典型岩溶土壤微生物丰度与多样性及其对碳循环的指示意义

探讨土壤微生物指标的变化规律,用于揭示其在岩溶土壤碳循环中的指示意义.以桂林岩溶试验场洼地、坡地和垭口这3种岩溶地貌形态下的剖面(0~10、10~20、20~30cm)土壤为研究对象,采用聚合酶链式反应-变性梯度凝胶电泳(PCRDGGE)和荧光定量PCR相结合的方法,分析这个典型岩溶土壤剖面中的微生物多样性和丰度变化.数据显示,16S rRNA最高丰度出现在洼地,为1.32×1011拷贝·g-1,而18S rRNA最高丰度出现在垭口,为1.12×1010拷贝·g-1;洼地和垭口剖面的16S rRNA丰度随着深度的增加而降低,3种岩溶地貌形态的18S rRNA丰度均随着剖面深度的增加而降低,与土壤有机碳质量分数的变化趋势一致.但是,在3种岩溶地貌形态中,3个16S rRNA和6个18S rRNA的多样性指数均随土壤剖面深度的增加而增大.由于16S rRNA和18S rRNA的多样性与丰度和土壤有机碳之间总体上表现出相反的变化趋势,说明微生物丰度指标在土壤碳循环中的指示意义比微生物多样性指数更重要.     

蚯蚓细胞色素P450酶系对土壤中芘或苯并[a]芘的响应

以赤子爱胜蚓(Eisenia fetida)为受试生物,通过人工污染草甸棕壤微宇宙试验方法,研究了暴露于不同环境浓度芘或苯并[a]芘(添加量分别为0.12、0.24、0.48、0.96 mg·kg~(-1))污染的土壤中14 d后,蚯蚓体内细胞色素P450(CYPs)酶系,如CYPs总量、CYP1A1及CYP2C9活性的变化.结果显示,芘或苯并[a]芘暴露导致蚯蚓CYPs总量、CYP1A1及CYP2C9活性的变化不同.其中,CYPs总量与CYP1A1活性对芘的响应趋势相似:试验3 d后,0.96 mg·kg~(-1)芘导致二者都显著高于对照水平;14 d后,都显著低于对照水平;CYP1A1活性对芘的响应更为敏感.CYPs总量与CYP2C9活性对苯并[a]芘的响应趋势相似:暴露初期,苯并[a]芘最高暴露剂量(0.96 mg·kg~(-1))导致二者都显著低于对照水平;试验结束后,苯并[a]芘最低暴露剂量(0.12 mg·kg~(-1))导致二者都显著高于对照水平,最高剂量暴露导致二者都显著低于对照水平,CYP2C9活性对苯并[a]芘的响应更为敏感.因此,推断CYPs亚酶对污染物的响应具有选择性且亚酶的响应敏感度高于CYPs总量.将CYPs总量与CYP1A1活性结合,或与CYP2C9活性结合分别诊断土壤芘污染或并[a]芘污染,较为准确有效.     

Diversity of bacterial isolates during full scale rotary drum composting

Bacterial diversity of full scale rotary drum composter from biodegradable organic waste samples were analyzed through two different approaches, i.e., Culture dependent and independent techniques. Culture-dependent enumerations for indigenous population of bacterial isolates mainly total heterotrophic bacteria (Bacillus species, Pseudomonas species and Enterobacter species), Fecal Coliforms, Fecal Streptococci, Escherichia coli, Salmonella species and Shigella species showed reduction during the composting period. On the other hand, Culture-independent method using PCR amplification of specific 16S rRNA sequences identified the presence of Acinetobacter species, Actinobacteria species, Bacillus species, Clostridium species, Hydrogenophaga species, Butyrivibrio species, Pedobacter species, Empedobactor species and Flavobacterium species by sequences clustering in the phylogenetic tree. Furthermore, correlating physico-chemical analysis of samples with bacterial diversity revealed the bacterial communities have undergone changes, possibly linked to the variations in temperature and availability of new metabolic substrates while decomposing organics at different stages of composting.     

Radionuclides in cigarettes may lead to carcinogenesis via p16 inactivation

It is widely accepted that tobacco smoke is responsible for the vast majority of lung cancers worldwide. There are many known and suspected carcinogens present in cigarette smoke, including α-emitting radioisotopes. Epidemiologic studies have shown that increased lung cancer risk is associated with exposure to ionizing radiation, and it is estimated that the majority of smoking-induced lung cancers may be at least partly attributable to the inhaled and deposited radiation dose from radioisotopes in the cigarette smoke itself. Recent research shows that silencing of the tumor suppressor gene p16^INK4a (p16) by promoter methylation plays a role in smoking-related lung cancer. Inactivation of p16 has also been associated with lung cancer incidence in radiation-exposed workers, suggesting that radionuclides in cigarette smoke may be acting with other compounds to cause smoking-induced lung cancer. We evaluated the mechanism of ionizing radiation as an accepted cause of lung cancer in terms of its dose from tobacco smoke and silencing of p16. Because both radiation and cigarette smoking are associated with inactivation of p16, and p16 inactivation has been shown to play a major role in carcinogenesis, ionizing radiation from cigarette smoke likely plays a role in lung cancer risk. How large a role it plays, relative to chemical carcinogens and other modes of action, remains to be elucidated.     

