Thraustochytrids as a promising source of fatty acids, carotenoids, and sterols: bioactive compound biosynthesis, and modern biotechnology.

Thraustochytrids are eukaryotes and obligate marine protists. They are increasingly considered to be a promising feed additive because of their superior and sustainable application in the production of health-benefiting bioactive compounds, such as fatty acids, carotenoids, and sterols. Moreover, the increasing demand makes it critical to rationally design the targeted products by engineering industrial strains. In this review, bioactive compounds accumulated in thraustochytrids were comprehensively evaluated according to their chemical structure, properties, and physiological function. Metabolic networks and biosynthetic pathways of fatty acids, carotenoids, and sterols were methodically summarized. Further, stress-based strategies used in thraustochytrids were reviewed to explore the potential methodologies for enhancing specific product yields. There are internal relationships between the biosynthesis of fatty acids, carotenoids, and sterols in thraustochytrids since they share some branches of the synthetic routes with some intermediate substrates in common. Although there are classic synthesis pathways presented in the previous research, the metabolic flow of how these compounds are being synthesized in thraustochytrids still remains uncovered. Further, combined with omics technologies to deeply understand the mechanism and effects of different stresses is necessary, which could provide guidance for genetic engineering. While gene-editing technology has allowed targeted gene knock-in and knock-outs in thraustochytrids, efficient gene editing is still required. This critical review will provide comprehensive information to benefit boosting the commercial productivity of specific bioactive substances by thraustochytrids.

Genome Sequencing and Analysis of Thraustochytriidae sp. SZU445 Provides Novel Insights into the Polyunsaturated Fatty Acid Biosynthesis Pathway.

Thraustochytriidae sp. have broadly gained attention as a prospective resource for the production of omega-3 fatty acids production in significant quantities. In this study, the whole genome of Thraustochytriidae sp. SZU445, which produces high levels of docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), was sequenced and subjected to protein annotation. The obtained clean reads (63.55 Mb in total) were assembled into 54 contigs and 25 scaffolds, with maximum and minimum lengths of 400 and 0.0054 Mb, respectively. A total of 3513 genes (24.84%) were identified, which could be classified into six pathways and 44 pathway groups, of which 68 genes (1.93%) were involved in lipid metabolism. In the Gene Ontology database, 22,436 genes were annotated as cellular component (8579 genes, 38.24%), molecular function (5236 genes, 23.34%), and biological process (8621 genes, 38.42%). Four enzymes corresponding to the classic fatty acid synthase (FAS) pathway and three enzymes corresponding to the classic polyketide synthase (PKS) pathway were identified in Thraustochytriidae sp. SZU445. Although PKS pathway-associated dehydratase and isomerase enzymes were not detected in Thraustochytriidae sp. SZU445, a putative DHA- and DPA-specific fatty acid pathway was identified.

Biological pretreatment of rice straw with Streptomyces griseorubens JSD-1 and its optimized production of cellulase and xylanase for improved enzymatic saccharification efficiency.

Biological pretreatment of rice straw and production of reducing sugars by hydrolysis of bio-pretreated material with Streptomyces griseorubens JSD-1 was investigated. After 10 days of incubation, various chemical compositions of inoculated rice straw were degraded and used for further enzymatic hydrolysis studies. The production of cellulolytic enzyme by S. griseorubens JSD-1 favored the conversion of cellulose to reducing sugars. The culture medium for cellulolytic enzyme production by using agro-industrial wastes was optimized through response surface methodology. According to the response surface analysis, the concentrations of 11.13, 20.34, 4.61, and 2.85 g L(-1) for rice straw, wheat bran, peptone, and CaCO3, respectively, were found to be optimum for cellulase and xylanase production. Then the hydrolyzed spent Streptomyces cells were used as a nitrogen source and the maximum filter paper cellulase, carboxymethylcellulase, and xylanase activities of 25.79, 78.91, and 269.53 U mL(-1) were achieved. The crude cellulase produced by S. griseorubens JSD-1 was subsequently used for the hydrolysis of bio-pretreated rice straw, and the optimum saccharification efficiency of 88.13% was obtained, indicating that the crude enzyme might be used instead of commercial cellulase during a saccharification process. These results give a basis for further study of bioethanol production from agricultural cellulosic waste.

