Roselei Claudete Fontana

Comparison of stirred tank and airlift bioreactors in the production of polygalacturonases by Aspergillus oryzae

The production of endo and exo-polygalacturonase (PG) by Aspergillus oryzae IPT 301 was studied in a stirred tank bioreactor (STR) and an internal circulation airlift bioreactor. Using a factorial experimental design, a soluble culture medium was defined which allowed the production of exo- and endo-PG comparable to that obtained in a medium containing suspended wheat bran. The soluble medium was used in tests to compare the production of these enzymes in the STR and airlift bioreactor. In these tests, after 96 h, maximum enzymatic activity values achieved for exo- and endo-PG were 65.2 units (U) per mL and 91.3 U mL(-1), in the STR, with similar activity values of 60.6 U mL(-1) and 86.2 U mL(-1), respectively, being achieved in the airlift bioreactor. The airlift bioreactor also showed satisfactory results regarding the oxygen transfer rate in this process, indicating its potential to be used in an eventual larger scale production of exo- and endo-PG, with lower costs for both installation and operation.

Increased production of cellulases and xylanases by Penicillium echinulatum S1M29 in batch and fed-batch culture.

The development of more productive strains of microorganisms and processes that increase enzyme levels can contribute to the economically efficient production of second generation ethanol. To this end, cellulases and xylanases were produced with the S1M29 mutant strain of Penicillium echinulatum, using different concentrations of cellulose (20, 40, and 60 g L(-1)) in batch and fed-batch processes. The highest activities of FPase (8.3 U mL(-1)), endoglucanases (37.3 U mL(-1)), and xylanases (177 U mL(-1)) were obtained in fed-batch cultivation with 40 g L(-1) of cellulose. The P. echinulatum enzymatic broth and the commercial enzyme Cellic CTec2 were tested for hydrolysis of pretreated sugar cane bagasse. Maximum concentrations of glucose and xylose were achieved after 72 h of hydrolysis. Glucose yields of 28.0% and 27.0% were obtained using the P. echinulatum enzymatic extract and Cellic CTec2, respectively.

Production of polygalacturonases by Aspergillus oryzae in stirred tank and internal- and external-loop airlift reactors

The production of endo- and exo-polygalacturonase (PG) by Aspergillus oryzae was assessed in stirred tank reactors (STRs), internal-loop airlift reactors (ILARs) and external-loop airlift reactors (ELARs). For STR production, we compared culture media formulated with either pectin (WBE) or partially hydrolyzed pectin. The highest enzyme activities were obtained in medium that contained 50% pectin in hydrolyzed form (WBE5). PG production in the three reactor types was compared for WBE5 and low salt WBE medium, with additional salts added at 48, 60 and 72h (WBES). The ELARs performed better than the ILARs in WBES medium where the exo-PG was the same concentration as for STRs and the endo-PG was 20% lower. These results indicate that PG production is higher under experimental conditions that result in higher cell growth with minimum pH values less than 3.0.

Enzymes for second generation ethanol: exploring new strategies for the use of xylose

Considering that the cost of cellulases and hemicellulases substantially contributes to the price of 2nd-generation ethanol, reducing the cost of the substances used as inducers of cellulose and xylose is essential to reducing the cost of these enzymes. Penicillium echinulatum is able to secrete most hemicellulolytic and cellulolytic enzymes. In this context, the aim of this work was to evaluate the use of xylose for the production of cellulases and xylanases by two mutant strains of P. echinulatum (9A02S1 and S1M29) and the parental 2HH. Xylose acts as an inducer for the production of xylanases and cellulases, especially endoglucanases. These data indicate the possibility of using the pentose xylose, which is not used by the majority of yeast for ethanol production, as a total or partial substitute in cellulose-based processes for the production of enzymes for enzymatic hydrolysis.

Influence of pectin, glucose, and pH on the production of endo- and exo-polygalacturonase by Aspergillus oryzae in liquid medium

Abstract - Endo- and exo-polygalacturonase (PG) production by Aspergillus oryzae IPT 301 was evaluated in a batch bioreactor in media containing 0, 10, and 20 g.L -1 pectin and 0 to 30 g.L -1 glucose. For cultivations in which the pH was not controlled, the use of 20 g.L -1 pectin and 10 g.L -1 glucose resulted in superior enzyme activities compared to control media with 0 and 10 g.L -1 of the inducer and the same glucose concentration. Maximum endo-PG and exo-PG activities were 125.0 and 76.3 U.mL -1 , respectively. For cultivations in which the pH was controlled to a minimum value of 2.7, media containing 20 g.L -1 pectin and 20 to 50 g.L glucose were tested and significant improvement of both activities was attained. Maximum enzyme activities (175.0 U.mL -1 for endo-PG and 103.0 U.mL for exo-PG) were obtained in pH-controlled batch experiments with 30 g.L -1 glucose. Keywords : Aspergillus oryzae ; Polygalacturonases; Glucose; Pectin; pH control. INTRODUCTION Pectinases, or pectinolytic enzymes, are naturally produced by plants, filamentous fungi, bacteria and yeasts (Gainvors

