一株可同时降解多种高环PAHs的丝状真菌——宛氏拟青霉(Paecilomyces variotii)

采用液体培养的方法,分离纯化了丝状真菌宛氏拟青霉(Paecilomyces variotii)并研究了其对苯并[a]蒽、苯并[a]芘、苯并[b]荧蒽、苯并[k]荧蒽、茚并[1,2,3-cd]芘的降解效果.结果表明:接种处理30 d,该菌株对混合体系中5种PAHs的降解率为16.1%～24.6%,而对单一体系中的降解率为10.4%～33.3%;同时,对单一与混合体系中PAHs的降解作用存在一定差异,苯并[k]荧蒽和苯并[b]荧蒽在单一体系中降解率增大,而其他种类的则减小.本研究结果为高环多环芳烃共代谢机理研究和多环芳烃复合污染水土环境的生物修复提供了一种新的种质资源.     

西沙永兴岛土壤中多环芳烃的分布特征及来源

通过采集西沙永兴岛表层土壤和土柱样品, 研究了21种多环芳烃(PAHs)在永兴岛土壤中的浓度和组成特征, 对土壤中PAHs的来源进行解析,并对生态风险进行了评估。结果表明, 永兴岛表层土壤中PAHs的浓度范围为38.9—176.4 ng·g-1, 16种优控PAHs的浓度为36.7—155.6 ng·g-1, 跟其它类似环境相比, 永兴岛土壤中PAHs污染相对较轻。芘、荧蒽、菲、苯并[b]荧蒽、、苯并[a]芘、茚并[1, 2, 3-cd]芘和苯并[e]芘是永兴岛表层土壤中最主要的PAHs。永兴岛土柱中总PAHs与2—3环PAHs浓度分布特征相似, 表层和底层浓度较高, 2—3环PAHs在土柱中占比为74%—96%。来源解析表明永兴岛土壤中PAHs主要以石油、木材或煤等燃烧源为主。16种PAHs的等效致癌风险浓度显示永兴岛土壤中PAHs生态风险较低。     

土壤中多环芳烃的微生物降解及土壤细菌种群多样性

利用室内模拟方法,研究中、低浓度多环芳烃(PAHs)污染土壤的微生物修复效果,阐明土壤微生物（接种和土著）与PAHs降解的关系.结果表明:投加PAHs高效降解菌可以促进土壤中PAHs的降解,2周内效果显著;典型PAHs降解的难易程度依据为：菲<蒽<芘<苯并(a)芘和屈;细菌种群丰度和多样性均与PAHs降解呈负相关关系,同一处理细菌种群结构随时间变化不大.对于中、低浓度PAHs原位污染土壤,增强土著菌的活性是提高土壤PAHs降解率的有效途径之一.     

长江口南支表层沉积物中多环芳烃分布特征及生态风险

2008年5月和8月先后2次采集长江口南支表层沉积物样品,采用高效液相色谱进行多环芳烃测定,研究其分布、来源与生态风险。结果表明:长江口南支表层沉积物中PAHs总量在8.9~312.2ng.g-1;PAHs组成以芘、菲、苯并[b]荧蒽、苯并[a]蒽、苯并[a]芘为主,各站芘的含量均最高,本研究PAHs总含量与长江口、黄河口和鸭绿江口近期的调查数据相近,但明显低于珠江口和闽江口数据,以及长江口潮滩沉积物中PAHs数据;PAHs环数组成以中、高环为主,表明长江口南支PAHs主要来源于相对高温条件下不完全燃烧过程。采用平均效应中值商法评价长江口南支PAHs生态风险结果表明,调查区域PAHs产生生态风险的概率较小(<10%)。     

一株高分子量多环芳烃降解菌的筛选、鉴定及降解特性研究

采用富集培养方法从多环芳烃污染土壤中筛选分离得到1株能以苯并[a]芘(B[a]P)为唯一碳源和能源生长的菌株.形态特征观察和16S rDNA序列分析结果表明,该菌株为副球菌属(Paracoccus sp.),编号为HPD-2.HPD-2在3.0 mg/L的B[a]P液体培养基中生长较慢,培养5 d后B[a]P的降解率为89.7%.同时,该菌株对四环的芘和荧蒽也具有较好的降解能力,培养7 d后芘和荧蒽的降解率分别达到47.2%和84.5%.可见,该菌株对高分子量PAHs具有很好的降解潜力.     

