Novel, cold-adapted D-laminaribiose- and D-glucose-releasing GH16 endo-ß-1,3-glucanase from Hymenobacter siberiensis PAMC 29290, a psychrotolerant bacterium from Arctic marine sediment.

Endo-ß-1,3-glucanase is a glycoside hydrolase (GH) that plays an essential role in the mineralization of ß-glucan polysaccharides. In this study, the novel gene encoding an extracellular, non-modular GH16 endo-ß-1,3-glucanase (GluH) from Hymenobacter siberiensis PAMC 29290 isolated from Arctic marine sediment was discovered through an in silico analysis of its whole genome sequence and subsequently overexpressed in Escherichia coli BL21. The 870-bp GluH gene encoded a protein featuring a single catalytic GH16 domain that shared over 61% sequence identity with uncharacterized endo-ß-1,3-glucanases from diverse Hymenobacter species, as recorded in the National Center for Biotechnology Information database. The purified recombinant endo-ß-1,3-glucanase (rGluH: 31.0 kDa) demonstrated peak activity on laminarin at pH 5.5 and 40°C, maintaining over 40% of its maximum endo-ß-1,3-glucanase activity even at 25°C. rGluH preferentially hydrolyzed D-laminarioligosaccharides and ß-1,3-linked polysaccharides, but did not degrade D-laminaribiose or structurally unrelated substrates, confirming its specificity as a true endo-ß-1,3-glucanase without ancillary GH activities. The biodegradability of various substrate polymers by the enzyme was evaluated in the following sequence: laminarin > barley ß-glucan > carboxymethyl-curdlan > curdlan > pachyman. Notably, the specific activity (253.1 U mg-1) and catalytic efficiency (k cat /K m : 105.72 mg-1 s-1 mL) of rGluH for laminarin closely matched its specific activity (250.2 U mg-1) and k cat /K m value (104.88 mg-1 s-1 mL) toward barley ß-glucan. However, the k cat /K m value (9.86 mg-1 s-1 mL) of rGluH for insoluble curdlan was only about 9.3% of the value for laminarin, which correlates well with the observation that rGluH displayed weak binding affinity (< 40%) to the insoluble polymer. The biocatalytic hydrolysis of D-laminarioligosaccharides with a degree of polymerization between 3 and 6 and laminarin generally resulted in the formation of D-laminaribiose as the predominant product and D-glucose as the secondary product, with a ratio of approximately 4:1. These findings suggest that highly active rGluH is an acidic, cold-adapted D-laminaribiose- and D-glucose-releasing GH16 endo-ß-1,3-glucanase, which can be exploited as a valuable biocatalyst for facilitating low temperature preservation of foods.

Antagonistic Efficacy of Symbiotic Bacterium Xenorhabdus sp. SCG against Meloidogyne spp.

The inhabitation and parasitism of root-knot nematodes (RKNs) can be difficult to control, as its symptoms can be easily confused with other plant diseases; hence, identifying and controlling the occurrence of RKNs in plants remains an ongoing challenge. Moreover, there are only a few biological agents for controlling these harmful nematodes. In this study, Xenorhabdus sp. SCG isolated from entomopathogenic nematodes of genus Steinernema was evaluated for nematicidal effects under in vitro and greenhouse conditions. The cell-free filtrates of strain SCG showed nematicidal activity against Meloidogyne species J2s, with mortalities of > 88% at a final concentration of 10%, as well as significant nematicidal activity against the three other genera of plant-parasitic nematodes in a dose-dependent manner. Thymine was isolated as active compounds by assay-guided fractionation and showed high nematicidal activity against M. incognita. Greenhouse experiments suggested that cell-free filtrates of strain SCG efficiently controlled the nematode population in M. incognita-infested tomatoes (Solanum lycopersicum L., cv. Rutgers). In addition, a significant increase in host plant growth was observed after 45 days of treatment. To our knowledge, this is the first to demonstrate the nematicidal activity spectrum of isolated Xenorhabdus species and their application to S. lycopersicum L., cv. Rutgers under greenhouse conditions. Xenorhabdus sp. SCG could be a promising biological nematicidal agent with plant growth-enhancing properties.

