Isolation of a phenol-utilizing marine bacterium from Durban Harbour (South Africa) and its preliminary characterization as Marinobacter sp. KM2

Many aromatic hydrocarbons assigned to the so-called high production volume chemicals (HPVCs) are frequently encountered constituents of wastewaters that end up in the sea. Although the pollutant-degrading capabilities of freshwater bacteria are well known, the catabolism of pollutants by marine bacteria has received limited attention. A marine bacterium with the ability to aerobically utilize phenol - an HPVC and common aromatic pollutant - as its sole source of carbon and energy, was isolated from water samples from Durban Harbour, South Africa. The isolate, designated strain KM2, was assigned to the genus Marinobacter based on a variety of phenotypic properties and by analysis of the 16S rRNA gene sequence. The isolate displays an absolute growth requirement for NaCl which cannot be offset by replacement of NaCl with other salts. In addition to 4-methylphenol and 3,4-dimethylphenol, it utilizes a range of aliphatic hydrocarbons such as butan-1-ol and hexadecane under aerobic conditions. The transient formation of an intermediate exhibiting the UV-Vis spectral characteristics for 2-hydroxymuconic semialdehyde in cultures growing on phenol suggests that the isolate catabolizes this compound via the meta cleavage pathway. These results indicate that members of the genus Marinobacter might participate in the elimination of aromatic pollutants in South African marine environments.     

Optimization of a bacterial consortium for nitrobenzene degradation

Three bacterial strains, Arthrobacter sp. NB1, Serratia sp. NB2 and Stenotrophomonas sp. NB3, were isolated from contaminated sludge by using nitrobenzene as a sole source of carbon and nitrogen. It was observed that all three strains could degrade nitrobenzene at 400 mg/L initial concentration and mixed-cultivation of these strains could enhance the degradation of nitrobenzene compared with mono-cultivation. Mixture design was used for adjusting the proportions of each strain and the optimal ratio of inoculation size was NB1:NB2:NB3 = 4:4:5, where the nitrobenzene degradation percentage was two times higher than for by the single strain. The results of Plackett-Burman design indicated that Mg(2+), Ca(2+), Fe(2+), Zn(2+) and Mn(2+) had a positive effect on the degradation of nitrobenzene, while Cu(2+) and Co(2+) had a negative effect on it.     

Enhanced biodegradation of 4-aminobenzenesulfonate in membrane bioreactor by Pannonibacter sp. W1

4-Aminobenzenesulfonate (4-ABS), an aromatic amine and recalcitrant toxic pollutant, is widely used in the dye and pharmaceutical industry. Pannonibactersp. W1 is a specialized microbial strain which can efficiently degrade 4-ABS. This study shows the feasibility of using the specialized strain in an MBR system to treat synthetic wastewater containing large amount of 4-ABS. Due to membrane retention, the biomass concentration is able to reach 5 g/L within two months of continuous operation. Pannonibacter sp. W1 is able to adapt to the high loading rate of 1000 mg 4-ABS/L and achieve a remarkable 4-ABS removal efficiency of 99% within 6 h. Strain W1 grows well under the MBR continuous operation and remains as the dominant bacterium at the end of 60 days continuous operation. Minor membrane fouling has been detected within 40 days of operating at 15 LMH. At a flux of 25 LMH, the system experiences the 'TMP jump'. The high organic removal rate and low membrane fouling results illustrate the excellent performance of the bioaugmented MBR system in 4-ABS wastewater treatment.     

光催化降解水环境中多环芳烃的研究进展

为分析光催化降解水环境中多环芳烃的研究进展状况,综述了Ti O2等紫外光响应材料和BiVO4等可见光响应材料催化降解水环境中多环芳烃的去除效果,并以萘为例,分析了多环芳烃的光催化降解机理。指出对可见光响应材料的开发和进一步提高材料的光响应能力是当前的研究热点,将光催化技术与其他技术联合使用也是高效去除多环芳烃的发展趋势。     

Biodegradation of bisphenol A and 4-alkylphenols by Novosphingobium sp. strain TYA-1 and its potential for treatment of polluted water

