Valorization of Lignocellulosic Residues for Cost-Effective Production of Thermo-Alkali-Stable Xylanase by Geobacillus thermodenitrificans X1 of Indian Himalayan Hot Spring

Verma, Ritika; Bhalla, Aditya; Kumar, Sudhir

doi:10.1007/s12649-018-0402-y

Cited by 7 publications

(5 citation statements)

References 38 publications

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“…In contrast, members of Geobacillus are among the bacteria of choice for the levels of production of Xyls with stability at elevated temperatures ( Chadha et al, 2019 ; Verma et al, 2019 ). For G. thermodenitrificans , Verma et al (2020) reported Xyl production in the range of values obtained in the present work (5–10 U/mL) using xylan as carbon source. That value was further improved by optimization up to a maximum of 24 U/mL using complex substrates such as wheat straw as carbon source ( Verma et al, 2020 ).…”

Section: Resultssupporting

confidence: 65%

“…For G. thermodenitrificans , Verma et al (2020) reported Xyl production in the range of values obtained in the present work (5–10 U/mL) using xylan as carbon source. That value was further improved by optimization up to a maximum of 24 U/mL using complex substrates such as wheat straw as carbon source ( Verma et al, 2020 ). In addition to Geobacillus species, Caldicellulosiruptor , Thermopolyspora , and several Bacillus species have been reported to be the more effective thermophilic bacteria for the production of thermostable Xyl ( Bala and Singh, 2019 ; Chadha et al, 2019 ).…”

Section: Resultssupporting

confidence: 65%

“…The bacteria B. thermoamylovorans 1141 and G. thermodenitrificans 3781 and the fungi T. lanuginosus 5718 and A. fumigatus 5731 were selected for this analysis. This selection was based on previous knowledge on enzyme production or lack of it in literature ( Koeck et al, 2014 ; Winger et al, 2014 ; de Gouvêa et al, 2018 ; Verma et al, 2020 ), the persistence during composting, the set of enzymes detected, and the range and optimal growth temperature for the particular strain. For bacteria, only Xyl production was determined, whereas for the fungi, Cel (CMCase) and ligninases (Lac, LiP, and MnP) were also analyzed along with, as shown in Table 4 .…”

Section: Resultsmentioning

confidence: 99%

“…In order to determine the biotechnological potential for lignocellulolytic enzyme production by isolates analyzed in the exploratory analysis previously described, thermophilic bacterial and fungal strains were cultured for 7 days in liquid media containing commercial inducers as carbon source (i.e., CMC, xylan), and the enzymatic activity was measured after reaction of the crude enzymatic extract with the corresponding substrate at 50 • C. The bacteria B. thermoamylovorans 1141 and G. thermodenitrificans 3781 and the fungi T. lanuginosus 5718 and A. fumigatus 5731 were selected for this analysis. This selection was based on previous knowledge on enzyme production or lack of it in literature (Koeck et al, 2014;Winger et al, 2014;de Gouvêa et al, 2018;Verma et al, 2020), the persistence during composting, the set of enzymes detected, and the range and optimal growth temperature for the particular strain. For bacteria, only Xyl production was determined, whereas for the fungi, Cel (CMCase) and ligninases (Lac, LiP, and MnP) were also analyzed along with, as shown in Table 4.…”

Section: Production Of Enzymesmentioning

confidence: 99%

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Characterization of Thermophilic Lignocellulolytic Microorganisms in Composting