Biodegradation Potential of Polyethylene Terephthalate by the Two Insect Gut Symbionts Xanthomonas sp. HY-74 and Bacillus sp. HY-75.

Polyethylene terephthalate (PET) is a plastic material that is widely used in beverage bottles, food packaging, and other consumer products, which is highly resistant to biodegradation. In this study, we investigated the effects of two insect gut symbionts, Xanthomonas sp. HY-74 and Bacillus sp. HY-75, during PET biodegradation. Both strains degraded PET-containing agar plates, and the sole nutrition source assay showed that HY-74 had different degradation rates depending on the presence of specific carbon and nitrogen sources, whereas HY-75 exhibited comparable degradation across all tested conditions. The two strains biodegraded the PET film with 1.57 ± 0.21% and 1.42 ± 0.46% weight loss after 6 weeks, respectively. Changes in the morphology and structure of the PET films, such as erosion, scratching, and surface roughening, were determined using scanning electron microscopy (SEM). Further, the two strains biodegraded PET powder, broke it into its degradation products, and changed the surface functional groups. This is the first study to investigate the biodegradation of PET by Hymenoptera gut-derived microbes and offers promising insights into the potential applications of insect gut symbionts in PET waste management.

Discovery and Feasibility Study of Medical Fluorophore 33 as a Novel Theranostic Agent.

Fluorescent dyes have garnered significant attention as theranostic platforms owing to their inherent characteristics. In this study, we present the discovery of Medical Fluorophore 33 (MF33), a novel and potent theranostic agent with a phenaleno-isoquinolinium salt structure that can serve as a cancer therapeutic strategy. The synthesis of MF33 is readily achievable through a simple Rh(III)-catalyzed reaction. Moreover, MF33 displayed strong fluorescence signals, excellent microsomal stability, and high biocompatibility in vivo. It induces significant apoptosis in cancer cells via the p53/p21/caspase-3 signaling pathway, leading to selective cytotoxicity in various cancer cells. In vivo fluorescence imaging with MF33 enabled the visualization of sentinel lymph nodes in living mice. Notably, repeated intraperitoneal administration of MF33 resulted in antitumor activity in mice with colorectal cancer. Collectively, our findings suggest that phenaleno-isoquinolinium salt-based MF33 is a viable theranostic agent for biomedical imaging and cancer treatment.

Assessment of nematicidal and plant growth-promoting effects of Burkholderia sp. JB-2 in root-knot nematode-infested soil.

Root-knot nematodes (RKN), Meloidogyne spp., are plant-parasitic nematodes that are responsible for considerable economic losses worldwide, because of the damage they cause to numerous plant species and the inadequate biological agents available to combat them. Therefore, developing novel and eco-friendly nematicides is necessary. In the present study, Burkholderia sp. JB-2, isolated from RKN-infested rhizosphere soil in South Korea, was evaluated to determine its nematicidal and plant growth-promoting effects under in vitro and in vivo conditions. Cell-free filtrates of the JB-2 strain showed high levels of nematicidal activity against second-stage juveniles (J2) of M. incognita, with 87.5% mortality following two days of treatment. In addition, the assessment of the activity against other six plant parasitic nematodes (M. javanica, M. hapla, M. arenaria, Ditylenchus destructor, Aphelenchoides subtenuis, and Heterodera trifolii) showed that the cell-free filtrates have a broad nematicidal spectrum. The three defense-responsive (MiMIF-2, MiDaf16-like1, and MiSkn1-like1) genes were activated, while Mi-cm-3 was downregulated when treated with cell-free filtrates of JB-2 cultures on J2. The greenhouse experiments suggested that the cell-free filtrates of the JB-2 strain efficiently controlled the nematode population in soil and egg mass formations of M. incognita in tomato (Solanum lycopersicum L., cv. Rutgers). An improvement in the host plant growth was observed, in which the shoot length and fresh weights of shoots and roots increased. The treatment with 10% of JB-2 cell-free filtrates significantly upregulated the expression levels of plant defenses (SlPR1, SlPR5, and SlPAL) and growth-promoting (ACO1, Exp18, and SlIAA1) genes compared with the corresponding parameters of the control group. Therefore, JB-2 could be a promising candidate for the sustainable management of RKN.