Lignocellulose degradation by the isolate of Streptomyces griseorubens JSD-1.

Streptomyces griseorubens JSD-1 is an isolate that can utilize lignocellulose (straw) as its sole carbon source for growth, and these lignocellulolytic genes involved in this biotransformation are expected to be crucial. However, little is known about the genetic basis related to this process. To further investigate the lignocellulose-degrading mechanisms, genome sequencing was carried out using MiSeq platform. After obtaining its draft genome, the key lignocellulolytic genes such as multicopper oxidase, exo-1, 4-ß-glucanase, endo-1,4-ß-glucanase, and ß-xylosidase were identified and characterized. Multiple sequence alignments were performed to find out the identities of these analyzed proteins to those of their similar species. Signal peptide cleavage sites were predicted by SignalP 4.1 to reflect the cellular localization of their mature proteins. Besides, predicted 3D structures of these proteins were modeled by Phyre2, which showed to be highly identical to the templates in the PDB database. Finally, quantitative real-time PCR revealed that expression levels of all analyzed enzymes were significantly and generally up-regulated during the whole cultivation, indicating that they all contributed to the biodegradation.

[The prevalence of asthma in children: a comparison between the year of 2010 and 2000 in urban China].

OBJECTIVE: To compare the prevalence of asthma in children aged 0-14 years by the epidemiological survey for children in urban China between the year of 2000 and 2010. METHODS: Cities participated in the national survey of asthma prevalence in urban children aged 0-14 years at 2000 and 2010 were selected. The surveyed sample sizes met the study requirements. Stratified multistage random cluster sampling and unified questionnaire screening were adopted in both surveys of 2000 and 2010. For screening-positive children, asthma was diagnosed by physicians through on-site visits, physical examination, medical records review and auxiliary examination results. Double entry and validation was adopted for all data using Epi-Info software, and analysis was carried out by SPSS V19.0. RESULTS: Thirty-three cities were selected for this study. The prevalence of asthma was 1.59% in 2000 and 2.11% in 2010, respectively. The highest prevalence of asthma was seen in Hefei and Shanghai respectively in the two surveys, while the lowest prevalence was seen in Xining and Lhasa. The prevalence rate increased in most of the cities, especially in Wenzhou, Shanghai and Xining. The prevalence of asthma in boys was significantly higher than that in girls in the two surveys, with a ratio of 1.67:1 and 1.58:1, respectively. Preschool age (aged 3-6) had the highest prevalence in both surveys, and nearly 80% of the onset was observed before age 6. Regarding the age of disease onset in the 2000 and 2010 surveys, 54.92% and 43.30% were found in infants, 45.08% and 56.70% in preschool and school-age, respectively. CONCLUSIONS: In the recent 10 years, childhood asthma prevalence rate increased significantly in urban China and the prevalence increased 32.70% in children younger than 14 years in 2010 than before. Most cities had a higher prevalence rate than before, but mainly in first-tier cities, provincial capitals and eastern coastal cities. Preschool children showed the highest prevalence of asthma. The age of asthma onset was increasing, with a higher prevalence in preschool and school-age children as compared to 10 years ago.

Identification and characterization of the nitrate assimilation genes in the isolate of Streptomyces griseorubens JSD-1.

BACKGROUND: Streptomyces griseorubens JSD-1 is a novel actinomycete isolated from soil that can utilize nitrate as its sole nitrogen source for growth and these nitrate assimilation genes active in this biotransformation are expected to be crucial. However, little is known about its genomic or genetic background related to nitrogen metabolism in this isolate. Thus, this study concentrates on identification and characterization of genes involved in nitrate assimilation. RESULTS: To investigate the molecular mechanism of nitrate metabolism, genome sequencing was performed by Illumina Miseq platform. Then the draft genome of a single linear chromosome with 8,463,223 bp and an average G+C content of 72.42% was obtained, which has been deposited at GenBank under the accession number JJMG00000000. Sequences of nitrate assimilation proteins such as nitrate reductase (EC 1.7.99.4), nitrite reductase (EC 1.7.1.4), glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.1.13) and glutamate dehydrogenase (EC 1.4.1.2) were acquired. All proteins were predicted to be intracellular enzymes and their sequences were highly identical to those from their similar species owing to the conservative character. Putative 3D structures of these proteins were also modeled based on the templates with the most identities in the PDB database. Through KEGG annotated map, these proteins proved to be located on the key positions of nitrogen metabolic signaling pathway. Finally, quantitative RT-PCR indicated that expression responses of all genes were up-regulated generally and significantly when stimulated with nitrate. CONCLUSION: In this manuscript, we describe the genome features of an isolate of S. griseorubens JSD-1 following with identification and characterization of these nitrate assimilation proteins such as nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase accounts for the ability to utilize nitrate as its sole nitrogen source for growth through cellular localization, multiple sequence alignment, putative 3D modeling and quantitative RT-PCR. In summary, our findings provide the genomic and genetic background of utilizing nitrate of this strain.

