Bioremediation of toxic metals mercury and cesium using three types of biosorbent: bacterial exopolymer,gall nut,and oak fruit particles

Cesium and mercury are two mono-valent elements which can be found in toxic industrial, medical, and nuclear wastes. Their presence in the environment has deleterious effects on the ecosystem, living organisms including humans. Due to the chemical nature of these metals, bioremediation by conventional methods is more difficult to achieve compared to other metals. In this study, we used three biosorbents (oak powder, gall nut, and bacterial exopolymer) for the bioremediation of Hg and Cs. Bio-polymer was produced in the GMS mineral broth. Synthetic wastes of Hg(NO₃)₂ and isotope Cs-133 as the single-metal solutions were used. The biorefining process was carried out in glass columns, made of Pyrex, with dimensions 20?×?7/2?cm² with a V-shaped bottom. The samples were analyzed using atomic absorption. The experimental results showed that eliminated metal percent by oak powder, gall nut, and bacterial exopolymer were, respectively, of 94.8%, 96%, and 13.8% for Hg and 7.8%, 4.4%, and 69.4% for Cs. The tests revealed that Ca⁺⁺, when used as flocculant, played a key role in both biosorption and bio-precipitation rates. Consequently, it was concluded that the investigated biosorbents could be use as an integrated biosorption system for the refinement of mixed wastes.     

A comparative study of microbial communities in soils amended by manures from pigs fed with organic versus synthetic feeds

We applied pyrosequencing to determine bacterial communities in soil samples taken from test fields amended by manures of pigs fed with green feeds (GPMS), synthetic feeds (APMS), and the reference field without swine manure amendment (NPMS), respectively. For each sample, 7050 effective sequences were selected and utilized to do the bacterial diversity and abundance analysis, respectively. In total, 2986, 2873, and 1602 operational taxonomic units were obtained at a 3% distance cut-off in GPMS, APMS, and NPMS, respectively. Bacterial phylotype richness in GPMS was higher than the other samples. NPMS had the least richness. The most dominant class in both GPMS and APMS is Betaproteobacteria, whereas Alphaproteobacteria is dominant in NPMS. Circa 7.5% sequences in GPMS were found to be affiliated with Burkholderiales order. Bacterial diversity and abundance in the soil varied with swine manure amendment, due to nutrient elements as well as toxic metals in swine manures. Compared with the soil amendment by manures from pigs bred with synthetic feeds, more bacterial diversity but less potentially pathogenic bacterial genera in the soil amended by manures of pigs fed with green feeds were found, which indicated that these manures were better land-applied organic fertilizers.     

细菌气溶胶在大气冰核核化过程中作用的研究进展

介绍了大气中细菌气溶胶的种类和浓度分布的变化特征,对冰核细菌促进冰核核化的分子生物学机制,影响成冰活性的因素以及冰核在大气冰核核化过程中作用的研究进展等做了重点介绍,对冰核细菌的生物学、分子生物学和形态学及其实际应用等方面的研究进展也做了讨论,同时也指出了今后需要进一步研究的问题,尤其是生物冰核在云和降水中作用方面的问题.     

Effects of cucl2 on UV‐mutagenesis and on DNA damage in a restriction fragment of E. Coli gpt∗

CuCl₂ does not cause Trp⁺ reversion in E. coli WP2. However, when the bacteria are exposed to CuCl₂ and UV‐irradiated, a greater than 3‐fold enhancement of mutagenesis (compared to UV alone) is seen at 30 μMCuCl₂, and significant enhancement is seen even at 3 μM. The mechanism for this comutagenic effect was studied using a restriction fragment of the E. coli gpt gene. Whereas UV or CuCl₂ alone caused few strand breaks, UV + CuCl₂ induced breaks at every site. This reaction was blocked by KI, a free radical scavenger. While UV alone induced alkali‐labile sites, UV+ CuCl₂ induced many more such sites and altered the sequence specificity. We suggest that at least some of the comutagenic effect might be due to hydroxyl radical formed via a Fenton reaction.     