固定化微生物对多环芳烃污染土壤的降解

利用微生物固定化技术,研究了微生物固定化菌剂对土壤中菲、蒽、芘、(艹屈)和苯并(a)芘的降解动态,并且采用Michaelis-Menton和Monod动力学模型对结果进行拟合.结果显示,4种处理(TB02、TB07、TBB03、TBB08)均有降解菲、蒽、芘、(艹屈)和苯并(a)芘的能力.其中,处理TB02的降解能力强、降解速率快、半衰期短且处理成本低,而处理TB07则需要较长时间作用于PAHs污染土壤,其降解能力才能充分发挥出来.当菲、蒽、芘、(艹屈)和苯并(a)芘的初始浓度均为20 mg·kg-1时,42 d后,TB02对菲、蒽、芘、(艹屈)和苯并(a)芘的降解率分别为84.32%、85.24%、82.59%、43.75%和62.25%; 133 d后,TB07对5种污染物的降解率分别为95.00%、95.24%、90.93%、74.82%和72.20%.通过比较5种污染物半衰期,其可降解性由大到小依次为菲、蒽、芘、苯并(a)芘、(艹屈).     

多环芳烃降解菌的筛选与降解能力测定

从本溪多环芳烃(PAHs)污染土壤中经富集培养筛选出8株PAHs降解菌,研究了8株菌及其等比例混合培养对菲、芘和苯并[a]芘的降解能力。结果表明,在28℃,培养基中菲、芘和苯并[a]芘的浓度分别为50、50和5mg·L-1的复合底物条件下,培养28d后,菌株B3的降解效果最好,对菲、芘和苯并[a]芘的降解率分别为88.4%、54.0%和68.4%,8株菌的混合培养对菲、芘和苯并[a]芘的降解率分别为87.7%、35.3%和42.0%;经生理生化实验和16SrRNA序列比对,初步鉴定B3菌为假单胞菌属(Pseudomonas sp.)。     

植物法生物修复PAHs和矿物油污染土壤的调控研究

选择苜蓿草为供试植物,以污染物含量水平、专性细菌和真菌及有机肥为调控因子,进行了植物法生物修复多环芳烃(PAHs)和矿物油污染土壤的调控研究。结果表明,PAHs和矿物油的降解率与有机肥含量呈正相关,增加有机肥5%,可提高矿物油降解率17.6%～25.6%,PAHs降解率9%.在植物存在条件下,土壤微生物降解功能增强。多环芳烃总量的平均降解率比无植物对照土壤提高2.0%～4.7%.投加特性降解真菌可不同程度地提高土壤PAHs总量和矿物油的降解率。真菌对萤蒽、芘和苯(a)蒽/(艹屈)的降解有明显促进作用。而细菌能明显提高苊稀/芴、蒽和苯(a)萤蒽/苯(k)萤蒽的降解率。     

乳白耙齿菌F17对单一和复合多环芳烃的降解差异解析

[目的] 针对菲、蒽、荧蒽多环芳烃（PAHs）污染物,利用乳白耙齿菌F17,研究单一和复合PAHs污染物的生物降解规律。[方法] 采用气相色谱-质谱法（GC-MS）分析降解过程中PAHs的浓度,并采用准一级反应动力学模型对降解结果进行拟合。[结果] 对于单一PAHs,第15天时菲、蒽、荧蒽的降解率由高到低依次为菲（97.8%） > 蒽（89.3%） > 荧蒽（81.5%）。菲、蒽和荧蒽的降解过程具有准一级反应动力学特征,菲的生物降解速率最快,其次是蒽,荧蒽的降解速率最慢。与单一PAHs的降解相比,在复合PAHs的降解过程中,乳白耙齿菌F17的生长和锰过氧化物酶的合成均表现出不同的特征。此外,水溶性极可能是复合污染物降解的重要控制因子,三者水溶性为：菲 > 荧蒽 > 蒽。因此,在菲或荧蒽加入条件下,微生物能优先降解这些污染物,抑制了污染物蒽的降解;同时,蒽或菲的存在对荧蒽的降解也有抑制作用;然而外源加入水溶性较差的蒽和荧蒽,则对菲的生物降解无显著影响。[结论] 复合PAHs的生物降解主要表现为相互竞争的特点,通过GC-MS分析了PAHs的生物降解途径。     