[Epidemiological survey of children asthma prevalence in Beijing urban area].

OBJECTIVE: To explore the prevalence, diagnosis and management of childhood asthma in Beijing urban area. METHODS: Multi-stage, stratified and random cluster sampling was used to recruit children born during November 1, 1995 to October 31, 2010 from Beijing or other provinces but residing in Beijing for over half a year. The same screening questionnaires for the third national epidemiological survey of children's asthma were distributed to parents of children at schools, kindergartens and communities during October 2010 to March 2011. Asthmatic children were picked among the screening-positive children based on on-the-spot inquiries, physical examinations, medical records and supporting test results. Further survey of asthmatics was carried out to investigate the diagnosis and treatment status of childhood asthma and other associated allergic diseases. All data required double entry by Epi-Info 3.5.3 software and were processed by SPSS 19.0. RESULTS: Among a total of 14 085 questionnaires, 13 513 were completed with a response rate of 95.94%. And 497 (3.68%) children were diagnosed with typical (n = 451, 3.34%) and cough variant (n = 46, 0.34%) asthma. Among them, 40.64% (202/497) were newly diagnosed and 59.36% (295/497) had been previously diagnosed with asthma. The prevalence of asthma was higher in boys than in girls (4.80% (345/1790) vs 2.40% (152/6323), χ(2) = 54.446, P < 0.01). The asthma prevalence of preschoolers (3 - < 7 years old) was the highest (5.05% (180/3563)). In the past two years, the symptoms of 69.42% (345/497) children persisted and the current two-year prevalence of asthma was 2.55% (345/13513). Among the 295 children with previous asthma, only 46.44% (137/295) received inhaled corticosteroids according to the Global Initiative for Asthma (GINA) and 82.37% (243/295) of them used antibiotics. CONCLUSIONS: The prevalence of asthma is 3.68% in children under 14 years old in Beijing urban area and it varies in children with different genders and ages. A considerable number of children are not diagnosed or treated properly. And the management of asthma requires further improvement.

Mechanistic Role of Scutellaria baicalensis Georgi in Breast Cancer Therapy.

Breast cancer is one of the most common malignancies in women, and exhibits high metastasis, recurrence and fatality rates. Novel therapies for breast cancer are constantly emerging, such as targeted therapy, oncolytic virotherapy, and immunotherapy. Despite their potential, these new therapies are still in their infancy, and chemotherapy remains the standard treatment for breast cancer. Therefore, it is of great significance to develop safe and efficient treatment drugs or adjuvants for breast cancer treatment. Traditional Chinese medicine (TCM) has a long clinical history in China, in which Scutellaria baicalensis Georgi exhibits favorable antibreast cancer activities. We therefore conducted a systematic review of the available literature to better understand the molecular mechanisms of S. baicalensis in breast cancer treatment. S. baicalensis and its active components (baicalein, baicalin, wogonin, wogonoside, oroxylin A and scutellarin) exhibited promising antibreast cancer activity through proliferation inhibition, apoptosis induction, invasion and metastasis blockading, and drug-resistance and non-coding RNA regulation. Additionally, senescence, autophagy, angiogenesis, and glycolysis mechanisms were observed to play a role in their antibreast cancer activity. Furthermore, multiple signaling pathways contributed to the antitumor effects of S. baicalensi, such as the NF-[Formula: see text]B, Wnt/[Formula: see text]-catenin, SATB1, Bcl2 family proteins, Caspase, PI3K/Akt, mTOR, ERK, p38-MAPK, TGF-[Formula: see text]/Smad, and Hippo/YAP pathways. This review provides valuable insights into the role of S. baicalensis as a breast cancer treatment and acts as a foundation for further investigations in this field.

