Changes in soil bacterial and fungal communities in response to Bacillus megaterium NCT-2 inoculation in secondary salinized soil.

BACKGROUND: Secondary salinized soil in greenhouses often contains excess nitrate. Inoculation of Bacillus megaterium NCT-2 with nitrate assimilation ability represents an attractive approach for soil remediation. However, the effects of NCT-2 on the structure and function of soil microbial communities have not been explored. METHODS: Greenhouse experiments were carried out to investigate changes in soil properties, Brassica chinensis L. growth, bacterial, and fungal community structure and function in response to NCT-2 inoculation. RESULTS: The NCT-2 inoculant significantly reduced the nitrate content in B. chinensis and inhibited the rebound of soil nitrate in the later stage. The shifts of bacterial community structure and function by NCT-2 was negligible, and a greater disturbance of soil fungal community structure and function was observed, for example the strong inhibitory effect on ectomycorrhizal fungi. These results indicated that the NCT-2 inoculant likely achieved the remediation effect in secondary salinized soil by shifting fungal community. The present findings add to the current understanding of microbial interactions in response to bacterial inoculation and can be of great significance for the application of NCT-2 inoculants in secondary salinized soil remediation.

Anti-Hyperlipidemia and Gut Microbiota Community Regulation Effects of Selenium-Rich Cordyceps militaris Polysaccharides on the High-Fat Diet-Fed Mice Model.

Supplementation of polysaccharides is a promising gut microbiota-targeted therapeutic method for obesity and metabolic diseases. Biological activities of Cordyceps militaris polysaccharides have been well reported, but the effect of selenium (Se)-rich C. militaris polysaccharides (SeCMP) on obesity and associated metabolic disorder and gut microbiota composition has been rarely studied. This study aimed to investigate the anti-obesity and gut microbiota modulatory effect of crude polysaccharides separated from Se-rich C. militaris on a high-fat diet (HFD)-fed C57BL/6J mice model. Mice were treated with a normal diet (CHOW), HFD alone, HFD plus C. militaris polysaccharides (CMP), or low/medium/high dosage of SeCMP for 8 weeks. Body weight, fat content, serum lipid, appetite hormone, lipid gene expression, inflammation cytokines, thermogenic protein, short-chain fatty acids (SCFAs), and gut microbiota structure of the mice were determined. Compared with HFD-fed mice, the serum triglyceride and low-density lipoprotein cholesterol (LDL-C) in the SeCMP-200 group were decreased by 51.5% and 44.1%, respectively. Furthermore, serum lipopolysaccharide-binding proteins (LBP), adiponectin level, and pro-inflammation gene expression in the colon and subcutaneous fat were inhibited, whereas anti-inflammation gene expression was improved, reflecting SeCMP-200 might mitigate obese-induced inflammation. Meanwhile, SeCMP-200 promoted satiety and thermogenesis of obese mice. It also significantly decreased gut bacteria, such as Dorea, Lactobacillus, Clostridium, Ruminococcus, that negatively correlated with obesity traits and increased mucosal beneficial bacteria Akkermansia. There was no significant difference between CMP and SeCMP-100 groups. Our results revealed a high dose of SeCMP could prevent HFD-induced dyslipidemia and gut microbiota dysbiosis and was potential to be used as functional foods.

Phytoremediation of secondary saline soil by halophytes with the enhancement of γ-polyglutamic acid.

