The hemicellulolytic enzyme arsenal of Thermobacillus xylanilyticus depends on the composition of biomass used for growth

Abstract

BackgroundThermobacillus 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.ResultsOur 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.ConclusionThis 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.

Study of the specific heat capacity of biomass from banana waste for application in the second‐generation ethanol industry

“…The state of crystallinity of the fibers in a cellulosic biomass indicates the hydrolytic capacity of the material, this being the main focus of the studies in the second-generation ethanol industries. The lignin content of the flower stalk was relatively low, and according to Masarin et al [39] it can be considered a desirable concentration as under mild pretreatment conditions the extraction of this component is disregarded, and the process proceeds to the subsequent step of sugar extraction from the cellulosic material [40]. The lignin content of the flower stalk was relatively low, and according to Masarin et al [39] it can be considered a desirable concentration as under mild pretreatment conditions the extraction of this component is disregarded, and the process proceeds to the subsequent step of sugar extraction from the cellulosic material [40].…”

“…These temperatures can be applied to both physical and electrical pretreatments, such as ultrasound power [43] and pulsed electric current [11], where cooling systems must be used to avoid the production of fermentation inhibitors in the aqueous biomass. Thus, cellulose degradation is one of the most important processes in the carbon cycle, normally involving the combined action of several synergistically functioning enzymes [19,40,44]. In the pH range studied, the use of mildly acid concentrations maintains the degree of crystallinity of the cellulose, and hence allowing for better enzymatic hydrolysis as a possible combined pretreatment application.…”

“…Therefore, the direct relationship of the crystallinity with the viability for the hydrolysis process (disruption/fragmentation) was reported owing to the fact that the sugar production could be proportional with the high digestion rates in any pretreatment [38]. The lignin content of the flower stalk was relatively low, and according to Masarin et al [39] it can be considered a desirable concentration as under mild pretreatment conditions the extraction of this component is disregarded, and the process proceeds to the subsequent step of sugar extraction from the cellulosic material [40]. The third compound of the flower stalk was hemicellulose and the low content present in this material does not affect the production of ethanol if the extraction and pretreatment processes are submitted to strictly controlled conditions [24].…”

Agrowastes as Feedstock for the Production of Endo-β-Xylanase from <b><i>Cohnella</i></b> sp. Strain AR92

“…1 ). Similarly, it was suggested that the growth of Thermobacillus xylanilyticus on lignocellulosic materials promoted the extracellular accumulation of proteins and simple sugars during the exponential growth phase, which extended the viability of the microorganism as well as a low degree of sporulation [Rakotoarivonina et al, 2012]. These findings might also be related to the result of a physiological adaptation to complex microbial niches related to lignocellulosic recycling in nature.…”

“…3 ). The usefulness of feedstocks for enzyme production was also reported for members of the Paenibacillaceae family [Arora et al, 2014;Rakotoarivonina et al, 2012]. Cohnella sp.…”