Green synthesis of silica-coated magnetic nanocarriers for simultaneous purification-immobilization of ß-1,3-xylanase.

Tailoring magnetic nanocarriers with tunable properties is of great significance for the development of multifunctional candidate materials in numerous fields. Herein, we report a one-pot biomimetic silicification-based method for the synthesis of silica-coated magnetic nanoparticles. The synthesis process was mild, low cost, and highly efficient, which took only about 21 min compared with 4.5-120 h in other literature. Then, the carriers had been characterized by VSM, SEM, TEM, XRD, FT-IR, and EDS to confirm their function. To evaluate the usefulness of the carriers, they were adopted to couple the purification and immobilization of ß-1,3-xylanase from the cell lysate in a single step with high immobilization yield (92.8 %) and high activity recovery (82.4 %). The immobilized enzyme also retained 58.4 % of the initial activity after 10 cycles and displayed good storage properties, and improved thermal stability, which would be promising in algae biomass bioconversion as well as other diverse applications.

The synergism of lytic polysaccharide monooxygenases with lichenase and their co-immobilization on silica nanospheres for green conversion of lichen biomass.

Enzyme-assisted valorization of lichenan represents a green and sustainable alternative to the conventional chemical industry. The recently discovered lytic polysaccharide monooxygenases (LPMOs) are essential components of state-of-the-art enzyme cocktails for lichenin bioconversion. The LPMOs named SpyTag fused LPMOs (AST) from Chaetomium globosum was functionally expressed in E. coli and exhibited 1.25-fold synergism with lichenase, whereas AST alone produced no detectable reducing sugars. HPLC results further confirm that AST does not alter the endogenous hydrolysis mode of lichenase but rather enhances its hydrolysis efficiency by disrupting the long chain of lichenan and releasing more reducing ends. To the best of our knowledge, this was the first report on the synergistic effect of LPMOs and lichenase, which may have great synergistic potential in the conversion of lichen biomass. Furthermore, a novel strategy for the covalently immobilizing AST and lichenase on silica nanoparticles (SNPs) from the cell lysate in a single step was proposed, which exhibited high activity recovery (82.9%) and high immobilization yield (94.8%). After 12 independent runs, about 67.4 % of the initial activity of the immobilized enzymes was retained. The resulted biocatalyst systems exhibited the green and sustainable strategy in the bioconversion of lichen biomass as well as other diverse polysaccharides.

Thermostability mechanisms of ß-agarase by analyzing its structure through molecular dynamics simulation.

Agarase is a natural catalyst with a good prospect in the industry. However, most of the currently discovered ß-agarases are unsuitable for relatively high-temperature and high-pressure conditions required by industrial production. In this study, molecular dynamics simulations were first used to investigate the dynamic changes of folding and unfolding of mesophile and thermophile ß-agarases (i.e., 1URX and 3WZ1) to explore the thermostability mechanism at three high temperatures (300 K, 400 K, and 500 K). Results showed that the sequence identity of 3WZ1 and 1URX reaches 48.8%. 1URX has a higher thermal sensitivity and less thermostability than 3WZ1 as more thermostable regions and hydrogen bonds exist in 3WZ1 compared with 1URX. The structures of 1URX and 3WZ1 become unstable with increasing temperatures up to 500 K. The strategies to increase the thermostability of 1URX and 3WZ1 are discussed. This study could provide insights into the design and modification of ß-agarases at a high temperature.

Viral diversity and biogeochemical potential revealed in different prawn-culture sediments by virus-enriched metagenome analysis.

As the most numerous biological entities on Earth, viruses affect the microbial dynamics, metabolism and biogeochemical cycles in the aquatic ecosystems. Viral diversity and functions in ocean have been relatively well studied, but our understanding of viruses in mariculture systems is limited. To fill this knowledge gap, we studied viral diversity and potential biogeochemical impacts of sediments from four different prawn-mariculture ecosystems (mono-culture of prawn and poly-culture of prawn with jellyfish, sea cucumber, and clam) using a metagenomic approach with prior virus-like particles (VLPs) separation. We found that the order Caudovirales was the predominant viral category and accounted for the most volume (78.39% of classified viruses). Sediment viruses were verified to have a high diversity by using the construct phylogenetic tree of terL gene, with three potential novel clades being identified. Meanwhile, compared with viruses inhabiting other ecosystems based on gene-sharing network, our results revealed that mariculture sediments harbored considerable unexplored viral diversity and that maricultural species were potentially important drivers of the viral community structure. Notably, viral auxiliary metabolic genes were identified and suggested that viruses influence carbon and sulfur cycling, as well as cofactors/vitamins and amino acid metabolism, which indirectly participate in biogeochemical cycling. Overall, our findings revealed the genomic diversity and ecological function of viral communities in prawn mariculture sediments, and suggested the role of viruses in microbial ecology and biogeochemistry.