Soil salinization has severely affected the quality of tillage land in China, and most greenhouse soils in Shanghai suburb suffer from secondary salinization with high salinity levels dominated by Ca2+, Mg2+ and NO3-. In this work, a sandy loam soil (Calcaric Fluvisols) contaminated by the above ions was selected as research object, and the binding conditions and abilities of γ-polyglutamic acid (γ-PGA) to water-soluble Ca2+ and Mg2+ in the soil were examined, and then pot experiments were conducted to remove Ca2+, Mg2+ and NO3- by two halophytes (Sedum aizoon L., Sesbania cannabina Pers.) integrated with γ-PGA application. The results showed that under the conditions of adding 1000 mg L-1γ-PGA (pH 7) and 25 °C, the binding efficiencies of Ca2+ and Mg2+ were 51.59% and 68.03%, respectively. Compared with Sesbania cannabina Pers., Sedum aizoon L. displayed better remediation performance for the soil with γ-PGA application in pot experiments, and the removal efficiencies of Ca2+, Mg2+ and NO3- reached 93.25%, 94.78% and 84.26% after applying 1000 mg L-1γ-PGA for 56 d, respectively. Moreover, γ-PGA application could mitigate salt stress and promote plant growth, and activate antioxidant defense systems. Compared with the control, 1000 mg L-1γ-PGA application significantly increased plant height and fresh weight of Sedum aizoon L., and the removal efficiencies of Ca2+, Mg2+ and NO3- increased by 45.48%, 82.62% and 69.91%, respectively. In the future, more in-depth mechanism of joint effect and field-scale investigation need to be further studied.

Streptomyces griseorubens JSD-1 promotes rice straw composting efficiency in industrial-scale fermenter: Evaluation of change in physicochemical properties and microbial community.

The influence of Streptomyces griseorubens JSD-1 on microbial community succession during rice straw composting in an industrial-scale fermenter was assessed by high-throughput sequencing technology. Compared to uninoculated control, JSD-1 inoculation effectively raised composting temperature and improved other maturation indices. JSD-1 inoculation increased the relative abundance of Actinobacteria in thermophilic phase and Firmicutes in cooling and maturation phases. At the genus level, JSD-1 inoculation increased the abundance of organic matter degrading bacteria (Virgibacillus) and lignocellulose degrading fungi (Chaetomium and Melanocarpus); while it decreased the abundance of pathogenic fungi (Geosmithia and Acremonium). Moreover, JSD-1 changed microbes that differed significantly and altered the key connecting nodes of microbial community. Organic matter and temperature were the most significant indices that had mutual influences on bacterial and fungal communities, respectively. This study demonstrated that JSD-1 was an effective inoculant on rice straw fast composting in the industrial-scale fermenter.

Influence of Cd toxicity on subcellular distribution, chemical forms, and physiological responses of cell wall components towards short-term Cd stress in Solanum nigrum.

Solanum nigrum is a well-documented cadmium (Cd) hyperaccumulator; however, its Cd-induced tolerance capability and detoxification mechanism remain elusive. Hence, a short-term hydroponic experiment was performed in a multiplane glasshouse to determine the influence of Cd toxicity on subcellular distribution, chemical forms, and the physiological responses of cell wall towards Cd stress in a 4-week-old plant. The experiment was conducted following completely randomized design (CRD) with five treatments (n = 4 replicates). The results showed that Cd stress showed dose-dependent response towards growth inhibition. The subcellular distribution of Cd in S. nigrum was in the order of cell wall > soluble fractions > organelles, and Cd was predominantly extracted by 1 M NaCl (29.87~43.66%). The Cd contents in different plant tissues and cell wall components including pectin, hemicellulose 1 (HC1), hemicellulose 2 (HC2), and cellulose were increased with the increase in Cd concentrations; however, the percentage of Cd concentration decreased in pectin and cellulose. Results of the polysaccharide components such as uronic acid, total sugar contents, and pectin methylesterase (PME) activity showed Cd-induced dose-dependent increase relative to exposure Cd stress. The pectin methylesterase (PME) activity was significantly (p < 0.05) enhanced by 125.78% at 75 µM Cd in root, 105.78% and 73.63% at 100 µM Cd in stem and leaf, respectively. In addition, the esterification, amidation, and pectinase treatment of cell wall and Fourier transform infrared spectroscopy (FTIR) assay exhibited many functional groups that were involved in cell wall retention Cd, especially on carboxyl and hydroxyl groups of cell wall components that indicated that the -OH and -COOH groups of S. nigrum cell wall play a crucial role in Cd fixation. In summary, results of the current study will add a novel insight to understand mobilization/immobilization as well as detoxification mechanism of cadmium in S. nigrum.

Rice straw as renewable components of horticultural growing media for purple cabbage.