We investigated the use of Novosphingobium sp. strain TYA-1 for the simultaneous removal of bisphenol A (BPA) and 4-alkylphenols (4-APs) from complex polluted waters. Strain TYA-1 degraded BPA and utilized it as a sole carbon and energy source via oxidative skeletal rearrangement involving the cytochrome p450 monooxygenase system. Strain TYA-1 also degraded 4-APs with branched side alkyl chains (4-tert-butylphenol [4-tert-BP], 4-sec-butylphenol, 4-tert-pentylphenol, 4-tert-octylphenol [4-tert-OP], and branched nonylphenol mixture) via 4-alkylcatechols but could not degrade 4-APs with linear side alkyl chains. Degradation of 4-APs, like that of BPA, involved the cytochrome p450 monooxygenase system in strain TYA-1. A sequencing batch bioreactor (100 mL of polluted water [50 mg/L BPA, 50 mg/L 4-tert-BP, and 5 mg/L 4-tert-OP]; 6 h of reaction time/cycle; 12 cycles in total) containing alginate-immobilized TYA-1 cells (15 mg dry cells) simultaneously removed BPA, 4-tert-BP, and 4-tert-OP from complex polluted waters. These immobilized TYA-1 cells could be reused for a total of 9 cycles without any loss of degradation activity. Our results support the potential of using immobilized TYA-1 cells for the simultaneous removal of BPA and 4-APs from complex polluted waters.     

BTEX degradation by fungi.

Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants that cause serious problems in groundwater, in surface water and in soil. Specifically, the coastal area of Bourgas bay (Bulgarian Black Sea coast) is very vulnerable to such pollution as the large petrochemical industry situated there poses a continuing threat to the environment. The potential for degradation of BTEX by fungi was studied. Two fungal strains were used in the experiments carried out in a batch reactor. The fungi were isolated from gasoline-polluted sites and were identified as deuteromycetes belonging to the Cladophialophora (CPH) and Cladosporium (CS) genera. It was found that neither of the fungal strains was able to degrade benzene. Ethylbenzene was easily degraded in all cases; o- and m-xylene were fully degraded by Cladophialophora sp. both as single substrates and in mixtures with toluene, whereas Cladosporium sp. was able to degrade them fully in mixtures with toluene only. p-Xylene was only partially degraded in all tests; however, the experiments with Cladosporium sp. showed better results compared to those with Cladophialophora sp. in this particular case. Ethylbenzene, o- and m-xylene negatively affected toluene removal rate of both fungal strains, which suggests possible competitive substrate interactions. In general, the results obtained with Cladophialophora sp. were better than those with Cladosporium sp., except in the case of p-xylene degradation.     

IAL-CHS (internal airlift loop--ceramic honeycomb supports) reactor used for biodegradation of 2,4-dichlorophenol and phenol.

The internal airlift loop reactor with ceramic honeycomb supports (IAL-CHS) was applied for biodegradation of 2,4-dichlorophenol (2,4-DCP) and phenol. A strain of DCP-degrading bacteria isolated from activated sludge, Achromobacter sp., was rapidly immobilized onto the ceramic honeycomb supports. The immobilized cells effectively biodegraded 2,4-DCP alone and together with phenol in batch and continuous-flow experiments. For example, 2,4-DCP was biodegraded from an influent concentration of 50 mg/L to less than 1 mg/L with a 6-h hydraulic retention time (HRT) in continuous flow tests. The immobilized biomass grew and accumulated through 2,4-DCP biodegradation, and the rate of degradation increased accordingly.     

Fatty Acid and Hydrocarbon Content of Settling Sediments in Lake Michigan

Fatty acid and aliphatic hydrocarbon contents have been examined in sediment collected in traps suspended at three depths at a location in Lake Michigan. Fatty acid distributions are similar at all depths and suggest an authochtonous origin of these materials. Concentrations of acids decrease with greater depths of traps and indicate a combination of active microbial reworking and of dilution by resuspended sedimentary materials. Hydrocarbons in the metalimnion trap contain mostly algal and bacterial components, whereas near-bottom hydrocarbons contain a large land plant contribution, presumably from resuspension of bottom sediments. Comparison of trap contents with fatty acid and hydrocarbons obtained from faunal debris and with published diatom compositions indicates that a mixture of such sources is combined in the organic matter settling in Lake Michigan. Estimated fluxes to the bottom of this part of the lake are 6.5 g/m²/yr for organic carbon, 1.8 g/m²/yr for fatty acids, and 27 mg/m²/yr for aliphatic hydrocarbons.     

