Phytoremediation of petroleum hydrocarbon-contaminated saline-alkali soil by wild ornamental Iridaceae species

As a green remediation technology, phytoremediation is becoming one of the most promising methods for treating petroleum hydrocarbons (PHCs)-contaminated soil. Pot culture experiments were conducted in this study to investigate phytoremediation potential of two representative Iridaceae species (Iris dichotoma Pall. and Iris lactea Pall.) in remediation of petroleum hydrocarbon-contaminated saline-alkali soil from the Dagang Oilfield in Tianjin, China. The results showed that I. lactea was more endurable to extremely high concentration of PHCs (about 40,000 mg/kg), with a relatively high degradation rate of 20.68%.The degradation rate of total petroleum hydrocarbons (TPHs) in soils contaminated with 10,000 and 20,000 mg/kg of PHCs was 30.79% and 19.36% by I. dichotoma, and 25.02% and 19.35% by I. lactea, respectively, which improved by 10–60% than the unplanted controls. The presence of I. dichotoma and I. lactea promoted degradation of PHCs fractions, among which saturates were more biodegradable than aromatics. Adaptive specialization was observed within the bacterial community. In conclusion, phytoremediation by I. dichotoma should be limited to soils contaminated with ≤20,000 mg/kg of PHCs, while I. lactea could be effectively applied to phytoremediation of contaminated soils by PHCs with at least 40,000 mg/kg.     

Impacts of vegetation and temperature on the treatment of domestic sewage in constructed wetlands incorporated with Ferric-Carbon micro-electrolysis material

Ferric-Carbon Micro-Electrolysis (Fe/C-M/E) material had been widely used for the pretreatment of wastewater. Therefore, we hypothesized that Fe/C-M/E material could enhance the treatment of domestic sewage when it was integrated into constructed wetlands (CWs). In this study, CWs integrated with Fe/C-M/E material were developed. Druing the experiment of effect of vegetation on the performance of CWs, percentages of NH₄⁺-N, NO₃^?-N, total nitrogen (TN), and Chemical Oxygen Demand (COD) removed in polyculture (W1) were up to 91.8%, 97.0%, 92.3%, and 85.4%, respectively, which were much higher than those in Lythrum salicaria monoculture (W2) and Canna indica monoculture (W3). In the experiment of temperature influences on the removal efficiency of CWs, temperature substantially influenced the performance of CWs. For example, NO₃^?-N removal percentages of W1, W2, and W3 at high temperature (25.5°C and 19.8°C) were relatively stable and greater than 85.4%. At 8.9°C, however, a sharp decline of NO₃^?-N removal percentage was observed in all CWs. Temperature also influenced the Chemical Oxygen Demand (COD) removal and soil microbial activity and biomass. Overall, the polyculture (Lythrum salicaria +Canna indica) showed the best performance during most of the operating time, at an average temperature ≥ 19.8°C, due to the functional complementarity between vegetation. All the CWs consistently achieved high removal efficiency (above 96%) for TP in all experiments, irrespective of vegetation types, phosphorous loadings, and temperatures. In conclusion, polyculture was an attractive solution for the treatment of domestic sewage during most of the operating time (average temperature ≥ 19.8°C). Furthermore, CWs with Fe/C-M/E material were ideally suitable for domestic sewage treatment, especially for TP removal.     

食品微生物检验技术研究进展

在食品微生物检验工作中,微生物检验分析技术以传统方法为主。传统方法存在检验操作繁琐、检验周期长、检验工作效率不高等问题。而近年来,微生物检验分析技术已经有了突飞猛进的发展。各种核酸扩增技术、高通量并行检测技术、DNA指纹分析技术、飞行时间质谱分析技术等新技术的发展层出不穷。这些技术对于推动微生物检验技术向着更加简便、快速、灵敏、高效和准确的方向发展具有非常重要的意义。     

不同来源溶藻菌的分离、鉴定及溶藻效果比较

为了探究从何种类型的自然生境中更易分离得到溶藻微生物,采用高氏1号培养基分别从水库底泥、湖泊底泥、农田土壤、林地土壤等四种来源共36份样品中分离了7 600株菌,并最终从中筛选得到了5株溶铜绿微囊藻(Microcystis aeruginosa)的溶藻菌,其中4株为假单胞菌(Pseudomonas sp.),1株为黄杆菌(Flavobacterium sp.),5株菌溶藻效率的变化范围为62%~95%。结果表明,当采用高氏1号培养基作为分离培养基时,湖泊底泥和水库底泥中的成功筛选概率最高,农田土壤次之,而林地土壤中则难以筛选得到,假单胞菌是较容易筛选得到的溶藻菌。     

黑土和棕壤中甲胺磷的根际降解脱毒模拟研究

利用塑料根际盒研究了甲胺磷在黑土和棕壤大豆根际和非根际环境中的降解脱毒行为.结果表明,甲胺磷虽是急性毒性较高的农药,但在土壤环境中能很快降解,并且同等条件下,甲胺磷在黑土中的残留量普遍低于棕壤.在无大豆种植情况下(对照处理),培养试验第2天,棕壤甲胺磷残留量约为33%,黑土只有26%.在大豆根际圈中,甲胺磷的降解明显加快,尤其是在黑土中.第9天,根际盒中层黑土和棕壤的农药残留分别比无植物对照低87.5%和76.0%.甲胺磷的土壤降解过程符合一级动力学方程,降解半衰期为2 d左右.     

