Exopolysaccharyde production by Cryptococcus laurentii SD7 using molasses and corn steep liquor as substrates / Exopolysaccharyde production by Cryptococcus laurentii SD7 using molasses and corn steep liquor as substrates

Microbial polysaccharides are of great biotechnological and commercial interest and have wide application in the food, cosmetic and medicine industries. Exopolysaccharide (EPS) production by the yeast Cryptococcus laurentii SD7, isolated from fresh water molluscs, was studied using agro-industrial byproducts as substrates in the submerged fermentation. The Central Composite Design (CCD) 23 was used to study the influence of pH, different concentrations on sugarcane molasses and corn steep liquor (CSL), for 48 hours. According to the results, the highest EPS production occurred at the initial pH 5 and at 8.4% concentration of sugarcane molasses, which were statistically significant variable at 10% (p < 0.1). The concentration of CSL had no influence in the studied range, thus, it can be used lowest concentration (0.3%). The time course of EPS production showed that while cell growth peaked within 48 hours, the highest EPS production (6.61 g L-1) occurred at 168 hours, with a productivity of about 0.04 g L-1 h-1. The pH of the medium remained approximately constant throughout the fermentation process. The yeast C. laurentii SD7 showed great potential for EPS production at a low cost and with sustainable substrates.

Microbial polysaccharides are of great biotechnological and commercial interest and have wide application in the food, cosmetic and medicine industries. Exopolysaccharide (EPS) production by the yeast Cryptococcus laurentii SD7, isolated from fresh water molluscs, was studied using agro-industrial byproducts as substrates in the submerged fermentation. The Central Composite Design (CCD) 23 was used to study the influence of pH, different concentrations on sugarcane molasses and corn steep liquor (CSL), for 48 hours. According to the results, the highest EPS production occurred at the initial pH 5 and at 8.4% concentration of sugarcane molasses, which were statistically significant variable at 10% (p < 0.1). The concentration of CSL had no influence in the studied range, thus, it can be used lowest concentration (0.3%). The time course of EPS production showed that while cell growth peaked within 48 hours, the highest EPS production (6.61 g L-1) occurred at 168 hours, with a productivity of about 0.04 g L-1 h-1. The pH of the medium remained approximately constant throughout the fermentation process. The yeast C. laurentii SD7 showed great potential for EPS production at a low cost and with sustainable substrates.

Levedura Pichia kudriavzevii SD5 como biocatalizador na descoloração do corante Preto Reativo 5 / Pichia kudriavzevii yeast as biocatalizer in Reactive Black 5

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.

Descoloração do corante Azul Brilhante de Remazol R por leveduras isoladas de moluscos do Rio Subaé, no estado da Bahia, Brasil / Decolorization of Remazol Brilliant Blue R dye by yeasts isolated from molluscs of the Subaé River (Bahia, Brazil)

RESUMO Os objetivos deste trabalho foram estudar o potencial de descoloração do corante Azul Brilhante de Remazol R (RBBR) por cinco isolados de leveduras identificados como OJU2, SJL6, SF5, SJ10 e SJU5, otimizar as condições de crescimento das leveduras e verificar a toxicidade do produto obtido após a descoloração. Para isso, foram realizados ensaios em batelada variando os seguintes parâmetros: pH (2 a 8), concentração de glicose (0 a 3%), concentração do corante (25 a 100 ppm) e temperatura (20 a 40ºC). As leveduras mostraram capacidade de descolorir o RBBR com eficiência entre 80 e 93%, depois de 24 horas. A melhor condição para descoloração do RBBR ocorreu em pH ácido, 2% de glicose, 25 ppm do corante e 25ºC. Com os ensaios com Artemia salina, foi observado diminuição da toxicidade após tratamento com os isolados SJ10 e SJU5, depois de 120 horas de incubação.

ABSTRACT This research aimed to study the potential for decolorization of the Brilliant Blue dye Remazol R (RBBR) by five yeasts, identified as OJU2, SJL6, SF5, SJ10 and SJU5, optimize the conditions of growth of these yeasts and verify the toxicity of the product obtained after decolorization. For this purpose, tests were performed in batch in varying parameters: pH (2 to 8), glucose concentration (0 to 3%), dye concentration (25 to 100 ppm) and temperature (20 to 40ºC). The yeasts showed ability to decolorize RBBR by biodegradation with rates ranging between 80 and 93% after 24 hours. The optimal conditions for decolorization were acid pH, glucose 2%, 25 ppm dye concentration and 25ºC. After the toxicity tests with Artemia salina, decreased toxicity was observed following treatment with isolated SJU5 and SJ10, after 120 hours incubation.