Visualizing mast cell migration to tumor sites using sodium iodide symporter of nuclear medicine reporter gene.

PURPOSE: Owing to the close relationship between mast cells and cancer progression, an imaging technique that can be applied in a clinical setting to explore the biological behavior of mast cells in the tumor microenvironment is needed. In this study, we visualized mast cell migration to lung tumor lesions in live mice using sodium iodide symporter (NIS) as a nuclear medicine reporter gene. EXPERIMENTAL DESIGN: The murine mast cell line MC-9 was infected with retrovirus including NIS, luciferase (as a surrogate marker for NIS), and Thy1.1 to generate MC-9/NFT cells. Radioiodine uptake was measured in MC-9/NFT cells, and an inhibition assay of radioiodine uptake using KCLO4 was also performed. Cell proliferation and FcεRI expression was examined in MC-9 and MC-9/NFT cells. The effect of mast cell-conditioned media (CM) on the proliferation of Lewis lung cancer (LLC) cells was examined. The migration level of MC-9/NFT cells was confirmed in the presence of serum-free media (SFM) and CM of cancer cells. After intravenous injection of MC-9/NFT cells into mice with an LLC tumor, I-124 PET/CT and biodistribution analysis was performed. RESULTS: MC-9/NFT cells exhibited higher radioiodine avidity compared to parental MC-9 cells; this increased radioiodine avidity in MC-9/NFT cells was reduced to basal level by KCLO4. Levels of FcεRI expression and cell proliferation were not different in parental MC-9 cell and MC-9/ NFT cells. The CM of MC-9/NFT cells increased cancer cell proliferation relative to that of the SFM. The migration level of MC-9/NFT cells was higher in the CM than the SFM of LLC cells. PET/CT imaging with I-124 clearly showed infiltration of reporter mast cells in lung tumor at 24 h after transfer, which was consistent with the findings of the biodistribution examination. CONCLUSION: These findings suggest that the sodium iodide symporter can serve as a reliable nuclear medicine reporter gene for non-invasively imaging the biological activity of mast cells in mice with lung tumors. Visualizing mast cells in the tumor microenvironment via a nuclear medicine reporter gene would provide valuable insights into their biological functions.

N-methyl-D-aspartate receptors induce M1 polarization of macrophages: Feasibility of targeted imaging in inflammatory response in vivo.

BACKGROUND: N-methyl-D-aspartate receptors (NMDARs) are considered to be involved in several physiological and pathophysiological processes in addition to the progression of neurological disorders. However, how NMDARs are involved in the glycolytic phenotype of M1 macrophage polarization and the possibility of using them as a bio-imaging probe for macrophage-mediated inflammation remain unclear. METHODS: We analyzed cellular responses to NMDAR antagonism and small interfering RNAs using mouse bone marrow-derived macrophages (BMDMs) treated with lipopolysaccharide (LPS). An NMDAR targeting imaging probe, N-TIP, was produced via the introduction of NMDAR antibody and the infrared fluorescent dye FSD Fluor™ 647. N-TIP binding efficiency was tested in intact and LPS-stimulated BMDMs. N-TIP was intravenously administered to mice with carrageenan (CG)- and LPS-induced paw edema, and in vivo fluorescence imaging was conducted. The anti-inflammatory effects of dexamethasone were evaluated using the N-TIP-mediated macrophage imaging technique. RESULTS: NMDARs were overexpressed in LPS-treated macrophages, subsequently inducing M1 macrophage polarization. Mechanistically, NMDAR-mediated Ca2+ accumulation resulted in LPS-stimulated glycolysis via upregulation of PI3K/AKT/mTORC1 signaling. In vivo fluorescence imaging with N-TIP showed LPS- and CG-induced inflamed lesions at 5 h post-inflammation, and the inflamed lesions could be detected until 24 h. Furthermore, our N-TIP-mediated macrophage imaging technique helped successfully visualize the anti-inflammatory effects of dexamethasone in mice with inflammation. CONCLUSION: This study demonstrates that NMDAR-mediated glycolysis plays a critical role in M1 macrophage-related inflammation. Moreover, our results suggest that NMDAR targeting imaging probe may be useful in research on inflammatory response in vivo.

