Single-step bioconversion of lignocellulosic biomass to biofuels using extreme thermophilic bacteria

Abstract

The present technology pertains to improved methods for the conversion of lignocellulosic biomass material to bio-fuels using novel isolated cellulolytic extreme thermophilic bacterial cells belonging to the genus Caldicellulosiruptor, and mutants thereof.

1 . A method for converting lignocellulosic biomass material to a biofuel comprising the step of contacting the lignocellulosic biomass material with a microbial culture for a period of time at an initial temperature and an initial pH, thereby producing an amount of a biofuel; wherein the microbial culture comprises an extremely thermophilic bacteria strain of the genus  Caldicellulosiruptor,  wherein the lignocellulosic biomass material is converted in a single step process as part of a consolidated bioprocessing (CBP) system. 
     
     
         2 . (canceled) 
     
     
         3 . The method according to  claim 1 , wherein the period of time is 10 h to 300 h, preferably 50 h to 200 h, 80 h to 160 h. 
     
     
         4 . The method according to  claim 1 , wherein the initial temperature is in the range between 55° C. and 80° C., preferably between 72° C. and 78° C. 
     
     
         5 . The method according to  claim 1 , wherein the initial pH is between 5 and 9, preferably between 6 and 8. 
     
     
         6 . The method according to  claim 1 , wherein the biofuel is an alcohol, preferably ethanol. 
     
     
         7 . The method according to  claim 1 , wherein the lignocellulosic biomass material is selected from the group consisting of grass, switch grass, cord grass, rye grass, reed canary grass, mixed prairie grass, miscanthus, sugar-methoding residues, sugarcane bagasse, sugarcane straw, agricultural wastes, rice straw, rice hulls, barley straw, corn cobs, cereal straw, wheat straw, canola straw, oat straw, oat hulls, corn fiber, stover, soybean stover, corn stover, forestry wastes, recycled wood pulp fiber, paper sludge, sawdust, hardwood, and softwood, pressmud from sugar beet, cotton stalk, banana leaves, and lignocellulosic biomass material obtained through processing of food plants. 
     
     
         8 . (canceled) 
     
     
         9 . The method according to  claim 1 , wherein said lignocellulosic biomass material is selected from the group consisting of corn stover, sugarcane bagasse, cotton stalks, switchgrass, and poplar wood. 
     
     
         10 - 13 . (canceled) 
     
     
         14 . The method according to  claim 1 , wherein said lignocellulosic biomass material is a grass or perennial grass, optionally miscanthus. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . The method according to  claim 1 , wherein said lignocellulosic biomass material is subjected to mechanical, thermochemical, and/or biochemical pretreatment. 
     
     
         18 . The method according to  claim 17 , wherein pretreating the lignocellulosic biomass material comprises exposing the lignocellulosic biomass to steam treatment. 
     
     
         19 . The method according to  claim 17 , wherein pretreating the lignocellulosic biomass material comprises mechanical commination and a subsequent treatment with sulfurous acid or its anhydride under heat and pressure with a sudden release of pressure. 
     
     
         20 . The method according to  claim 17 , wherein pretreating the lignocellulosic biomass comprises milling the lignocellulosic biomass. 
     
     
         21 . (canceled) 
     
     
         22 . The method according to  claim 17 , wherein the lignocellulosic biomass material is pretreated in addition with enzymes, preferably cellulose and hemicellulose degrading enzymes. 
     
     
         23 . The method according to  claim 1 , wherein the strain is selected from the group consisting of  Caldicellulosiruptor  sp. DIB041C, deposited as DSM 25771,  Caldicellulosiruptor  sp. DIB087C, deposited as DSM 25772,  Caldicellulosiruptor  sp. DIB103C, deposited as DSM 25773,  Caldicellulosiruptor  sp. DIB104C, deposited as DSM 25774,  Caldicellulosiruptor  sp. DIB107C, deposited as DSM 25775,  Caldicellulosiruptor  sp. DIB101C, deposited as DSM 25178 and  Caldicellulosiruptor  sp. DIB004C, deposited as DSM 25177, microorganism derived therefrom, progenies or mutants thereof. 
     
     
         24 . (canceled) 
     
     
         25 . (canceled)