This study was conducted to estimate the influence of composted rice straw (CRS) on the growth and nutritional composition of purple cabbage (Brassica oleracea L. var. capitate L.). In order to select the proper preparation method of CRS based media, growing media were prepared by mixing peat, perlite, vermiculite and sand with CRS in different ratios. The general proportions of CRS in substrates were 25% and 50% (v/v). A mixture of 50% peat with 50% perlite (v/v) was the control (CK). Completely randomized design was used in the experiment under greenhouse conditions. The physicochemical characteristics of all growing media were determined before transplanting. Plant growth parameters as well as the mineral elements were also measured. In general, plants grown in most CRS based media were improved in growth and element nutrition in comparison with control. 25% CRS addition was the most-suitable rate for the growth of purple cabbage. The highest leaves yield obtained from T3 (25% CRS: 25% peat: 50% vermiculite, v:v:v) increased by 105.99% compared to control. CRS can be an alternative constituent to replace the generally using peat in growing media.

Dynamic bacterial assembly driven by Streptomyces griseorubens JSD-1 inoculants correspond to composting performance in swine manure and rice straw co-composting.

The effect of Streptomyces griseorubens JSD-1 inoculant on composting performance and bacterial community assembly during the swine manure and rice straw co-composting was studied by a high-throughput pyrosequencing technology. The JSD-1 inoculant contributed to a higher temperature (maximum 66.8 °C), a longer thermophilic phase (46 days), and a lower bacterial diversity in JSD-1 compost. The principle component analysis confirmed that JSD-1 inoculant significantly reshaped the microbial communities. The difference in genera significantly increased during both composting processes. The predominant biomarkers were members of Bacteroidetes in JSD-1 composting. The network analysis also showed different chief "connecting" genera in both composts. Moreover, JSD-1 inoculant increased the total nitrogen, phosphorus, and potassium content in composts. The redundancy analysis showed that the bacterial community was mainly influenced by temperature; additionally, the nutrient contents were positively correlated with temperature. These results demonstrated that JSD-1 inoculant drove the bacterial assembly to induce physicochemical property changes in co-composting.

Genomic Analysis of Bacillus megaterium NCT-2 Reveals Its Genetic Basis for the Bioremediation of Secondary Salinization Soil.

Bacillus megaterium NCT-2 is a nitrate-uptake bacterial, which shows high bioremediation capacity in secondary salinization soil, including nitrate-reducing capacity, phosphate solubilization, and salinity adaptation. To gain insights into the bioremediation capacity at the genetic level, the complete genome sequence was obtained by using a multiplatform strategy involving HiSeq and PacBio sequencing. The NCT-2 genome consists of a circular chromosome of 5.19 Mbp and ten indigenous plasmids, totaling 5.88 Mbp with an average GC content of 37.87%. The chromosome encodes 5,606 genes, 142 tRNAs, and 53 rRNAs. Genes involved in the features of the bioremediation in secondary salinization soil and plant growth promotion were identified in the genome, such as nitrogen metabolism, phosphate uptake, the synthesis of organic acids and phosphatase for phosphate-solubilizing ability, and Trp-dependent IAA synthetic system. Furthermore, strain NCT-2 has great ability of adaption to environments due to the genes involved in cation transporters, osmotic stress, and oxidative stress. This study sheds light on understanding the molecular basis of using B. megaterium NCT-2 in bioremediation of the secondary salinization soils.

Optimization of NPK fertilization combined with phytoremediation of cadmium contaminated soil by orthogonal experiment.

