Bioethanol from sea lettuce with the use of crude enzymes derived from waste

Abstract

The mid-gut gland of the scallop contains saccharification enzymes such as cellulase and amylase, and these enzymes have been disposed of together with the mid-gut gland after the removal of the adductor muscle, an edible part of the scallop. We used a drip from the mid-gut gland of the scallop, obtained by squeezing the gland, as an inexpensive enzyme mixture and tried to produce bioethanol from the glucans present in sea lettuce by the method of simultaneous saccharification and fermentation (SSF) with the use of baker's yeast. The ethanol concentration attained was as high as 7.2 g/L, which corresponded to *37% of the conversion of glucans in sea lettuce in the solid-state SSF. Furthermore, we ascertained that the drip and sea lettuce contain nutrients that are indispensable for maintaining the yeast activity, and, thus, the SSF did not require any additional nutrients, such as yeast extract or peptone, the use of which increases the cost of fermentation to a high level.

Strategies for the production of high concentrations of bioethanol from seaweeds

“…Because crude enzymes were used for the hydrolysis of glucans, the conversion rate of glucans from U. pertusa, which is defined as the ratio of the amount of ethanol produced by simultaneous saccharification and fermentation to the potential amount of ethanol produced from glucans contained in the seaweed, was not higher than 37%. 27 A commercial enzyme (Meicelase) was also used for the hydrolysis of glucans contained in U. pertusa. 15 hydrolyze Enteromorpha with dilute sulfuric acid at 121°C for 30-90 min and obtained a mixture of glucose, xylose, glucuronic acid and rhamnose.…”

“…Ulva pertusa, classified as a green seaweed, has been used as the raw material for ethanol production by combining the enzymatic hydrolysis of glucans and the fermentation of glucose. 15,27 A concentration of 7.2 g/L ethanol was produced from U. pertusa by simultaneous saccharification and fermentation at 35°C for 72 h, using crude enzymes containing cellulase and amylase together with Saccharomyces cerevisiae. 27 The crude enzymes used to hydrolyze glucans in U. pertusa during simultaneous saccharification and fermentation were obtained from the mid-gut gland of scallops, which is ordinarily wasted after the removal of edible parts.…”

“…15,27 A concentration of 7.2 g/L ethanol was produced from U. pertusa by simultaneous saccharification and fermentation at 35°C for 72 h, using crude enzymes containing cellulase and amylase together with Saccharomyces cerevisiae. 27 The crude enzymes used to hydrolyze glucans in U. pertusa during simultaneous saccharification and fermentation were obtained from the mid-gut gland of scallops, which is ordinarily wasted after the removal of edible parts. Because crude enzymes were used for the hydrolysis of glucans, the conversion rate of glucans from U. pertusa, which is defined as the ratio of the amount of ethanol produced by simultaneous saccharification and fermentation to the potential amount of ethanol produced from glucans contained in the seaweed, was not higher than 37%.…”

Marine yeast isolation and industrial application

“…Various biological materials have been investigated for the generation of bioethanol, such as wheat straw ( Pensupa et al ., 2013 ), sugarcane bagasse ( Chandel et al ., 2013 ) and corn stover ( Bondesson et al ., 2013 ). Recently, various marine biomass sources, for example seaweed ( Khambhaty et al ., 2013 ) and sea lettuce ( Yanagisawa et al ., 2011 ), have attracted increasing attention as a promising nonfood material for bioethanol production, as they do not compete with edible crops in terms of land and freshwater resources. The hydrolysis of marine biomass could result in a salty hydrolysate, which would require desalting (e.g.…”

Assessment of holocellulose for the production of bioethanol by conserving Pinus radiata cones as renewable feedstock

“…The generation of fermentation inhibitors like acetic acid, hydroxy methyl furfural, furfural, glycol aldehyde and soluble phenolic compounds is also a prominent issue to be solved (Cavka et al, 2011;Sanda et al, 2011;Carter et al, 2011a, b;Raghu et al, 2011;Yong-Jin et al, 2011;Lee et al, 2011;Huang et al, 2011;Zhang et al, 2011;Bellido et al, 2011;Geddes et al, 2011;Sainio et al, 2011;Jayakody et al, 2011). A variety of biomass (cashew apple pulp, coffee pulp waste, switch grass, oil palm empty fruit bunches, seaweeds, bamboo, sugar-cane tops) are being examined as economically viable feedstock for the production of bioethanol (Sindhu et al, 2011;Zhao-Yong et al, 2011;Shenoy et al, 2011;Martin and Grossmann, 2011;Han et al, 2011;Yanagisawa et al, 2011aYanagisawa et al, , 2011b. Bioethanol is a renewable and environmentallyfriendly (carbon neutral) fuel in contrast to the fast depleting, petroleum-based fuels (Pulidindi et al, 2012;Parmar et al, 2011;Sasaki et al, 2011;Paivi et al, 2011;Dias et al, 2011).…”