Differences in Physiological Performance and Gut Microbiota between Deep-Sea and Coastal Aquaculture of Thachinotus Ovatus: A Metagenomic Approach.

Aquaculture has become the fastest growing sector in global agriculture. The environmental degradation, diseases, and high density of mariculture has made for an inevitable shift in mariculture production from coastal to deep-sea areas. The influence that traditional coastal and emerging deep-sea farming environments exert on aquatic growth, immunity and gut microbial flora is unclear. To address this question, we compared the growth performance, physiological indicators and intestinal microbiological differences of deep-sea and coastal aquaculture in the Guangxi Beibu Gulf of China. The results showed that the growth performance and the complement of C3 and C4 (C3, C4), superoxide dismutase (SOD), and lysozyme (LYS), these physiological and biochemical indicators in the liver, kidney, and muscle of Trachinotus ovatus (T. ovatus), showed significant differences under different rearing conditions. Metagenome sequencing analysis showed Ascomycota, Pseudomonadota, and Bacillota were the three dominant phyla, accounting for 52.98/53.32 (coastal/deep sea), 24.30/22.13, and 10.39/11.82%, respectively. Aligned against the CARD database, a total of 23/2 (coastal/deep-sea) antibiotic resistance genes were screened and grouped into 4/2 genotypes. It indicated that compared with deep-sea fish, higher biological oxygen levels (3.10 times), inorganic nitrogen (110.00 times) and labile phosphate levels (29.00 times) in coastal waters might contributed to the existence of eutrophication with antibiotic resistance. The results of the study can provide complementary data on the study of the difference between deep-sea farming and traditional coastal farming, serving as a reference to future in-depth work on the transformation of fisheries development and scientific standardization of deep-sea farming.

Noninvasive Intratracheal Lipopolysaccharide Instillation in Mice.

The acute lung injury (ALI) mouse model induced by lipopolysaccharide (LPS) or endotoxin is still among the most commonly used models in animal studies of acute lung injury or acute inflammation. The current most commonly used methods in acute lung injury mouse models are an intraperitoneal injection of LPS and tracheostomy for the tracheal infusion of LPS. However, the former method lacks lung targeting and damages other organs, and the latter method induces operative trauma, infection risk, and a low survival rate. Here, we recommend a noninvasive oropharyngeal endotracheal intubation method for LPS instillation in mice. In this method, LPS is noninvasively introduced into the trachea through the oropharyngeal cavity to be instilled into the lung with the help of an apparatus for endotracheal intubation. This method not only assures lung targeting but also avoids damage and the risk of death in the animals. We expect that this approach will become widely used in the field of acute lung injury.

[Effect of Colloids in Sediment and Soil on Their Sorption Behavior of Chloramphenicol].

Natural colloids (NCs) are ubiquitous in sediments and soils, which could affect the environmental fate of antibiotics. Focusing on chloramphenicol (CAP), different sources of the sediments and soil samples were selected to research the sorption capacity of NCs with different relative molecular weights towards CAP, as well as the impactors, combined with a multi-method approach including cross-flow ultrafiltration, dynamic light scattering, UV-visible absorption spectroscopy, and three-dimensional excitation-emission matrix fluorescence spectroscopy. The results revealed that the low molecular weight (LMW) of NCs was associated with a low autochthonous origin and a higher humification degree. The high molecular weight (HMW) of NCs were mainly terrestrial sources, and the aromatic rings contained more oxygen-containing functional groups such as carboxyl, hydroxyl, and carbonyl groups. Four fluorescence components were identified using the parallel factor analysis model, and the humic-like substances were the primary fluorescent components. Moreover, based on batch experiments, the study investigated the sorption behavior of CAP by the different fractions of the solid samples. The results showed that the sorption processes of CAP were well fitted by the linear model and Freundlich model. The average sorption rate of CAP by the original solid samples and the solid samples with removed organic and inorganic carbon were 4.46%, 3.93%, and 6.61%, respectively, indicating that organic carbon played an important role in the sorption behavior of CAP. The results of the sorption experiments indicated that CAP was more easily adsorbed on the LMW NCs that had a high degree of humification and a more aliphatic chain on the aromatic rings. In addition, tryptophan-like protein substances in NCs showed the inhibiting effect on the sorption progress of CAP. Redundancy analysis indicated that the sorption of CAP by NCs in sediment and soil was mainly related to the source, aromatics, oxygen functional groups on aromatic rings, humification degree, and humic-like substances of NCs.