A Simple Technique for Direct Immobilization of Target Enzymes from Cell Lysates Based on the SpyTag/SpyCatcher Spontaneous Reaction.

Many of the current methods for enzyme purification and immobilization suffer from several drawbacks, such as requiring tedious multistep procedures or long preparation, and being environmentally unfriendly, due to the chemicals and conditions involved. Thus, a simple technique for direct purification and immobilization of target enzymes from cell lysates was proposed. The elastin-like polypeptides (ELPs)-SpyCatcher chimera could mediate the formation of silica carriers within seconds and the target enzymes were then covalently immobilized on silica carriers via SpyCatcher/SpyTag spontaneous reaction. These tailor-made carriers were easily prepared, with precisely controlled morphology and size, as well as none-consuming surface modification needed, which could specifically immobilize the SpyTag-fused target enzymes from the cell lysate without pre-purification.

A novel all-in-one strategy for purification and immobilization of ß-1,3-xylanase directly from cell lysate as active and recyclable nanobiocatalyst.

BACKGROUND: Exploring a simple and versatile technique for direct immobilization of target enzymes from cell lysate without prior purification is urgently needed. Thus, a novel all-in-one strategy for purification and immobilization of ß-1,3-xylanase was proposed, the target enzymes were covalently immobilized on silica nanoparticles via elastin-like polypeptides (ELPs)-based biomimetic silicification and SpyTag/SpyCatcher spontaneous reaction. Thus, the functional carriers that did not require the time-consuming surface modification step were quickly and efficiently prepared. These carriers could specifically immobilize the SpyTag-fused target enzymes from the cell lysate without pre-purification. RESULTS: The ELPs-SpyCatcher hardly leaked from the carriers (0.5%), and the immobilization yield of enzyme was up to 96%. Immobilized enzyme retained 85.6% of the initial activity and showed 88.6% of the activity recovery. Compared with free ones, the immobilized ß-1,3-xylanase showed improved thermal stability, elevated storage stability and good pH tolerance. It also retained more than 70.6% of initial activity after 12 reaction cycles, demonstrating its excellent reusability. CONCLUSIONS: The results clearly highlighted the effectiveness of the novel enzyme immobilization method proposed here due to the improvement of overall performance of immobilized enzyme in respect to free form for the hydrolysis of macromolecular substrates. Thus, it may have great potential in the conversion of algae biomass as well as other related fields.

Enzymatic degradation of algal 1,3-xylan: from synergism of lytic polysaccharide monooxygenases with ß-1,3-xylanases to their intelligent immobilization on biomimetic silica nanoparticles.

Lytic polysaccharide monooxygenases (LPMOs) with synergistic effect on polysaccharide hydrolase represent a revolution in biotechnology, which may accelerate the conversion of biomass to the second-generation biofuels. Discovering more hydrolases that have synergism with LPMOs will considerably expand the knowledge and application of biomass degradation. The LPMOs named CgAA9 were verified to exhibit 1.52-fold synergism when incubated with ß-1,3-xylanase at a molar ratio of 3:1. The ion chromatography results proved that CgAA9 did not alter the endogenous hydrolysis mode of ß-1,3-xylanase. Meanwhile, to decrease the operational cost of enzymes, a novel strategy for immobilizing LPMOs and ß-1,3-xylanases based on the biomimetic silica nanoparticles was developed. It enabled preparation of immobilized enzymes directly from the cell lysate. The immobilization efficiency and activity recovery reached 84.6 and 81.4%. They showed excellent reusability for 12 cycles by retaining 68% of initial activity. The optimum temperature for both free and immobilized biocatalyst were 40 and 37 °C, indicating they were ideal candidates for typical simultaneous saccharification and fermentation (SSF) in ethanol production from algea biomass. This was the first report on the synergy between LPMOs and ß-1,3-xylanase, and the strategy for enzyme self-immobilization was simple, timesaving, and efficient, which might have great potentials in algae biomass hydrolysis. KEY POINTS: • The lytic polysaccharide monooxygenases (LPMOs) from Chaetomium globosum were firstly verified to boost the hydrolysis of ß-1,3-xylanases for ß-1,3-xylan. • A novel strategy for simple preparation of SpyCather-modifed silica nanopartilcles and intelligent immobilization of target enzymes from the cell lysate was proposed. • The immobilized LPMOs and ß-1,3-xylanases could be reasonable alternatives for typical simultaneous saccharification and fermentation (SSF) in manipulation of algae biomass.

