Bio-butanol production from bread waste with using the amylolytic Clostridium isolated from Parishan Lake

Bio-butanol has been regarded as an alternative to petroleum fuels due to its renewability. The aim of this study is to produce bio-butanol using bread waste and environmental bacteria.

In this study, samples were randomly taken from the depth of 50 to 100 cm of Parishan Lake sediments. After culturing under anaerobic conditions and phenotypic diagnosis of the Clostridium genus, 16S rRNA primer was used for genotypic identification. Isolates were screened based on amylase activity in starch-agar medium. To evaluate the effect of environmental factors (pH, temperature and raw material) on amylase activity of the selected isolates, a modified culture medium containing starch was used. Then, in an optimal culture medium, merely consisting of water and dry bread, bio-butanol was produced and separated by fractional distillation. The accuracy of its presence was confirmed by chromic acid test and gas chromatography.

Out of a total of 530 isolated bacteria, three clostridium isolates had the highest amylase activity and bio-butanol production, which after 16S rRNA sequencing, were registered as Clostridium Beijerinckii (KM999944), Clostridium diolis (KM999945) and Clostridium roseum (KM999946) in NCBI. The highest yield with a concentration of 2.344g/l in the culture medium containing 25g/l bread waste, pH7 and 35°C has been related to Clostridium roseum.

The results showed that under optimal conditions, environmental clostridia have a good potential for the production of bio-butanol from cheap raw materials like bread waste.