“…5 ). Interestingly, the thermostability of our B. subtilis cellulosome was similar to that of the native cellulosome of different C. thermocellum strains [ 38 , 39 ]. Fig.…”
BackgroundEnzymatic conversion of lignocellulosic biomass into soluble sugars is a major bottleneck in the plant biomass utilization. Several anaerobic organisms cope these issues via multiple-enzyme complex system so called ‘cellulosome’. Hence, we proposed a “biomimic operon” concept for making an artificial cellulosome which can be used as a promising tool for the expression of cellulosomal enzymes in Bacillus subtilis.ResultsAccording to the proteomic analysis of Clostridium thermocellum ATCC27405 induced by Avicel or cellobiose, we selected eight highly expressed cellulosomal genes including a scaffoldin protein gene (cipA), a cell-surface anchor gene (sdbA), two exoglucanase genes (celK and celS), two endoglucanase genes (celA and celR), and two xylanase genes (xynC and xynZ). Arranging these eight genes in two different orders, we constructed two different polycistronic operons using the ordered gene assembly in Bacillus method. This is the first study to express the whole CipA along with cellulolytic enzymes in B. subtilis. Each operon was successfully expressed in B. subtilis RM125, and the protein complex assembly, cellulose-binding ability, thermostability, and cellulolytic activity were demonstrated. The operon with a higher xylanase activity showed greater saccharification on complex cellulosic substrates such as Napier grass than the other operon.ConclusionsIn this study, a strategy for constructing an efficient cellulosome system was developed and two different artificial cellulosomal operons were constructed. Both operons could efficiently express the cellulosomal enzymes and exhibited cellulose saccharification. This strategy can be applied to different industries with cellulose-containing materials, such as papermaking, biofuel, agricultural compost, mushroom cultivation, and waste processing industries.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1151-7) contains supplementary material, which is available to authorized users.
“…5 ). Interestingly, the thermostability of our B. subtilis cellulosome was similar to that of the native cellulosome of different C. thermocellum strains [ 38 , 39 ]. Fig.…”
BackgroundEnzymatic conversion of lignocellulosic biomass into soluble sugars is a major bottleneck in the plant biomass utilization. Several anaerobic organisms cope these issues via multiple-enzyme complex system so called ‘cellulosome’. Hence, we proposed a “biomimic operon” concept for making an artificial cellulosome which can be used as a promising tool for the expression of cellulosomal enzymes in Bacillus subtilis.ResultsAccording to the proteomic analysis of Clostridium thermocellum ATCC27405 induced by Avicel or cellobiose, we selected eight highly expressed cellulosomal genes including a scaffoldin protein gene (cipA), a cell-surface anchor gene (sdbA), two exoglucanase genes (celK and celS), two endoglucanase genes (celA and celR), and two xylanase genes (xynC and xynZ). Arranging these eight genes in two different orders, we constructed two different polycistronic operons using the ordered gene assembly in Bacillus method. This is the first study to express the whole CipA along with cellulolytic enzymes in B. subtilis. Each operon was successfully expressed in B. subtilis RM125, and the protein complex assembly, cellulose-binding ability, thermostability, and cellulolytic activity were demonstrated. The operon with a higher xylanase activity showed greater saccharification on complex cellulosic substrates such as Napier grass than the other operon.ConclusionsIn this study, a strategy for constructing an efficient cellulosome system was developed and two different artificial cellulosomal operons were constructed. Both operons could efficiently express the cellulosomal enzymes and exhibited cellulose saccharification. This strategy can be applied to different industries with cellulose-containing materials, such as papermaking, biofuel, agricultural compost, mushroom cultivation, and waste processing industries.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1151-7) contains supplementary material, which is available to authorized users.
