Effects of Oxygen-Releasing Materials on Aerobic Bacterial Degradation Processes

The aerobic microbial degradation of p-nitrophenol (PNP) and phenol was examined under oxygen-limiting conditions in the presence of three known oxygen-releasing materials: (1) polyvinylidene chloride-encapsulated sodium percarbonate; (2) REGENESIS oxygen-releasing compound (magnesium peroxide); and (3) PermeOx® solid peroxygen (calcium peroxide). The degradation of PNP or phenol in buffered solutions was measured in 40-mL reaction chambers containing 25 to 300 mg of oxygen-releasing materials in the presence of immobilized chemical-degrading bacteria. Radiometric studies were used to determine total chemical mineralization and material balances of ¹⁴C-residues. Degradation of PNP and phenol increased in proportion to both the supplemented amount and the relative oxygen content of each oxygen-releasing material. Comparison of actual to theoretical degradation, based on stoichiometry of balanced equations for mineralization, showed that chemical uptake (primary degradation) at lower concentrations of oxygen-releasing materials was two-fold higher than could be mineralized theoretically. Radiometric studies confirmed the relationships between chemical uptake, cellular ¹⁴C-residues, mineralization, and the concentration of oxygen-releasing material. Further studies with PermeOx(identified supplementation levels required to support aerobic bacterial mineralization of PNP and phenol at levels similar to those of aerobic controls. These results show how the concentration of oxygen-releasing materials affects the rate and extent of aerobic chemical under oxygen-limiting conditions.     

Mechanism of calcium accumulation in acetate-fed aerobic granule

High calcium content has been widely reported in acetate-fed aerobic granules, but the reason behind this is unclear yet. By SEM–energy dispersive X-ray mapping analysis, this study showed that the majority of calcium was presented in the central part of the acetate-fed aerobic granule, and the granule shell part was nearly calcium-free. The elemental analysis of calcium ions coupled with the chemical titration of carbonate further revealed that the calcium ions that accumulated in the acetate-fed aerobic granule mainly existed in the form of calcium carbonate (CaCO₃). The formation of the CaCO₃ appeared to be highly dependent on the size of the aerobic granule, i.e., the CaCO₃ precipitation was found only in aerobic granules with radiuses larger than 0.5 mm. These experimental observations with regard to the formation of CaCO₃ in the acetate-fed aerobic granule were further confirmed by the model simulation, which was based on the principles of mass diffusion and carbonate dissociation in liquid phase. This study for the first time showed that the size of the acetate-fed aerobic granule would indeed play an essential role in the CaCO₃ formation, and provided experimental evidence that a crystal CaCO₃ core was not necessarily required for granulation.     

苯酚高效降解菌的筛选和降解特性的研究

从天津市煤气厂的活性污泥中筛选、分离得到一株高效苯酚降解菌。经BIOLOG细菌自动鉴定系统及16SrDNA鉴定,该菌株为粪产碱杆菌(Alcaligenesfaecalis)。苯酚降解实验证实,该菌能在76h内完全降解1600mg·L-1的苯酚,并且随着苯酚浓度的增加,底物抑制作用增强,细胞得率下降。     

Physiological traits of bacterial strains isolated from phenol-degrading aerobic granules

The physiological characteristics of ten bacterial strains isolated from phenol-degrading aerobic granules were evaluated in order to identify competitive traits for dominant growth in aerobic granules. The ten strains showed a wide diversity in specific growth rates and oxygen utilization kinetics, and could be divided into four catabolic types of phenol degradation. While some strains degraded phenol mainly via the meta pathway or the ortho pathway, other strains degraded phenol via both these pathways. The ten strains also exhibited high levels of autoaggregation and coaggregation activity. Within the collection of ten strains, 36.7% of all possible strain pairings displayed a measurable degree of coaggregation. Strain PG-08 possessed the strongest autoaggregation activity and showed significant coaggregation (coaggregation indices of 67% to 74%) with PG-02. The three strains PG-01, PG-02 and PG-08 belonging to dominant groups in the granules possessed different competitive characteristics. Microcosm experiments showed the three strains could not coexist at the high phenol concentration of 250 mg L(-1), but could coexist at lower phenol concentrations in a spatially heterogeneous environment. This study illustrated that the spatial heterogeneity provided by the aerobic granules led to niche differentiation and increased physiological diversity in the resident microbial community.     