外源和内源呼吸模式下好氧活性污泥的微生物群落演替及生物活性特征

通过模拟好氧活性污泥实验,采用PCR-DGGE技术并监测不同时期的CODCr、脱氢酶和总蛋白质的质量浓度,研究在外源和内源呼吸模式下,微生物群落结构及相关生物活性的变化。结果表明：未添加碳源处理中 CODCr的质量浓度稳定在100 mg·L-1左右;脱氢酶的质量浓度从1μg·mL-1降低到接近0μg·mL-1;总蛋白的质量浓度从0.05 mg·mL-1上升至0.07 mg·mL-1后下降至0.01 mg·mL-1左右;同时,微生物群落结构变化不大。外加葡萄糖处理中CODCr的质量浓度从1000 mg·L-1下降并稳定在100 mg·L-1左右;脱氢酶的质量浓度从2μg·mL-1上升到5μg·mL-1;总蛋白的质量浓度均从0.05 mg·mL-1上升至0.07 mg·mL-1后下降至0.005 mg·mL-1左右;同时,微生物群落多样性呈现收敛趋势。内源和外源呼吸模式下的活性污泥中,变形菌门（ Proteobacteria ）都是绝对优势种群,其次是拟杆菌门（ Bacteroidetes ）。内源呼吸末期δ-变形菌门（Deltaproteobacteria）消失,外源呼吸末期硝化螺菌门（Nitrospirae）消失。     

Response of bacterial communities to short-term pyrene exposure in red soil

Pyrene, a representative polycyclic aromatic hydrocarbon (PAH) compound produced mainly from incomplete combustion of fossil fuels, is hazardous to ecosystem health. However, long-term exposure studies did not detect any significant effects of pyrene on soil microorganism. In this study, short-term microcosm experiments were conducted to identify the immediate effect of pyrene on soil bacterial communities. A freshly-collected pristine red soil was spiked with pyrene at 0, 10, 100, 200, and 500 mg·kg^-1 and incubated for one day and seven days. The bacterial communities in the incubated soils were analyzed using 16S rRNA sequencing and terminal restriction fragment length polymorphism (T-RFLP) methods. The results revealed high bacterial diversity in both unspiked and pyrene-spiked soils. Only at the highest pyrene-spiking rate of 500 mg·kg^-1, two minor bacteria groups of the identified 14 most abundant bacteria groups were completely suppressed. Short-term exposure to pyrene resulted in dominance of Proteobacteria in soil, followed by Acidobacteria, Firmutes, and Bacteroidetes. Our findings showed that bacterial community structure did respond to the presence of pyrene but recovered rapidly from the perturbation. The intensity of impact and the rate of recovery showed some pyrene dosage-dependent trends. Our results revealed that different levels of pyrene may affect the bacterial community structure by suppressing or selecting certain groups of bacteria. It was also found that the bacterial community was most susceptible to pyrene within one day of the chemical addition.     

1株微小杆菌对4种蓝藻的生长影响

利用过滤的天然珍珠养殖水参照BG11配制加富培养液,将1株能促进鱼害微囊藻生长的微小杆菌属菌株(Exiguobacterium sp.013,简写为E.sp.013)进行纯化扩大培养后与铜绿微囊藻(Microcystis aeruginosa)、水华微囊藻(Microcystis flosaquae)、平裂藻(Merismopedia sp.)和惠氏微囊藻(Microcystis wesenbergii)按一定菌、藻密度比例同时接种后进行为期24 d的培养试验,利用特定生长率和细胞密度等指标观察并检验E.sp.013菌株对4种蓝藻生长的影响,同时检测培养液中优势菌群的数量变化趋势.结果表明:E.sp.013菌对铜绿微囊藻、水华微囊藻和惠氏微囊藻具有显著促生长和延长稳定生长期作用,对平裂藻不具有显著促生长作用,但对延长其稳定生长期具有显著效果;试验培养过程中E.sp.013菌落数量占所有菌落总数的比例始终高于46％,处于绝对优势地位,表明E.sp.013菌具有调控其他菌群的能力.     

