Cellulosic Ethanol Production by Recombinant Cellulolytic Bacteria HarbouringpdcandadhII Genes ofZymomonas mobilis

Abstract

The ethanol fermenting genes such as pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adhII) were cloned fromZymomonas mobilisand transformed into three different cellulolytic bacteria, namelyEnterobacter cloacaeJV,Proteus mirabilisJV andErwinia chrysanthemiand their cellulosic ethanol production capability was studied. RecombinantE. cloacaeJV was found to produce 4.5% and 3.5% (v/v) ethanol, respectively, when CMC and 4% NaOH pretreated bagasse were used as substrates, whereas recombinantP. mirabilisandE. chrysanthemiwith the same substrates could only produce 4%, 3.5%, 1%, and 1.5 % of ethanol, respectively. The recombinantE. cloacaestrain produced twofold higher percentage of ethanol than the wild type. The recombinantE. cloacaestrain could be improved further by increasing its ethanol tolerance capability through media optimization and also by combining multigene cellulase expression for enhancing ethanol production from various types of lignocellulosic biomass so that it can be used for industrial level ethanol production.