Researchers have performed all three fermentation processes (batch, fed-batch, and continuous) for biomass conversion into ethanol. The most suitable fermen­tation strategy depends upon the growth kinetics of the microorganism, the type of hydrolysate, and the economics of the process. For ethanol production from lig — nocellulosic biomass, batch fermentation has been extensively utilized in the past. The batch process is a multivessel approach that allows flexible operation and easy control in the bioconversion process [33]. In fed-batch fermentation, the micro­bial cells can be acclimatized at low substrate concentrations that later assist in accelerating the rate of ethanol formation during the entire course of the biocon­version process. Fed-batch fermentation processes are ideal to obtain a high cell density, which may help to achieve higher ethanol yields with greater productivity. Higher cell density also helps to reduce the toxicity of lignocellulose hydrolysates, particularly acid hydrolysates, to yeast cells. Continuous fermentation is another state-of-the-art technology in which microorganisms work at a lower substrate con­centration, maintaining higher ethanol concentration during the entire course of the fermentation reaction [34]. Table 3 summarizes the fermentation profiles of different microorganisms utilizing a variety of lignocellulose hydrolysates.

# Soliddiquid (Lignocellulose substrate: dilute acid solution). ## Details are not available.