再生水补水对河流湿地香蒲根际细菌群落结构影响研究

以典型的再生水补水河流湿地为例,采用末端限制性片段长度多态性技术(T-RFLP)分析河道不同空间香蒲根际细菌群落结构差异,并借助单因素方差分析(one-way ANOVA)、Spearman等级相关分析和典范对应分析(CCA)方法解析麻峪湿地香蒲根际细菌群落结构空间差异特征的形成原因,以揭示再生水补水过程对河道湿地香蒲根际细菌群落的影响,并尝试找出空间差异形成的驱动因子.结果表明:随再生水干扰强度的增加,各类群细菌群落的丰富度、均匀度及多样性均呈现不同程度的降低趋势;其中γ-变形菌门(Gammaproteobacteria)、δ-变形菌门(Deltaproteobacteria)和绿弯菌门(Chloroflexi)、ε-变形菌门(Epsilonproteobacteria)和放线菌门(Actinobacteria)在再生水影响下均显著降低(P<0.05).Spearman等级相关分析显示pH值、DO(溶解氧)、TDS(总溶解固体)、ORP(氧化还原电位)、Sal(盐度)和NH₄⁺-N(氨氮)与植物根际细菌群落多样性空间演替紧密相关.CCA分析结果进一步表明再生水补水口的上游细菌群落与TN(总氮)、TOC(总有机碳)及重金属Cr、Ni、Cu具有密切关系,这可能与这些污染物累积效应有关;补水口附近植物根际细菌群落则因补水口再生水水质不同而具显著差异,其中第Ⅱa类群主要受到水质变量pH值影响较大,而第Ⅱb类群与T(温度)、ORP和NH₄⁺-N具有较高的相关性;补水口的下游细菌群落则因水体内源杂质及人为活动影响而同样与TOC及持久性痕量重金属生物循环密切相关.     

模拟光伏曝气硝化SBR自动控制策略及其AOB群落结构

采用模拟光伏曝气硝化SBR(序批式反应器)去除污水中的NH₄+-N,探究适用于反应器硝化过程的自动控制策略,并采用PCR(聚合酶链式反应)和TA克隆考察反应器内AOB(氨氧化细菌)群落结构. 结果表明,反应器可在15 d内成功启动,NH₄+-N平均去除率达97.8%,出水ρ(NH₄+-N)平均值为0.67 mg/L. ρ(DO)和pH变化曲线上均存在指示氨氧化终点的特征点——氨谷和DO肘,可通过d pH/d t(pH导数)准确判断氨氧化终点,而d ρ(DO)/d t〔ρ(DO)导数〕信号波动较大. Nitrosomonas为反应器内绝对优势AOB,但AOB的群落结构并不稳定,只有2个OTU(分类操作单元)在7个克隆文库(d15、d30、d45、d60、d75、d90和d105)中均有分布,AOB群落结构的平均变化率(Δ₁₅ d)为22.1%±16.5%,20%的AOB累积相对丰度随时间变化范围为40.0%~60.7%,表明维持硝化SBR稳定运行的关键是AOB的多样性及群落结构的动态变化,而不是某些特定的AOB种.      

Treatment of swine wastewater in aerobic granular reactors: comparison of different seed granules as factors

The granulation process, physic-chemical properties, pollution removal ability and bacterial communities of aerobic granules with different feed-wastewater (synthetic wastewater, R1; swine wastewater, R2), and the change trend of some parameters of two types of granules in long-term operated reactors treating swine wastewater were investigated in this experiment. The result indicated that aerobic granulation with the synthetic wastewater had a faster rate compared with swine wastewater and that full granulation in R1 and R2 was reached on the 30th day and 39th day, respectively. However, although the feed wastewater also had an obvious effect on the biomass fraction and extracellular polymeric substances of the aerobic granules during the granulation process, these properties remained at a similar level after long-term operation. Moreover, a similar increasing trend could also be observed in terms of the nitrogen removal efficiencies of the aerobic granules in both reactors, and the average specific removal rates of the organics and ammonia nitrogen at the steady-state stage were 35.33 mg·g⁻¹ VSS and 51.46 mg·g⁻¹ VSS for R1, and 35.47 mg·g⁻¹ VSS and 51.72 mg·g⁻¹ VSS for R2, respectively. In addition, a shift in the bacterial diversity occurred in the granulation process, whereas bacterial communities in the aerobic granular reactor were not affected by the seed granules after long-term operation.