Abstract This work investigated the ability of a recently isolated strain of Candida guilliermondii to convert hexoses and pentoses obtained from acid-enzymatic soybean hull hydrolysates into ethanol and, in smaller amounts, into xylitol. Operational conditions and media formulation were optimized concerning ethanol production using experimental designs (Plackett-Burman and Central Composite Design). Results showed that C. guilliermondii BL 13 was capable of growing in non-supplemented, non-detoxified biomass hydrolysates, and the best culture conditions were determined to be 28 °C, pH 5.0, and 109 CFU mL-1 of inoculum size. Ethanol productivity reached 1.4 g L-1 h-1, and maximal yields of 0.41 g g-1 were obtained, representing 80.4 % of the expected theoretical yields, whereas small amounts of xylitol were also produced. These results suggest that C. guilliermondii BL13 is a potentially useful yeast strain to be applied in second-generation ethanol production from lignocellulosic biomass based on its natural capacity to metabolize C-5 and C-6 sugars.

RESUMO Um experimento em campo foi conduzido por dois anos consecutivos, a fim de estudar o efeito de diferentes densidades de Parthenium (0, 2, 4, 6, 8, 10, 12, 14 e 16 plantas m-2) sobre os componentes de produção e produtividade de sorgo forrageiro, bem como seu nível de dano econômico. O experimento foi realizado durante o verão, em delineamento de blocos completos (DBC) com quatro repetições. Os resultados mostraram que diferentes densidades de Parthenium reduziram o rendimento e seus componentes do sorgo forrageiro. Contudo, o efeito foi menos proeminente em baixa densidade de Parthenium. Com o aumento da densidade de plantas de Parthenium, observou-se declínio significativo no rendimento e seus componentes Além disso, verificou-se redução na altura das plantas de 17,19% e 15,32%; diâmetro do caule, de 31,79% e 28,10%; número de folhas por planta, de 18,88% e 10,16%; colmo, de 51,01% e 45,03%; e rendimento de forragem fresca, de 24,97% e 26,49%, durante 2013 e 2014, respectivamente. O índice competitivo das plantas de Parthenium, a matéria seca e a captação dos principais nutrientes (NPK) também aumentaram à medida que a densidade delas foi aumentada. O nível de dano econômico sugerido de Parthenium foi de 2,2 plantas m-2, sendo recomendado o seu controle a partir dessa densidade, visando obter alto rendimento e boa qualidade de forragem das plantas de sorgo.

ABSTRACT A field trial was conducted for two consecutive years to evaluate the effect of different parthenium densities (0, 2, 4, 6, 8, 10, 12, 14 and 16 plants m-2) on the yield and yield components of forage sorghum along with parthenium economic threshold level. The experiment was laid out during the summer in a randomized complete block design with four replications. Different parthenium densities reduced yield and yield components of forage sorghum, as the parthenium density increased significant decline in yield and yield components. The highest parthenium density (16 plants m-2) reduced plant height by 17.19% and 15.32%, stem diameter by 31.79% and 28.10%, leaf area per plant by 18.88% and 10.16%, leaf to stem ratio by 51.01% and 45.03% and fresh fodder yield by 24.97% and 26.49% throughout 2013 and 2014, respectively. Parthenium relative competitive index (RCI), dry weight and nutrient uptake (NPK) also increased as parthenium density increased. The suggested economic threshold level of parthenium was 2.2 and 1.6 plants m-2 in 2013 and 2014, respectively. Thus, control the parthenium at this density level is suggested for achieving high yield of good quality sorghum fodder.

The enzymatic treatment of hides in tannery processes is a promising technology. However, the reaction kinetics of commercial enzymes available to the leather industry are not fully understood and their activities have been mainly determined with model proteins such as casein as substrate, which are not of direct relevance for cattle hides. Therefore, it is important to determine their activities on collagen and keratin, the main proteins of skin, in order to use these enzymes in leather processing. This work describes the study of five proteases, used commercially in tanneries, to assess their ability to act upon collagen and keratin and to determine their unhairing. Results showed that all commercial enzymes tested had more activity on collagen than on keratin. Unhairing was also tested and four out of the five enzymes tested showed some unhairing activity. Optima of the temperature and pH of the enzymes were very similar for all five enzymes, with maximal activities around 55ºC and pH 9 to 12, respectively.

Production, viscosity, and chemical composition of xanthan synthesized by bacterium Xanthomonas campestris pv pruni strain 101 were evaluated in bioreactor systems. During the process, the volumetric oxygen mass transfer coefficient (kLa) and the biomass were determined and the pH was monitored. The cultures were grown in a 3 l bioreactor, with aeration and agitation varying as follows: conditions (A) 300 rpm, 3 vvm and (B) 200 rpm, 2 vvm, at 28 °C. Our results showed that gum production was dependent on kLa, with a maximum yield of 8.15 g/l at 300 rpm, 3 vvm, 54 h of fermentation, kLa 21.4/h, while biomass was not affected. All aqueous solutions of 3% (w/v) xanthans synthesized showed a pseudoplastic behavior. The highest viscosity was reached under the strongest aeration/agitation conditions. All xanthan samples contained glucose, mannose, rhamnose, and glucuronic acid as their main components. The highest agitation and aeration rates used under condition A (300 rpm and 3 vvm) favorably influenced the yield and viscosity of the xanthan produced by bacterium X. campestris pv pruni 101 at different fermentation times.

Se evaluó la producción, viscosidad y composición química del xantano sintetizado por la bacteria Xanthomonas campestris pv. pruni cepa 101 en un fermentador. Durante el proceso se controló el pH y se determinaron el coeficiente de transferencia de masa de oxígeno (kLa) y la producción de masa celular seca. Los cultivos se realizaron en un fermentador de 3 l variando la aireación y la agitación, en las siguientes condiciones: (A) 300 rpm, 3 vvm y (B) 200 rpm, 2 vvm; a 28 °C. Nuestros resultados mostraron que la producción de goma fue dependiente del kLa, con un rendimiento máximo de 8,15 g/l a 300 rpm y 3 vvm a las 54 h de fermentación, kLa de 21,4/h, mientras que la producción de biomasa no se afectó. Todas las soluciones acuosas de xantano al 3% (m/v) sintetizadas presentaron comportamiento pseudoplástico. La mayor viscosidad se alcanzó en la condición de aireación/agitación más intensa. Todas las muestras de xantano contenían glucosa, manosa, ramnosa y ácido glucurónico como constituyentes principales. La mayor tasa de agitación y aireación utilizada en la condición A (300 rpm y 3 vvm) influyó favorablemente en el rendimiento y la viscosidad del xantano producido por la bacteria X. campestris pv. pruni 101 a diferentes tiempos de fermentación.

Saccharomyces cerevisiae strain W303 was transformed with two yeast integrative plasmids containing Kluyveromyces lactis LAC4 and LAC12 genes that codify beta-galactosidase and lactose permease respectively. The BLR030 recombinant strain was selected due to its growth and beta-galactosidase production capacity. Different culture media based on deproteinized cheese whey (DCW) were tested and the best composition (containing DCW, supplemented with yeast extract 1 %, and peptone 3 % (w/v)) was chosen for bioreactor experiments. Batch, and fed-batch cultures with linear ascending feeding for 25 (FB25), 35 (FB35), and 50 (FB50) hours, were performed. FB35 and FB50 produced the highest beta-galactosidase specific activities (around 1,800 U/g cells), and also the best productivities (180 U/L.h). Results show the potential use of fed-batch cultures of recombinant S. cerevisiae on industrial applications using supplemented whey as substrate.