In the current experiment, influence of NPK composition on the Cd contaminated soil-plant (Solanum nigrum L.) system as well as the phytoremediation efficiency were comprehensively studied. The composition of NPK was optimized for a sustainable phytoremediation and simultaneous agronomic technique in Cd-contaminated soil by orthogonal (L14) experiment, aimed to achieve plant productivity and maximum phytoremediation potential enhancement. Results showed that different treatments of NPK composition enhanced soil properties including saccharase, urease, catalase and acid phosphatase activities as compared to the control treatment, however, soil pH was slightly decreased by 3.64%~6.67% with different composition of NPK treatments. Plant biomass and Cd concentration in the aboveground part (stem and leaves) of S. nigrum were significantly (P < 0.05) enhanced by 14.19%~48.97% and 38.50%~127.15% as compared to control plants with the addition of NPK fertilizers having different composition. Meanwhile, with the application of NPK fertilizer root/shoot Cd ratio and translocation factor (TF) was significantly decreased, however, bioconcentration factor (BCF) was increased as compared to control. Additionally, different composition of NPK fertilizers significantly increased photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids) and soluble protein in comparison to control. The activities of antioxidant enzymes in S. nigrum including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and glutathione reductase (GR) were increased, while malonaldehyde (MDA) and proline contents were decreased. Principal component analysis (PCA) showed that N3P2K2 treatment had the highest comprehensive score amongst other studied treatments of NPK composition, owing to its optimal composition for the investigated soil-S. nigrum system. Moreover, it was found that optimal composition (N3P2K2) of fertilizer resulted in increase of the plant resistance to Cd and the efficiency of phytoextraction. Therefore, it is suggested to all the small-holder famers and scientific community that precise composition of NPK fertilizer should be utilized according to soil properties, environmental conditions and plant requirements under Cd-stress condition in order to achieve maximum biomass, Cd uptake efficiency as well phytoremediation potential in moderately Cd contaminated soil.

Microencapsulation of Bacillus megaterium NCT-2 and its effect on remediation of secondary salinization soil.

Aim: To prolong the shelf life of Bacillus megaterium NCT-2 by preparing microcapsules through spray drying, and evaluate their efficiency in secondary salinisation soil remediation.Methods: The wall material and spray drying conditions were optimised. Morphological characteristics of microcapsule were measured, and soil remediation effects were tested under field conditions.Results: A relatively higher survival rate of B. megaterium microcapsule was obtained with 1:1 of chitosan/maltodextrin (w/w) when spray drying was performed at 150.0 °C, with the feed flow rates of 800 mL h-1 and 1000 mL h-1, respectively. The span value of 0.93 ± 0.01 was obtained under above conditions. Microcapsule survival rate was 64.09 ± 0.12% after 6 months of storage. Moreover, microcapsule successfully decreased NO3- and EC value in strongly saline soil by 46.5 ± 1.48% and 45.2 ± 1.51%, respectively.Conclusion: Bacillus megaterium NCT-2 microcapsules have application potential in the remediation of secondary salinisation soil.

Metabolic profiling of natural and cultured Cordyceps by NMR spectroscopy.

Cordyceps, a type of Chinese herbal medicine that exhibits anti-angiogenesis and tumor growth suppression effects, has recently gained increasing popularity. However, high-quality, natural Cordyceps, such as Ophiocordyceps sinensis, is very rare and difficult to obtain in large amounts. Cordyceps is cultured instead of harvested from natural sources, but the quality with respect to the ingredients has not been fully studied. In this study, we performed an NMR metabolic profiling of aqueous extracts of Cordyceps without any sample treatment to evaluate the proper species and medium and influence of two different disinfection methods. It was discovered that Cordyceps militaris fungus and silkworm chrysalis medium were suitable for cultivation of Cordyceps. Furthermore, cordycepin, a Cordyceps-specific functional compound, was produced at different growth stages during different cultivation processes, even at the mycelial stage, and was found at three times higher concentrations in cultured C. militaris compared to that in naturally occurring C. militaris.

Microfluidic Device Directly Fabricated on Screen-Printed Electrodes for Ultrasensitive Electrochemical Sensing of PSA.

How to fabricate scale low-cost microfluidic device for detection of biomarkers owns a great requirement. Herein, it is for the first time reported that a new microfluidic device based on bonding polydimethylsiloxane microfluidic channels onto the substrate of a screen-printed electrode with coating glass solution was fabricated for electrochemical sensing of prostate-specific antigen (PSA). Compared to traditional microfabrication processes, this method is simple, fast, low cost, and also suitable for mass production. The prepared screen-printed electrode-based microfluidic device (CASPE-MFD) was used for the detection of the PSA in human serum. The prepared CASPE-MFD had a detection limit of 0.84 pg/mL (25.8 fM) and a good linearity with PSA concentration ranging from 0.001 to 10 ng/mL, which showed a great promise platform toward the development of miniaturized, low-cost electrochemical microfluidic device for use in human health, environmental monitoring, and other applications.

