Low-cost homemade cocktails for enzymatic conversion of sugarcane and cassava bagasses.

The agricultural industries generate lignocellulosic wastes that can be modified by fungi to generate high value-added products. This work aimed to analyze the efficiency and the cost-effectiveness of the bioconversion of sugarcane and cassava bagasses using low-cost homemade enzymatic cocktails from Aspergillus niger LBM 134. Both bagasses were pretreated with a soft alkaline solution without any loss of polysaccharides. After the hydrolysis, a 28% of conversion to glucose and 42% to xylose were reached in the hydrolysis of sugarcane bagasse while an 80% of saccharification yield, in the hydrolysis of cassava bagasse using the homemade enzymes. Furthermore, a more disorganised surface and no starch granules were observed in the sugarcane and cassava bagasses, respectively. The bioethanol yield from sugarcane and casava bagasses was predicted to be 4.16 mg mL-1 and 2.57 mg mL-1, respectively. A comparison of the cost of the homemade and the commercial enzymes was carried out. Similar hydrolysis percentages were achieved employing any enzyme; however, it was 1000-2000 times less expensive using the homemade cocktails than using the commercial enzymes. Therefore, the cost of obtaining glucose from bagasses was most expensive when applying the commercial enzymes. Moreover, the hydrolysis of the cassava bagasse was most efficient with the homemade cocktails. The importance and novelty of this work lie in the similar performance and the lower cost of the homemade cocktails from the fungus A. niger LBM 134 compared with the commercial enzymes on the hydrolysis of the sugarcane and cassava bagasses.

Solid-state bioprocessing of sugarcane bagasse with Auricularia fuscosuccinea for phenolic compounds extraction.

Sugarcane bagasse is a natural source of phenolic compounds. However, these compounds are bound to lignocellulose components, reducing their ability to function as good antioxidants. These linkages are hydrolyzed by enzymes like ß-glucosidases, increasing free phenolics. Auricularia is a food-grade genus capable of producing ß-glucosidases. The aim of this work was (I) to determine naturally occurring species of Auricularia and (II) to obtain phenolic compounds through the solid-state bioprocessing of sugarcane bagasse. We have successfully isolated five strains that were assigned to the taxon A. fuscosuccinea. We determined ß-glucosidase activity by fluorescence plate assay of the five isolated strains and adjusted an optimal temperature for mycelial growth at 30 °C. A. fuscosuccinea LBM 243 was chosen for solid-state bioprocessing of sugarcane bagasse. ß-glucosidase activity (12.2 ± 0.62 U l-1) and protein content (51.58 ± 6.26 mg l-1) were highest on day 20 of culture. The maximum value of total phenolic content (507.5 ± 9.05 mg l-1) was obtained at day 20 and antioxidant capacity (34.44% ± 11.20) was highest at day 10, both in ethanolic extracts. The best performance of ethanol against methanol extraction in this work is highlighted considering ethanol to be a safe, efficient, and low-cost solvent.

Aspergillus niger LBM 134 isolated from rotten wood and its potential cellulolytic ability.

Aspergillus is a genus of filamentous and cosmopolitan fungi that includes important species for medical mycology, food, basic research and agro-industry areas. Aspergillus section Nigri are efficient producers of hydrolytic enzymes such as cellulases that are employed in the cellulose conversion. Hence, the search of new cellulolytic isolates and their correct identification is important for carrying out safe biotechnological processes. This study aimed to characterise the cellulolytic potential of Aspergillus sp. LBM 134, isolated from the Paranaense rainforest (Argentina) and to identify the isolate through a polyphasic approach. The fungus was identified as Aspergillus niger and its cellulolytic potential was evaluated by using Congo red technique and fluorescence plate assays for carboxymethyl cellulase, ß-glucosidase and cellobiohydrolase, respectively. All three cellulase activities were positive; this bio-prospective positioned A. niger LBM 134 as a promising alternative for industries that require organisms capable of carrying out cellulosic biomass processing.

Secretomic analysis of cheap enzymatic cocktails of Aspergillus niger LBM 134 grown on cassava bagasse and sugarcane bagasse.

Currently, agroindustrial wastes are little used for generating value-added products; hence, their use of these waste to produce enzymatic cocktails for the conversion of lignocellulosic biomass to fermentable sugars is a very interesting alternative in the second-generation bioethanol process. The Ascomycota fungus Aspergillus niger LBM 134 produces hydrolytic enzymes in large proportions. In this work, A. niger LBM 134 was grown on sugarcane and cassava bagasses under optimized conditions. To identify the extracellular enzymes involved in the degradation of these agroindustrial wastes, the secretomes of the culture supernatants of the fungus were analyzed and validated by biochemical assays of the enzymatic activities. A. niger LBM 134 secreted higher quantities of xylanases and accessory hemicellulases when it grew on sugarcane bagasse, whereas more cellulases, amylases, and pectinases were secreted when it grew on cassava bagasse. These findings suggest two promising enzyme cocktails for the hydrolysis of lignocellulose carbohydrate polymers to fermentable sugars. These bioinformatic analysis were functional validates through enzymatic biochemical assays that confirm the biotechnological potential of A. niger LBM 134 for the bioconversion of hemicellulosic substrates such as sugarcane and cassava bagasses.

Enzymatic hydrolysis of barley straw for biofuel industry using a novel strain of Trametes villosa from Paranaense rainforest.

Agricultural practices generate lignocellulosic waste that can be bioconverted by fungi to generate value-added products such as biofuels. In this context, fungal enzymes are presented as an alternative for their use in the hydrolysis of cellulose to sugars that can be fermented to ethanol. The aim of this work was to characterize LBM 033 strain and to analyze its efficiency in the hydrolysis of cellulosic substrates, including barley straw. LBM 033 strain was identified as Trametes villosa by molecular techniques, through the use of the ITS and rbp2 markers and the construction of phylogenetic trees. The cell-free supernatant of T. villosa LBM 033 showed high titers of hydrolytic enzymatic activities, necessary for the hydrolysis of the holocellulosic substrates, hydrolyzing pure cellulose to cellobiose and glucose and also degraded the polysaccharides contained in barley straw to short soluble oligosaccharides. These results indicate that macro fungi from tropical soil environments, such as T. villosa LBM 033 can be a valuable resource for in-house, cost effective production of enzymes that can be applied in the hydrolysis stage, which could reduce the total cost of bioethanol production.

Adding value to lignocellulosic wastes via their use for endoxylanase production by Aspergillus fungi.

Agroforestry industries in the world generate lignocellulosic wastes that can be a huge problem of pollution, or the wastes can be used for different biotechonological applications such as substrates for microorganism growth and enzyme production. Fungi such as Aspergillus niger can grow in almost every substrate and produce hydrolytic enzymes such as endoxylanases, giving added value to agroforestry wastes generated by industries in the northeast of Argentina. In this context, the aim of this work was to use agroforestry wastes as substrates for the production of endoxylanases by Aspergillus niger and to optimize nitrogen sources and physical variables for the highest endoxylanase activity. A. niger LBM 055 and A. niger LBM 134 produced high endoxylanase levels when they were grown with sugarcane and cassava bagasses as carbon sources. A. niger LBM 134 reached the highest endoxylanase activity when nitrogen sources and physical variables were optimized. The fungus exhibited up to 110 U mL-1 of endoxylanase activity when it was grown with sugarcane bagasse and more than 160 U mL-1 with cassava bagasse. Therefore, endoxylanase production was optimized using agricultural bagasses and cost 20 times less than enzyme production using synthetic xylan.