Thermophilic Bacterium Geobacillus Sp Research Articles

Recombinant Expression and Characterization of a Novel Thermo-Alkaline Lipase with Increased Solvent Stability from the Antarctic Thermophilic Bacterium Geobacillus sp. ID17.

Lipases are enzymes that hydrolyze long-chain carboxylic esters, and in the presence of organic solvents, they catalyze organic synthesis reactions. However, the use of solvents in these processes often results in enzyme denaturation, leading to a reduction in enzymatic activity. Consequently, there is significant interest in identifying new lipases that are resistant to denaturing conditions, with extremozymes emerging as promising candidates for this purpose. Lip7, a lipase from Geobacillus sp. ID17, a thermophilic microorganism isolated from Deception Island, Antarctica, was recombinantly expressed in E. coli C41 (DE3) in functional soluble form. Its purification was achieved with 96% purity and 23% yield. Enzymatic characterization revealed Lip7 to be a thermo-alkaline enzyme, reaching a maximum rate of 3350 U mg-1 at 50 °C and pH 11.0, using p-nitrophenyl laurate substrate. Notably, its kinetics displayed a sigmoidal behavior, with a higher kinetic efficiency (kcat/Km) for substrates of 12-carbon atom chain. In terms of thermal stability, Lip7 demonstrates stability up to 60 °C at pH 8.0 and up to 50 °C at pH 11.0. Remarkably, it showed high stability in the presence of organic solvents, and under certain conditions even exhibited enzymatic activation, reaching up to 2.5-fold and 1.35-fold after incubation in 50% v/v ethanol and 70% v/v isopropanol, respectively. Lip7 represents one of the first lipases from the bacterial subfamily I.5 and genus Geobacillus with activity and stability at pH 11.0. Its compatibility with organic solvents makes it a compelling candidate for future research in biocatalysis and various biotechnological applications.

Recombinant expression and characterization of a new laccase, bioinformatically identified, from the Antarctic thermophilic bacterium Geobacillus sp. ID17.

Geobacillus sp. ID17 is a gram-positive thermophilic bacterium isolated from Deception Island, Antarctica, which has shown to exhibit remarkable laccase activity in crude extract at high temperatures. A bioinformatic search using local databases led to the identification of three putative multicopper oxidase sequences in the genome of this microorganism. Sequence analysis revealed that one of those sequences contains the four-essential copper-binding sites present in other well characterized laccases. The gene encoding this sequence was cloned and overexpressed in Escherichia coli, partially purified and preliminary biochemically characterized. The resulting recombinant enzyme was recovered in active and soluble form, exhibiting optimum copper-dependent laccase activity at 55°C, pH 6.5 with syringaldazine substrate, retaining over 60% of its activity after 1h at 55 and 60°C. In addition, this thermophilic enzyme is not affected by common inhibitors SDS, NaCl and L-cysteine. Furthermore, biodecolorization assays revealed that this laccase is capable of degrading 60% of malachite green, 54% of Congo red, and 52% of Remazol Brilliant Blue R, after 6h at 55°C with aid of ABTS as redox mediator. The observed properties of this enzyme and the relatively straightforward overexpression and partial purification of it could be of great interest for future biotechnology applications.

Two new exopolysaccharides from a thermophilic bacterium Geobacillus sp. WSUCF1: Characterization and bioactivities

The production, characterization and bioactivities of exopolysaccharides (EPSs) from a thermophilic bacterium Geobacillus sp. strain WSUCF1 were investigated. Using glucose as a carbon source 525.7 mg/L of exoproduct were produced in a 40-L bioreactor at 60 °C. Two purified EPSs were obtained: EPS-1 was a glucomannan containing mannose and glucose in a molar ratio of 1:0.21, while EPS-2 was composed of mannan only. The molecular weights of both EPSs were estimated to be approximately 1000 kDa, their FTIR and NMR spectra indicated the presence of α-type glycosidic bonds in a linear structure, and XRD analysis indicated a low degree of crystallinity of 0.11 (EPS-1) and 0.27 (EPS-2). EPS-1 and EPS-2 demonstrated high degradation temperatures of 319 °C and 314 °C, respectively, and non-cytotoxicity to HEK-293 cells at 2 and 3 mg/mL, respectively. In addition, both showed antioxidant activities. EPSs from strain WSUCF1 may expand the applications of microorganisms isolated from extreme environments and provide a valuable resource for exploitation in biomedical fields such as drug delivery carriers.

Synthesis of Biopolymers from a Geobacillus sp. WSUCF1 Using Unprocessed Corn Stover

A lignocellulolytic and thermophilic bacterium Geobacillus sp. WSUCF1 was investigated for its production of biopolymers (exopolysaccharides, EPSs) using agricultural waste corn stover. The maximum...

Purification, immobilization and characterization of thermostable α-amylase from a thermophilic bacterium Geobacillus sp. TF14

Abstract Objective In this study, α-amylase from a thermophilic bacterium Geobacillus sp. TF14 was purified and immobilized on two different supports. Methods Ion exchange and hydrophobic interaction chromatography techniques were employed for the purification. Results The enzyme was purified as 17.11 fold and determined as a single band of 54 kDa on SDS-PAGE. Purified enzyme showed two pH optimums of pH 5.00 and pH 9.00 and the enzyme is quite stable at these pHs over a period of 48 h. Purified enzyme showed maximal activity at 75°C and stability at this temperature over a period of 72 h. It was observed that Ca2+ activated the enzyme at about 70% at 5 mM final concentration. SDS, Triton X100, Triton X114 and Tween 20 caused around 50% loss of initial activity at a final concentration of 1% (w/v). Purified enzyme was immobilized on the surface of Dowex and chitin. Immobilization highly enhanced temperature optima and thermal stability. Dowex immobilized enzyme maintained most of its initial activity in the presence of SDS, Triton X100, Triton X114 and Tween 20 at a concentration of 1%. Conclusion It can be concluded that the purified enzyme may find application in many fields of starch based industries.