Enhanced removal of nitrate in the maize rhizosphere by plant growth-promoting Bacillus megaterium NCT-2, and its colonization pattern in response to nitrate.

High soil nitrate concentrations can lead to the secondary salinization of soils. Bacillus megaterium NCT-2 is a wild-type strain isolated from secondary salinized soil and is very effective in reducing nitrate. Laboratory and greenhouse experiments were carried out to investigate its nitrate reduction capabilities, colonization pattern, and plant growth promotion responses to nitrate content in the soil. B. megaterium NCT-2 was marked with a green fluorescent protein (gfp) gene and was left to successfully colonize maize roots and the rhizosphere. Inoculation with gfp-tagged NCT-2 significantly promoted nitrate removal from the soil and improved plant growth. Confocal microscopy results revealed that NCT-2 is an endophyte that can colonize the meristematic and elongation zones of the root tip, and the middle segment of the root. Soil nitrate concentration had no significant effect on NCT-2 distribution. The gfp-tagged NCT-2 populations in the roots and rhizosphere soil first increased, but then decreased, and at the end of the experiment, colonization levels in the rhizosphere soil stabilized at ∼5 × 104 CFU g-1 soil. However, the levels in the roots increased again to 1-3 × 104 CFU g-1 root in the different treatments. The NCT-2 population in the roots was significantly affected by nitrate content. A nitrate-nitrogen concentration of 72 mg kg-1 was the optimum concentration for NCT-2 colonization of maize roots. This study will improve the agricultural application of NCT-2 as a biofertilizer for nitrate removal and plant growth promotion.

Heterologous expression and biochemical characterization of assimilatory nitrate and nitrite reductase reveals adaption and potential of Bacillus megaterium NCT-2 in secondary salinization soil.

Large accumulation of nitrate in soil has resulted in "salt stress" and soil secondary salinization. Bacillus megaterium NCT-2 which was isolated from secondary salinization soil showed high capability of nitrate reduction. The genes encoding assimilatory nitrate and nitrite reductase from NCT-2 were cloned and over-expressed in Escherichia coli. The optimum co-expression condition was obtained with E. coli BL21 (DE3) and 0.1mM IPTG for 10h when expression was carried out at 20°C and 120rpm in Luria-Bertani (LB) medium. The molecular mass of nitrate reductase was 87.3kDa and 80.5kDa for electron transfer and catalytic subunit, respectively. The large and small subunit of nitrite reductase was 88kDa and 11.7kDa, respectively. The purified recombinant enzymes showed broad activity range of temperature and pH. The maximum activities were obtained at 35°C and 30°C, pH 6.2 and 6.5, which was similar to the condition of greenhouse soils. Maximum stimulation of the enzymes occurred with addition of Fe3+, while Cu2+ caused the maximum inhibition. The optimum electron donor was MV+Na2S2O4+EDTA and MV+Na2S2O4, respectively. Kinetic parameters of Km and Vmax were determined to be 670µM and 58U/mg for nitrate reductase, and 3100µM and 5.2U/mg for nitrite reductase. Results of quantitative real-time PCR showed that the maximum expression levels of nitrate and nitrite reductase were obtained at 50mM nitrate for 8h and 12h, respectively. These results provided information on novel assimilatory nitrate and nitrite reductase and their properties presumably revealed adaption of B. megaterium NCT-2 to secondary salinization condition. This study also shed light on the role played by the nitrate assimilatory pathway in B. megaterium NCT-2.

[Straw Composts with Composite Inoculants and Their Effects on Soil Carbon and Nitrogen Contents and Enzyme Activity].

