芳香烃类化合物的微生物降解

摘要：近年来，芳香烃类化合物正以惊人的速度被制造出来，不仅带来了严重的环境问题，还威胁到了人类的生存、发展。目前，人类正在探索如何利用微生物技术更快、更彻底的消除环境中有害的芳香烃类化合物。本文简要介绍了传统的降解菌株及其降解机理，并着重探讨了生物强化技术，以及基因工程菌在芳香烃类化合物的降解中所达到的显著成果，对未来芳香烃类化合物的微生物降解事业作出了展望。

Isolation,Screening and Primary Identification of a Keratin-degrading Fungus

[Objective] The paper was to provide new germplasm sources for efficient and economical degradation and utilization of animal keratin.[Method] The keratin-degrading fungus was isolated,screened and primarily identified by using the combination method of traditional isolation and screening,solid culture-medium degradation and animal test.[Result] A strain of non-pathogenic filamentous fungi with high degradation efficiency was obtained,which was preliminarily identified to be a species in Mucoraceae.[Conclusion] The discovery of the strain enriched the family members of keratin-degrading fungus,and provided new germplasm resources for degradation and utilization of animal keratin.

Biodegradation of microcystin-RR and -LR by an indigenous bacterial strain MC-LTH11 isolated from Lake Taihu

The indigenous bacterial strain MC-LTH11 with the capability of degrading microcystin-RR MC-RR and microcystin-LR MC-LR was successfully isolated from Lake Taihu.The bacterium was identified as Stenotrophomonas sp. which possessed a mlrA gene. The MC-LTH11 thoroughly degraded MC-RR and MC-LR with the initial concentration of 37.13 mg/L and 18.49 mg /L respectively in the medium containing crude microcystins extract within 6 d.The degradation rates were affected by temperature pH initial MCs concentration and the kinds of media. Additionally the bacterial strain MC-LTH11 also degraded thoroughly microcystins in the water body of Lake Taihu within 1 d.These results suggest that the Stenotrophomonas sp.MC-LTH11 has the capacity to bioremediate water bodies contaminated by microcystins and may contribute to the degradation of microcystins after the outbreak of harmful cyanobacterial blooms in Lake Taihu.

Microbial PAH-Degradation in Soil: Degradation Pathways and Contributing Factors

Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

Removal of Pyrene from Contaminated Soils by White Clover

Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons(PAHs),ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes,in the last decade.In this study,a pot experiment was conducted to investigate the potential of phytoremediation of pyrene from spiked soils planted with white clover(Trifolium repens)in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1.The results showed that growth of white clover on pyrenecontaminated soils was not affected.The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils.At the end of the experiment(60 d),the average removal ratio of pyrene in the spiked soils with white clover was 77%,which was 31%and 57%higher than those of the controls with or without micobes, respectively.Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration.However,the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation.Bioconcentration factors of pyrene(BCFs,ratio of pyrene,on a dry weight basis,in the plant to that in the soil)tended to decrease with increase in the residual soil pyrene concentration.Therefore,removal of pyrene in the contaminated soils was feasible using white clove.

Minimization of Phenols and Phenolic Compounds in Pulp and Paper Industries： Biological Approaches

The liquid effluents released from several industries including the pulp and paper industries contain phenol and phenolic compounds. The hazardous phenols and their chlorinated phenolic derivatives from pulp and paper industries bear the potential to exert deleterious effects on the human health and aquatic ecosystems, if they are released untreated in the environment. Biodegradation of phenolic compounds in the effluent streams from pulp and paper industries is an important eco-friendly method for the removal of toxicity in industrial waste water, while the minimization of formation of these toxic compounds require several in-plant biotechnological techniques such as biopulping and biobleaching. Present paper reviews, the biochemical pathways involved in degradation of phenols and chlorophenols through microorganisms. Various biotechnological strategies involved in minimization and biodegradation of phenol and phenolic compounds and their related environmental engineering aspects such as utility of different bioreactor configurations have been discussed for the treatment of pulp and paper mill effluents.

Effect of Inoculation with Effective Microorganisms and Leachate Recycle on Degradation of Municipal Refuse

Biodegradation of waste in landfill is a slow process requiring decades for completion. Accelerated degradation of municipal refuse in modulated landfill environments may alleviate or eliminate pollution to the land, water and air. In this work, nineteen effective microorganisms (EMs) were isolated from old landfill refuse by enrichment culturing techniques and used for the inoculum of municipal refuse. The preliminary experiments demonstrate that a combination of EMs inoculation in landfill with leachate recycle resulted in increased rates of decomposition and faster process stability. The concentrations of COD, VFA and SO4^2- in digester with EMs inoculation and leachate recycle decreased more rapidly than others. Gas production from digester with EMs inoculation and leachate recycle commenced around 32 days, which is a week shorter than with leachate recycle only. And peak cumulative gas production was obtained much earlier in digester with EMs inoculation and leachate recycle (150 days) compared to 180 days with leachate recycle only. Moreover, in the first two months, the rate of settlement in digester with EMs inoculation and leachate recycle was more rapid than others.

