Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

BACKGROUND: Methanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruta et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission. RESULTS: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m−3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. CONCLUSIONS: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.

High-temperature ethanol production using thermotolerant yeast newly isolated from Greater Mekong Subregion

Abstract The application of high-potential thermotolerant yeasts is a key factor for successful ethanol production at high temperatures. Two hundred and thirty-four yeast isolates from Greater Mekong Subregion (GMS) countries, i.e., Thailand, The Lao People's Democratic Republic (Lao PDR) and Vietnam were obtained. Five thermotolerant yeasts, designated Saccharomyces cerevisiae KKU-VN8, KKU-VN20, and KKU-VN27, Pichia kudriavzevii KKU-TH33 and P. kudriavzevii KKU-TH43, demonstrated high temperature and ethanol tolerance levels up to 45 °C and 13% (v/v), respectively. All five strains produced higher ethanol concentrations and exhibited greater productivities and yields than the industrial strain S. cerevisiae TISTR5606 during high-temperature fermentation at 40 °C and 43 °C. S. cerevisiae KKU-VN8 demonstrated the best performance for ethanol production from glucose at 37 °C with an ethanol concentration of 72.69 g/L, a productivity of 1.59 g/L/h and a theoretical ethanol yield of 86.27%. The optimal conditions for ethanol production of S. cerevisiae KKU-VN8 from sweet sorghum juice (SSJ) at 40 °C were achieved using the Box-Behnken experimental design (BBD). The maximal ethanol concentration obtained during fermentation was 89.32 g/L, with a productivity of 2.48 g/L/h and a theoretical ethanol yield of 96.32%. Thus, the newly isolated thermotolerant S. cerevisiae KKU-VN8 exhibits a great potential for commercial-scale ethanol production in the future.

HSF-1, HIF-1and HSP90 expression on recombinant Pichia pastoris under fed-batch fermentation

Pichia pastoris is a methylotrophic yeast used as an efficient expression system for heterologous protein production as compared to other expression systems. Considering that every cell must respond to environmental changes to survive and differentiate, determination of endogenous protein related to heat stress responses and hypoxia, it would necessary to establish the temperature and methanol concentration conditions for optimal growth. The aim of this study is characterize the culture conditions through the putative biomarkers in different conditions of temperature and methanol concentration. Three yeast cultures were performed: 3X = 3% methanol -10 °C, 4X = 3% methanol -30 °C, and 5X = 1% methanol -10 °C. The expression level of HIF-1α, HSF-1, HSP-70 and HSP-90 biomarkers were measured by Western blot and in situ detection was performed by immunocytochemistry. The western blot results of HIF-1α and HSP-90 did not indicate statistically significant in the culture conditions studied. Respect to biomarkers location, HIF-1α and HSP-90 presented differences between cultures. In conclusion, the results suggest the cultures in a hypoxic condition produce a high density and yeast cells smaller. Beside the high density would not necessary related with a high production of recombinant proteins in modified-genetically P. pastoris.

Sugar cane bagasse as feedstock for second generation ethanol production: part II: hemicellulose hydrolysate fermentability

Sugar cane bagasse is produced in Brazil as waste of the sugar and ethanol industries. This lignocellulosic material is a potential source for second-generation ethanol production; however a pretreatment stage is essential, which aims at removing the hemicellulose component by disorganizing the lignocellulosic complex. In this work sugar cane bagasse was pretreated by diluted acid hydrolysis resulting in xylose-rich hydrolysates, which could be fermented to ethanol by a strain of the yeast Pichia stipitis. Statistical approach was used to investigate the effects of factors associated with the diluted acid hydrolysis process (acid concentration, solid:liquid ratio and time of exposure) on the fermentability of different hydrolysates. The statistical analysis was useful for determining the effects of the individual factors and their interactions on the response variables. An acid concentration of 1.09 percent (v/v), a solid:liquid ratio of 1:2.8 (g:ml), and an exposure time of 27 min were established and validated as the optimum pretreatment conditions for ethanol production from hemicellulose hydrolysates of sugar cane bagasse. Under these conditions, a hydrolysate with 50 g/l of xylose, 6.04 g/l of acetic acid, 0.55 g/l of hydroxylmethylfurfural and 0.09 g/l of furfural was obtained and its fermentation yielded roughly 20 g/l of ethanol in 40 hrs.