et al. 2021

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Composting involves the selection of a microbiota capable of resisting the high temperatures generated during the process and degrading the lignocellulose. A deep understanding of the thermophilic microbial community involved in such biotransformation is valuable to improve composting efficiency and to provide thermostable biomass-degrading enzymes for biorefinery. This study investigated the lignocellulose-degrading thermophilic microbial culturome at all the stages of plant waste composting, focusing on the dynamics, enzymes, and thermotolerance of each member of such a community. The results revealed that 58% of holocellulose (cellulose plus hemicellulose) and 7% of lignin were degraded at the end of composting. The whole fungal thermophilic population exhibited lignocellulose-degrading activity, whereas roughly 8–10% of thermophilic bacteria had this trait, although exclusively for hemicellulose degradation (xylan-degrading). Because of the prevalence of both groups, their enzymatic activity, and the wide spectrum of thermotolerance, they play a key role in the breakdown of hemicellulose during the entire process, whereas the degradation of cellulose and lignin is restricted to the activity of a few thermophilic fungi that persists at the end of the process. The xylanolytic bacterial isolates (159 strains) included mostly members of Firmicutes (96%) as well as a few representatives of Actinobacteria (2%) and Proteobacteria (2%). The most prevalent species were Bacillus licheniformis and Aeribacillus pallidus. Thermophilic fungi (27 strains) comprised only four species, namely Thermomyces lanuginosus, Talaromyces thermophilus, Aspergillus fumigatus, and Gibellulopsis nigrescens, of whom A. fumigatus and T. lanuginosus dominated. Several strains of the same species evolved distinctly at the stages of composting showing phenotypes with different thermotolerance and new enzyme expression, even not previously described for the species, as a response to the changing composting environment. Strains of Bacillus thermoamylovorans, Geobacillus thermodenitrificans, T. lanuginosus, and A. fumigatus exhibiting considerable enzyme activities were selected as potential candidates for the production of thermozymes. This study lays a foundation to further investigate the mechanisms of adaptation and acquisition of new traits among thermophilic lignocellulolytic microorganisms during composting as well as their potential utility in biotechnological processing.

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Section: Resultssupporting

confidence: 65%

Section: Resultssupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Production Of Enzymesmentioning

confidence: 99%

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Characterization of Thermophilic Lignocellulolytic Microorganisms in Composting

et al. 2021

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“…According to the results, the concentration of xylooligosaccharides increase as a function of the reaction time. Previous studies have indicated that endoxylanase is the key enzyme for conversion of xylans into xylooligosaccharides [ 78 , 79 ]. The soft and green conditions used for enzymatic production of xylooligosaccharides and the specificity of the biocatalysts make enzymatic methods more convenient than chemical procedures [ 80 ], constituting a reasonable and reliable alternative to produce the large amounts required, for example, in aquaculture and poultry industry [ 81 ].…”

Section: Resultsmentioning

confidence: 99%

Optimization of β-1,4-Endoxylanase Production by an Aspergillus niger Strain Growing on Wheat Straw and Application in Xylooligosaccharides Production

et al. 2021

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Plant biomass constitutes the main source of renewable carbon on the planet. Its valorization has traditionally been focused on the use of cellulose, although hemicellulose is the second most abundant group of polysaccharides on Earth. The main enzymes involved in plant biomass degradation are glycosyl hydrolases, and filamentous fungi are good producers of these enzymes. In this study, a new strain of Aspergillus niger was used for hemicellulase production under solid-state fermentation using wheat straw as single-carbon source. Physicochemical parameters for the production of an endoxylanase were optimized by using a One-Factor-at-a-Time (OFAT) approach and response surface methodology (RSM). Maximum xylanase yield after RSM optimization was increased 3-fold, and 1.41- fold purification was achieved after ultrafiltration and ion-exchange chromatography, with about 6.2% yield. The highest activity of the purified xylanase was observed at 50 °C and pH 6. The enzyme displayed high thermal and pH stability, with more than 90% residual activity between pH 3.0–9.0 and between 30–40 °C, after 24 h of incubation, with half-lives of 30 min at 50 and 60 °C. The enzyme was mostly active against wheat arabinoxylan, and its kinetic parameters were analyzed (Km = 26.06 mg·mL−1 and Vmax = 5.647 U·mg−1). Wheat straw xylan hydrolysis with the purified β-1,4 endoxylanase showed that it was able to release xylooligosaccharides, making it suitable for different applications in food technology.

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