High rate composting of herbal pharmaceutical industry solid waste

High rate composting studies of hard to degrade herbal wastes were conducted in a 3.5 m(3) capacity rotary drum composter. Studies were spread out in four trials: In trial 1 and 2, one and two turns per day rotation was observed, respectively, by mixing of herbal industry waste with cattle (buffalo) manure at a ratio of 3:1 on wet weight basis. In trial 3 inocula was added in raw waste to enhance the degradation and in trial 4 composting of a mixture of vegetable market waste and herbal waste was conducted at one turn per day. Results demonstrated that the operation of the rotary drum at one turn a day (trial 1) could provide the most conducive composting conditions and co-composting (trial 4) gave better quality compost in terms of temperature, moisture, nitrogen, and Solvita maturity index. In addition a FT-IR study also revealed that trial 1 and trial 4 gave quality compost in terms of stability and maturity due to the presence of more intense peaks in the aromatic region and less intense peaks were found in the aliphatic region compared with trial 2 and trial 3.     

Behavior of cellulose-degrading bacteria in thermophilic anaerobic digestion process.

Previously, we found that the newly isolated Clostridium sp. strain JC3 became the dominant cellulose-degrading bacterium in thermophilic methanogenic sludge. In the present study, the behavior of strain JC3 in the thermophilic anaerobic digestion process was investigated quantitatively by molecular biological techniques. A cellulose-degrading experiment was conducted at 55 degrees C with a 9.5 L of anaerobic baffled reactor having three compartments (Nos. 1, 2, 3). Over 80% of the COD input was converted into methane when 2.5 kgCOD m(-3) d(-1) was loaded for an HRT of 27 days. A FISH probe specific for strain JC3 was applied to sludge samples harvested from the baffled reactor. Consequently, the ratio of JC3 cells to DAPI-stained cells increased from below 0.5% (undetectable) to 9.4% (compartment 1), 13.1% (compartment 2) and 21.6% (compartment 3) at day 84 (2.5 kgCOD m(-3)d(-1)). The strain JC3 cell numbers determined by FISH correlated closely with the cellulose-degrading methanogenic activities of retained sludge. A specific primer set targeting the cellulase gene (cellobiohydrolaseA: cbhA) of strain JC3 was designed and applied to digested sludge for treating solid waste such as coffee grounds, wastepaper, garbage, cellulose and so on. The strain JC3 cell numbers determined by quantitative PCR correlated closely with the cellulose-sludge loading of the thermophilic digester. Strain JC3 is thus important in the anaerobic hydrolysis of cellulose in thermophilic anaerobic digestion processes.     

低温苯胺降解菌的筛选及其特性

通过驯化培养,从含苯胺的管道污泥中分离出1株高效苯胺降解菌7#,在苯胺质量浓度低于5500 mg/L的普通培养基中均可生长。7#菌株降解苯胺的最适温度为30℃,经低温驯化后,10℃和30℃时对苯胺的降解率接近,最适pH=7.0,当苯胺质量浓度在400 mg/L以下时,对该菌不表现出明显抑制作用。在苯胺质量浓度200 mg/L的无机盐溶液中,10℃下培养60 h可使苯胺降解率达89.14%,降解符合二级动力学模型。经鉴定,该菌株为假单胞菌属。     

Mass transfer limitation in pah-contaminated soil remediation

Batch experiments were conducted to determine the effects of Triton X-I 00, a nonionic phenolic ethoxylate surfactant, on the biodegradation of soil-bound naphthalene and phenanthrene. Two different types of soils, one contaminated with polynuclear aromatic hydrocarbons (PAHs) for different lengths of time, 2 days to 10 months, in the laboratory and the other, a field-contaminated soil from a manufactured gas plant (MGP) site, were used. Biodegradation of PAHs was measured by monitoring the ₁₄CO² production for the artificially contaminated soils and the residual PAHs in soil phase for the MGP soil. Without adding surfactant, the mineralization rate of phenanthrene was significantly smaller in the 10-month contaminated soil compared to that in the 2-day contaminated soil. Presumably, mineralization was mass-transfer limited in the soil with longer contamination period. Triton X-100 significantly enhanced mineralization in the 10 month-old soil but none in the 2-day old soil. The MGP soil, weathered over 2–3 decades, exhibited even greater enhancement of mineralization. Mineralization of PAHs in aged soils appears to be controlled by mass transfer rather than the rate of biodegradation. Surfactants increase the rate of release of soil-bound contaminant and thus help promote biodegradation.     

红球菌Rhodococcus sp-1对地下Mn(Ⅱ)生物去除特性的研究

利用传统的细菌分离方法,从地下水生物除锰滤池中分离、纯化出一种细菌,经LBB法检测其具有Mn(Ⅱ)氧化能力,利用Sherlock~?细菌鉴定系统初步确定其属于红球菌属(Rhodococcussp.).对红球菌Rhodococcus sp-1菌株的Mn(Ⅱ)生物去除特性进行研究,结果表明:Rhodococcussp-1茵株在接种20 h左右达到生长稳定期,Mn(Ⅱ)的去除量趋于稳定,可达到12 mg/L,具有很强的地下水Mn(Ⅱ)生物去除能力;同时Rhodococcus sp-1菌株的生长可以改变其培养环境的pH,使pH升高.为锰生物氧化机理和特性的研究提供了优势菌株,同时为后续的锰氧化细菌固定化和酶学研究奠定了基础.     

