresentaram uma taxa de descoloração de 100 % em MCL na presença do corante RP5. Definido o valor de pH, foram realizados novos ensaios com diferentes concentrações de NaCl adicionado à composição do MCL com o corante RP5. Os melhores resultados de descoloração e atividade enzimática foram obtidos em MCL contendo 15 g·l-1 de NaCl na sua composição, onde a estirpe T. versicolor MUM 04.100 foi a única que apresentou uma taxa de descoloração de 100 %. Esta estirpe apresentou atividade de lacase (Lcc) e lignina-peroxidase (LiP) em valores superiores aos obtidos nas melhores condições de alcalinidade. Em MCL agitado e com os parâmetros pH e concentração de NaCl otimizados, comparou-se a capacidade da estirpe T. versicolor imobilizada em dois suportes sintéticos: espuma de poliuretano (EPO) e esponja de “nylon” (EN), com os resultados obtidos com células livres. Esta estirpe imobilizada em EPO e EN manteve uma taxa de descoloração do corante RP5 igual ou superior a 85 % por 18 (6 ciclos) e 21 (7 ciclos) dias. A ampliação da escala neste estudo foi feita em dois tipos de reatores: de leito fixo e de bancada. O conjunto de experimentos realizados no reator de leito fixo com células livres e imobilizadas proporcionou uma taxa de descoloração de 100 %. A adição de glicerol ao meio de cultivo promoveu uma maior atividade da enzima lacase. Em contrapartida, o controle rígido do pH nos ensaios com reator de bancada denotou a inibição do microrganismo, necessitando-se assim uma maior investigação dos parâmetros de operação. Além disso, verificou-se que indução da expressão genética da lacase foi superior quando o MCL possuía glicerol como co-substrato. Em conclusão, os excelentes resultados obtidos com a estirpe T. versicolor MUM 04.100, proporcionará boas perspectivas futuras quanto a estudos de avaliação dos mecanismos metabólicos e de compostos intermediários que são formados a partir deste corante. Do mesmo modo, o aprofundamento do estudo do processo degradativo do corante com esta estirpe poderá ser avaliado com fontes alternativas de carbono, que poderão potencializar a síntese e consequente aumento da atividade enzimática Lcc.The main goal of this work was to select and evaluate different strains of white rot fungi (Wrf) to the capability to decolourise azo dyes in similar conditions to those presented in the textile industry, using the Reactive Black 5 (RB5). The dye Poly R-478 (PR478) was used as a comparative parameter for being considered as an indicator of the activity of the ligninolytic system of the Wrf. The initial assays were performed with twelve strains of Wrf in solid medium which allowed the selection of strains able to decolourise these dyes in restringent conditions. The extension of the decolourisation for both dyes and the activity of the ligninolytic enzymes involved in this process were evaluated, using the strains Trametes versicolor MUM 94.04, 04.100 and 04.101, and the Phanerochaete chrysoporium MUM 94.15 (ATCC 24725) as reference strain, in alkaline liquid culture medium (LCM) under stirring conditions. The strains T. versicolor MUM 94.04 and MUM 04.100 showed a decolourising rate of 100 % in LCM with the presence of RB5. A optimal value of pH was defined and new assays were made with different concentrations of NaCl added to the composition of the MCL with the dye RB5. The best decolourising results and the enzymatic activity were obtained in MCL containing 15g·l-1 of NaCl in its composition, where the strain T. versicolor MUM 04.100 presented a decolourising rate of 100 %. This strain presented higher values of laccase (Lcc) and lignin-peroxidase (LiP) activity when compared to those obtained in the best alkaline conditions. In stirred MCL with RB5 and under optimised parameters of pH and NaCl, the capacity of the immobilised strain in two synthetic carriers, polyurethane foam (EPO) and nylon sponge (EN), to decolourise the dye was studied and compared with the results obtained for the free cell cultures. This strain, immobilized in EPO and EN maintained a decolourising rate, for the dye RB5, equal or higher than 85 % for 18 (6 cycles) and 21 (7 cycles) days. The scale-up of this assay was performed using two types of reactors: fixed bed and stirred tank. The set of assays performed in the fixed bed reactor with free and immobilized cells provided a decolourising rate of 100 %. The addition of glycerol to the medium promoted a higher activity of laccase. However, the pH control on the assays with the stirred tank denoted the inhibition of the microorganism, thus requiring further research of the operation parameters. Moreover, it was found that the induction of the genic expression of the laccase was higher when using MCL with glycerol as a co-substrate. In conclusion, the excellent results obtained with strain T. versicolor MUM 04.100 will provide future prospects for studies of metabolic pathways and intermediates meatabolites that are formed from this dye under biodegradation conditions. Additionally, further study of degradation process of the dye with this strain can be assessed with alternative sources of carbon, which may stimulate the synthesis and consequent increase the Lcc activity

Metagenomic analysis of dental calculus in ancient Egyptian baboons

Dental calculus, or mineralized plaque, represents a record of ancient biomolecules and food residues. Recently, ancient metagenomics made it possible to unlock the wealth of microbial and dietary information of dental calculus to reconstruct oral microbiomes and lifestyle of humans from the past. Although most studies have so far focused on ancient humans, dental calculus is known to form in a wide range of animals, potentially informing on how human-animal interactions changed the animals' oral ecology. Here, we characterise the oral microbiome of six ancient Egyptian baboons held in captivity during the late Pharaonic era (9th-6th centuries BC) and of two historical baboons from a zoo via shotgun metagenomics. We demonstrate that these captive baboons possessed a distinctive oral microbiome when compared to ancient and modern humans, Neanderthals and a wild chimpanzee. These results may reflect the omnivorous dietary behaviour of baboons, even though health, food provisioning and other factors associated with human management, may have changed the baboons' oral microbiome. We anticipate our study to be a starting point for more extensive studies on ancient animal oral microbiomes to examine the extent to which domestication and human management in the past affected the diet, health and lifestyle of target animals

Effect of different carbon sources on decolourisation of an industrial textile dye under alkaline-saline conditions

White-rot fungal strains of Trametes versicolor and Phanerochaete chrysosporium were selected to study the decolourisation of the textile dye, Reactive Black 5, under alkaline–saline conditions. Free and immobilised T. versicolor cells showed 100 % decolourisation in the growth medium supplemented with 15 g l-1 NaCl, pH 9.5 at 30 C in liquid batch culture. Continuous culture experiments were performed in a fixed-bed reactor using free and immobilised T. versicolor cells and allowed 85–100 % dye decolourisation. The immobilisation conditions for the biomass and the additional supply of carbon sources improved the decolourisation performance during a long-term trial of 40 days. Lignin peroxidase, laccase and glyoxal oxidase activities were detected during the experiments. The laccase activity varied depending on carbon source utilized and glycerol-enhanced laccase activity compared to sucrose during extended growth