用于分子生态学研究的土壤微生物DNA提取方法

利用SDS高盐法和变性剂加SDS高盐法对土壤微生物总DNA进行了提取,然后通过电泳加树脂柱回收和连续2次树脂柱回收方法进行了纯化.结果表明,变性剂加SDS高盐法的DNA提取效率明显高于前者,电泳加树脂柱法的纯化效果更好.通过PCR扩增表明,经过纯化后的DNA,都可以进行16SrDNA扩增和nirK、nosZ、nifH等功能基因的扩增.因此,变性剂加SDS高盐法是一种更为高效、可靠且适合于环境微生物分子生态学研究的DNA提取方法.     

Transformation of Ginsenosides Rb1 and Re from <Emphasis Type="Italic">Panax ginseng</Emphasis> by Food Microorganisms

Ginsenosides Rb1 and Re, respectively belonging to the major protopanaxadiol and protopanaxatriol ginsenosides, were transformed using cell-free extracts from food microorganisms. Rb1 was transformed into compound K via Rd and F2 by Bifidobacterium sp. Int57, Bif. sp. SJ32, Aspergillus niger and A.␣usamii. Lactobacillus delbrueckii, and Leuconostoc paramesenteroides transformed Rb1 into Rh2 via Rd and F2. Bifidobacterium sp. SH5 transformed Rb1 into F2 via Rd. Re was transformed into Rh1 via Rg2 by Bif. sp. Int57 and Bif. sp. SJ32. A. niger transformed Re into Rh1 via Rg1. A. usamii transformed Re into Rg2. Transformation of Rb1 proceeded at a higher rate and needed less amount of enzymes than that of Re. Taken together, these processes would allow a specific bioconversion process possible to obtain specific ginsenosides using an appropriate combination of ginsenoside substrates and specific microbial enzymes.     

Microbiological degradation of pentane by immobilized cells of <Emphasis Type="Italic">Arthrobacter sp.</Emphasis>

The increasing production of several plastics such as expanded polystyrene, widely used as packaging and building materials, has caused the release of considerable amounts of pentane employed as an expanding agent. Today many microorganisms are used to degrade hydrocarbons in order to minimize contamination caused by several industrial activities. The aim of our work was to identify a suitable microorganism to degrade pentane. We focused our attention on a strain of Arthrobacter sp. which in a shake-flask culture produced 95% degradation of a 10% mixture of pentane in a minimal medium after 42days of incubation at 20°C. Arthrobacter sp. cells were immobilized on a macroporous polystyrene particle matrix that provides a promising novel support for cell immobilization. The method involved culturing cells with the expanded polystyrene in shake-flasks, followed by in situ growth within the column. Scanning electron microscopy analysis showed extensive growth of Arthrobacter sp. on the polymeric surface. The immobilized microorganism was able to actively degrade a 10% mixture of pentane, allowing us to obtain a bioconversion yield of 90% after 36h. Moreover, in repeated-batch operations, immobilized Arthrobacter sp. cells were able to maintain 85–95% pentane degradation during a 2month period. Our results suggest that this type of bioreactor could be used in pentane environmental decontamination.     

基因工程微生物生态学研究进展

基因工程微生物(genctically enginccred microorganism,GEM)生态学的研究已成为微生物分子生态学的一项主要研究内容之一．随着分子标记和分子生物学检测手段的引入,传统的微生物生态学研究被注入了新的活力,在分子水平上探讨基因工程微生物与环境及环境中土著生物之间的关系已成为可能．基因工程微生物生态学是一门内容涉及分子生物学、微生物学、生态学等诸多学科的新型交叉边缘学科．本文提出加紧进行转基因生物生态学和转基因生物的风险评价的研究工作,建立适合中国国情的检测手段和评价标准,有助于我国基因工程微生物生态学的健康发展．     

Application of targeted metagenomics to explore abundance and diversity of CO2-fixing bacterial community using cbbL gene from the rhizosphere of Arachis hypogaea

Sequestration of CO₂ by autotrophic bacteria is a key process of biogeochemical carbon cycling in soil ecosystem. Rhizosphere is a rich niche of microbial activity and diversity, influenced by change in atmospheric CO₂. Structural changes in rhizosphere composition influence microbial communities and the nutrient cycling. In the present study, the bacterial diversity and population dynamics were established using cbbL and 16S rRNA gene targeted metagenomics approach from the rhizosphere of Arachis hypogaea. A total of 108 cbbL clones were obtained from the rhizospheric soil which revealed predominance of cbbL sequences affiliated to Rhizobium leguminosarum, Bradyrhizobium sp., Sinorhizobium meliloti, Ochrobactrum anthropi and a variety of uncultured cbbL harboring bacteria. The 16S rRNA gene clone library exhibited the dominance of Firmicutes (34.4%), Proteobacteria (18.3%), Actinobacteria (17.2%) and Bacteroidetes (16.1%). About 43% nucleotide sequences of 16S rRNA gene clone library were novel genera which showed < 95% homology with published sequences. Gene copy number of cbbL and 16S rRNA genes, determined by quantitative real‐time PCR (qRT PCR), was 9.38 ± 0.75 × 10⁷ and 5.43 ± 0.79 × 10⁸ (per g dry soil), respectively. The results exhibited bacterial community structure with high bacterial diversity and abundance of CO₂‐fixing bacteria, which can be explored further for their role in carbon cycling, sustainable agriculture and environment management.