BioChem - DOS

Single-step ethanol production from lignocellulose using novel extremely thermophilic bacteria

Biotechnology for biofuels

Svetlitchnyi, Vitali A; Kensch, Oliver; Falkenhan, Doris A; Korseska, Svenja G; Lippert, Nadine; Prinz, Melanie; Sassi, Jamaleddine; Schickor, Anke; Curvers, Simon

<P><B>Background</B></P><P>Consolidated bioprocessing (CBP) of lignocellulosic biomass to ethanol using thermophilic bacteria provides a promising solution for efficient lignocellulose conversion without the need for additional cellulolytic enzymes. Most studies on the thermophilic CBP concentrate on co-cultivation of the thermophilic cellulolytic bacterium <I>Clostridium thermocellum</I> with non-cellulolytic thermophilic anaerobes at temperatures of 55°C-60°C.</P><P><B>Results</B></P><P>We have specifically screened for cellulolytic bacteria growing at temperatures >70°C to enable direct conversion of lignocellulosic materials into ethanol. Seven new strains of extremely thermophilic anaerobic cellulolytic bacteria of the genus <I>Caldicellulosiruptor</I> and eight new strains of extremely thermophilic xylanolytic/saccharolytic bacteria of the genus <I>Thermoanaerobacter</I> isolated from environmental samples exhibited fast growth at 72°C, extensive lignocellulose degradation and high yield ethanol production on cellulose and pretreated lignocellulosic biomass. Monocultures of <I>Caldicellulosiruptor</I> strains degraded up to 89-97% of the cellulose and hemicellulose polymers in pretreated biomass and produced up to 72 mM ethanol on cellulose without addition of exogenous enzymes. In dual co-cultures of <I>Caldicellulosiruptor</I> strains with <I>Thermoanaerobacter</I> strains the ethanol concentrations rose 2- to 8.2-fold compared to cellulolytic monocultures. A co-culture of <I>Caldicellulosiruptor</I> DIB 087C and <I>Thermoanaerobacter</I> DIB 097X was particularly effective in the conversion of cellulose to ethanol, ethanol comprising 34.8 mol% of the total organic products. In contrast, a co-culture of <I>Caldicellulosiruptor saccharolyticus</I> DSM 8903 and <I>Thermoanaerobacter mathranii</I> subsp. <I>mathranii</I> DSM 11426 produced only low amounts of ethanol.</P><P><B>Conclusions</B></P><P>The newly discovered <I>Caldicellulosiruptor</I> sp. strain DIB 004C was capable of producing unexpectedly large amounts of ethanol from lignocellulose in fermentors. The established co-cultures of new <I>Caldicellulosiruptor</I> strains with new <I>Thermoanaerobacter</I> strains underline the importance of using specific strain combinations for high ethanol yields. These co-cultures provide an efficient CBP pathway for ethanol production and represent an ideal starting point for development of a highly integrated commercial ethanol production process.</P>

2013

BioMed Central

cc-by

1754-6834

6

pp.31-31

10.1186/1754-6834-6-31

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART74364645

https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/1754-6834-6-31

Anaerobic; Caldicellulosiruptor; Consolidated bioprocessing; Ethanol; Extremely thermophilic bacteria; High temperature; Lactate; Lignocellulose; Thermoanaerobacter