Biomineralization of 2,3,4,6-Tetrachlorophenol by Bacillus sp. and Staphylococcus sp. Isolated from Secondary Sludge of Pulp and Paper Mill

Three 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP)-mineralizing bacteria were isolated from the secondary sludge of a pulp and paper industry. The isolates used 2,3,4,6-TeCP as a source of carbon and energy and were capable of degrading this compound, as indicated by stoichiometric release of chloride and biomass formation. Based on 16S rRNA gene sequence analysis, the bacteria were identified as Bacillus megaterium (CL3), Staphylococcus suciri (CL10), and Bacillus thuringensis (CL11). High-performance liquid chromatography (HPLC) analysis revealed that these isolates were able to degrade 2,3,4,6-TeCP at higher concentrations (600 mg/L or 2.5 mM). A consortia of the isolates completely removed 2,3,4,6-TeCP from the sludge obtained from a pulp and paper mill within 2 weeks when supplemented at a rate of 100 mg/L or 0.43 mM. A bacterial consortium also significantly reduced absorbable organic halogen (AOX) and extractable organic halogen (EOX) by 63% and 68%, respectively, from the sludge. These isolates have a high potential to remove 2,3,4,6-TeCP and may be used for remediation of pulp paper mill waste containing 2,3,4,6-TeCP.     

Mixtures of Associating and Non-associating Chains on Activated Surfaces: A Monte Carlo Approach

Abstract

The behavior of mixtures of associating and non-associating chains confined in pores with activated surfaces is studied by means of molecular simulation. The fluid molecules are modeled as a chain of four tangent Lennard-Jones spheres. Some of the chains have an additional associating square-well site placed in an end sphere. The activated surfaces of the slit pore are modeled via an integrated Lennard-Jones (10-4-3) potential with specific association sites protruding from the surface. We present Gibbs ensemble Monte Carlo simulation results for the partitioning of mixtures of chains in the bulk and confined phases for this particular model. The chain-wall association governs the adsorption behavior of the system. The preferential adsorption of associating chains is seen to strongly depend on temperature and pore width. Selectivities obtained are in the range of those seen in experiments of alkane-alkanol mixtures.     

Structural Basis of DEPTOR to Recognize Phosphatidic Acid Using its Tandem DEP Domains

DEP domain containing mTOR-interacting protein (DEPTOR) plays pivotal roles in regulating metabolism, growth, autophagy and apoptosis by functions as an endogenous inhibitor of mTOR signaling pathway. Activated by phosphatidic acid, a second messenger in mTOR signaling, DEPTOR dissociates from mTORC1 complex with unknown mechanism. Here, we present a 1.5 Å resolution crystal structure, which shows that the N-terminal two tandem DEP domains of hDEPTOR fold into a dumbbell-shaped structure, protruding the characteristic β-hairpin arms of DEP domains on each side. An 18 amino acids DDEX motif at the end of DEP2 interacts with DEP1 and stabilizes the structure. Biochemical studies showed that the tandem DEP domains directly interact with phosphatidic acid using two distinct positively charged patches. These results provide insights into mTOR activation upon phosphatidic acid stimulation.     

Formation of metabolites during biodegradation of linear alkylbenzene sulfonate in an upflow anaerobic sludge bed reactor under thermophilic conditions.

Biodegradation of linear alkylbenzene sulfonate (LAS) was shown in an upflow anaerobic sludge blanket reactor under thermophilic conditions. The reactor was inoculated with granular biomass and fed with a synthetic medium and 3 micromol/L of a mixture of LAS with alkylchain length of 10 to 13 carbon atoms. The reactor was operated with a hydraulic retention time of 12 h with effluent recirculation in an effluent to influent ratio of 5 to 1. A sterile reactor operated in parallel revealed that sorption to sludge particles initially accounted for a major LAS removal. After 8 days of reactor operation, the removal of LAS in the reactor inoculated with active granular biomass exceeded the removal in the sterile reactor inoculated with sterile granular biomass. The effect of sorption ceased after 185 to 555 h depending on the LAS homologs. 40% of the LAS was biodegraded, and the removal rate was 0.5 x 10(-6) mol/h/mL granular biomass. Acidified effluent from the reactor was subjected to dichloromethane extraction followed by gas chromatography/mass spectrometry. Benzenesulfonic acid and benzaldehyde were detected in the reactor effluent from the reactor with active granular biomass but not in the sterile and unamended reactor effluent. Benzenesulfonic acid and benzaldehyde are the first identified degradation products in the anaerobic degradation of LAS.     

两株苯酚降解菌的分离及降解特性的初步研究

从南昌钢铁公司焦化污水处理厂的活性污泥中分离出64株能降解苯酚的细菌,通过耐受性试验从中筛选出2株降解活性较高的苯酚降解菌,编号为F-38和F-64。研究表明:F-38和F-64都为G—菌,苯酚浓度越高,生长延滞期越长;两株菌降解苯酚基本发生在对数期,其对苯酚降解适宜条件为温度30℃,pH值8-9,通气有利于苯酚的降解。     

活性污泥总DNA提取方法的研究

采用冻融＋玻璃珠、溶菌酶＋SDS和冻融＋玻璃珠＋溶菌酶＋SDS的方法提取活性污泥的微生物总DNA,并对以上三种方法进行比较,从中确定最佳的方法,以实现普通实验条件下成功提取符合PCR扩增要求的DNA。经紫外光度分析及电泳结果表明,冻融＋玻璃珠＋溶菌酶＋SDS方法所得的DNA的OD260/OD280为1．81,电泳结果显示,所提DNA片段分子量大于10kb,适于酶解和PCR扩增要求,为PCR技术应用于活性污泥的研究提供了一种简便、可靠的DNA提取方法。     

酵母双杂交技术研究与人孕酮受体B相互作用的蛋白质

应用酵母双杂交技术研究与人孕酮受体B（hPRB）发生相互作用的蛋白质,有助于进一步阐明其在乳腺癌的发生发展中发挥重要作用的调控机制。应用酵母双杂交系统3,以hPRB不同结构域为诱饵,筛选人乳腺cDNA文库,寻找能与之相互作用的蛋白质,并运用X—α—Gal等实验提供的信息,筛除假阳性克隆。最终以AF1-DBD结构域作为诱饵最终筛出了1个阳性克隆,经测序及生物信息学分析,这个克隆所编码的蛋白为PIAS3（活化的STAT3的蛋白抑制剂）。结果表明,孕激素受体可以和PIAS3发生相互作用,它们的相互作用有可能参与乳腺癌的生长调控。     

几种花卉植物对污泥中铅的富集特征

土地利用是资源化利用城市污水厂污泥的有效途径。为了解污泥中重金属污染物在土壤、植物之间的迁移富集规律,选用8种园林用植物进行污泥混配土种植实验。结果表明,植物对污泥混配土土壤中铅的富集能力,以及铅在植物中各器官的富集系数均不同,且不同种类植物差别较大。植物根部对铅有较强的富集能力,其次是叶和茎。菊花对铅的富集能力较强。植物对土壤中铅的富集能力也受土壤铅含量和赋存形态影响。