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Characterization of two styrene monooxygenases from marine microbes
No full textStyrene monooxygenases (SMOs) are highly stereoselective enzymes that catalyze the formation of chiral epoxides as versatile building blocks. To expand the enzyme toolbox, two bacterial SMOs were identified from the genome of marine microbes Paraglaciecola agarilytica NO2 and Marinobacteriwn litorale DSM 23545, and heterologously expressed in Escherichia coli in soluble form. Both of the resulting whole-cell biocatalysts exhibited maximal activity at 30 degrees C and pH 8.0. They catalyzed the sulfoxidation reactions, and the epoxidation of both conjugated and unconjugated styrene derivatives with up to > 99%ee. MISMO displayed higher activity toward most substrates tested. Compared to an established SMO from Pseudomonas species (PsSMO), MISMO achieved 3.0-, 3.4- and 2.6-fold conversions for substrates styrene, cinnamyl alcohol and 4-vinyl-2, 3-dihydrobenzofuran, respectively
Ornithinibacillus salinisoli sp nov., a moderately halophilic bacterium isolated from a saline-alkali soil
No full textA taxonomic study was performed on strain LCB256(T), which was isolated from a saline-alkali soil sample taken from northwestern China. Cells of strain LCB256(T) were Gram-stain-positive, aerobic, rod-shaped and grew at 3-17 % (w/v) NaCl (optimum 10-15 %), 10-52 degrees C (optimum 25-30 degrees C) and pH 7.0-9.0 (optimum 8.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LCB256(T) was most closely related to the two genera of Ornithinibacillus and Oceanobacillus, showing highest sequence similarity to Oceanobacillus limi KCTC 13823(T) (97.8 %) and Ornithinibacillus bavariensis WSBC 24001(T) (97.2 %). The peptidoglycan amino acid type was found to be A4 beta and the major respiratory quinone was determined to be MK-7. The polar lipid profile of strain LCB256(T) contained diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and two unidentified aminolipids. The dominant cellular fatty acids were anteiso-C-15:0 and iso-C-15:0. The G+C content of genomic DNA was 39.3 mol%. DNA-DNA relatedness values between strain LCB256(T) and Ornithinibacillus halophilus KCTC 13822(T) and Oceanobacillus limi KCTC 13823(T) were 46.2 and 34.8 %, respectively. Based on this polyphasic taxonomic study, a novel species of the genus Ornithinibacillus, Ornithinibacillus salinisoli sp. nov. is proposed. The type strain is LCB256(T) (=CGMCC 1.15809(T)=KCTC 33862(T))
Flavonoid glycosides and alkaloids from the embryos of Nelumbo nucifera seeds and their antioxidant activity
No full textChemical investigation of the embryos of Nelumbo nucifera afforded four new flavone C-glycosides, named nelumbosides A-D (1-4), together with nine known ones, comprising five flavonoids (5-9) and four alkaloids (10 13). The chemical structures of the new compounds were elucidated by 1D, 2D-NMR and HR-ESI-MS techniques, together with chemical methods. Nelumbosides A-D (1-4) are rarely present in naturally occurring flavone C-glycosides featuring a 4-hydroxystyrene unit connected to the flavonoid skeleton. Compounds 2-13 were evaluated for their antioxidant activity by ABTS and DPPH radical-scavenging assay. Among them, compounds 2, 6, 7 and 11 exhibited strong scavenging activity with SC50 values ranging from 12.07 to 25.68 mu M compared with the positive control L-ascorbic acid
Simultaneous efficient removal of oxyfluorfen with electricity generation in a microbial fuel cell and its microbial community analysis
No full textThe performance of a microbial fuel cell (MFC) to degrade oxyfluorfen was investigated. Approximately 77% of 50 mg/L oxyfluorfen was degraded within 24 h by anodic biofilm. The temperature, pH, and initial oxyfluorfen concentration had a significant effect on oxyfluorfen degrading, and a maximum degradation rate of 94.95% could theoretically be achieved at 31.96 degrees C, a pH of 7.65, and an initial oxyfluorfen concentration of 120.05 mg/L. Oxyfluorfen was further catabolized through various microbial metabolism pathways. Moreover, the anodic biofilm exhibited multiple catabolic capacities to 4-nitrophenol, chloramphenicol, pyraclostrobin, and sulfamethoxazole. Microbial community analysis indicated that functional bacteria Arcobacter, Acinetobacter, Azospirillum, Azonexus, and Comamonas were the predominant genera in the anodic biofilm. In terms of the efficient removal of various organic compounds and energy recovery, the MFC seemed to be a promising approach for the treatment of environmental contaminants