Biochemical pathway and degradation of phthalate ester isomers by bacteria.

Degradation of dimethyl isophthalate (DMI) and dimethyl phthalate ester (DMPE) was investigated using microorganisms isolated from mangrove sediment of Hong Kong Mai Po Nature Reserve. One enrichment culture was capable of utilizing DMI as the sole source of carbon and energy, but none of the bacteria in the enrichment culture was capable of degrading DMI alone. In co-culture of two bacteria, degradation was observed proceeding through monomethyl isophthalate (MMI) ester and isophthalic acid (IPA) before the aromatic ring opening. Using DMI as the sole carbon and energy source, Klebsiella oxytoca Sc and Methylobacterium mesophilicum Sr degraded DMI through the biochemical cooperation. The initial hydrolytic reaction of the ester bond was by K. oxytoca Sc and the next step of transformation was by M. mesophilicum Sr, and IPA was degraded by both of them. In another investigation, a novel bacterium, strain MPsc, was isolated for degradation of dimethyl phthalate ester (DMPE) also from the mangrove sediment. On the basis of phenotypic, biochemical and 16S rDNA gene sequence analyses, the strain MPsc should be considered as a new bacterium at the genus level (8% differences). This strain, together with a Rhodococcus zopfii isolated from the same mangrove sediment, was able to degrade DMPE aerobically. The consortium consisting of the two species degraded 450 mg/l DMPE within 3 days as the sole source of carbon and energy, but none of the individual species alone was able to transform DMPE. Furthermore, the biochemical degradation pathway proceeded through monomethyl phthalate (MMP), phthalic acid (PA) and then protocatechuate before aromatic ring cleavage. Our results suggest that degradation of complex organic compounds including DMI and DMPE may be carried out by several members of microorganisms working together in the natural environments.     

Direct force measurement of bacteria adhesion on metal in aqueous media.

The adhesion of bacteria on metal surfaces in aqueous media and the development of biofilm and resultant biofouling are important phenomena in both the natural environment and engineering systems. This work reports on the use of a force microscopy technique to measure bacterial metal adhesion by two anaerobic sulphate-reducing bacteria (Desulfovibrio desulfuricans and a local marine isolate) and an aerobe (Pseudomonas sp.). Using a modified bacteria tip, the atomic force microscope was able to quantify the attraction and repulsion force in the nano-Newton range between the bacteria cell and metal surface in aqueous media. Results show that increasing surface hydrophobicity of the metal, and increasing the ionic strength of the aqueous medium both enhance the adhesion force. The adhesion forces were also influenced by the physiological properties of the bacterium, such as the bacterial surface charges and hydrophobicity.     

碾压混凝土穿透型诱导缝不同扩展阶段的强度指标试验研究

在不同削弱度碾压混凝土轴拉试件的穿透型诱导缝周围粘贴了应变片，得到在不同应力状态下诱导缝应变发展规律为：在加载初期，离缝端不同距离的应变发展较为均匀，数值上相差不突出；随着荷载的增加，应变开始出现不均匀发展，离缝端越远，应变变化越缓慢；当接近最大荷载的阶段，缝端应变急速发展，试件瞬间断裂。应变从均匀发展变为不均匀发展，实质上隐含了诱导缝起裂、稳定发展、失稳断裂的整个过程，针对这一试验现象，结合断裂力学理论，建立了诱导缝不同开裂阶段的远场温度应力强度指标模型。     

Algicidal effect of bacterial isolates of Pedobacter sp. against cyanobacterium Microcystis aeruginosa

The aim of this study was to isolate algicidal bacteria so as to control harmful cyanobacterium Microcystis aeruginosa (M.aeruginosa) blooms using biological methods. Nine bacterial strains were isolated to inhibit the growth of M. aeruginosa, among which the MaI11-5 bacterial strain exhibited remarkable algicidal activity against M. aeruginosa cells during the test. Based on the 16S rDNA analysis, the isolated MaI11-5 was identified as Pedobacter sp. through morphology and homology research. The results of cocultivation of the cyanobacteria with MaI11-5 algicidal isolates showed obvious algicidal activity against cyanobacterial cells. The algicidal effect of MaI11-5 exceeded 50% after two days, exceeded 70% after four days, and reached 80% after seven days. The observation results with a scanning electron microscope showed that the cyanobacterial cells aggregated and produced mucous-like substances when cocultivated with the algicidal bacteria. The results indicated that the MaI11-5 bacterial strain may possess a novel function for controlling harmful blooms and further studies will provide new insights into its role in water environment.     

