Bioethanol production by <i>Enterobacter hormaechei</i> through carbon monoxide‐rich syngas fermentation
Swayamsidha Pati, M. Mohanty, Swati Mohapatra, Deviprasad Samantaray
Abstract
Fossil fuel depletion and environmental contamination coupled with food vs fuel conflict motivated sustainable bioethanol production through syngas fermentation utilizing lignocellulosic biomass as feedstock. Herein, Enterobacter sp. RF2 strain was selected for the investigation out of the nine anaerobes that were screened for bioethanol production using the pyridinium chlorochromate assay. Under optimal conditions, Enterobacter sp. RF2 and the reference strain Clostridium ljungdahlii ATCC-55383 produced 21.8 and 37.7 g/L of bioethanol in an anaerobic culture bottle and 25.3 and 39.6 g/L of bioethanol in a stirred tank reactor via syngas fermentation. Furthermore, infra-red spectra and proton nuclear magnetic resonance illustrated chemical shift patterns of bioethanol. The high bioethanol producer was identified as Enterobacter hormaechei RF2 by in silico analysis. Here, it was reported for the first time that E. hormaechei RF2 is high ethanol tolerant and genetically stable bioethanol producer that can be exploited for pilot-scale production to meet the rising demand for fossil fuels and lessen eco-pollution. Thus, this research will pave the way for the commercialization of green chemicals which is the need of the hour in the current scenario. However, the cost of biomass conversion to bioethanol must be less than the existing price of gasoline to be competitive and get economic acceptance. Although this method is now at the pre-commercialization stage due to lack because of techno-economic feasibility, but usage of suitable substrates and concurrent production of different valuable products can make the entire process cost affordable. Therefore, by providing employment to the rural population through the exploitation of lignocellulosic biomass, eco-friendly fuel to the customer, and lucrative fuel business to industries, it might thus hypothesize an intriguing future for our global economy.