A global plastid phylogeny uncovers extensive cryptic speciation in the fern genus Hymenasplenium (Aspleniaceae)
No full textThe fern genus Hymenasplenium (Aspleniaceae) is one of the two genera in the family. It is generally recognized among modern pteridologists. However, its infrageneric relationships and species diversity have been unclear and controversial. The molecular studies so far have had small taxon and character sampling. In the present study, DNA sequences of six plastid markers of 158 accessions representing ca. 40 out of ca. 50 known species of Hymenasplenium, and 16 species of Asplenium were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include: (1) Hymenasplenium as currently defined is strongly supported as monophyletic; (2) three major clades representing early splits in Hymenasplenium are identified, with the Old World species being strongly supported as monophyletic; it is ambiguous if the New World species are monophyletic; (3) extensive cryptic speciation in the Old World is discovered demonstrating the complexity of evolution of the genus; and (4) six strongly or moderately supported subclades in the Old World Glade are revealed, differing from one another in molecular, morphological, and geographical features
Production and flocculating properties of a compound biopolymer flocculant from corn ethanol wastewater
No full textA compound biopolymer flocculant (CBF) produced using corn ethanol wastewater as substrate was investigated. After optimization of culture conditions, 3.08 g/L of purified CBF was extracted from the culture broth following 48 h of cultivation. The CBF macromolecule is mainly composed of protein (15.9%) and polysaccharide (81.8%). The polysaccharide component includes neutral sugars (28.92%), amino sugars (4.04%) and uronic acid (11.69%), with the neutral sugars being glucose, mannose, and lactose at a molar ratio of 4.1:1.5:1.9. CBF is pH tolerant from 3.0 to 12.0 and thermal tolerant from 20 to 100 degrees C, allowing for its application over a wide range of conditions. Furthermore, the Langmuir model better describes CBF adsorption on kaolin clay, as compared to the Freundlich model. Charge neutralization and bridging mechanisms are the primary flocculation mechanisms. In addition, CBF shows a high methylene blue removal efficiency. These results indicate that this compound biopolymer flocculant has great potential in dye wastewater treatment
PLANT TRAITS AND BIOMASS ALLOCATION OF GENTIANA HEXAPHYLLA ON DIFFERENT SLOPE ASPECTS AT THE EASTERN MARGIN OF QINGHAI-TIBET PLATEAU
No full textThe growth, biomass partitioning and reproduction of alpine Gentiana hexaphylla species in local microclimates have important ecological significance in the study of the adaptation strategies of alpine plants. At the eastern edge of the Qinghai-Tibet Plateau in China we set up eight sample positions surrounded by mountains at an altitude of 4000 m and subsequently transplanted and measured the indices of growth, biomass allocation and reproduction of Gentiana hexaphylla to investigate the adaptation strategies in different slope aspects. Our results showed that slope aspects significantly affected the survival and reproduction strategies of Gentiana hexaphylla. Plants growing on sunny slopes tend to reproduce sexually, and those growing on shady slope are inclined to reproduce asexually. Along the circumference of the mountain, from slope S to slope SW, the growth of plant height from the early vegetation stage to the full bloom stage showed a wave shape and biomass accumulation showed a "W"-like pattern. The adaption strategy of Gentiana hexaphylla has a stronger correlation with soil organic carbon, soil total nitrogen and phosphorus than with light intensity, soil annual temperature and soil water content. Our results will help to understand the physiological adaptation of Gentiana hexaphylla in different slope aspects and explore the rule of plant functions and character responses to various habitats, so as to reveal the life cycle strategy