The utilization of straw resources is of great significance to agricultural environmental protection and sustainable agricultural development. Based on the isolated 15 high-efficient cellulose degrading bacteria in the laboratory, the composite inoculants (JFB-1) which can effectively degrade crop straw were screened, and the effects of straw composts with the composite inoculants on soil carbon and nitrogen contents and enzyme activity were studied. The results showed that the composite inoculants could accelerate straw decomposition for 1-2 d during single fermentation period, and the organic matter contents in straw composts reached 403.5-515.1 g·kg-1, while the ratio of carbon and nitrogen decreased from 10.53 to 15.30. The pot experiments found that the application effects of rice straw composts were generally better than those of corresponding asparagus straw composts. Compared with the control compost of rice straw, when the application amount of rice straw compost using the composite inoculants was 150 g·kg-1, the contents of soil organic matter and total nitrogen increased by 33.5% and 7.3%, and soil urease and cellulase activities increased by 16.7% and 30.8%, respectively. Compared with no fertilization treatment, the application of straw composts could improve soil microbial community structure, and increase microbial diversity indices. When the application amount of rice straw compost using the composite inoculants was 100 g·kg-1, the biomass of common Chinese cabbage cultivated for 30 d increased by 46.4% compared to the control compost of rice straw. These results indicated that the composite inoculants have great application potential in straw composts.

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.

The cytotoxic effect of the NOS-mediated oxidative stress in MCF-7 cells after PbCl2 exposure.

The potential Pb-induced cytotoxicity in various tissues and biological systems has been reported. Some evidences also indicate that the Pb-caused cytotoxicity may be associated with the nitric oxide synthase (NOS). However, there remains uncertainty about the role of the NOS signaling pathway during the Pb-induced cytotoxicity. In this report, we provide data showing that PbCl2 treatment depresses the expressions of the three distinct NOS isoforms: neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS) on both transcriptional and translational levels in MCF-7 cells. The down-regulation of NOSs expressions by PbCl2 exposure leads to reduced NOS activity and nitric oxide (NO) production. Meanwhile, the intracellular reactive oxygen species (ROS) level is elevated after PbCl2 exposure, which leads to the alpha subunit of eukaryotic initiation factor 2 (elF2α) phosphorylation. The reduction effects of the free radical scavenger N-acetyl-L-cysteine or the NOS substrate l-arginine on the Pb-induced ROS generation suggest that the NOS signaling pathway plays a key role in the Pb-induced oxidative stress, which further results in the elF2α phosphorylation and cytotoxicity.

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.

Spectral Characteristics of Salinized Soils during Microbial Remediation Processes.

In this study, the spectral reflectance of saline soils, the associated soil salt content (SSC) and the concentrations of salt ions were measured and analysed by tracing the container microbial remediation experiments for saline soil (main salt is sodium chloride) of Dongying City, Shandong Province. The sensitive spectral reflectance bands of saline soils to SSC, Cl- and Na+ in the process of microbial remediation were analysed. The average-dimension reduction of these bands was conducted by using a combination of correlation coefficient and decision coefficient, and by gradually narrowing the sampling interval method. Results showed that the tendency and magnitude of the average spectral reflectance in all bands of saline soils during the total remediation processes were nearly consistent with SSC and with Cl- coocentration, respectively. The degree of salinity of the soil, including SSC and salt ion concentrations, had a significant positive correlation with the spectral reflectance of all bands, particularly in the near-infrared band. The optimal spectral bands of SSC were 1370 to 1445 nm and 1447 to 1608 nm, whereas the optimal spectral bands of Cl- and Na+ were 1336 to 1461 nm and 1471 to 1561 nm, respectively. The relationship model among SSC, soil salt ion concentrations (Cl- and Na+) and soil spectral reflectance of the corresponding optimal spectral band was established. The largest R2 of relationship model between SSC and the average reflectance of associated optimal band reached to 0.95, and RMSEC and RMSEP were 1.076 and 0.591, respectively. Significant statistical analysis of salt factors and soil reflectance for different microbial remediation processes indicated that the spectral response characteristics and sensitivity of SSC to soil reflectance, which implied the feasibility of high spectrum test on soil microbial remediation monitoring, also provided the basis for quick nondestructive monitoring soil bioremediation process by soil spectral reflectance.

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.