Enzyme Feed Additive with Arazyme Improve Growth Performance, Meat Quality, and Gut Microbiome of Pigs.

The supplementation of pig diets with exogenous enzymes is widely used with the expectation that it will improve the efficiency of nutrient utilization, thereby, improving growth performance. This study aims to evaluate the effects of a 0.1% (v/v) multi-enzyme (a mixture of arazyme (2,500,000 Unit/kg), xylanase (200,000 Unit/kg) and mannanase (200,000 Unit/kg)) supplementation derived from invertebrate symbiotic bacteria on pig performance. Here, 256 growing pigs were assigned to control and treatment groups, respectively. The treatment group exhibited a significantly reduced average slaughter age; the final body weight and average daily gain increased compared with that of the control group. In the treatment group, the longissimus muscle showed a remarkable decrease in cooking loss, shear force, and color values with increased essential and non-essential amino acid concentrations. Furthermore, the concentrations of mono- and polyunsaturated fatty acids in the treatment group increased. Feed additive supplementation increased the family of Ruminococcaceae and genera Lactobacillus, Limosilactobacillus, Turicibacter, and Oscillibacter, which play a positive role in the host physiology and health. Predicted metabolic pathway analysis confirmed that operational taxonomic units and predicted amino acid biosynthesis pathways were strongly associated. The results suggest that applying exogenous enzymes derived from invertebrate symbiotic bacteria enhances animal performance.

An Inverse Agonist of Estrogen-Related Receptor Gamma, GSK5182, Enhances Na+/I- Symporter Function in Radioiodine-Refractory Papillary Thyroid Cancer Cells.

Previously, we reported that an inverse agonist of estrogen-related receptor gamma (ERRγ), GSK5182, enhances sodium iodide (Na+/I-) symporter (NIS) function through mitogen-activated protein (MAP) kinase signaling in anaplastic thyroid cancer cells. This finding helped us to further investigate the effects of GSK5182 on NIS function in papillary thyroid cancer (PTC) refractory to radioactive iodine (RAI) therapy. Herein, we report the effects of ERRγ on the regulation of NIS function in RAI-resistant PTC cells using GSK5182. RAI-refractory BCPAP cells were treated with GK5182 for 24 h at various concentrations, and radioiodine avidity was determined with or without potassium perchlorate (KClO4) as an NIS inhibitor. We explored the effects of GSK5182 on ERRγ, the mitogen-activated protein (MAP) kinase pathway, and iodide metabolism-related genes. We examined whether the MAP pathway affected GSK5182-mediated NIS function using U0126, a selective MEK inhibitor. A clonogenic assay was performed to evaluate the cytotoxic effects of I-131. GSK5182 induced an increase in radioiodine avidity in a dose-dependent manner, and the enhanced uptake was completely inhibited by KClO4 in BCPAP cells. We found that ERRγ was downregulated and phosphorylated extracellular signal-regulated kinase (ERK)1/2 was upregulated in BCPAP cells, with an increase in total and membranous NIS and iodide metabolism-related genes. MEK inhibitors reversed the increase in radioiodine avidity induced by GSK5182. Clonogenic examination revealed the lowest survival in cells treated with a combination of GSK5182 and I-131 compared to those treated with either GSK518 or I-131 alone. We demonstrate that an inverse agonist of ERRγ, GSK5182, enhances the function of NIS protein via the modulation of ERRγ and MAP kinase signaling, thereby leading to increased responsiveness to radioiodine in RAI-refractory papillary thyroid cancer cells.

