| 1. |
- Crespo, Carla, et al.
(författare)
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Caloramator boliviensis sp. nov., a novel thermophilic, ethanol-producing bacterium isolated from a hot spring
- 2012
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 62:7, s. 1679-1686
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Tidskriftsartikel (refereegranskat)abstract
- A novel moderately thermophilic, anaerobic, ethanol-producing bacterial strain, 45B(T), was isolated from a mixed sediment water sample collected from a hot spring at Potosi, Bolivia. The cells were straight to slightly curved rods, 2.5 μm long and 0.5 μm wide, approximately. The strain was variable to Gram stain, spore-forming and monotrichously flagellated. Growth of the strain was observed at 45-65 °C and at pH 5.5-8.0, at an optimum temperature of 60 °C and pH 6.5. The substrates utilized by the strain 45B(T) were xylose, cellobiose, glucose, arabinose, sucrose, lactose, maltose, fructose, galactose, mannose, glycerol, xylan, carboxy methylcellulose and yeast extract. The main fermentation product from xylose and cellobiose was ethanol (0.70 and 0.45 grams of ethanol per gram of consumed sugar, respectively). Acetate, lactate, propionate, carbon dioxide and hydrogen were also produced in minor quantities. 1,3-propanediol was produced when glycerol-containing medium was supplemented with yeast extract. The major cellular fatty acids were anteiso-C(15:0), C(16:0), iso-C(16:0), C(15:1), iso-C(14:0), C(13:0) and C(14:0). Polar lipids such as DPG, PG, PE, NGL and other 15 unidentified lipids were predominant in the cell. The DNA G+C content of strain 45B(T) was 32.6 mol %. Phylogenetic analysis based on 16S rDNA gene sequence similarity revealed that strain 45B(T) is located within the Gram-type positive Bacillus-Clostridium branch of the phylogenetic tree. On the basis of morphological, physiological properties and phylogenetic analysis, strain 45B(T) represents a novel species, for which the name Caloramator boliviensis sp. nov., is proposed. The type strain is 45B(T) (=DSM 22065(T) =CCUG 57396(T)).
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| 2. |
- Deraz, Sahar, et al.
(författare)
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Capture of bacteriocins directly from non-clarified fermentation broth using macroporous monolithic cryogels with phenyl ligands
- 2007
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 40:4, s. 786-793
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Tidskriftsartikel (refereegranskat)abstract
- The bacteriocin, sakacin P was produced by the bacteriocin-producing strain Lactobacillus sakei CCUG 42687 at 20 degrees C without pH control. The bacteriocin was captured directly from the fermentation broth using macroporous octyl- and phenyl-monolith columns. The large size of the interconnected macropores (up to 100 mu m) in the macroporous monolith allowed for direct fermentation broth processing with no clarification needed. Screening for optimal bacteriocin binding demonstrated that at pH 6.2 about 80% of the bacteriocin activity could be recovered with a purification factor of 150-160 in the cell-free eluate. Capture of bacteriocins from the fermentation broth using macroporous monoliths in the 96-well plate format presents a promising approach for rapid analytical isolation of bacteriocins from numerous samples.
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| 3. |
- Deraz, Sahar, et al.
(författare)
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Mode of action of acidocin D20079, a bacteriocin produced by the potential probiotic strain, Lactobacillus acidophilus DSM 20079
- 2007
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Ingår i: Journal of Industrial Microbiology & Biotechnology. - : Oxford University Press (OUP). - 1367-5435 .- 1476-5535. ; 34:5, s. 373-379
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, mode of action using three various concentrations of acidocin D20079 (2,048, 128 and 11.3 AU/ml) was determined against an indicator strain L. delbrueckii subsp. lactis DSM 20076. These concentrations all led to marked decreases in both the number of viable cells and in optical density, indicating that the activity of the acidocin D20079 was bactericidal with concomitant cell lysis. Moreover, the probiotic potential of L. acidophilus DSM 20079 was analyzed for its ability to survive and retain viability at conditions (acid and bile concentrations) mimicking the gastrointestinal (GI) tract, under which it survived exposure to pH 2.0 with a 1.2 log cycle reduction in viability and where 45% of the original population survived in a medium containing 0.3% bile for 3 h.
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| 4. |
- Deraz, Sahar, et al.