Biodegradation of DTP and PET Fiber by Microbe

The degradation of diethylene glycol terephthalate (DTP) and polyethylene terephthalate (PET) fiber by microbe was studied.The degree of DTP degradation was determined by High Performance Liquid Chromatography (HPLC) to be more than 90%.The products after degradation of DTP and PET fiber were various.The degradation of DTP can be described by the first-order reaction model.The degradation of PET fiber was found to be little,but surface erosion of PET fiber could be clearly seen from the SEM photographs indicating there occurred some traces of biodegradation on the PET fiber surface.

Aerobic biodegradation of di-n-butyl phthalate by Xiangjiang River sediment and microflora analysis

Di-n-butyl phthalate (DBP),one of phthalate acid esters (PAEs),was investigated to determine its biodegradation rate using Xiangjiang River sediment and find potential DBP degraders in the enrichment culture of the sediment. The sediment sample was incubated with an initial concentration of DBP of 100 mg/L for 5 d. The biodegradation rate of DBP was detected using HPLC and the degraded products were analyzed by GC/MS. Subsequently,the microbial diversity of the enrichment culture was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results reveal that almost 100% of DBP is degraded after merely 3 d,generating two main degraded products:mono-butyl phthalate (MBP) and 9-octadecenoic acid. After a six-month enrichment period under the pressure of DBP,the dominant family in the final enrichment culture is clustered with the Comamonas sp.,the remaining are affiliated with Sphingomonas sp.,Hydrogenophaga sp.,Rhizobium sp.,and Acidovorax sp. The results show the potential of these bacteria to be used in the bioremediation of DBP in the environment.

Environmental Capacity of Petroleum Hydrocarbon Pollutants in Jiaozhou Bay, China: Modeling and Calculation

An environmental capacity model for the petroleum hydrocarbon pollutions （PHs） in Jiaozhou Bay is constructed based on field surveys, mesocosm, and parallel laboratory experiments. Simulated results of PHs seasonal successions in 2003 match the field surveys of Jiaozhou Bay resaonably well with a highest value in July. The Monte Carlo analysis confirms that the variation of PHs concentration significantly correlates with the river input. The water body in the bay is reasonably subjected to self-purification processes, such as volatilization to the atmosphere, biodegradation by microorganism, and transport to the Yellow Sea by water exchange. The environmental capacity of PHs in Jiaozhou Bay is 1500 tons per year IF the seawater quality criterion （Grade Ⅰ/Ⅱ, 0.05 mgLl） in the region is to be satisfied. The contribution to self-purification by volatilization, biodegradation, and transport to the Yellow Sea accounts for 48%, 28%, and 23%, respectively, which make these three processes the main ways of PHs purification in Jiaozhou Bay.

Utilization of Starch to Accelerate the Growth of Degrading Microorganisms on the Surface of Natural Rubber Latex Films

NRL （natural rubber latex） films with 0 （control） and 10 phr sago starch loading were buried in compost soil for 4 weeks. The biodegradation assessments were carried out through films WVT （water vapor transmission） and mass loss. Scanning electron microscopy was carried out to identify and monitor the properties of rubber degrading organism colonies. Results showed that incorporation of sago starch increased the formation and rates of propagation for microorganism colonies on NRL films with duration of biodegradation. The results also indicate the mechanism of sago starch granules utilization as sole source of energy for microbial growth. The behavior and characteristics of microorganisms involved in NRL films degradation also successfully discussed.

Development and characterization of a functional microbial consortium for crude oil degradation

Crude oil-degrading microbial consortia were enriched from three oil-contaminated sites to achieve the efficient biodegradation of crude oil,especially its refractory residues.The gravimetric method was used to analyze the degradation efficiency of the enriched consortia and changes in the fractions of the crude oil.The effects of changes in environmental factors were also studied to determine the optimal oil-reducing conditions and assess the dominant bacteria of the mixed flora.Results show that all three consortia exhibit reliable crude oil-biodegradation abilities and that their mixture results in biodegradation rate are as high as(48.0±3.5)%over 30 d of incubation.The consortium mixture can degrade 11.1%of the refractory resins,79.7%of the saturated hydrocarbons,and 45.7%of the aromatics in crude oil.Neutral pH,an incubation temperature of 30℃,and low mineral salt concentrations(0.8%to 4.0%)are optimal for crude oil biodegradation.The dominant genera in the consortium mixture include Pseudomonas,Stenotrophomonas,Brucella,Serratia,Brevundimonas,and Achromobacter.The richness and diversity of the microbial community in the consortium remain stable during crude oil degradation.Therefore,microbial enrichment from multiple sources may be performed to construct a mixed consortium for crude oil pollution bioremediation.

