Ethanol production byKlebsiellasp. SWET4 using banana peel as feasible substrate

Ethanol has gained its importance as one of the highly demanded biofuels and is being produced from different food crops or food crop wastes after vigorous pretreatment compelling the production process economically incompatible to some extent. The process also becomes non-ecofriendly as the pretreatment process generally produces acid fumes and toxic effluents as well as consumes high energy. In this current study, the potential of the banana peel as a probable substrate for ethanol production was evaluated with the help of logical prediction. Moreover, a single-step ethanol production process was investigated to eliminate hazardous pretreatment processes. A potential bacterial strain SWET4 was isolated from a sewage treatment pond and was identified as a member of theKlebsiellagenus by partial sequencing of the 16S rRNA gene. The isolated strain showed ethanol tolerance up to 12% and exhibited its potential as a cellulolytic strain. The bacterial strain SWET4 was found able to ferment banana peel in MSM broth without any other carbon source with a comparatively prolonged lag phase of cellular growth. Trace of ethanol in banana peel fermentation broth of SWET4 was confirmed by high-pressure liquid chromatography. The optimization study for ethanol production enlightened the fact that high temperature and pH supported higher ethanol production. However, due to the growth restriction of the bacterial cell at higher temperatures and pH, only 40 degrees C and pH 8 were considered optimum. At the optimum substrate concentration (40 g l(-1)), ethanol concentration was found to be 5.48 g l(-1)after 5 days of incubation which summed as a total yield of 0.137 g of ethanol per g of dried banana peel. This current study evaluates the potential of banana peel as a probable substrate for ethanol production and emphasizes on a new possibility of single-step ethanol production without any pretreatment, although metabolic optimization of the strain SWET4 is required to make the process industrially feasible.

Automated summary

This study evaluates the potential of banana peel as a substrate for ethanol production and investigates a single-step ethanol production process without any pretreatment. It is found that banana peel has the potential for ethanol production and high temperature and pH support higher ethanol production.