“…However, Li and coauthors [38] studying the effect of temperature on endoxylanase activity from Streptomyces rameus L2001 observed a maximal relative activity at 70ºC. Several other bacterial and also fungal endoxylanase activity have presented maximal activity at 35ºC (Bacillus tequilensis) [3], 50 ºC (Jonesia denitrificans) [32], 52 ºC (Bacillus subtilis) [39], 60 ºC (Bacillus subtilis) [40], 65 ºC (Clostridium thermocellum) [9], or even 70 ºC (Chaetomium thermophilum) [41]. So, the optimum of temperature of 60 ºC, and also the fact that almost 90% of this activity is still retained at 70 ºC, seems to be a good characteristic for endoxylanase activity from S. malaysiensis AMT-3, in comparison to endoxylanases from other microorganisms, indicating a real possibility to industrial application.…”
Section: Resultsmentioning
confidence: 99%
“…So, the optimum of temperature of 60 ºC, and also the fact that almost 90% of this activity is still retained at 70 ºC, seems to be a good characteristic for endoxylanase activity from S. malaysiensis AMT-3, in comparison to endoxylanases from other microorganisms, indicating a real possibility to industrial application. Wang and coauthors [30] observed that after 30 min of pre-incubation at 60 ºC, endoxylanase activity of Streptomyces actuosus A-151 retained more than 80% of its original activity, whereas Osiro andf coauthors [9] observed a 40% decrease of endoxylanase activity from Clostridium thermocellum after 48 hours of its original activity at 60 ºC. Li and coauthors [35] observed a slight decreased (around 14%) of endoxylanase (from Penicillium oxalicum ZH-30) activity after 60 min at 50 ºC.…”
Section: Resultsmentioning
confidence: 99%
“…Since endoxylanases randomly cleave the xylan backbone, the reaction products are diverse, which may include xylose, xylobiose, xylooligomers, heterodisaccharides of xylose and glucose and their positional isomers [5]. Endoxylanases are produced by many mesophilic microorganisms, and have already been found in bacteria, such as Bacillus and Clostridium species [3,4,9], in several species of Streptomyces [10][11][12], and in fungi such as Thermomyces, Aspergillus and Trichoderma [6,13,14].…”
This study evaluated the production of endoxylanases by Streptomyces malaysiensis AMT-3 in submerged fermentation using by-products of the food industry at 28ºC. In shake-flasks experiments, the highest endoxylanase activity of 45.8 U.mL-1 was observed within 6 days in a medium containing (w/v) 2.5% wheat bran and 1.2% corn steep liquor. The same culture conditions were used to evaluate the enzyme production in a 2 L stirred tank reactor under different agitation (300, 450 and 600 rev.min-1) and aeration (30 and 60 L.h-1) conditions. The use of 450 rev.min-1 coupled to an aeration of 90 L.h-1 resulted on 81.3 U.mL-1 endoxylanase activity within 5 days. The effect of temperature and pH on endoxylanase activity and stability showed the highest activity at 60 ºC and pH 6.0. Zymography showed the presence of three xylanolytic bands with molecular masses of 690, 180 and 142 kDa. The results showed that the thermotolerant actinobacterial endoxylanase can be produced in high titers using by-product of the food industry.
“…It usually grows at a high temperature (50-60 • C), leading to better degradation efficiency compared to medium-temperature bacteria. Additionally, its enzymes can tolerate extreme environments, including phenolic compounds from the pretreated lignocellulose, which can be directly used for lignocellulose degradation without the movement of phenolic compounds [64].…”
Section: Typical Microorganisms For Lignocellulose Degradationmentioning
Lignocellulose is a kind of renewable bioresource containing abundant polysaccharides, which can be used for biochemicals and biofuels production. However, the complex structure hinders the final efficiency of lignocellulosic biorefinery. This review comprehensively summarizes the hydrolases and typical microorganisms for lignocellulosic degradation. Moreover, the commonly used bioprocesses for lignocellulosic biorefinery are also discussed, including separated hydrolysis and fermentation, simultaneous saccharification and fermentation and consolidated bioprocessing. Among these methods, construction of microbial co-culturing systems via consolidated bioprocessing is regarded as a potential strategy to efficiently produce biochemicals and biofuels, providing theoretical direction for constructing efficient and stable biorefinery process system in the future.
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