Kinetics of methanogenic degradation of phenol by activated-carbon-supported and granular biomass

A continuous-feed recycle bioreactor was used to study the kinetics of methanogenic degradation of phenol at 35 degrees C by bacteria supported on a bed of granular activated carbon (GAC). At dilution rates well above the growth rate of the culture, the cells not only populated the GAC, but also formed a layer of granular biomass. This layer was stabilized by the presence of the GAC, and accounted for over half of the phenol-degrading activity in the bioreactor. The specific phenol degradation rates for GAC-attached biomass, suspended biomass, and granular biomass were all in the range 0.15 to 0.22 mg phenol/mg volatile solids per day as measured under pseudo-steady-state conditions. (c) 1992 John Wiley & Sons, Inc.     

Isolation and Characterization of High-Strength Phenol-Degrading Novel Bacterium of the Pantoea Genus

A new indigenous soil bacterium Pantoea strain NII-153 utilizing phenol as a sole carbon source was isolated and characterized. Phylogenetic analysis suggested its classification to the Enterobacteriaceae family, with 95.0% gene sequence similarity to Pantoea ananatis ATCC 33244. Biodegradation rates of phenol by NII-153 were found to be more effective at 64 h with initial concentration of 600 mg L^{? 1} of phenol and this is the first report of such activity in Pantoea species. Strain NII-153 has showed high tolerance to phenol concentration (900 mg L^{? 1}). Therefore, strain NII-153 could be used for biotreatment of high-strength phenol-containing industrial effluents and for bioremediation of phenol-contaminated soils.     

FISH-FCM方法检测酵母-细菌二元体系中微生物数量

以废水生物处理系统和生物发酵系统出现的酵母-细菌二元体系作为研究对象,探讨了二元体系生物样品的最佳超声分散条件以及同时检测酵母和细菌数量时荧光原位杂交（FISH）-流式细胞术（FCM）技术的测量精度。染色-FCM检测表明：同时适用于混合酵母样品（酵母假菌丝）和混合细菌样品（活性污泥絮体）的最佳超声分散条件为100W、60～90s,但过强超声条件（120s）对酵母Candida tropicalis纯培养物（或细菌Escherichia coli纯培养物）的超声粉碎效果完全不同于混合酵母样品（或混合细菌样品）。在此基础上,以C．tropicalis和E．coli分别作为酵母和细菌的模式微生物,采用双探针杂交的FISH—FCM技术检测了背景微生物（C．tropicalis或Ecoll）浓度为10^7个／ml时二元体系中目标微生物（10^2～10^7个／ml）的数量。流式细胞仪能够明显区分噪音和二元体系中的酵母和细菌,因而一次进样时能够同时分析两种微生物数量,并且目标微生物浓度可以精确到10^4个／ml,此时微生物含量仅为0．1％,其中细菌浓度甚至可以精确到10^3个／ml（相应含量仅为0．01％）。然而,当二元体系中目标微生物浓度过低时（〈10^4个酵母／ml或〈10^4个细菌／ml）,背景微生物的存在会严重影响FISH—FCM技术的测量准确性。     

Dynamics of phenol degradation by Pseudomonas putida

Pure cultures of Pseudomonas putida (ATCC 17484) were grown in continuous culture on phenol at dilution rates of 0.074-0.085 h(-1) and subjected to step increases in phenol feed concentration. Three distinct patterns of dynamic response were obtained depending on the size of the step change used: low level, moderate level, or high level. During low level responses no accumulations of phenol or non-phenol, non-glucose-dissolved organic carbon, DOC(NGP), were observed. Moderate level responses were characterized by the transient accumulation of DOC(NGP) with a significant delay prior to phenol leakage. High level responses demonstrated a rapid onset of phenol leakage and no apparent accumulations of DOC(NGP). The addition of phenol to a continuous culture of the same organism on glucose did not result in transient DOC(NGP) accumulations, although transient phenol levels exceeded 90 mg l(-1). These results were consistent with intermediate metabolite production during phenol step tests coupled with substrate-inhibited phenol uptake and suggested that traditional kinetic models based on the Haldane equation may be inadequate for describing the dynamics of phenol degrading systems. (c) 1993 John Wiley & Sons, Inc.     