Arazyme in combination with dietary carbohydrolases influences odor emission and gut microbiome in growing-finishing pigs.

This study evaluated the effects of supplementing feed with arazyme and dietary carbohydrolases derived from invertebrate gut-associated symbionts on the noxious gas emissions, gut microbiota, and host-microbiome interactions of pigs. Here, 270 and 260 growing pigs were assigned to control and treatment groups, respectively. The tested feed additives contained a mixture of arazyme (2,500,000 Unit/kg) and synergetic enzymes, xylanase (200,000 Unit/kg) and mannanase (200,000 Unit/kg), derived from insect gut-associated symbionts in a 7.5:1:1 ratio. The control group was fed a basal diet and the treatment group was fed the basal diet supplemented with 0.1 % enzyme mixture (v/v) for 2 months. Odorous gases were monitored in ventilated air from tested houses. Fecal samples were collected from steel plate under the cage at the completion of the experiment to determine chemical composition, odor emissions, and bacterial communities. There was a significant decrease in the concentration of NH3 (22.5 vs. 11.2 ppm; P < 0.05), H2S (7.35 vs. 3.74 ppm; P < 0.05), trimethylamine (TMA) (0.066 vs. 0.001 ppm; P < 0.05), and p-cresol (0.004 ppm vs. 0 ppm; P < 0.05) at 56 d in treatment group compared with the control group. Moreover, fecal analysis results showed that exogenous enzyme supplementation caused a reduction in VFAs and indole content with approximately >60 % and 72.7 %, respectively. The result of gas emission analysis showed that NH3 (9.9 vs. 5.3 ppm; P < 0.05) and H2S (5.8 vs. 4.1 ppm; P < 0.05) were significantly reduced in the treatment group compared to the control group. The gut microbiota of the treatment group differed significantly from that of the control group, and the treatment group altered predicted metabolic pathways, including sulfur and nitrogen related metabolism, urea degradation. The results demonstrated that supplementing feed with arazyme with dietary carbohydrolases effectively controls noxious gas emissions and improves health and meat quality of pigs.

Whole-genome sequencing and analysis of Streptomyces strains producing multiple antinematode drugs.

BACKGROUND: Nematodes are parasitic animals that cause over 100 billion US dollars loss in agricultural business. The whole-genomes of two Streptomyces strains, Streptomyces spectabilis KCTC9218T and Streptomyces sp. AN091965, were sequenced. Both strains produce spectinabilin, an antinematode drug. Its secondary metabolism was examined to aid the development of an efficient nematicidal drug-producing host strain. RESULTS: The whole-genome sequences of S. spectabilis KCTC9218T and Streptomyces sp. AN091965 were analyzed using PacBio and Illumina sequencing platforms, and assembled using hybrid methodology. The total contig lengths for KCTC9218T and AN091965 were 9.97 Mb and 9.84 Mb, respectively. A total of 8,374 and 8,054 protein-coding genes, as well as 39 and 45 secondary metabolite biosynthetic gene clusters were identified in KCTC9218T and AN091965, respectively. 18.4 ± 6.45 mg/L and 213.89 ± 21.30 mg/L of spectinabilin were produced by S. spectabilis KCTC9218T and Streptomyces sp. AN091965, respectively. Pine wilt disease caused by nematode was successfully prevented by lower concentration of spectinabilin injection than that of abamectin recommended by its manufacturer. Production of multiple antinematode drugs, including spectinabilin, streptorubin B, and undecylprodigiosin was observed in both strains using high-resolution liquid chromatography mass spectrometry (LC-MS) analysis. CONCLUSIONS: Whole-genome sequencing of spectinabilin-producing strains, coupled with bioinformatics and mass spectrometry analyses, revealed the production of multiple nematicidal drugs in the KCTC9218T and AN091965 strains. Especially, Streptomyces sp. AN091965 showed high production level of spectinabilin, and this study provides crucial information for the development of potential nematicidal drug producers.

