Encapsulation of Trichoderma harzianum with nanocellulose/carboxymethyl cellulose nanocomposite.

This study proposes the use of green matrices of cellulose nanocrystals (CNC) and a nanocomposite of CNC with carboxymethyl cellulose (CMC) for efficiently encapsulating the plant biocontrol agent Trichoderma harzianum. Beads containing spores of the microorganism were produced by dripping dispersions of the polymers into a CaCl2 coagulation bath, resulting in the crosslinking of CNC chains by Ca2+ ions. SEM micrographs evidenced the T. harzianum spores in the encapsulation matrices. X-ray microtomography confirmed the random distribution of the microorganism within the polymeric matrix and the presence of internal pores in the CNC:CMC:spores beads. Encapsulation in the CNC:CMC nanocomposite favored growth of the fungus after 10 days of storage at room temperature, which could be attributed to the presence of internal pores and to the extra carbon source provided by the CMC. The results indicated that CNC:CMC nanocomposites are promising materials for protecting and delivering microbial inoculants for agricultural applications.

Cellulose nanostructures obtained using enzymatic cocktails with different compositions.

Cellulose nanostructures obtained from lignocellulosic biomass by the enzymatic route can offer advantages in terms of material properties and processing sustainability. However, most of the enzymatic cocktails commonly used in the saccharification of biomass are designed to promote the complete depolymerization of the cellulose structure into soluble sugars. Here, investigation was made of the way that the action of different commercially available cellulase enzyme cocktails can affect the production of nanocellulose. For this, enzymatic cocktails designed for complete or partial saccharification were compared, using eucalyptus cellulose pulp as a model feedstock. The results showed that all the enzymatic cocktails were effective in the formation of nanocellulose structures, with the complete saccharification enzymes being more efficient in promoting the coproduction of glucose (36.5 g/L, 87% cellulose conversion). The presence of auxiliary enzymes, especially xylanases, acted cooperatively to favor the production of nanostructures with higher crystallinity (up to 79%), higher surface charge (zeta potential up to -30.9 mV), and more uniform dimensions within the size range of cellulose nanocrystals (80 to 350 nm). Interestingly, for the enzymatic cocktails designed for partial saccharification, the xylanase activity was more important than the endoglucanase activity in the production of nanocellulose with improved properties. The findings showed that the composition of the enzymatic cocktails already used for complete biomass saccharification can be suitable for obtaining nanocellulose, together with the release of a glucose stream, in a format compatible with the biorefinery concept.

On-Site Production of Cellulolytic Enzymes by the Sequential Cultivation Method.

The conversion of renewable lignocellulosic biomass into fuels, chemicals, and high-value materials using the biochemical platform has been considered the most sustainable alternative for the implementation of future biorefineries. However, the high cost of the cellulolytic enzymatic cocktails used in the saccharification step significantly affects the economics of industrial large-scale conversion processes. The on-site production of enzymes, integrated to the biorefinery plant, is being considered as a potential strategy that could be used to reduce costs. In such approach, the microbial production of enzymes can be carried out using the same lignocellulosic biomass as feedstock for fungal development and biofuels production. Most of the microbial cultivation processes for the production of industrial enzymes have been developed using the conventional submerged fermentation. Recently, a sequential solid-state followed by submerged fermentation has been described as a potential alternative cultivation method for cellulolytic enzymes production. This chapter presents the detailed procedure of the sequential cultivation method, which could be employed for the on-site production of the cellulolytic enzymes required to convert lignocellulosic biomass into simple sugars.

Soybean protein as a cost-effective lignin-blocking additive for the saccharification of sugarcane bagasse.

Addition of surfactants, polymers, and non-catalytic proteins can improve the enzymatic hydrolysis of lignocellulosic materials by blocking the exposed lignin surfaces, but involves extra expense. Here, soybean protein, one of the cheapest proteins available, was evaluated as an alternative additive for the enzymatic hydrolysis of pretreated sugarcane bagasse. The effect of the enzyme source was investigated using enzymatic cocktails from A. niger and T. reesei cultivated under solid-state, submerged, and sequential fermentation. The use of soybean protein led to approximately 2-fold increases in hydrolysis, relative to the control, for both A. niger and T. reesei enzymatic cocktails from solid-state fermentation. The effect was comparable to that of BSA. Moreover, the use of soybean protein and a 1:1 combination of A. niger and T. reesei enzymatic cocktails resulted in 54% higher glucose release, compared to the control. Soybean protein is a potential cost-effective additive for use in the biomass conversion process.

Correlation between Agar Plate Screening and Solid-State Fermentation for the Prediction of Cellulase Production by Trichoderma Strains.

The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93 UI·g(-1)). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient (R(2)) of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement.