| 1. |
- Aulitto, Martina, 1991, et al.
(författare)
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Bacillus coagulans MA-13: a promising thermophilic and cellulolytic strain for the production of lactic acid from lignocellulosic hydrolysate
- 2017
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 10:210
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Tidskriftsartikel (refereegranskat)abstract
- Background: The transition from a petroleum-based economy towards more sustainable bioprocesses for the production of fuels and chemicals (circular economy) is necessary to alleviate the impact of anthropic activities on the global ecosystem. Lignocellulosic biomass-derived sugars are suitable alternative feedstocks that can be fermented or biochemically converted to value-added products. An example is lactic acid, which is an essential chemical for the production of polylactic acid, a biodegradable bioplastic. However, lactic acid is still mainly produced by Lactobacillus species via fermentation of starch-containing materials, the use of which competes with the supply of food and feed. Results: A thermophilic and cellulolytic lactic acid producer was isolated from bean processing waste and was identified as a new strain of Bacillus coagulans, named MA-13. This bacterium fermented lignocellulose-derived sugars to lactic acid at 55 degrees C and pH 5.5. Moreover, it was found to be a robust strain able to tolerate high concentrations of hydrolysate obtained from wheat straw pre-treated by acid-catalysed (pre-) hydrolysis and steam explosion, especially when cultivated in controlled bioreactor conditions. Indeed, unlike what was observed in microscale cultivations (complete growth inhibition at hydrolysate concentrations above 50%), B. coagulans MA-13 was able to grow and ferment in 95% hydrolysate-containing bioreactor fermentations. This bacterium was also found to secrete soluble thermophilic cellulases, which could be produced at low temperature (37 degrees C), still retaining an optimal operational activity at 50 degrees C. Conclusions: The above-mentioned features make B. coagulans MA-13 an appealing starting point for future development of a consolidated bioprocess for production of lactic acid from lignocellulosic biomass, after further strain development by genetic and evolutionary engineering. Its optimal temperature and pH of growth match with the operational conditions of fungal enzymes hitherto employed for the depolymerisation of lignocellulosic biomasses to fermentable sugars. Moreover, the robustness of B. coagulans MA-13 is a desirable trait, given the presence of microbial growth inhibitors in the pre-treated biomass hydrolysate.
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| 2. |
- Aulitto, Martina, 1991, et al.
(författare)
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Draft genome sequence of bacillus coagulans ma-13, a thermophilic lactic acid producer from lignocellulose
- 2019
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Ingår i: Microbiology Resource Announcements. - 2576-098X. ; 8:23
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus coagulans MA-13 is an efficient lactic acid producer which withstands high concentrations of the growth inhibitors formed during the pretreatment of lignocellulosic feedstock. This draft genome sequence is expected to pave the way toward the understanding of mechanisms responsible for the robustness of MA-13 during simultaneous saccharification and fermentation.
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| 3. |
- Aulitto, Martina, 1991, et al.
(författare)
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Seed culture pre-adaptation of Bacillus coagulans MA-13 improves lactic acid production in simultaneous saccharification and fermentation
- 2019
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Lignocellulosic biomass is an abundant and sustainable feedstock, which represents a promising raw material for the production of lactic acid via microbial fermentation. However, toxic compounds that affect microbial growth and metabolism are released from the biomass upon thermochemical pre-treatment. So far, susceptibility of bacterial strains to biomass-derived inhibitors still represents a major barrier to lactic acid production from lignocellulose. Detoxification of the pre-treated lignocellulosic material by water washing is commonly performed to alleviate growth inhibition of the production microorganism and achieve higher production rates. Results In this study, we assessed the feasibility of replacing the washing step with integrated cellular adaptation during pre-culture of Bacillus coagulans MA-13 prior to simultaneous saccharification and lactic acid fermentation of steam exploded wheat straw. Using a seed culture pre-exposed to 30% hydrolysate led to 50% shorter process time, 50% higher average volumetric and 115% higher average specific productivity than when using cells from a hydrolysate-free seed culture. Conclusions Pre-exposure of B. coagulans MA-13 to hydrolysate supports adaptation to the actual production medium. This strategy leads to lower process water requirements and combines cost-effective seed cultivation with physiological pre-adaptation of the production strain, resulting in reduced lactic acid production costs.
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| 4. |
- Aulitto, Martina, et al.
(författare)
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Thermus thermophilus as source of thermozymes for biotechnological applications: homologous expression and biochemical characterization of an alpha-galactosidase
- 2017
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The genus Thermus, which has been considered for a long time as a fruitful source of biotechnological relevant enzymes, has emerged more recently as suitable host to overproduce thermozymes. Among these, alpha-galactosidases are widely used in several industrial bioprocesses that require high working temperatures and for which thermostable variants offer considerable advantages over their thermolabile counterparts. Results: Thermus thermophilus HB27 strain was used for the homologous expression of the TTP0072 gene encoding for an a-galactosidase (TtGalA). Interestingly, a soluble and active histidine-tagged enzyme was produced in larger amounts (5 mg/L) in this thermophilic host than in Escherichia coli (0.5 mg/L). The purified recombinant enzyme showed an optimal activity at 90 degrees C and retained more than 40% of activity over a broad range of pH (from 5 to 8). Conclusions: TtGalA is among the most thermoactive and thermostable a-galactosidases discovered so far, thus pointing to T. thermophilus as cell factory for the recombinant production of biocatalysts active at temperature values over 90 degrees C.
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| 5. |
- Carbonaro, Miriam, et al.
(författare)
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Genomic mining of Geobacillus stearothermophilus GF16 for xylose production from hemicellulose-rich biomasses using secreted enzymes
- 2024
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Ingår i: New Biotechnology. - 1876-4347 .- 1871-6784. ; 82, s. 14-24
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Tidskriftsartikel (refereegranskat)abstract
- The valorization of lignocellulosic biomass, derived from various bio-waste materials, has received considerable attention as a sustainable approach to improve production chains while reducing environmental impact. Microbial enzymes have emerged as key players in the degradation of polysaccharides, offering versatile applications in biotechnology and industry. Among these enzymes, glycoside hydrolases (GHs) play a central role. Xylanases, in particular, are used in a wide range of applications and are essential for the production of xylose, which can be fermented into bioethanol or find use in many other industries. Currently, fungal secretomes dominate as the main reservoir of lignocellulolytic enzymes, but thermophilic microorganisms offer notable advantages in terms of enzyme stability and production efficiency. Here we present the genomic characterization of Geobacillus stearothermophilus GF16 to identify genes encoding putative enzymes involved in lignocellulose degradation. Thermostable GHs secreted by G. stearothermophilus GF16 were investigated and found to be active on different natural polysaccharides and synthetic substrates, revealing an array of inducible GH activities. In particular, the concentrated secretome possesses significant thermostable xylanase and β-xylosidase activities (5 ×103 U/L and 1.7 ×105 U/L, respectively), highlighting its potential for application in biomass valorization. We assessed the hemicellulose hydrolysis capabilities of various agri-food wastes using the concentrated secretome of the strain cultivated on xylan. An impressive 300-fold increase in xylose release compared to a commercially available cocktail was obtained with the secretome, underscoring the remarkable efficacy of this approach.
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| 6. |
- Franzén, Carl Johan, 1966, et al.
(författare)
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High gravity lignocellulose bioprocess development for ethanol and lactic acid production by multi-feed simultaneous saccharification and fermentation
- 2017
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Ingår i: Oral presentation at: Recent Advances in Fermentation Technology, RAFT12. Oct 29 - Nov 1, Bonita Springs, FL, USA..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Second generation bioethanol production is becoming established in production plants across the world. The process can also be viewed as a model biorefinery concept for biotechnological conversion of recalcitrant lignocellulosic raw materials to chemicals and other products. We have developed a Multi-Feed SSCF process: a systematic, model-driven design of fed-batch simultaneous saccharification and co-fermentation of steam-pretreated lignocellulosic materials in standard stirred tank reactors. The design includes feeding of solid substrate, enzymes, and active, robust cell factories adapted to the present substrate. The concept has been applied not only to ethanol production with S. cerevisiae, but also to lactic acid production from wheat straw by the thermophilic, cellulolytic strain Bacillus coagulans MA-13, isolated from bean processing waste. High Gravity operation, i.e. fermentation at high concentrations of water insoluble solids (WIS), pushes the process towards higher product concentrations and productivities, and improved energy and water economy. By using the multi-feed SSCF approach, the ethanol process was pushed towards final product concentrations above 60 g/L, at about 90% of the theoretical yields on consumed substrate, using 22% w/w accumulated WIS additions of acid- and steam explosion-pretreated wheat straw. Bacillus coagulans MA-13 was found to secrete cellulolytic enzymes and ferment lignocellulose-derived sugars to lactic acid; thus, it may be a potential platform for consolidated bioprocessing of lactic acid. We investigated its performance in multi-feed SSF and found that pre-adaptation of cells to the liquid fraction of the steam-pretreated lignocellulosic material improves lactate productivity and reduces the SSF time from 33 to 12 hours.
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| 7. |
- Gaglione, R., et al.
(författare)
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Insights into the anticancer properties of the first antimicrobial peptide from Archaea
- 2017
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 1872-8006 .- 0304-4165. ; 1861:9, s. 2155-2164
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Tidskriftsartikel (refereegranskat)abstract
- Background: The peptide VLL-28, identified in the sequence of an archaeal protein, the transcription factor Stf76 from Sulfolobus islandicus, was previously identified and characterized as an antimicrobial peptide, possessing a broad-spectrum antibacterial activity. Methods: Through a combined approach of NMR and Circular Dichroism spectroscopy, Dynamic Light Scattering, confocal microscopy and cell viability assays, the interaction of VLL-28 with the membranes of both parental and malignant cell lines has been characterized and peptide mechanism of action has been studied. Results: It is here demonstrated that VLL-28 selectively exerts cytotoxic activity against murine and human tumor cells. By means of structural methodologies, VLL-28 interaction with the membranes has been proven and the binding residues have been identified. Confocal microscopy data show that VLL-28 is internalized only into tumor cells. Finally, it is shown that cell death is mainly caused by a time-dependent activation of apoptotic pathways. Conclusions: VLL-28, deriving from the archaeal kingdom, is here found to be endowed with selective cytotoxic activity towards both murine and human cancer cells and consequently can be classified as an ACP.
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