New discovery on the nematode activity of aureothin and alloaureothin isolated from endophytic bacteria Streptomyces sp. AE170020.

Endophytic bacteria, a rich source of bioactive secondary metabolites, are ideal candidates for environmentally benign agents. In this study, an endophytic strain, Streptomyces sp. AE170020, was isolated and selected for the purification of nematicidal substances based on its high nematicidal activity. Two highly active components, aureothin and alloaureothin, were identified, and their chemical structures were determined using spectroscopic analysis. Both compounds suppressed the growth, reproduction, and behavior of Bursaphelenchus xylophilus. In in vivo experiments, the extracts of strain Streptomyces sp. AE170020 effectively suppressed the development of pine wilt disease in 4-year-old plants of Pinus densiflora. The potency of secondary metabolites isolated from endophytic strains suggests applications in controlling Bursaphelenchus xylophilus and opens an avenue for further research on exploring bioactive substances against the pine wood nematode.

Polyurethane biodegradation by Serratia sp. HY-72 isolated from the intestine of the Asian mantis Hierodula patellifera.

Polyurethane (PU), currently replacing existing synthetic materials worldwide, is a synthetic polymer derived from polyols, isocyanates, and a chain extender added by condensation reactions. PU wastes which are difficult to recycle, are commonly discarded in landfills and flow into ecosystems, thereby causing serious environmental problems. In recent years, insect-associated microbes have become a promising, eco-friendly strategy as an alternative to plastic recycling. This study aimed to evaluate the potential of Serratia sp. HY-72 strain isolated from the intestine of the Asian mantis (Hierodula patellifera) for PU degradation. The 65 kDa family I.3 lipase which degrades PU was identified and characterized, with a specific activity of 2,883 U mg-1. The bacterial filtrates and the recombinant lipase degraded Impranil (a colloidal polyester-PU dispersion, 100 g l-1) by 85.24 and 78.35% after 72 h incubation, respectively. Fourier transform infrared spectroscopy analysis revealed changes in Impranil functional groups, with decreased C=O functional group and aliphatic chain signals, and increased N-H bending with C-N stretching and C-O stretching. The current study also revealed that the HY-72 strain biodegraded the commercial PU foams (polyester- and polyether- PU) with 23.95 and 10.95% weight loss after 2 weeks, respectively with changes in surface morphology and structure such as cracks, roughness, and surface roughening. Altogether, this is one of the few studies reporting biodegradation of PU by the insect-associated microbe. These findings suggest that the insect-associated microbe could be a promising resource for biodegradation and recycling of plastic waste.

Novel Bi-Modular GH19 Chitinase with Broad pH Stability from a Fibrolytic Intestinal Symbiont of Eisenia fetida, Cellulosimicrobium funkei HY-13.

Endo-type chitinase is the principal enzyme involved in the breakdown of N-acetyl-d-glucosamine-based oligomeric and polymeric materials through hydrolysis. The gene (966-bp) encoding a novel endo-type chitinase (ChiJ), which is comprised of an N-terminal chitin-binding domain type 3 and a C-terminal catalytic glycoside hydrolase family 19 domain, was identified from a fibrolytic intestinal symbiont of the earthworm Eisenia fetida, Cellulosimicrobium funkei HY-13. The highest endochitinase activity of the recombinant enzyme (rChiJ: 30.0 kDa) toward colloidal shrimp shell chitin was found at pH 5.5 and 55 °C and was considerably stable in a wide pH range (3.5-11.0). The enzyme exhibited the highest biocatalytic activity (338.8 U/mg) toward ethylene glycol chitin, preferentially degrading chitin polymers in the following order: ethylene glycol chitin > colloidal shrimp shell chitin > colloidal crab shell chitin. The enzymatic hydrolysis of N-acetyl-ß-d-chitooligosaccharides with a degree of polymerization from two to six and colloidal shrimp shell chitin yielded primarily N,N'-diacetyl-ß-d-chitobiose together with a small amount of N-acetyl-d-glucosamine. The high chitin-degrading ability of inverting rChiJ with broad pH stability suggests that it can be exploited as a suitable biocatalyst for the preparation of N,N'-diacetyl-ß-d-chitobiose, which has been shown to alleviate metabolic dysfunction associated with type 2 diabetes.