[Spectral Characteristics of Dissolved Organic Matter in Sediments from Poyang Lake].

At present, there are few studies on the spectral characteristics of dissolved organic matter (DOM) in the sediments of the Poyang Lake basin. Therefore, excitation-emission matrix spectroscopy (EEMs) technology and ultraviolet-visible spectra combined with the parallel factor analysis (PARAFAC) were applied to investigate the fluorescent components and sources of DOM in sediments from Poyang Lake. The results showed that the DOM in sediments originated from both terrestrial and autochthonous sources with a high humification. Compared with the sub-lakes, the DOM from the main lake was characterized with a higher concentration of colored DOM, larger particle size, and higher aromaticity and humification degree. In addition, four fluorescence components of DOM in sediments were identified by the PARAFAC model, including three humic-like components (C1, C2, and C4) and one protein-like component (C3). The fluorescence intensity of the humic substances in the sub-lakes was higher than those in the main lake. Furthermore, the percentage of fluorescence abundance of C1 was the highest both in the sub-lakes (42%) and main lake (46%). The spatial distribution of the fluorescence intensity of the four components gradually increased from west to east, and the peak values were observed in the Duchang and Nanji Wetland. This may be related to the death of a large number of plants due to the rise in the water level during the wet season and human activities. Principal component analysis showed that although there were no significant differences in the four fluorescent components between the sub-lakes and the main lake, the humification degree of DOM in the sub-lakes was slightly higher than that in the main lake.

Study on the Hemostasis Characteristics of Biomaterial Frustules Obtained from Diatom Navicula australoshetlandica sp.

Diatoms, known as photosynthetic unicellular algae, can produce natural biosilica frustules that exhibit great biocompatibility, superhydrophilicity, and superhemophilicity. In our study, the diatom Navicula australoshetlandica sp. was isolated from aquaculture wastewater and pretreated to obtain frustules so as to explore their hemostasis characteristics. A special "porous web" (6-8 nm) substructure in the ordered nanopores (165-350 nm) of boat-shaped diatom frustule was observed in Navicula australoshetlandica sp. using SEM and TEM analysis. Moreover, X-ray, N2 adsorption-desorption isotherms, and BET analysis showed that the diatom frustule is a mesoporous material with a surface area of 401.45 m2 g-1 amorphous silica. FTIR analysis showed that Navicula australoshetlandica sp. frustules possessed abundant OH functional groups. A low hemolysis ratio was observed for 1-5 mg mL-1 diatom frustules that did not exceed 1.55 ± 0.06%, which indicates favorable hemocompatibility. The diatom frustules exhibited the shortest clotting time (134.99 ± 7.00 s) with a hemostasis material/blood (mg/µL) ratio of 1:100, which is 1.83 times (112.32 s) shorter than that of chitosan. The activated partial thromboplastin time (aPTT) of diatom frustule was also 44.53 s shorter than the control. Our results demonstrate the potential of Navicula australoshetlandica sp. diatom frustules to be used as medical hemostasis material.

Multivariant ligands stabilize anionic solvent-oriented α-CsPbX3 nanocrystals at room temperature.