Kinetics of riboflavin production by Brewers' yeasts

The kinetics of riboflavin production by Saccharomyces cerevisiae and Saccharomyces carlsbergensis in synthetic media and wort were studied. The results indicated that riboflavin was produced by growing cells only. Riboflavin production rate was proportional to growth rate of the yeasts in the exponential phase. Riboflavin was depleted in the stationary phase. The depletion rate was expressed with a first-order kinetic expression in yeast concentration. The kinetics of substrate utilization and ethanol production were also given to describe better the associated phenomena and fermentation pattern.     

酵母菌转化人参皂苷Rb1的动力学

在分批发酵中,对酵母菌转化人参皂苷的动力学进行了研究。应用Logistic方程和Luedeking-Piret方程,得到了描述分批发酵过程中,酵母菌体生长、底物消耗和产物合成的动力学模型及模型参数,并对实验数据与模型进行了验证比较,模型计算值与实验值拟合良好,所建模型能很好地描述酵母菌转化人参皂苷的动力学特征。为进一步研究和预测酵母菌生物转化过程奠定理论基础。     

Studies on composition and stability of a large membered bacterial consortium degrading phenol

A ten member microbial consortium (AS) consisting of eight phenol-degrading and two non-phenol-degrading strains of bacteria was developed and maintained in a fed-batch reactor by feeding 500 mg l⁻¹ phenol for four years at 28 ± 3 °C. The consortium could degrade 99% of 500 mg l⁻¹ phenol after 24 hours incubation with a biomass increase of 2.6 × 10⁷ to 4 × 10¹² CFU ml⁻¹. Characterization of the members revealed that it consisted of 4 principal genera, Bacillus, Pseudomonas, Rhodococcus, Streptomyces and an unidentified bacterium. Phenol degradation by the mixed culture and Bacillus subtilis, an isolate from the consortium was compared using a range of phenol concentrations (400 to 700 mg l⁻¹) and by mixing with either 160 mg l⁻¹ glucose or 50 mg l⁻¹ of 2,4-dichlorophenol in the medium. Simultaneous utilization of unrelated mixed substrates (glucose/2,4-dichlorophenol) by the consortium and Bacillus subtilis, indicated the diauxic growth pattern of the organisms. A unique characteristic of the members of the consortia was their ability to oxidize chloro aromatic compounds via meta pathway and methyl aromatic compounds via ortho cleavage pathway. The ability of a large membered microbial consortia to maintain its stability with respect to its composition and effectiveness in phenol degradation indicated its suitability for bioremediation applications.     

A Toluene-tolerant Mutant of Pseudomonas aeruginosa Lacking the Outer Membrane Protein F

The outer membrane protein profiles of a toluene-tolerant mutant, Pseudomonas aeruginosa, strain PAK103, were compared with those of its parent strain PAO1161. Protein F (OprF), the most abundant outer membrane protein in the parental strain PAO1161, was missing in the toluene-tolerant strain PAK103. The absence of OprF may lead to the loss of toluene diffusion across in the outer membrane of the mutant cells     

石油中长链烷烃微生物降解及分子机制研究进展

中长链烷烃是石油烃中的重要组成部分,由于其疏水性强、黏度大、化学活性低、难降解,是地下原油黏度大、石油采收率低、泄漏后长期污染生态环境的重要原因,因此成为提高石油采收率和石油污染环境治理中的重要降解目标。微生物降解中长链烷烃作为一种新型高效的绿色技术日益受到重视。本文总结了微生物降解中长链烷烃的间期适应与转运过程,与转运过程相关的膜蛋白,微生物好氧与厌氧降解的代谢途径,以及好氧降解过程中的基因调控机制,并对微生物降解中长链烷烃的研究方向提出了展望,以期为后续的相关研究工作提供参考。