Clostridium sp. as Bio-Catalyst for Fuels and Chemicals Production in a Biorefinery Context

Abstract

Clostridium sp. is a genus of anaerobic bacteria capable of metabolizing several substrates (monoglycerides, diglycerides, glycerol, carbon monoxide, cellulose, and more), into valuable products. Biofuels, such as ethanol and butanol, and several chemicals, such as acetone, 1,3-propanediol, and butyric acid, can be produced by these organisms through fermentation processes. Among the most well-known species, Clostridium carboxidivorans, C. ragsdalei, and C. ljungdahlii can be highlighted for their ability to use gaseous feedstocks (as syngas), obtained from the gasification or pyrolysis of waste material, to produce ethanol and butanol. C. beijerinckii is an important species for the production of isopropanol and butanol, with the advantage of using hydrolysate lignocellulosic material, which is produced in large amounts by first-generation ethanol industries. High yields of 1,3 propanediol by C. butyricum are reported with the use of another by-product from fuel industries, glycerol. In this context, several Clostridium wild species are good candidates to be used as biocatalysts in biochemical or hybrid processes. In this review, literature data showing the technical viability of these processes are presented, evidencing the opportunity to investigate them in a biorefinery context.

Low‐cost medium for 1,3‐propanediol production from crude glycerol by Clostridium butyricum

“…The idea of using residual organic materials, industrial waste streams, and by-products to produce fuels, solvents, lubricants, surfactants, polymers, specialty, and bulk chemicals is in the spotlight. 1,2 In this context, the biobased economy has been emerging and attracting investment from companies around the world. 3 The biobased economy is an important approach to the replacement of fossil fuels by biomass for the production of chemicals, pharmaceuticals, materials, fuels, electricity, and heat.…”

“…2 The use of by-products such as glycerol can reduce operational costs (associated with feedstock acquisition) and environmental impact resulting from the improper disposal of residues. 1 Biodiesel production results in about 10% (w/w) crude glycerol as the main by-product. 3,4 As glycerol is in excess supply in the market due to the large growth of the biodiesel industry, making it a low-cost feedstock, its use in industry is an important opportunity.…”

“…3,4 As glycerol is in excess supply in the market due to the large growth of the biodiesel industry, making it a low-cost feedstock, its use in industry is an important opportunity. 1 To encourage the biodiesel industry on a large scale, many companies are interested in using crude glycerol. 5 Crude glycerol may contain some impurities, such as water, methanol, soap, and non-glycerol organic matter.…”

Butanol production by Clostridium pasteurianum NRRL-598 using corn steep liquor as nutrient source

“…ABE fermentation is composed of two phases: acidogenic and solventogenic. The first is characterized by organic acid production (butyric and acetic), and the second by assimilation of these acids as a carbon source for subsequent transformation into acetone, butanol, and ethanol (Jones and Woods, 1986;Liberato et al, 2019). The most used solventogenic clostridial strains for butanol production are C. acetobutylicum, C. beijerinckii, C. pasteurianum, and C. saccharoperbutylacetonicum (Sun et al Liberato et al, 2019).…”

“…It can be used as a fuel additive or a fuel (replacing the gasoline). Butanol is also an important building block for the chemical industry, being used as an intermediate to the production of methacrylate esters, butyl acrylate, butyl glycol ether, butyl acetate, and plasticizers (Lee et al, 2008;Jin et al 2011;Liberato et al, 2019). For many years, butanol production by ABE fermentation was commercially applied.…”