新疆石油污染土壤苯并(a)芘降解微生物多样性研究

为研究新疆石油开采区污染土壤中苯并(a)芘降解微生物的群落结构特点,采集克拉玛依石油开采区受污染程度不同的土壤样品, 以苯并(a)芘为唯一碳源、氮源的无机盐培养基五代富集培养, 采用PCR-DGGE 技术对第五代富集培养物的微生物群落结构开展研究, 根据DGGE 指纹图谱分析它们的遗传多样性。研究显示: 三个不同污染样品微生物多样性指数(H) 丰度(S)和均匀度(EH)均有所不同, 重度污染土样降解苯并(a)芘的微生物类群最为丰富, 其次是中度污染土样, 最少的是轻度污染土样; 并且三个样品微生物类群种类差异较大, 菌落相似性低。对 DGGE 的优势条带序列分析, 同源性最高的微生物分别属于变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)和厚壁菌门(Firmicutes)。研究表明新疆石油开采区污染程度不同土壤中降解苯并(a)芘的微生物群落结构不同, 提示污染严重的环境里可能蕴藏着高效降解苯并(a)芘的微生物资源。     

超滤法浓缩谷氨酰胺转胺酶的影响因素研究

对微生物谷氨酰胺转胺酶(MTG)超滤浓缩的工艺条件进行了探讨及优化。实验采用截留分子量为30 kDa的聚醚砜(PES)膜,当发酵液初始pH为7,超滤浓缩倍数为4倍时,可以得到理想的MTG回收率。同时对超滤液中蛋白酶的变化进行了分析,发现随着超滤倍数的提高蛋白酶也逐渐提高,但在浓缩4倍以后达到较稳定的水平。聚醚砜(PES)超滤膜使用后用稀释的NaOH溶液浸泡清洗处理50 min后,膜通量可以恢复98.12%。     

pH Shaping the Composition of sqhC-Containing Bacterial Communities

Sediment and tailings samples were collected from sites with a contrasting physicochemical gradient to investigate microbial squalene-hopene cyclase (sqhC) composition and distribution in terrestrial environments. Acidobacteria (66%), Alphaproteobacteria (96%) and Gammaproteobacteria (55%) were found to dominate sqhC communities, respectively, at the acidic Dajiuhu Peatland, the alkaline Heshang Cave and strongly acidic tailings of Tongling copper mine in China. Statistical analysis confirmed that pH was the important factor impacting the geographical distribution of sqhC at phylum level. sqhC gene abundance is comparable at the three sites. However, the total amount of hopanoids in per gram total organic matter content (TOC) is 1.75 times higher in the acidic peatland than that in the alkaline Cave and it is below the detecting limit in tailings of Tongling copper mine, inferring the potential impact of pH in regulating the hopanoid production.     

微生物肥料作用机理的研究新进展

综述了近几年国内外有关微生物肥料研究与应用的文献,系统阐述了微生物肥料的作用及其研究进展.涉及微生物肥料的作用主要有产生和协助植物对营养元素的吸收、产生多种生理活性物质刺激调节植物生长、产生抑病作用间接促进植物生长、提高植物抗逆能力、改善农作物产品的品质等以综合作用来降低化肥用量的效应等.指出微生物肥料的功效和发展趋势,为进一步开发和应用微生物肥料提供依据.     