Novel Anti-Fungal d-Laminaripentaose-Releasing Endo-ß-1,3-glucanase with a RICIN-like Domain from Cellulosimicrobium funkei HY-13.

Endo-ß-1,3-glucanase plays an essential role in the deconstruction of ß-1,3-d-glucan polysaccharides through hydrolysis. The gene (1650-bp) encoding a novel, bi-modular glycoside hydrolase family 64 (GH64) endo-ß-1,3-glucanase (GluY) with a ricin-type ß-trefoil lectin domain (RICIN)-like domain from Cellulosimicrobium funkei HY-13 was identified and biocatalytically characterized. The recombinant enzyme (rGluY: 57.5 kDa) displayed the highest degradation activity for laminarin at pH 4.5 and 40 °C, while the polysaccharide was maximally decomposed by its C-terminal truncated mutant enzyme (rGluYΔRICIN: 42.0 kDa) at pH 5.5 and 45 °C. The specific activity (26.0 U/mg) of rGluY for laminarin was 2.6-fold higher than that (9.8 U/mg) of rGluYΔRICIN for the same polysaccharide. Moreover, deleting the C-terminal RICIN domain in the intact enzyme caused a significant decrease (>60%) of its ability to degrade ß-1,3-d-glucans such as pachyman and curdlan. Biocatalytic degradation of ß-1,3-d-glucans by inverting rGluY yielded predominantly d-laminaripentaose. rGluY exhibited stronger growth inhibition against Candida albicans in a dose-dependent manner than rGluYΔRICIN. The degree of growth inhibition of C. albicans by rGluY (approximately 1.8 µM) was approximately 80% of the fungal growth. The superior anti-fungal activity of rGluY suggests that it can potentially be exploited as a supplementary agent in the food and pharmaceutical industries.

Identification and Characterization of a Novel, Cold-Adapted d-Xylobiose- and d-Xylose-Releasing Endo-ß-1,4-xylanase from an Antarctic Soil Bacterium, Duganella sp. PAMC 27433.

Endo-ß-1,4-xylanase is a key enzyme in the degradation of ß-1,4-d-xylan polysaccharides through hydrolysis. A glycoside hydrolase family 10 (GH10) endo-ß-1,4-xylanase (XylR) from Duganella sp. PAMC 27433, an Antarctic soil bacterium, was identified and functionally characterized. The XylR gene (1122-bp) encoded an acidic protein containing a single catalytic GH10 domain that was 86% identical to that of an uncultured bacterium BLR13 endo-ß-1,4-xylanase (ACN58881). The recombinant enzyme (rXylR: 42.0 kDa) showed the highest beechwood xylan-degrading activity at pH 5.5 and 40 °C, and displayed 12% of its maximum activity even at 4 °C. rXylR was not only almost completely inhibited by 5 mM N-bromosuccinimide or metal ions (each 1 mM) including Hg2+, Ca2+, or Cu2+ but also significantly suppressed by 1 mM Ni2+, Zn2+, or Fe2+. However, its enzyme activity was upregulated (>1.4-fold) in the presence of 0.5% Triton X-100 or Tween 80. The specific activities of rXylR toward beechwood xylan, birchwood xylan, oat spelts xylan, and p-nitrophenyl-ß-d-cellobioside were 274.7, 103.2, 35.6, and 365.1 U/mg, respectively. Enzymatic hydrolysis of birchwood xylan and d-xylooligosaccharides yielded d-xylose and d-xylobiose as the end products. The results of the present study suggest that rXylR is a novel cold-adapted d-xylobiose- and d-xylose-releasing endo-ß-1,4-xylanase.

