BIOETHANOL PRODUCTION FROM LEAFY BIOMASS OF MANGO (Mangifera indica) INVOLVING NATURALLY ISOLATED AND RECOMBINANT ENZYMES

Abstract

The present study describes the usage of dried leafy biomass of mango (Mangifera indica) containing 26.3% (w/w) cellulose, 54.4% (w/w) hemicellulose, and 16.9% (w/w) lignin, as a substrate for bioethanol production from Zymomonas mobilis and Candida shehatae. The substrate was subjected to two different pretreatment strategies, namely, wet oxidation and an organosolv process. An ethanol concentration (1.21 g/L) was obtained with Z. mobilis in a shake-flask simultaneous saccharification and fermentation (SSF) trial using 1% (w/v) wet oxidation pretreated mango leaves along with mixed enzymatic consortium of Bacillus subtilis cellulase and recombinant hemicellulase (GH43), whereas C. shehatae gave a slightly higher (8%) ethanol titer of 1.31 g/L. Employing 1% (w/v) organosolv pretreated mango leaves and using Z. mobilis and C. shehatae separately in the SSF, the ethanol titers of 1.33 g/L and 1.52 g/L, respectively, were obtained. The SSF experiments performed with 5% (w/v) organosolv-pretreated substrate along with C. shehatae as fermentative organism gave a significantly enhanced ethanol titer value of 8.11 g/L using the shake flask and 12.33 g/L at the bioreactor level. From the bioreactor, 94.4% (v/v) ethanol was recovered by rotary evaporator with 21% purification efficiency.

Evolution toward the utilization of mango leaves as lignocellulosic material in bioethanol production: A review of process parameter and integrated technologies

“…It was reported that mango leaves contain 26.3% cellulose, 54.4% hemicellulose, and 16.9% lignin . Table depicts the biochemical composition of lignocellulosic feedstocks that have been used in bioethanol production.…”

“…Mango leaves belong to the group of agricultural lignocellulosic waste with high avaibility especially after pruning session . The prospective of mango leaves in bioethanol production industry is attributed by their elevated holocellulose content . In this article, issues related to the limitations in primary bioethanol production and the prospective of secondary bioethanol will be discussed.…”

Scale up and efficient bioethanol production involving recombinant cellulase (Glycoside hydrolase family 5) from Clostridium thermocellum

“…The leafy biomass of mango contributed an ethanol titre of 12.3 g L -1 using naturally isolated cellulase and recombinant enzymes from C. thermocellum [26]. Z. mobilis upon fermentation of 20% (w v -1 ) sugarcane bagasse resulted in an ethanol titre of 6.24 g L -1 and yield of 79% with productivity of 3.04 g L -1 h -1 [27].…”

Comparison between solid-state and powder-state alkali pretreatment on saccharification and fermentation for bioethanol production from rice straw

“…The pretreatment methods are: milling and grinding, pyrolysis, high-energy radiation, high pressure steaming, alkaline (sodium hydroxide) or acid hydrolysis (sulfuric acid), gas treatment (chlorine dioxide, nitrogen dioxide, sulfur dioxide, and ozone), hydrogen peroxide treatment, organic solvent treatment, hydrothermal treatment, steam explosion, wet oxidation and biological treatment, ionic liquids pretreatment. [9,10,11,12,13,14] Alkaline pretreatment is one of the important approaches that has several potential advantages compared to other pretreatment processes, including low operation cost and the reduced degradation of holocellulose and subsequent formation of inhibitors for downstream processing. [15] The main mechanisms of alkaline pretreatment are the degradation of ester bonds and cleavage of glycosidic linkages in the lignocellulosic cell wall matrix, which lead to the alteration of the structure of lignin, the reduction of the lignin-hemicellulose complex, cellulose swelling and partial decrystallization of cellulose.…”