Fermentation Of Lignocellulosic Hydrolysates: Lab Analysis

Fermentation of lignocellulosic hydrolysates involves the conversion of sugars to ethanol which is mainly performed by bacteria or yeast. The organism chosen should possess certain characters in terms of tolerance I,e towards inhibitors ,sugars and ethanol concentrations in the hydrolysates and should also withstand higher temperatures and lower pH and with minimal by product formation [161]. Fermentation is the key component where advancement in technology plays key role and is required to be feasible. The technologies like Separate hydrolysis and fermentation (SHF), Simultaneous saccharification and fermentation (SSF) and Consolidated bio processing(CBP) are developing. CBP is in the early stages of its development and hence gaining more
CBP is expanding its recognition as a promising leap forward to produce bioethanol with low cost, yet its feasibility extraordinarily relies upon whether a suitable microorganism can be found in nature or built by engineering strategies in the laboratory[167] . S.cerevisiae in not capable of utilizing pentoses and due to the lack of suitable enzymes for exploiting the lignocellulosic feed stocks, is making the organisms unsuitable for CBP applications[168]. Genetic engineering approaches in this area like integration of genes from a cellulase producing strain into the ethanol producing strains like Saccharomyces cerevisiae was found to be inappropriate since transfer of very high number of these genes might influence the execution of cell, their co-expression at the transcriptional level is often lop-sided causing ER-stress to the host cell [167]. Although the fungi like Trichoderma reesei are found be efficient producers of cellulase, they are not broadly been proposed as possibility for CBP applications because of low ethanol yields obtained, as well as the slow fermentation rates [169]. However few fungi like Mucor[170] and Pestalotiopsis [171] seems to be fermenting lignocellulosic components to ethanol. Fusarium oxysporum is the best contemplated filamentous organism for CBP applications with cellulolytic and hemicellulolytic properties [172] to the enhancement of its CBP execution through Genetic engineering methodologies[173]. The ascomycete Paecilomyces variotii ATHUM 8891 was evaluated as a candidate species in CBP appications. The fungus is capable of fermenting glucose and xylose to ethanol, closer to the maximum theoretical yields, edifying an unusually powerful pentose metabolic pathway and the fungus possesses the necessary enzyme factory for the exploitation of lignocellulosic biomass, as it can grow and produce ethanol on