Genomic analysis of Butanol production in a novel thermophilic butanol producer.

DÍAZ PEÑA, ROCÍO; BEATRIZ S. MÉNDEZ; M. JULIA PETTINARI

Cordoba

Congreso; XI Congreso de la Sociedad Argentina de Microbiología General (SAMIGE 2015); 2015

Sociedad Argentina de Microbiología General (SAMIGE 2015)

Over the past decades, development of biofuels has raised a great interest as an alternative to fossil fuels which generate large amounts CO2, emissions and toxic byproducts, (causative agents of greenhouse effect), and are non-renewable resources. In this context, butanol has attracted special attention due to its advantages over ethanol. Not only it is capable of producing more energy if properly harnessed but is also less corrosive and water soluble, so it can be used in blending with gasoline or diesel. Moreover its use does not require modifications to existing engines, it has a lower vapor pressure and is less hygroscopic than ethanol, a characteristic that enables its transportation without altering the product. The microbial production of butanol by bacteria of the genus Clostridium has been studied in detail. Such is the case of C. acetobutylicum, which has been used in industrial processes for the synthesis of acetone and butanol from different substrates. In our laboratory we have isolated and characterized a new species, originally named C. thermopapyrolyticum, an anaerobic thermopilic bacterium that is capable of producing butanol once it has reached stationary state. To complete the genetic characterization of this microorganisms its genome has been sequenced. Genome to genome comparisons with previously sequenced bacteria revealed that it is most probably a member of the genus Thermoanaerobacterium, and not Clostridium. In view of this, we denominated it as Thermoanaeobacterium sp. GCU5.To identify genes encoding the key enzymes in the metabolic pathway of n-butanol production, we performed a genomic analysis using RAST annotation Server and Blast algorithm. Eight genes involved in this pathway were identified: thl, hbd, crt, bcd, etfA, etfB, adh, bdh. It was observed that the genes thl, hbd, crt, bcd, etfA, etfB are organized in the operon bcs, whereas in C. acetobutylicum the gene thl is not part of this operon.Furthermore, we observed that Thermoanaeobacterium sp. GCU5 presents genes coding for enzymes involved in the metabolism of xylan (hemicellulose main component), cellobiose and sucrose, all components present on sugar cane agroindustrial residue.Knowing this bacterium has all genes responsible for butanol production as well as those involved in xylan, we decided to evaluate its ability to grow on xylose and arabinose (monosaccharide present in xylan), sucrose and cellobiose. We demonstrate that Thermoanaeobacterium sp. GCU5 is able to grow on arabinose, xilose, saccharose and celobiose as well as galactose. Ongoing studies are focused on analyzing butanol production from these substrates.