活性污泥体系中聚糖菌的富集与鉴定

活性污泥体系中，聚糖菌(GAOs)在厌氧环境下与聚磷菌(PAOs)形成对底物的竞争关系，对聚糖菌的研究对于优化生物除磷工艺有重要意义。以葡萄糖为惟一碳源，在磷限制条件下，利用特殊运行方式对活性污泥进行驯化培养出了稳定的聚糖菌颗粒污泥，厌氧阶段磷释放量与有机物吸收量浓度(mg/L)比从7.4%下降为0.25%。从培养好的活性污泥反应器中分离获得2株聚糖菌，经菌落PCR和16S rRNA序列分析确定了所得聚糖菌菌株G1和菌株G2分别是枯草芽孢杆菌(Bacillus subtilis)和解鸟氨酸克雷伯氏菌(Klebsiella ornithinolytica)。     

Effects of temperature and fertilization on total vs. active bacterial communities exposed to crude and diesel oil pollution in NW Mediterranean Sea

The dynamics of total and active microbial communities were studied in seawater microcosms amended with crude or diesel oil at different temperatures (25, 10 and 4 °C) in the presence/absence of organic fertilization (Inipol EAP 22). Total and hydrocarbon-degrading microbes were enumerated by fluorescence microscopy and Most Probable Number (MPN) method, respectively. Total (16S rDNA-based) vs. active (16S rRNA) bacterial community structure was monitored by Capillary-Electrophoresis Single Strand Conformation Polymorphism (CE-SSCP) fingerprinting. Hydrocarbons were analyzed after 12 weeks of incubation by gas chromatography-mass spectrometry. Total and hydrocarbon-degrading microbial counts were highly influenced by fertilization while no important differences were observed between temperatures. Higher biodegradation levels were observed in fertilized microcosms. Temperature and fertilization induced changes in structure of total bacterial communities. However, fertilization showed a more important effect on active bacterial structure. The calculation of Simpson's diversity index showed similar trends among temperatures whereas fertilization reduced diversity index of both total and active bacterial communities.     

降解SO2功能菌的16S rRAN基因测序及降解特性

用低浓度SO2诱导驯化方法获得高效脱硫菌群,并用分离培养与16S rRNA基因测序技术相结合的方法鉴定菌群种属,分析驯化过程中种群结构的动态变化,同时研究分离纯菌种的脱硫性能。结果表明,从诱导驯化7 d和14 d菌液中分别分离出23株菌和22株菌,16S rRNA序列分析发现这些菌归属于13个种,其中有6个种(Rhodococcus erythropolis、Pseudomonas putida、Microbacterium oxydans、Sphingomonas koreensis、Acinetobacter junii、Acinetobacter johnsonii)对SO2-3有较强的降解能力,并在持续驯化过程中稳定的生长传代,降解产物以硫酸根为主,还有极少量的单质硫。与含混合菌的驯化菌液降解SO2-3的能力相比,单一脱硫菌的脱硫性能较弱。脱硫功能菌株及其基本特性的研究为微生物处理SO2烟气提供了丰富的菌源信息和理论基础。     

实时荧光定量PCR法快速测定水中微囊藻

以铜绿微囊藻（Microcystis aeruginosa）16S rRNA基因片段为靶序列设计一对特异性引物，采用Real-time PCR法，对铜绿微囊藻进行定性、定量检测。试验表明，仅含铜绿微囊藻DNA模板的样品有特异性扩增，扩增产物熔解曲线平稳，峰尖且窄，熔解温度为（87±1）℃。以重组质粒pMD-18T-16S为标准品，检测区间为1．1×102 copies/mL～1．1×108 copies/mL，所得标准曲线符合制备实时定量PCR标准曲线的要求，对标准品进行测定，方法检出限为11 copies/mL。用该标准曲线对实验室培养获得的铜绿微囊藻DNA样品进行定量检测，与显微镜计数结果基本一致。     

一种活性污泥总DNA提取方法的优化

对3种活性污泥DNA提取方法———传统蛋白酶K-SDS-氯仿异戊醇法(CPSCI法)、液氮研磨法和脱腐处理法进行了对比,并针对CPSCI法从污泥量、保温时间、裂解方式及沉淀时间等4个方面进行了优化。结果表明,优化的蛋白酶K-氯仿-异戊醇法(OPSCI法)采用污泥量0.10 g、37℃静置10 min,加SDS常温旋涡振荡及异丙醇直接离心等条件可获得长度在23.1 kb左右的DNA,OD260nm/OD280nm为1.86,稀释10倍后即可进行16S rDNA PCR。该方法重复性好,提取得率高,纯度好,操作简便,为常规实验室开展活性污泥微生物多样性研究提供了帮助。