Saccharolysis of laccase delignified Aloe vera leaf rind and fermentation through free and immobilized yeast for ethanol production

Abstract

Aloe vera gel has found prominent application in food, therapeutic and cosmetics manufacturing that eventually increased the generation of leaf rind as processing waste. This biomass was previously delignified by laccase to have better accessibility of holocellulose and an attempt has been made through this study to optimize enzymatic hydrolysis using crude cellulase (5.25 [U/ml]) produced from Aspergillus sp. A maximum saccharification of 63.00 ± 0.45% was achieved under the optimum conditions (solid‐to‐liquid ratio 1:17 [wt/vol], 53°C and 8.5 hr) with sugar yield of 309 ± 2.1 mg/g. Fermentation of saccharified liquid to ethanol using Saccharomyces cerevisiae (yeast) was performed using three different modes of inoculum application such as free cell suspension; Ca‐alginate immobilized yeast suspension and immobilized yeast loaded in a packed bed reactor (PBR) under uniform process conditions. Immobilized yeast in PBR has resulted in maximum ethanol yield of about 16.50 ± 1.02 g/L with a fermentation efficiency of 76.14%. Practical application In a global scenario of diminishing resources, there is dire need to establish the cradle‐to‐grave approach for each of industrial operations. Especially, with food processing industries and its waste management this became truly inevitable, as these wastes are rich in nutrient and perishable in nature. On the other hand, it could also serve as a potent source for value added products. Thus, the utilization of Aloe vera (AV) leaf rind to produce bioethanol could underpin the AV gel processing industries toward circular bioeconomy as an option of waste to wealth. The methodology followed to develop this technology is a complete green approach where there is no requirement of chemicals and harsh reagents that remain recalcitrant postprocessing. Adoption of this technology could add value to the sustainable goals and reduce the carbon footprint of the food processing industrial operations.

Comprehensive Treatment Strategy for Banana Inflorescence Bract to Synthesize Biodiesel and Bioethanol Through Fungal Biorefinery

“…For crude cellulolytic enzyme production, a substrate sugarcane bagasse and Aspergillus sp., a well-grown spore from the fungus slant, is done through the solid-state fermentation process [14]. The sugarcane bagasse was subjected to solar drying for 10-12 hours followed by grinding to attain a coarse powder with a particle size of 0.5 mm.…”

“…For the production of cellulolytic enzymes, the substrate with 0.5 mm particle size, solid-to-liquid ratio-1:2.5 (w/v) was prepared using mineral media (pH-6) containing the following components (g/L): FeSO 4 -0.005; KH 2 PO 4 -2; MnSO 4 -0.0016; tryptone-0.75; (NH 4 ) 2 SO 4 -1.4; Tween 80 − 2 ml; MgSO 4 -0.3; ZnSO 4 -0.0014 and CaCl 2 -0.3. The conditions were maintained at 25 ± 3°C for 96 hours with a moisture level of 70-80% [14]. Suspension of the solid fraction of biomass acquired by the fungal mycelia in 15 ml of glycerol (5%, v/v): water (1:3) for 3 hours and the maximum level of squeezing was employed for collecting the liquid and then ltered to obtain crude extracellular enzyme.…”

“…Further, the cellulosic component (solid fraction) of BIB was sacchari ed using crude cellulolytic enzymes from Aspergillus niger to obtain the C6 sugars i.e., glucose. This glucose-enriched hydrolysate was fermented with Saccharomyces cerevisiae which has a high capacity for ethanol tolerance with high productivity and yield from LCB-derived hexose sugars [14]. For ethanol production from lignocellulosic biomass, numerous technologies have been developed, but its integrated utilization of pretreated liquor and a cellulosic fraction of biomass for fuel production necessitates providing a techno-economic feasibility process.…”

Strategies to achieve high productivity, high conversion, and high yield in yeast fermentation of algal biomass hydrolysate

“…Immobilized yeast have been used for ethanol production in different reactor configurations including continuous stirred tank bioreactor, flow‐through column, packed‐bed column, and rotating bed bioreactor [ 14 ]. Due to the ease of preparation and the mild conditions, cell immobilization in calcium alginate beads has been used in several studies to produce ethanol from biomass hydrolysates [ 9 , 15 , 16 , 17 , 18 ].…”