A Novel Benzoquinone Compound Isolated from Deep-Sea Hydrothermal Vent Triggers Apoptosis of Tumor Cells.

Microorganisms are important sources for screening bioactive natural products. However, natural products from deep-sea microbes have not been extensively explored. In this study, the metabolites of bacteriophage GVE2 -infected (Geobacillus sp. E263 virus) thermophilic bacterium Geobacillus sp. E263, which was isolated from a deep-sea hydrothermal vent, were characterized. A novel quinoid compound, which had anti-tumor activity, was isolated from the phage-challenged thermophile. The chemical structure analysis showed that this novel quinoid compound was 2-amino-6-hydroxy-[1,4]-benzoquinone. The results indicated that 2-amino-6-hydroxy-[1,4]-benzoquinone and its two derivatives could trigger apoptosis of gastric cancer cells and breast cancer cells by inducing the accumulation of intracellular reactive oxygen species. Therefore, our study highlighted that the metabolites from the phage-challenged deep-sea microbes might be a kind of promising sources for anti-tumor drug discovery, because of the similarity of metabolic disorder between bacteriophage-infected microbes and tumor cells.

Gene cloning, expression, immobilization and characterization of endo-xylanase from Geobacillus sp. TF16 and investigation of its industrial applications

The xylanase gene (xynTF16) from a thermophilic bacterium Geobacillus sp. TF16 was cloned into pET-28a(+) vector and expressed in Escherichia coli BL21(DE3)pLysS. Recombinant enzyme (GsXynTF16) was purified 52-fold by nickel affinity chromatography, and determined as a single band 39.8kDa on SDS-PAGE with a specific activity of 246U/mg protein. The recombinant enzyme was immobilized on chitosan with a yield of 85.6%. The enzyme showed the highest activity towards xylan. The immobilized enzyme displayed an increase in optimum temperature from 55 to 65°C in comparison with free enzyme. While the free enzyme was optimally active at pH 8.5, immobilized enzyme showed higher activity in the pH range 6.0–8.5. Thermal and pH stability of immobilized enzyme was determined to be higher than that of the free enzyme. Immobilized xylanase could be reused for 6 consecutive cycles retaining 80% of its initial activity. It was also found to be effective in releasing the reducing sugar from juice and poultry feed and oven spring in bakery. These results suggest that this study provides an alternative xylanase enzyme with enhanced properties.

Complete genome sequence of the crude oil-degrading thermophilic bacterium Geobacillus sp. JS12

Here, we report the complete genome sequence of Geobacillus sp. JS12, isolated from composts located in Namhae, Korea, which shows extracellular lipolytic activities at high temperatures. An array of genes related to the utilization of lipids was identified by whole genome analysis. The genome sequence of the strain JS12 provides basic information for wider exploitation of thermostable industrial lipases.

Characterization of the Thermophilic Bacterium Geobacillus sp. Strain GWE1 Isolated from a Sterilization Oven

A gram-positive, rod-shaped, spore-forming, motile thermophilic bacterium was isolated from a sterilization oven. The microorganism GWE1, formally named Geobacillus wiegelii identified as a member of the genus Geobacillus. GWE1 grew under aerobic conditions of between 60-80oC (optimum 70oC), in a pH range of 3.0-8.0 (optimum pH70oC 5.8), and between 0 and 2 M NaCl (optimum 0.3 M). The membrane polar lipids were dominated by branched saturated fatty acids, which included as the major constituents; iso-15:0 (13.3%), 16:1(ω7) (12.8%), 16:0 (28.5%), iso-17:0 (13.5%) and anteiso-17:0 (12.3%). The DNA G+C content was 47.2 mol% (determined by HPLC). The 16S rRNA gene sequence of GWE1 showed a high similarity with Geobacillus caldoxylosilyticus (97%). However, the level of DNA?DNA relatedness was only 58%. These data suggest that GWE1 is probably a novel specie of the genus Geobacillus.

Cloning and characterization of a thermostable carboxylesterase from inshore hot spring thermophile Geobacillus sp. ZH1

The gene (741 bp) encoding carboxylesterase from the thermophilic bacterium Geobacillus sp. ZHl was cloned and overexpressed in Escherichia coli. The purified recombinant protein presented a molecular mass of about 40 kDa by SDS-PAGE analysis. Enzyme assays using p-nitrophenyl esters with different acyl chain lengths as the substrates confirmed its esterase activity, yielding highest specific activity with p-nitrophenyl acetate. Among the p-nitrophenyl esters tested, the carboxylesterase presented preference for p-nitrophenyl caprylate, but hydrolyzed p-nitrophenyl butyrate more efficiently. When p-nitrophenyl butyrate was used as a substrate, the recombinant carboxylesterase exhibited highest activity at pH 8.0 and 60°C. Almost no decrease in esterase activity was observed at 60°C for 3 h, and over 40% of activity was still maintained after incubation at 90°C for 3 h. These results indicate that Geobacillus sp. ZH1 recombinant esterase was thermostable. The enzymatic activity was inhibited by the addition of phenylmethylsulfonyl fluoride, indicating that it contains serine residue, which plays a key role in the catalytic mechanism. Except SDS and xylene, this esterase showed stability toward other tested detergents and organic solvents. Cloning, expression, and biochemical characterization of Geobacillus sp. ZH1 carboxylesterase lay a good foundation for its structural characterization and industrial application.