Cubic phase CsPbX3 nanocrystals (NCs) are promising candidates for optoelectronic applications. However, their chemical stability heavily depends on the dynamic ionic surface. In this work, based on the interdependency of the ligands and the reaction solvent, a protocol is developed for high-quality α-CsPbX3 under ambient conditions. Utilizing this method, the size and full width at half maximum of CsPbX3 NCs can be simply tuned via changing the cationic ligands or reaction solvent, such as CH3Cl, CH2Cl2, or toluene. One remarkable result is the synthesis of cubic CsPbI3 NCs, for which large-scale syntheses have not been reported in the literature except for our method, due to significant phase transition at room temperature. Another result is that we have realized ultrasmall sized CsPbCl3 NCs with emission at 385 nm for the first time. Furthermore, the elimination of reaction solvent (such as ODE, DMSO, DMF) in our protocol reduces the purification-induced surface ligand loss and the irreversible phase transition to a nonfluorescent phase. Our CsPbX3 NCs show near-perfect photoluminescence quantum yield (PL QY) and long-term stability in the presence of moisture. Further characterization demonstrates that all the ligands, whether the initial paired X type or the degenerated hybrid L-X type, remain perfectly passivating on the defect sites throughout.

Synthesis and luminescence properties of a broadband near-infrared emitting non-gallate persistent luminescence Mg1.4Zn0.6SnO4:Cr3+ phosphor.

A series of novel non-gallate near-infrared long-persistent phosphorescence Mg2-xZnxSnO4:Cr3+ phosphors were synthesized, and their structure and luminescence properties were investigated systematically. Under 448 nm blue light excitation, all the phosphors exhibit a broad emission band centered at 730 nm and a shoulder peak at 708 nm, which are attributed to the 4T2(4F) → 4A2 and 2E → 4A2 transitions of Cr3+, respectively. The excitation spectra of the samples clearly show the characteristic excitation of Cr3+ in the octahedral crystal field, with three obvious peaks at 324, 448 and 620 nm respectively. The phosphor with a composition of Mg1.4Zn0.6SnO4:0.03Cr3+ shows the strongest photoluminescence intensity which is 2.87 times and 3.09 times that of Mg2SnO4:0.03Cr3+ and Zn2SnO4:0.03Cr3+, respectively. Besides, all the samples show intense near-infrared long-persistent phosphorescence. For the optimized sample Mg1.4Zn0.6SnO4:0.005Cr3+, its phosphorescence can still be observed with a night vision instrument 18 h after removing the 365 nm UV light source. Finally, a feasible phosphorescence mechanism of the Mg1.4Zn0.6SnO4:Cr3+ phosphor was proposed and discussed. This study may provide a new method for developing novel near-infrared long-persistent phosphorescence phosphors through crystal structure modification.

Origin of Color Centers in the Perovskite Oxide CeAlO3.

In view of the significant impact of color centers on the physical and chemical properties of materials, studies on the origin of such color centers are needed. In this article, detailed crystal structure analysis and compositional characterization of CeAlO3 was carried out by applying XRD, XPS, HRTEM, STEM-EDS and ICP-OES techniques. The results revealed that crystal defects may be the main cause of color centers. The existence of oxygen and aluminum vacancy was proved and confirmed by the application of XPS, ICP-OES and STEM-EDS characterization methods. Overall, it unlikely that a single crystal defect would generate the yellow-green color of CeAlO3 crystals.

Diagnostic value of elevated serum carbohydrate antigen 199 level in acute cholangitis secondary to choledocholithiasis.

AIM: To investigate the diagnostic value of abnormal serum carbohydrate antigen 199 (CA199) level in acute cholangitis secondary to choledocholithiasis. METHODS: In this retrospective cohort study, the clinical data of 727 patients with choledocholithiasis admitted to the Third Affiliated Hospital of Zunyi Medical College from June 2011 to June 2017 were collected. Among these patients, 258 patients had secondary acute cholangitis and served as observation group, and the remaining 569 choledocholithiasis patients served as the control group. Serum liver function indexes and tumor markers were detected in both groups, and the receiver operating characteristic (ROC) curves were constructed for markers showing statistical significances. The cutoff value, sensitivity, and specificity of each marker were calculated according to the ROC curves. RESULTS: The results of liver function tests showed no significant differences between the two groups (P > 0.05). Tumor markers including serum CA125, CA153, carcinoembryonic antigen, and alpha fetoprotein levels were also not significantly different (P > 0.05); however, the serum CA199 level was significantly higher in the observation group than in the control group (P < 0.05). The ROC curve analysis showed that the area under the curve was 0.885 (95%CI: 0.841-0.929) for CA199, and the cutoff value of 52.5 kU/L had the highest diagnostic accuracy, with a sensitivity of 86.8% and a specificity of 81.6%. CONCLUSION: Abnormally elevated serum CA199 level has an important value in the diagnosis of acute cholangitis secondary to choledocholithiasis. It may be a specific inflammatory marker for acute cholangitis.