Aerobic decolorization of azo dye orange g by a new yeast isolate Candida cylindracea SJL6 / Descoloração aeróbica do azo corante alaranjado g por um novo isolado da levedura Candida cylindracea SJL6

Biodecolorization of the azo dye Orange G was investigated using a new strain of Candida cylindracea SJL6, isolated from freshwater samples of the Subaé river in Bahia state, Brazil. Strain SJL6 was identified as C. cylindracea on the basis of 26S rDNA region. The various parameters of dye decolorization and cell growth were studied, including the Orange G dye concentration (100 to 500 ppm), temperature (20 to 40 °C), glucose concentration (0 to 5%), and initial pH (3 to 8). Biotoxicity tests were performed using shrimp (Artemia salina) to determine the lethal concentration (LC50) and onion bulbs (Allium cepa) to determine the cytotoxic and genotoxic effects of both Orange G dye and metabolites formed after decolorization. Up to 90% of decolorization of the Orange G dye at 500 ppm was achieved by C. cylindracea SJL6 at 30 °C, pH 3, and 1% glucose. However, the biotoxicity tests showed that there was increased toxicity after decolorization, suggesting partial Orange G dye degradation and production of toxic metabolites.

A biodescoloração do corante Alaranjado G foi investigada utilizando um novo isolado de Candida cylindracea SJL6, isolado de amostras de água do Rio Subaé, Bahia, Brasil. A linhagem SJL6 foi identificada como Candida cylindracea com base na região 26S do rDNA. Os parâmetros estudados na descoloração do corante e crescimento celular foram: concentração do Alaranjado G (100 a 500 ppm), temperatura (20 a 40 ºC), concentração de glicose (0 a 5%) e pH inicial (3 a 8). Os testes de biotoxicidade foram realizados utilizando o microcrustáceo Artemia salina para determinar a concentração letal (L50) e bulbos de cebola (Alium cepa) para determinar os efeitos citotóxicos e genotóxicos tanto do corante alaranjado G quanto dos metabólitos produzidos após a descoloração. Uma taxa de descoloração acima de 90% foi atingida a 500 ppm por C. cylindracea SJL6 a 30 ºC, pH 3 e 1% de glicose. Entretanto, os testes de biotoxicidade mostraram que ocorreu um aumento da toxicidade após a descoloração, o que sugere uma degradação parcial da molécula do corante Alaranjado G e produção de metabólitos tóxicos.

Agave syrup as a substrate for inulinase production by Kluyveromyces marxianus NRRL Y-7571 / Xarope de agave como substrato para produção de inulinase por Kluyveromyces marxianus NRRL Y-7571

The factorial planning was used to plan and optimize inulinase production by the yeast Kluyveromyces marxianus NRRL Y-7571. The experiments were conducted using a Central Composite Design (CCD) 22, at different concentrations of agave syrup (3.6 to 6.4%) and yeast extract (2.2 to 3.0%). After 96 hours of fermentation, the best condition for the inulinase production was 5% agave syrup and 2.5% yeast extract, which yielded an average of 129.21 U mL-1 of inulinase. Partial characterization of the crude enzyme showed that the optimal pH and temperature were 4.0 and 60°C, respectively. The enzyme showed thermal stability at 55°C for 4 hours.

O planejamento fatorial foi utilizado para planejar e otimizar a produção de inulinase pela levedura Kluyveromyces marxianus NRRL Y-7571. Os experimentos foram conduzidos por meio de Delineamento Composto Central Rotacional (DCCR) 22 em diferentes concentrações de xarope de agave (3,6 a 6,4%) e extrato de levedura (2,2 a 3,0%). Depois de 96 horas de fermentação, a melhor condição para produção de inulinase foi xarope de agave 5% e extrato de levedura 2,5%, com uma produção média de 129,21 U mL-1. A caracterização parcial do extrato enzimático bruto mostrou que a enzima apresenta pH e temperatura ótimos de 4,0 e 60oC, respectivamente. A enzima mostrou estabilidade térmica a 55oC durante 4 horas.

