title: The hemicellulolytic enzyme arsenal of Thermobacillus xylanilyticus depends on the composition of biomass used for growth.
abstract: BACKGROUND
  Thermobacillus xylanilyticus is a thermophilic and highly xylanolytic bacterium. It produces robust and stable enzymes, including glycoside hydrolases and esterases, which are of special interest for the development of integrated biorefineries. To investigate the strategies used by T. xylanilyticus to fractionate plant cell walls, two agricultural by-products, wheat bran and straw (which differ in their chemical composition and tissue organization), were used in this study and compared with glucose and xylans. The ability of T. xylanilyticus to grow on these substrates was studied. When the bacteria used lignocellulosic biomass, the production of enzymes was evaluated and correlated with the initial composition of the biomass, as well as with the evolution of any residues during growth.
  
  
  RESULTS
  Our results showed that T. xylanilyticus is not only able to use glucose and xylans as primary carbon sources but can also use wheat bran and straw. The chemical compositions of both lignocellulosic substrates were modified by T. xylanilyticus after growth. The bacteria were able to consume 49% and 20% of the total carbohydrates in bran and straw, respectively, after 24 h of growth. The phenolic and acetyl ester contents of these substrates were also altered. Bacterial growth on both lignocellulosic biomasses induced hemicellulolytic enzyme production, and xylanase was the primary enzyme secreted. Debranching activities were differentially produced, as esterase activities were more important to bacterial cultures grown on wheat straw; arabinofuranosidase production was significantly higher in bacterial cultures grown on wheat bran.
  
  
  CONCLUSIONS
  This study provides insight into the ability of T. xylanilyticus to grow on abundant agricultural by-products, which are inexpensive carbon sources for enzyme production. The composition of the biomass upon which the bacteria grew influenced their growth, and differences in the biomass provided resulted in dissimilar enzyme production profiles. These results indicate the importance of using different biomass sources to encourage the production of specific enzymes.
authors.affiliation: UMR FARE614 Université de Reims Champagne-Ardenne, Reims, France. harivony.rakotoarivonina@univ-reims.fr
authors.forename: Harivony
authors.initials: H
authors.lastname: Rakotoarivonina
authors.forename: Béatrice
authors.initials: B
authors.lastname: Hermant
authors.forename: Nina
authors.initials: N
authors.lastname: Monthe
authors.forename: Caroline
authors.initials: C
authors.lastname: Rémond
mesh_terms: D056449:Bacillales / Q000201:enzymology / Q000254:growth & development*; D001426:Bacterial Proteins / Q000378:metabolism*; D018533:Biomass; D002473:Cell Wall / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism*; D007700:Kinetics; D011134:Polysaccharides / Q000378:metabolism; D014908:Triticum / Q000737:chemistry; D014990:Xylans / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004043:Dietary Fiber; D011134:Polysaccharides; D014990:Xylans; C007916:hemicellulose; D006867:Hydrolases; D004950:Esterases; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase; D043364:Endo-1,4-beta Xylanases