Enhancement of Cellulase and Xylanase Production Using pH-Shift and Dissolved Oxygen Control Strategy with Streptomyces griseorubens JSD-1.

In this study, the production of cellulase and xylanase by Streptomyces griseorubens JSD-1 was improved by integrating the pH-shift and dissolved oxygen (DO)-constant control strategies. The pH-shift control strategy was carried out by analyzing the specific cell growth rate (µ) and specific enzyme formation rate (Q p) of S. griseorubens JSD-1. The pH was controlled at 8.0 during the first 48 h to maintain high cell growth, which then shifted to 7.5 after 48 h to improve the production of cellulase and xylanase. Using this method, the maximum activities of cellulase, xylanase, and filter paper enzyme (FPase) increased by 47.9, 29.5, and 113.6 %, respectively, compared to that obtained without pH control. On the basis of pH-shift control, the influence of DO concentrations on biomass and enzyme production was further investigated. The maximum production of cellulase, xylanase, and FPase reached 114.38 ± 0.96 U mL(-1), 330.57 ± 2.54 U mL(-1), and 40.11 ± 0.38 U mL(-1), which were about 1.6-fold, 0.6-fold, and 3.2-fold higher than that of neutral pH without DO control conditions. These results supplied a functional approach for improving cellulase and xylanase production.

Performance comparison of LUR and OK in PM2.5 concentration mapping: a multidimensional perspective.

Methods of Land Use Regression (LUR) modeling and Ordinary Kriging (OK) interpolation have been widely used to offset the shortcomings of PM2.5 data observed at sparse monitoring sites. However, traditional point-based performance evaluation strategy for these methods remains stagnant, which could cause unreasonable mapping results. To address this challenge, this study employs 'information entropy', an area-based statistic, along with traditional point-based statistics (e.g. error rate, RMSE) to evaluate the performance of LUR model and OK interpolation in mapping PM2.5 concentrations in Houston from a multidimensional perspective. The point-based validation reveals significant differences between LUR and OK at different test sites despite the similar end-result accuracy (e.g. error rate 6.13% vs. 7.01%). Meanwhile, the area-based validation demonstrates that the PM2.5 concentrations simulated by the LUR model exhibits more detailed variations than those interpolated by the OK method (i.e. information entropy, 7.79 vs. 3.63). Results suggest that LUR modeling could better refine the spatial distribution scenario of PM2.5 concentrations compared to OK interpolation. The significance of this study primarily lies in promoting the integration of point- and area-based statistics for model performance evaluation in air pollution mapping.

Expression and Characterization of a Recombinant Laccase with Alkalistable and Thermostable Properties from Streptomyces griseorubens JSD-1.

Streptomyces griseorubens JSD-1 is a novel actinomycete that could grow efficiently upon lignin, and the ligninolytic genes active in this biotransformation were expected to be crucial. To investigate the molecular mechanism of utilizing lignin, genome sequencing was carried out to obtain its draft genome, which was deposited at GenBank under the accession No. JJMG00000000. Multiple copper oxidase (MCO) was obtained, which proved to be an extracellular enzyme and have relative high expression with the stimulation of ligninolytic materials. Judging from its putative 3D structure, the N-terminal of MCO was bared, which was fit for the linkage of poly-HIS10 tag. As a result, heterogeneous expression conditions of recombinant laccase was achieved with TransB(DE3) grown in a modified terrific broth (TB) medium with an extra addition of 0.5% glucose at 30 °C until optical density at 600 nm (OD600) reached 0.8 when expression was induced by 25 µM isopropyl ß-D-1-thiogalactopyranoside (IPTG) and also 100 µM copper sulphate as supplement. Finally, it exhibited special characters of thermal robustness, alkaline activity profiles, high resistance to metallic ions and chemical inhibitors as well as dye decolourization. In summary, our findings illustrated the genetic basic of utilizing lignin in this isolate. Additionally, a novel laccase expected to be potential in agricultural and industrial application was expressed and characterized as well.