Statistical optimization of culture medium for improved production of antimicrobial compound by Streptomyces rimosus AG-P1441.

The nutritional requirements for antimicrobial activity of Streptomyces rimosus AG-P1441 were optimized using statistically-based experimental designs at a flask level. Based on a one-factor-at-a-time (OFAT) approach, glucose, corn starch and soybean meal were identified as the carbon and nitrogen sources having a significant effect on antimicrobial productivity. As a result of investigating the effect of glucose concentration, the highest antimicrobial activity was observed at 3% concentration. Response surface methodology (RSM) was then applied to optimize the growth medium components (corn starch, soybean meal, MgCl2 and glutamate). Antimicrobial productivity increased sharply when the medium consisted of 3% glucose, 3.5% corn starch, 2.5% soybean meal, 1.2 mM MgCl2 and 5.9 mM glutamate. The fermentation using optimized culture medium in a 5-L bioreactor allowed a significant increase in antimicrobial activity, evaluated by the paper disc assay, revealed a 29 mm inhibition zone diameter against Phytophthora capsici.

Genetic and functional characterization of a novel GH10 endo-ß- 1,4-xylanase with a ricin-type ß-trefoil domain-like domain from Luteimicrobium xylanilyticum HY-24.

The gene (1488-bp) encoding a novel GH10 endo-ß-1,4-xylanase (XylM) consisting of an N-terminal catalytic GH10 domain and a C-terminal ricin-type ß-trefoil lectin domain-like (RICIN) domain was identified from Luteimicrobium xylanilyticum HY-24. The GH10 domain of XylM was 72% identical to that of Micromonospora lupini endo-ß-1,4-xylanase and the RICIN domain was 67% identical to that of Actinospica robiniae hypothetical protein. The recombinant enzyme (rXylM: 49kDa) exhibited maximum activity toward beechwood xylan at 65°C and pH 6.0, while the optimum temperature and pH of its C-terminal truncated mutant (rXylM△RICIN: 35kDa) were 45°C and 5.0, respectively. After pre-incubation of 1h at 60°C, rXylM retained over 80% of its initial activity, but the thermostability of rXylM△RICIN was sharply decreased at temperatures exceeding 40°C. The specific activity (254.1Umg-1) of rXylM toward oat spelts xylan was 3.4-fold higher than that (74.8Umg-1) of rXylM△RICIN when the same substrate was used. rXylM displayed superior binding capacities to lignin and insoluble polysaccharides compared to rXylM△RICIN. Enzymatic hydrolysis of ß-1,4-d-xylooligosaccharides (X3-X6) and birchwood xylan yielded X3 as the major product. The results suggest that the RICIN domain in XylM might play an important role in substrate-binding and biocatalysis.

Biocatalytic characterization of an endo-ß-1,4-mannanase produced by Paenibacillus sp. strain HY-8.

OBJECTIVES: To evaluate the biocatalytic characteristics of a new endo-ß-1,4-D-mannan-degrading enzyme (ManP) from Paenibacillus sp. strain HY-8, a gut bacterium of the longicorn beetle Moechotypa diphysis. RESULTS: Purified ManP (32 kDa) with an N-terminal amino acid sequence of APSFAVGADFSYVPG displayed the greatest degree of biocatalytic activity toward locust bean gum (LBG) at 55 °C and pH 7.0. The enzyme degraded LBG, guar gum, ivory nut mannan, and mannooligosaccharides (M2-M5), but did not exhibit any hydrolytic activity against structurally unrelated substrates. The biocatalytic activity of ManP against LBG and guar gum was 695 and 450 U mg-1, respectively. Especially, enzymatic hydrolysis of mannobiose yielded a mixture of mannose (16.6 %) and mannobiose (83.4 %), although the degree of mannobiose degradation by ManP with was relatively limited. CONCLUSION: The present results suggest that ManP is an endo-ß-1,4-mannanase and is distinct from various other characterized endo-ß-1,4-mannanases.