(författare)
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Production and physicochemical characterization of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079
- 2007
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 23:7, s. 911-921
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, a partial sequence of this peptide is determined, together with data on its secondary structure. A modification of the MRS-growth medium (replacing the detergent Tween 80 with oleic acid), was shown to improve the production level of the peptide by one order of magnitude, as well as to stabilize the activity level. Addition of a detergent (Tween 20, less interfering in mass spectrometric analysis), was however necessary for solubilization of the purified acidocin D20079. Digestion of the peptide followed by de-novo sequencing of generated fragments, allowed determination of a partial sequence consisting of 39 of the totally estimated 65 residues. Acidocin D20079 has a high content of glycine residues, hydrophobic residues, and acidic residues. No modified amino acids were found. Edman degradation, and C-terminal sequencing failed, suggesting that the peptide may be cyclic, and a novel member of class IIc bacteriocins. Circular dichroism spectroscopy and secondary structure prediction showed random coil conformation in aqueous solution, but secondary structure was induced in the presence of sodium-dodecyl sulfate. The data could be fitted assuming 2-13% of the residues to be in alpha-helix and 23-27% of the residues to be in beta-strand conformation. This indicates that a membrane/membrane-mimicking hydrocarbon-water interface induces an active conformation.
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| 5. |
- Deraz, Sahar, et al.
(författare)
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Purification and characterisation of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079
- 2005
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 117:4, s. 343-354
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Tidskriftsartikel (refereegranskat)abstract
- Bacteriocins are natural antimicrobial agents produced by food fermentative bacteria. Lactobacillus acidophilus DSM 20079 produces a small bacteriocin, with a molecular mass of 6.6 kDa, designated acidocin D20079. This antimicrobial peptide was extremely heat-stable (30 min at 121 degrees C) and was active over a wide pH range. It was found to be sensitive to proteolytic enzymes (trypsin, ficin, pepsin, papain, and proteinase K). Acidocin D20079 has a narrow inhibitory spectrum restricted to the genus Lactobacillus which includes L. sakei NCDO 2714, an organism known to cause anaerobic spoilage of vacuum-packaged meat. Maximum production of acidocin D20079 in MRS broth was detected at pH 6.0, and the peptide was purified by ammonium sulphate precipitation followed by sequential cation exchange and hydrophobic interaction chromatography. Purified acidocin D20079 spontaneously formed spherulite crystals during dialysis. As the N-terminus was found to be blocked for sequencing, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to determine a partial sequence. and the molecular mass of the bacteriocin in the formed crystals (6.6 kDa). Estimates of the molecular weight of the partially purified peptide, using tricine-SDS-PAGE, in which bacteriocin activity was confirmed by overlayer techniques were in accordance with this value. (c) 2005 Published by Elsevier B.V.
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| 6. |
- Faryar, Reza, et al.
(författare)
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Production of prebiotic xylooligosaccharides from alkaline extracted wheat straw using the K80R-variant of a thermostable alkali-tolerant xylanase
- 2015
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Ingår i: Food and Bioproducts Processing. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 93:Online 22 November 2014, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural by-products are raw materials of importance for increased utilization of renewable biomass. Wheat straw is a raw material of significant production volume and is in this work used for production of xylooligosaccharides (XOS). Extraction of xylan by dilute alkali was followed by hydrolysis using a variant of the alkali-tolerant Bacillus halodurans S7 endoxylanase A mutated at K80R. The xylan yield was on average 56.5 g xylose equivalents per kg dried, ground wheat straw, with 1 arabinose per 12 xylose residues. The K80R variant, which displayed higher specific activity than the wild-type enzyme, was added at a load of 96 U/g extracted xylan. The XOS-yield (xylobiose – xylopentaose) was evaluated at time intervals in the temperature range of 50 to 65 degrees C, at pHs from 7 to 10. The enzyme was optimally active at 60 degrees C up to pH 9. Hydrolysis was completed within 7 h, resulting in 36 % conversion of the xylan to predominantly xylobiose. Xylose content was low (2.4%) despite extended incubation, which is desirable for XOS-production. The XOS-containing hydrolysate was confirmed as a suitable carbon source for the putative probiotic strain Lactobacillus brevis DSM 1269, showing the applicability of the method to obtain prebiotic XOS.
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