Contaminations of laboratory surfaces with Staphylococcus aureus are affected by the carrier status of laboratory staff

Aim: As a biosafety laboratory, we take samples from surfaces in microbiological laboratories to survey the handling of micro‐organisms. Whereas contaminations with other micro‐organisms were rare, Staphylococcus aureus was found in the working environment of many laboratories. As 20–60% of the healthy population are carriers of S. aureus we wanted to asses the effect of carriers on our sampling results. Methods and Results: Nasal swabs of staff members in nonmicrobiological laboratories and offices as well as surface samples from their personal work environment were taken and analysed for S. aureus DNA. In addition S. aureus strains were isolated using S. aureus‐specific agar plates and analysed by randomly amplified polymorphic DNA (RAPD)–PCR and multilocus sequence typing (MLST). Our data show that contaminations with S. aureus in nonmicrobiological environments are common with 29% of the surface samples containing S. aureus DNA. In the working environment of carriers, the number of contaminations was significantly increased compared to the environment of noncarriers. Conclusion: The carrier status of staff members significantly affects the number of contaminations on laboratory surfaces. Therefore, even in the absence of intentional handling of S. aureus, contaminations can be detected on a substantial amount of surfaces. Significance and Impact of the Study: Sampling procedures need to be adapted based on these results with respect to the locations where samples are taken and the threshold for significant contaminations. Because of its wide distribution, S. aureus can serve as a marker for hygienic standards in laboratories.     

The impact of pH control on the volumetric productivity of mixed culture PHA production from fermented molasses

Polyhydroxyalkanoate (PHA) production via mixed microbial cultures (MMCs) can potentially decrease process operational costs as compared to conventional pure culture techniques. However, the volumetric productivity of PHA by MMCs must be augmented to increase its cost competitiveness. For this purpose, a three‐stage bioreactor system was operated in this study, with (i) anaerobic fermentation of molasses, (ii) culture selection, and (iii) PHA accumulation and harvesting stages. In stage 2, bioreactor operation with pH control at 8 led to twice the biomass concentration (up to 8 g VSS L^?1, where VSS is the volatile suspended solids) as compared to operation without pH control (maximum pH 9). No loss in the specific PHA storage efficiency was observed (PHA content up to 57.5% and PHA storage rate up to 0.27 Cmol PHA Cmol X^?1 h^?1, where X is the active biomass), thereby resulting in twice the volumetric PHA production rate. The limited biomass growth at the higher pH level was not due to nutrient limitation, but likely to a shift in the microbial community. It is hypothesized that the increased enrichment of Azoarcus at pH 8 led to higher PHA productivity. pH control in the culture selection stage can lead to enhanced PHA production from MMCs, improving the viability of the process.     

微生物燃料电池在固体废物堆肥中的应用进展

微生物燃料电池(Microbial fuel cell,MFC)是一种近几年快速发展的废物处理与能源化技术,可以与污水处理、污染物降解、脱盐等环境技术结合。微生物燃料电池与堆肥技术结合可以在处理日益增长的固体废弃物的同时回收能量,具有很好的发展前景。文中分析了堆肥微生物燃料电池系统的微生物特征,探讨了堆肥过程中影响微生物燃料电池产电性能的因素,包括电极,隔膜,供氧和构型。最后归纳说明了堆肥微生物电池作为一种新的废弃物处理技术的特点:较高的微生物量并可产生较高的电流密度;对不同环境的适应性强;可以自身调节温度,能源利用效率高;质子从阳极向阴极的移动会受到不同堆肥原料的影响。     

EPS and SMP dynamics at different heights of a submerged anaerobic membrane bioreactor (SAMBR)

Membrane bioreactors (MBR) technology for wastewater offers many advantages over conventional technologies such as high effluent quality, less footprint and others. The main disadvantage of membrane bioreactors (MBR) is related to membrane fouling, which is mainly caused by extracellular polymeric substance (EPS) and soluble microbial products (SMP). This research studied EPS and SMP dynamics at different heights of a submerged anaerobic membrane bioreactor (SAMBR). The SAMBR was operated under two organic loading rates (OLR) (0.79 and 1.56 kg/m³ d) and was fed with synthetic wastewater with glucose as the carbon source. The results showed percentages of chemical oxygen demand (COD) removal above 95% and the highest COD removal rates were observed at the bottom of the reactor (>83%) for both OLR. The EPS showed a stratification with highest quantities in the supernatant. For the SMP the highest concentration was in the bottom of SAMBR where utilization predominated associated products whereas in the SAMBR supernatant predominated biomass associated products. The OLR change led to a significant increase in SMP accumulation but not in EPS. These facts showed that EPS and SMP dynamic in the SAMBR seemed to be mainly influenced by biological activity, total suspended solids concentration and substrate composition.