Using Magnetic Technique to Increase Efficiency of Organic Pollutants Biodegradation in Wastewater

The intensity of Magnetic field by 200, 300 and 400 gaos were selective to study their impacts on bacteria Bacillus, Pseudomonas and yeasts Candida dubliniensis, Candida glabrata, lssatchenkia orientalis and Rhodotorula mucilaginosa growth and to reduce organic pollutants in wastewater by COD, TOC, TN and TP in concentrations of 180, 75, 52 and 84 ppm in pH 7.6 and treatment periods of 2, 4, 6 and 18 h in batch system. Results showed that magnetic field 300 gaos had higher ability to increase bacterial and yeasts growth by 400-600% in 18 h and reduced COD, TOC, TN and TP by 88, 85, 90 and 98.5% in same period treatment. While, the intensity of magnetic field 200 and 400 gaos have no effect on microorganisms growth and reducing organic pollutants. This study is first record for showing and explaining the positive effective of magnetic field on microorganisms growth.

Biodegradation of High Concentration of p-Nitrophenol （PNP） by Wastewater Microflora

Many nitrophenols tend to persist in the environment and they may become public health hazards. Among nitrophenols, p-nitrophenol （PNP） is a priority pollutant that has been widely used as pesticide. PNP is a toxic compound that enters the environment during manufacturing and processing of a variety of industrial products. This situation generalized its presence in multiple natural ecosystems： rivers, wastewaters, subterranean waters, soil treated by pesticides and urban atmosphere. This study aims to test the ability of wastewater microflora to degrade high concentration of PNP （500 rag/L） aerobically. An identification of the dominant microorganisms involved in the biodegradation is also carried. The cultures are performed using a minimum medium, where PNP is the sole source of carbon, energy and nitrogen. The kinetic of biodegradation is followed for more than 30 days of incubation at 30 ~C on a shaker （150 tours/min）. The obtained results show that more than 90% of PNP initial concentration is decomposed at the end of incubation. The isolation of microorganisms degrading PNP gave two bacterial colonies with different macroscopic aspects. Sequence analysis of 16S ribosomal DNA indicated that the PNP degrading isolates were closely related to members of the species： Pseudomonas aeruginosa and Bacillus cereus.

Study of Succinic Acid Production by Actinobacillus Succinogenes

Succinic acid has recently emerged as an important chemical （commodity） because it can be used for the manufacturing of synthetic resins and biodegradable polymers and as an intermediate for chemical synthesis. Till date, succinic acid is mainly produced by chemical processes, however, due to the environmental concerns and the concepts of sustainability, researches are directed towards the production of succinic acid by microbial fermentation. The fact that carbon dioxide （CO2） is needed by the microorganisms for succinic acid production is another interesting feature. The fermentation was carried out with Actinobacillus succinogenes using a two-level fractional factorial design 2sl. The variables analyzed and their levels were： concentration of glucose, yeast extract, temperature, pH and agitation. The results show that the variables that more influenced on succinic acid production were pH, temperature and yeast extract.

Evolution of Petroleum Hydrocarbons in Soil Polluted with Crude Oil Treated with a Natural Product

Bioremediation of petroleum hydrocarbons contaminated/polluted soils has been recognized as an efficient, economic, versatile and environmentally good treatment. This method is limited by the microorganisms activity in degrading the spills hydrocarbons. Low solubility of the hydrocarbons involves low bioavailability to microorganisms. The main objective of this research is to increase biodegradation of petroleum hydrocarbons by treating the crude oil polluted soil with the natural biodegradable product and bacterial inoculum. Biodegradation was quantified by total petroleum hydrocarbons （TPH） analyses. The paper presents data obtained in biodegradation process of an artificial polluted soil with 5% and 10% crude oil, treated with a natural biodegradable product and bacterial inoculum during two years of experiment. Biodegradation process takes time to rehabilitate and reuse of the soil in agricultural scopes.

The POM-DOM piezophilic microorganism continuum(PDPMC)—The role of piezophilic microorganisms in the global ocean carbon cycle

The deep ocean piezosphere accounts for a significant part of the global ocean,hosts active and diverse microbial communities which probably play a more important role than hitherto recognized in the global ocean carbon cycle.The conventional biological pump concept and the recently proposed microbial carbon pump mechanism provide a foundation for our understanding of the role of microorganisms in cycling of carbon in the ocean.However,there are significant gaps in our knowledge and a lack of mechanistic understanding of the processes of microbially-mediated production,transformation,degradation,and export of marine dissolved and particulate organic matter(DOM and POM)in the deep ocean and the ecological consequence.Here we propose the POM-DOM piezophilic microorganism continuum(PDPMC)conceptual model,to address these important biogeochemical processes in the deep ocean.We propose that piezophilic microorganisms(bacteria and archaea)play a pivotal role in deep ocean carbon cycle where microbial production of exoenzymes,enzymatic breakdown of DOM and transformation of POM fuels the rapid cycling of marine organic matter,and serve as the primary driver for carbon cycle in the deep ocean.