A new alkalophilic isolate of Bacillus as a producer of cyclodextrin glycosyltransferase using cassava flour

Abstract Cyclodextrin glycosyltransferase (CGTase) catalyzes the conversion of starch into non-reducing cyclic sugars, cyclodextrins, which have several industrial applications. This study aimed to establish optimal culture conditions for β-CGTase production by Bacillus sp. SM-02, isolated from soil of cassava industries waste water lake. The optimization was performed by Central Composite Design (CCD) 2, using cassava flour and corn steep liquor as substrates. The maximum production of 1087.9 U mL−1 was obtained with 25.0 g L−1 of cassava flour and 3.5 g L−1 of corn steep after 72 h by submerged fermentation. The enzyme showed optimum activity at pH 5.0 and temperature 55 °C, and maintained thermal stability at 55 °C for 3 h. The enzymatic activity was stimulated in the presence of Mg+2, Ca+2, EDTA, K+, Ba+2 and Na+ and inhibited in the presence of Hg+2, Cu+2, Fe+2 and Zn+2. The results showed that Bacillus sp. SM-02 have good potential for β-CGTase production.

A new alkalophilic isolate of Bacillus as a producer of cyclodextrin glycosyltransferase using cassava flour.

Cyclodextrin glycosyltransferase (CGTase) catalyzes the conversion of starch into non-reducing cyclic sugars, cyclodextrins, which have several industrial applications. This study aimed to establish optimal culture conditions for ß-CGTase production by Bacillus sp. SM-02, isolated from soil of cassava industries waste water lake. The optimization was performed by Central Composite Design (CCD) 2, using cassava flour and corn steep liquor as substrates. The maximum production of 1087.9UmL(-1) was obtained with 25.0gL(-1) of cassava flour and 3.5gL(-1) of corn steep after 72h by submerged fermentation. The enzyme showed optimum activity at pH 5.0 and temperature 55°C, and maintained thermal stability at 55°C for 3h. The enzymatic activity was stimulated in the presence of Mg(+2), Ca(+2), EDTA, K(+), Ba(+2) and Na(+) and inhibited in the presence of Hg(+2), Cu(+2), Fe(+2) and Zn(+2). The results showed that Bacillus sp. SM-02 have good potential for ß-CGTase production.

Influence of high osmotic pressure on sorbitol production by Zymomonas mobilis

The objective of the present work was to study the variation on the sorbitol production in relation to the concentration of sugars, (metabolizable or not) and the cultivation time. A full factorial design was used considering the factors such as sucrose and maltose concentration and cultivation time. The addition of sugars caused increases on the sorbitol production up to the concentration of 300g/L however, decreases on the sorbitol production were observed when the concentration reached values above this. Increasing the time of fermentation was statistically significant to sorbitol production, however, little increase the production was noticed after 36h.

Zymomonas mobilis produz o poliálcool sorbitol como principal subproduto. Sua formação é atribuída principalmente a sua função A produção de sorbitol foi avaliada através de um planejamento fatorial completo utilizando as variáveis concentração de sacarose, concentração de maltose e tempo de cultivo. A adição de açúcares causou um aumento na produção de sorbitol até a concentração de 300g/L, porém decréscimos na produção de sorbitol foram observados a concentrações superiores a esta. Aumento no tempo de fermentação foi estatisticamente significativo para aumentos da produção de sorbitol, porém pequeno aumento foi observado de 12 para 36 horas de cultivo.

Effects of culture conditions on the production of inulinase by Kluyveromyces marxianus

The present study was conducted to investigate the influence of initial sucrose concentration, pH and aeration rate on biomass and inulinase production by Kluyveromyces marxianus var. bulgaricus in a stirred batch reactor. Maximum inulinase activity (15.29 UmL-1) was obtained at a sucrose concentration of 10 g L-1, pH 5.0 and aeration rate of 1 vvm. The 20 g L-1 sucrose concentration was suitable for cell growth; however, enzymatic activity at this concentration was inhibited due to catabolic repression. The increase in aeration rate caused a reduction in enzyme activity with no relevant biomass increase.

O estudo foi conduzido para investigar a influência da concentração inicial da sacarose, a taxa da aeração e do pH na biomassa e na produção da inulinase pela Kluyveromyces marxianus var. bulgaricus em um reator em batelada. A máxima atividade de inulinase, 15.29 UmL-1, foi obtida na concentração de 10 g L-1 de sacarose, no pH 5.0 e na taxa da aeração de 1 vvm. A concentração de sacarose de 20g L-1 foi apropriada para o crescimento celular, porém nesta concentração a atividade enzimática foi inibida, devido a repressão catabólica. O aumento na taxa da aeração propiciou redução da atividade enzimática, ao mesmo tempo em que não houve aumento considerável do biomassa.