Isolation and characterization of Lake Erie bacteria that degrade the cyanobacterial microcystin toxin MC-LR

Microcystin-LR (MC-LR) is a cyclic hepatotoxin produced by cyanobacteria, including Microcystis sp. and Planktothrix sp. Harmful algal blooms (HABs) in Lake Erie have become a major human health concern in recent years, highlighted by the August 2014 City of Toledo, Ohio, municipal water “do not drink” order that affected nearly 500,000 residents for 3?days. Given that microcystin degrading bacteria have been reported from HAB-affected waters around the world, we hypothesized that MC-LR degrading bacteria could be isolated from Lake Erie. To test this hypothesis, 13 water samples were collected from various Lake Erie locations during the summers of 2014 and 2015, MC-LR was continuously added to each water sample for 3 to 5?weeks to enrich for MC-LR-degrading bacteria, and MC-LR was quantitated over time. Whereas MC-LR was relatively stable in sterile-filtered lake water, robust MC-LR degradation (up to 19?ppb/day) was observed in some water samples. Following the MC-LR selection process, 67 individual bacterial isolates were isolated from MC-LR degrading water samples and genotyped to exclude potential human pathogens, and MC-LR degradation by smaller groups of bacterial isolates (e.g., groups of 22 isolates, groups of 11 isolates, etc.) was examined. Of those smaller groups, selected groups of four to five bacterial isolates were found to degrade MC-LR into non-toxic forms and form robust biofilms on siliconized glass tubes. Taken together, these studies support the potential use of isolated bacterial isolates to remove MC-LR from drinking water.     

A novel method for evaluating bioavailability of polycyclic aromatic hydrocarbons in sediments of an urban stream.

Hydrophobic organic pollutants in urban wet weather discharges can accumulate in the sediments of receiving waters and may have adverse effects on the ecological system, especially on benthic organisms. Here, a novel method is developed for evaluating the bioavailability of such hydrophobic organic pollutants by considering the digestive guts in deposit-feeding polychaetes. We compared the amount of polycyclic aromatic hydrocarbons (PAHs) extracted by an organic solvent and by sodium dodecyl sulfate (SDS) solution (as a hypothetical digestive gut fluid of polychaetes) and interpreted the ratio of the two values as bioavailability. The sediment extracts were applied to bacterial acute toxicity tests and algal growth inhibition tests. Sediment samples were collected from an urban stream system receiving wet weather discharges. The bioavailability of the total amount of 12 PAHs in the sediments was in the range 14-38% based on the results from the GC/MS determination of the two different extracts. Lower molecular PAHs showed higher bioavailability compared to the higher molecular ones. The sediment extracts were shown to be toxic towards both algae and bacteria. The SDS extracts showed similar or higher toxicity in the two biotests compared to the organic solvent extracts in spite of their lower PAHs content.     

Historical Monitoring of Biomarkers of PAH Exposure of Brown Bullhead in the Remediated Black River and the Cuyahoga River,Ohio

Biomarkers of exposure to chemical contamination, benzo[a]pyrene (BAP)- and naphthalene (NAPH)-type metabolites, were measured in brown bullhead from a heavily polycyclic aromatic hydrocarbons (PAHs) contaminated section of the Black River, Ohio, during and immediately after remedial sediment dredging in 1990–1991, and in follow-up revisits in 1993 and 1998. Biomarker levels of bullhead from the historically polluted Cuyahoga River and the protected Old Woman Creek National Estuarine Sanctuary in Ohio were also measured over the same time periods. PAH-bile metabolite concentrations of bullheads from the Black River were still elevated in the year following dredging, but were significantly lower in the later resampling years. Metabolite concentrations of Cuyahoga River bullhead decreased significantly between 1991 and 1993, possibly in response to the shutdown of coking operations on the river. Fish from Old Woman Creek showed some variation in metabolite concentrations among periods, but were consistently lower than the other two rivers at each time. Measurement of bile metabolites proved an effective tool for estimating changes in exposure over time and among sampling sites. Trends in biomarkers indicated lowered exposures in the Black and Cuyahoga Rivers. These findings are likely a result of remediation activities in the Black River and source reduction and incidental sediment displacement in the Cuyahoga River.