Ethanol production from candidate energy crops: Water
hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.)
Abstract
Fermentation modes and microorganisms related to two typical free-floating aquatic plants, water hyacinth and water lettuce, were
investigated for their use in ethanol production. Except for arabinose, sugar contents in water lettuce resembled those in water hyacinth
leaves. Water lettuce had slightly higher starch contents and lower contents of cellulose and hemicellulose. A traditional strain, Saccharomyces
cerevisiae NBRC 2346, produced 14.4 and 14.9 g l1 ethanol, respectively, from water hyacinth and water lettuce. Moreover, a
recombinant strain, Escherichia coli KO11, produced 16.9 and 16.2 g l1 ethanol in the simultaneous saccharification and fermentation
mode (SSF), which was more effective than the separated hydrolysis and fermentation mode (SHF). The ethanol yield per unit biomass
was comparable to those reported for other agricultural biomasses: 0.14–0.17 g g-dry1 for water hyacinth and 0.15–0.16 g g-dry1 for
water lettuce.