Effect of freezing and processing technologies on the antioxidant capacity of fruit pulp and jelly

The effect of freezing and processing technology on the antioxidant capacity of grape (Vitis vinifera), apple (Malus domestica), strawberry (Fragaria x Anassa), pear (Pyrus communis L.), guava (Psidium guajava L.), and fig (Ficus carica L.) was evaluated for 90 days. Under a storage temperature of -15 o C, there was no significant difference in the antioxidant capacity of grape and fig pulp, and a higher antioxidant capacity was found for guava pulp (27 µmol/g). While the technological processing did not affect the antioxidant capacity of pear and apple jellies, all other jellies studied showed a reduced antioxidant capacity. The processing reduced the antioxidant capacity of grapes in 45%. Among the fruit products, the highest antioxidant activities were found for guava pulp and jelly (27 and 25 µmol/g, respectively), followed by grape pulp (22 µmol/g).

Evaluation of productivity and antioxidant profile of solid-state cultivated macrofungi Pleurotus albidus and Pycnoporus sanguineus

The aim of this study was to investigate the production profile of Pleurotus albidus and Pycnoporus sanguineus on different waste substrates containing natural phenolics, and also to investigate whether phenolic-rich substrates can improve the phenolic content of these macrofungi. The medium formulated with Pinus sp. sawdust (PSW) made possible the highest yields (2.62±0.73%) of P. sanguineus. However, the supplementation of PSW with apple waste (AW) resulted in better P. albidus yields (23.94±2.92%). The results indicated that the substrate composition affected macrofungi production, also the chemical composition and the presence of phenolic compounds in the production media influence phenolic content and antioxidant activity in macrofungi.

The influence of sorbitol on the production of cellulases and xylanases in an airlift bioreactor.

The production of cellulases and xylanases by Penicillium echinulatum in an airlift bioreactor was evaluated. In batch production, we tested media with isolated or associated cellulose and sorbitol. In fed-batch production, we tested cellulose addition at two different times, 30 h and 48 h. Higher liquid circulation velocities in the downcomer were observed in sorbitol 10 g L(-1) medium. In batch production, higher FPA (filter paper activity) and endoglucanase activities were obtained with cellulose (7.5 g L(-1)) and sorbitol (2.5 g L(-1)), 1.0 U mL(-1) (120 h) and 6.4 U m L(-1) (100 h), respectively. For xylanases, the best production condition was cellulose 10 g L(-1), which achieved 5.5 U mL(-1) in 64 h. The fed-batch process was favorable for obtaining xylanases, but not for FPA and endoglucanases, suggesting that in the case of cellulases, the inducer must be added early in the process.

Second-generation ethanol production from elephant grass at high total solids

The enzymatic hydrolysis of Pennisetum purpureum (elephant grass) was evaluated at high total solid levels (from 4% to 20% (w/v)) in a concomitant ball milling treatment in a rotating hydrolysis reactor (RHR). The greatest glucose yield was 20.17% when 4% (w/v) untreated biomass was employed. When sugars obtained from enzymatic hydrolysis were submitted to fermentation with Saccharomyces cerevisiae, the greatest ethanol yield was 22.61% when 4% (w/v) untreated biomass was employed; however, the highest glucose concentration (12.47g/L) was obtaining using 20% (w/v) solids and highest ethanol concentration (6.1g/L) was obtained using 16% (w/v) solids. When elephant grass was hydrolyzed in the rotating hydrolysis reactor, ethanol production was about double that was produced when the biomass was hydrolyzed in a static reactor (SR). These data indicate that it is possible to produce ethanol from elephant grass when milling treatment and enzymatic hydrolysis are performed at the same time.

Enzymatic surface modification of sisal fibers (Agave Sisalana) by Penicillium echinulatum cellulases

We report on the effect of a new microbial enzymatic system, Penicillium echinulatum cellulase, on the surface morphological (SEM), structural (XRD), and thermal (TGA/DTG) properties as well as the surface chemical composition (FT-IR and FT-Raman) of sisal fibers (Agave sisalana)—a potential replacement for glass fibers in composite materials. Cellulase treatment greatly improved the properties of sisal fibers, rendering the surface topography and chemical composition of the fibers free of contaminants and reducing the content of amorphous materials (hemicellulose, pectin, lignin, and disordered cellulose) to yield the crystalline cellulose network. Thermal stability and crystallinity were also greatly enhanced. This work demonstrated that microbial enzymes offer an inexpensive and environmentally attractive option to improve the surfaces of natural fibers for composite applications.