[Mining and engineering of microbial carbonic anhydrases for biomimetic carbon dioxide sequestration].

The increasing atmospheric carbon dioxide levels have been correlated with global warming. Carbonic anhydrases (CA) are the fastest among the known enzymes to improve carbon capture. The capture of carbon dioxide needs high temperature and alkaline condition, which is necessary for CaCO3 precipitation in the mineralization process. In order to use CAs for biomimetic carbon sequestration, thermo-alkali-stable CAs are, therefore, essential, and polyextremophilic microbes are one of the important sources of these enzymes. The current review focuses on both those isolated by thermophilic organisms from the extreme environments and those obtained by protein engineering techniques, and the industrial application of the immobilized CAs is also briefly addressed. To reduce the greenhouse effect and delay global warming, we think further research efforts should be devoted to broadening the scope of searching for carbonic anhydrase, modifying the technology of protein engineering and developing highly efficient immobilization strategies.

Low Serum Levels of ABCA1, an ATP-Binding Cassette Transporter, Are Predictive of Preeclampsia.

Preeclampsia is a pregnancy-specific disorder characterized by hypertension and proteinuria, but the exact cause of preeclamptic hypertension remains unknown. ATP-binding cassette subfamily A member 1 (ABCA1) reverses cholesterol transport and eliminates excess cholesterol from tissues, whereas higher levels of cholesterol may lead to hypertension. Thus, ABCA1 affects the blood lipid profile. We have hypothesized that serum ABCA1 levels may influence the onset of hypertension and increase the risk of preeclampsia. To test this hypothesis, we measured serum ABCA1 levels in 50 normal pregnancies, 36 preeclamptic pregnancies, and 24 small-for-gestational-age (SGA) pregnancies during three trimesters. We also measured the concentrations of serum ABCA1 in non-pregnant women (n = 60), showing its normal ranges of 0.16 to 0.52 ng/ml. Importantly, the serum levels of ABCA1 were similar among non-pregnant women, normal pregnancies and SGA pregnancies. In contrast, the serum ABCA1 levels were significantly lower in preeclamptic pregnancies (0.06 ± 0.03 ng/ml) than those in non-pregnant women, and normal and SGA pregnancies (P < 0.05). Low serum ABCA1 levels were associated with the increases in the concentrations of blood lipid (low density lipoprotein cholesterol, total cholesterol and triglycerides) and with the decrease in the concentration of high-density lipoprotein cholesterol (P < 0.01), all of which may contribute to the onset of hypertension and eventually preeclampsia. Moreover, the preeclamptic pregnancy was diagnosed with high sensitivity from the nulliparous pregnancies if the cutoff value for serum ABCA1 was 0.06 ng/ml. Thus, low serum levels of ABCA1 are predictive of preeclampsia.

PAH-degrading microbial consortium and its pyrene-degrading plasmids from mangrove sediment samples in Huian, China.

PAH-degrading microbial consortium and its pyrene-degrading plasmids were enriched from the sediment samples of Huian mangroves. The consortium YL showed degrading abilities of 92.1%, 87.6%, 92.3%, and 95.8% for pyrene, fluoranthene, phenanthrene, and fluoene at 50 mg l(-1) after 21 days incubation, respectively. The dynamics of pH changes in the cultures was consistent with that of PAH concentration change. Bacillus cereus Py5 and Bacillus megaterium Py6 were isolated from the consortium and observed consuming 65.8% and 33.7% of pyrene (50 mg l(-1)) within three weeks, respectively. The enriched Escherichia coli DH5alpha cells containing the plasmids of YL were demonstrated to degrade 85.7% of the original pyrene concentration at the 21st day.