Effects of temperature on the performance of anaerobic co-digestion of vegetable waste and swine manure
No full textThe amount of vegetable wastes (VW) obtained from vegetable supply chain increased rapidly in recent years in China, which has posed environmental pollution problems. In view of the high moisture and organic content of VW, anaerobic digestion (AD) has shown to be an alternative with multi- environmental benefits such as waste disposal and renewable energy production. In this research, the anaerobic co-digestion of VW and swine manure (SM) in a 10 L fed-batch anaerobic digester was investigated, and the effects of temperature at psychrophilic (20 degrees C), mesophilic (32 degrees C and 37 degrees C) and thermophilic (55 degrees C) conditions on biogas production characteristics were studied with the aim of finding the better temperature for the enhanced performance of co-digestion. The results indicated that the operation performance of the anaerobic digester were maintained stability with no accumulation of volatile fatty acids (VFA) at mesophilic and thermophilic condition, as indicated by the low VFA/alkalinity ratio, which was lower than 0.10. The results of anaerobic co-digestion also showed that the value of pH, ammonia nitrogen (NH4+-N) and VFA ranked in normal range. The optimal temperature for co-digestion of VW with SM was mesophilic digestion at 32 degrees C. Under this condition, the biogas and methane production yields reached 1232.94 L/kg VS and 682.11 L CH4/kg VS, respectively. The average methane content in biogas at 32 degrees C was the highest and reached 55.33%. Anaerobic digestion at 37 degrees C and 55 degrees C provided slightly lower methane yields of 249.56 L CH4/kg VS and 381.10 L CH4/kg VS, respectively. The lowest methane yield of 59.01 L CH4/kg VS was obtained at 20 degrees C, with 22.88% of methane composition in biogas. The pilot-scale experimental results in 3 m(3) household biogas digester showed that the cumulative biogas production was 70.52 m(3) during the 42 d fermentation period. The average daily biogas production was 1.680 m(3) and the average content of CH4 was 58.2%. The experimental results showed that the co-digestion with VW and SM at 32 degrees C in a household biogas system could improve the stability of anaerobic process and achieve a higher biogas yield, which can satisfy farmers' domestic biogas demand
Degradation of chitin and antagonism in Phomopsis asparagi by Bacillus amyloliquefaciens MY001
No full text几丁质每年自然总产量高达100亿吨,目前由于工业上缺乏清洁高效的几丁质降解工艺,几丁质资源的利用受到严重制约.以壳聚糖为唯一碳源从土壤中分离筛选出一株具有产壳聚糖酶能力的菌株MY001,发酵上清酶活力约为2.7 U/mg,利用16S rDNA、gyrA及gyrB基因测序的方法将该菌株鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens).通过分析MY001菌株在不同培养基中的生长曲线特点,结合MY001菌株降解后的几丁质的扫描电镜观察结果,发现该菌株可以直接利用几丁质.另外,发现该菌株对芦笋茎枯病菌[Phomopsis asparagi (Sacc.) Bubak]具有拮抗作用.当胶体几丁质和MY001菌株同时存在时,对芦笋茎枯病菌的抑制更加明显.上述结果表明,解淀粉芽孢杆菌MY001菌株具有降解几丁质和拮抗芦笋茎枯病菌的功能,而且添加几丁质具有拮抗增效作用,因此该菌株有望用于几丁质资源清洁利用和农作物真菌病害生物防治
Outstanding universal value of plant diversity and conservation in Emeishan World Heritage Site
No full text该研究在申遗文本和大量文献资料的基础上,以峨眉山世界遗产地原生植物及植被群落为研究对象,从物种多样性、物种组成、植物区系、植被类型及垂直分布格局等方面,分析论证了峨眉山世界遗产地植物多样性的全球突出普遍价值,并简要概述了当前峨眉山世界遗产地植物受威胁状况以及在保护与发展中出现的问题。结果表明:( 1)峨眉山世界遗产地目前拥有高等植物242科3 200种以上,特有植物、孑遗植物种类丰富。( 2)与中国其他湿润性亚热带山地森林垂直带谱相比,峨眉山亚热带森林植被类型完整,常绿阔叶林东部类型在山地垂直带谱中占据显著地位,海拔上限最高,跨度最大,具有典型的亚热带常绿阔叶林东部亚区森林群落特点。( 3)植物区系复杂,既有热带、亚热带和温带植物区系成份,又有中国日本与中国喜马拉雅植物区系分布。( 4)受人为活动(旅游发展、基础设施建设等)和自然扰动(气候变暖、地质灾害等)影响,峨眉山世界遗产地植物多样性下降明显,珍稀濒危植物受威胁程度增加,典型群落面积退化,稳定性降低。建议在划定珍稀植物保护区,对植物栖息地进行专门保护的基础上,开展植物多样性、环境因子、人为活动动态监测,预见性地保护其突出普遍价值,实现世界遗产地的可持续发展