Biodegradation of Crude Oil in Contaminated Soils by Free and Immobilized Microorganisms

The efficiencies of free and immobilized bacterial cultures of petroleum hydrocarbon degraders were evaluated and compared in this study. Hydrocarbon-degrading microbial communities with high tolerance to and high degrading ability of crude oil were obtained from the soil contaminated with crude oil in the Yellow River Delta. Then, the microbial cells were immobilized in sodium alginate （SA） beads and sodium Mginate-diatomite （SAD） beads. The biodegradation of crude oil in soil by immobilized cells was compared with that by free cells at three inoculation concentrations, 1× 104 colony forming units （cfu） kg-^（-1）（low concentration, L）, 5 × 104 cfu kg^（-1） （medium concentration, M）, and 1× 105 cfu kg^（-1） （high concentration, H）. At 20 d after inoculation, the maximum degradation rate in the immobilized systems reached 29.8% （SAD-M）, significantly higher （P 〈 0.05） than that of the free cells （21.1%）, and the SAD beads showed greater degradation than the SA beads. Moreover, both microbial populations and total microbial activity reached significantly higher level （P 〈 0.05） in the immobilized systems than free cell systems at a same initial inoculation amount. The scanning electronic microscope （SEM） images also confirmed the advantages of the immobilized microstructure of SAD beads. The enhanced degradation and bacterial growth in the SAD beads indicated the high potential of SAD beads as an effective option for bioremediation of crude oil-contaminated soils in the Yellow River Delta.

Fluorescence characterization and microbial degradation of dissolved organic matter leached from salt marsh plants in the Yellow River Delta

Aims Salt marsh vegetation is an important contributor of dissolved organic matter(DOM)to coastal waters.The dynamics of DOM leaching from different marsh plants,however,have not been well studied or compared.Methods In this study,we conducted laboratory experiments to investigate the processes of DOM leaching from three common marsh plants(Phragmites australis,Suaeda salsa and Aeluropus littoralis)collected from the Yellow River Delta(YRD)salt marsh in October 2016.The YRD is one of the largest and most well-protected coastal ecosystems on the east coast of China.Important Findings We found that the plant leaves released DOM at much higher concentrations than the plant roots or stems,as measured by the dissolved organic carbon(DOC)and dissolved nitrogen(DN).On average,15%of the biomass C and 30%of the biomass N were released from the plant leaves as DOC and DN during the 27-day incubation period.The DOM released from the plants was very labile,and 92.4%-98.1%of the DOC and 88.0%-94.6%of the DN released from the plants were consumed by bacteria during the 27-day incubation period.The fluorescence characteristics of the plant-released DOM indicated that chromophoric dissolved organic matter was a major fraction of the DOM and that protein-like components were the primary organic fractions released from the plants.Bacterial degradation altered both the fluorescence properties and the chemical composition of the DOM.The results of the laboratory experiments were well supported by the field investigation,which indicated that a large amount of DOM was outwelled from the YRD salt marshes in late autumn.Our study suggests that the DOM released from the biomass of salt marsh plants provides an important source of both DOC and DN for marsh and coastal waters.The highly labile DOC and DN provide essential food sources to support microbial communities in the YRD salt marsh and adjacent coastal waters.

Using a Two-Liquid-Phase System to Investigate the Biodegradation of Trichlorobenzenes

Due to easy volatilization of volatile organic compounds from water,it is difficult to monitor their aerobic biodegradation in the traditional single water system.Whether a two-liquid-phase system(TLPS) could overcome this obstacle and enhance the degradation of volatile contaminants? In this study,a TLPS composed of silicone oil and water was employed to investigate the biodegradation of volatile compounds,trichlorobenzenes(TCBs),by the adapted microorganisms in an activated soil.The degradation and volatilization of TCBs in TLPS and in a single water system were compared.The results showed that due to volatilization losses of TCBs,the mass balance of TCBs in a single water system was very low.In contrast,using TLPS could effectively inhibit the volatilization losses of TCBs and achieved a very good mass balance during the biodegradation process.Meanwhile,the TLPS could increase microbial activity and microbial growth during the degradation process.With TLPS,the TCB degradation was in descending order of 1,2,4-TCB> 1,2,3-TCB>> 1,3,5-TCB,which was related to the exposed concentration of the contaminants in soil.This study showed that TLPS could be employed as an effective tool to evaluate the biodegradation of volatile hydrophobic organic compounds,which could not be achieved with the traditional single water system.