Influenza de la concentración de oxígeno en la producción de etanol a partir de la fermentación de mezclas D-glucosa/D-xilosa e hidrolizados de aserrín de Curupaú por Pichia stipitis CBS 5773 / Influence of oxygen concentration in ethanol production by Pichia stipitis CBS 5773 through fermentation of D-glucose/D-sylose mixtures and Curupaú hydrolyzed

El aserrin de Curupaú, un residuo de la industria maderera en Bolivia, es un substrato potencial para la producción de etanol de segunda generación.

Removal of arsenic from an aqueous solution by pretreated waste tea fungal biomass

Arsenic contamination in water poses a serious threat on human health. The tea fungus known as Kombucha is a waste produced during black tea fermentation. The objective of this study was to examine the main aspect of a possible strategy for the removal of arsenates employing tea fungal biomass. The pretreatment of biomass with FeCl3 was found to improve the biosorption efficiency. Arsenics uptake was found to be rapid for all concentrations and reached to 79% of equilibrium capacity of biosorption in 20 min and reached equilibrium in 90 min. The pseudo second-order and first-order models described the biosorption kinetics of As [V] with good correlation coefficient [R2>0.93] and better than the other equations. The data obtained from the experiment of biosorption isotherm were analyzed using the Freundlich and Langmuir isotherm models. The equation described the isotherm of As [V] biosorption with relatively high correlation coefficient [R2>0.93]. According to the Langmuir model, the maximum uptake capacities [qm] of tea fungal biomass for As [V] were obtained 3.98 +/- 10-3 mmol/gr. The effect of Na+, K+, Mg+2 and Ca+2 on equilibrium capacities of As was not significant. The variation of sorption efficiency with pH showed that optimum biosorption takes place in the pH ranges of 6 to 8. Promising results were obtained in laboratory experiments and effective As [V] removals were observed

Biological values of pichia pinus protein and dietary fibre of mango wastes in rats

Pichia pinus was grown in a semi-solid state fermentation process on mango wastes. The bioconversion can be carried out to produce protein which enriched mango wastes to be used as animal food. The nutritive values of Pichia pinus protein and mango waste dietary fibers at zero time [M1] and after 60 hour of fermentation [M2] were studied using the experimental animals. Rats were fed on three different diets [control and two experimental diets] exhibited good nutritional values during the first four weeks. Then, these values began to decrease with increasing the time of feeding period in cases of those fed on experimental diets [II and III]. The results also showed a highly significant decrease in the level of glucose in the sera and glycogen contents in the liver and muscle of rats fed diets II and III over the control diet I, especially after eight weeks of feeding

The ionic character of the environment in the flocculation of Pichia sptipitis

Embora células de uma linhagem floculante de Pichia stipitis tornaram-se completamente dispersas após lavagens com água destilada, essas mesmas células reflocularam quando suspensas em soluçöes de componentes individuais do meio. A força iônica de tais soluçöes foi suposta ser a causa primária do fenômeno. A medida da condutividade elétrica mostrou ser um modo prático de avaliar a força iônica do meio ambiente. A floculaçäo foi mais intensa quanto maior o valor da condutividade elétrica das soluçöes, atingindo o seu ótimo e permanecendo praticamente constante para valores de condutividade elétrica acima de 1000s. Isto sugere que reduçäo de cargas associadas a mudanças conformacionais na estrutura das proteínas da parede celular tenham sido responsáveis pela agregaçäo de células. Adicionalmente, uma diminuiçäo da condutividade elétrica do meio, através de diálise, reduziu a habilidade das células de flocular. O caráter iônico do meio mostrou ser um importante fator influenciador na floculaçäo