黄土高原地区土壤石油污染状况及生物修复技术研究进展

概述了黄土高原地区土壤石油污染状况及近年来该区油污土壤生物修复的研究进展,分别对微生物、植物及微生物-植物联合修复方法进行综述,强调生物强化技术在生物修复中的突出地位及植物-微生物联合修复方法的应用潜能。由于石油污染物的复杂性,现存技术在实际修复中效果并不明显,提出运用分子生物学技术研究酶功能基因、将代谢组研究融入油污土壤的修复、深入探究植物根际分泌物与微生物作用及菌根真菌生物降解机制的建议,旨在对黄土高原地区石油污染土壤修复探究工作奠定理论基础,对促进黄土高原地区土壤的保护及可持续利用具有重大意义。     

Interaction of Cd-hyperaccumulator Solanum nigrum L. and functional endophyte Pseudomonas sp. Lk9 on soil heavy metals uptake

Bioaugmentation is a promising method for assisting phytoextraction of heavy metals from contaminated soil, and the development of bioaugmentation-assisted phytoextraction requires the understanding of the mechanism involved in the interaction between plants and inocula. In this study, a pot study was conducted to evaluate the effect of bacterial endophyte Pseudomonas sp. Lk9 which can produce biosurfactants, siderophores and organic acids on the growth and metal uptake of Cd-hyperaccumulator Solanum nigrum L. growing in multi-metal-contaminated soil. The results revealed that Lk9 inoculation could improve soil Fe and P mineral nutrition supplies, enhance soil heavy metal availability, and affect host-mediated low-molecular-weight organic acids secretion, thereby significantly increasing S. nigrum shoot dry biomass by 14% and the total of Cd by 46.6%, Zn by 16.4% and Cu by 16.0% accumulated in aerial parts, compared to those of non-inoculated control. The assessment of phytoextraction showed that Lk9 inoculation elevated the bioaccumulation factor of Cd (28.9%) and phytoextraction rates of all metals (17.4%, 48.6% and 104.6% for Cd, Zn and Cu, respectively), while the translocation factors had negligible difference between Lk9 inoculation (3.30, 0.50 and 0.40 for Cd, Zn and Cu, respectively) and non-inoculated control (2.95, 0.53 and 0.42 for Cd, Zn and Cu, respectively). It was also found that the symbiotic association between S. nigrum and Lk9 significantly increased the soil microbial biomass C by 39.2% and acid phosphatase activity by 28.6% compared to those in S. nigrum without Lk9. This study would provide a new insight into the bioaugmentation-assisted phytoextraction of heavy metal-contaminated soils.     

生物强化技术治理维纶废水研究

利用筛选出的优势菌种在四川维尼纶厂进行了废水处理工程的技术改造研究。结果表明,DO和COD的检测值显示废水在曝气池中分布不均,有短流现象存在;进行技术改造后,相同条件下较以前对COD的去除率提高5%左右,系统的处理能力提高20%～30%,曝气停留时间缩短2 h,填料可提高COD的平均去除率为7.9%;并且试验后续1个月的运行结果表明系统运行状况良好。     

Bioaugmentation and biostimulation effects on PAH dissipation and soil ecotoxicity under controlled conditions

The degradation of spiked anthracene (ANT), pyrene (PYR) and benzo[a]pyrene (B[a]P) in soil (3000 mg ∑ 3 PAHs kg⁻¹ dry soil) was studied in aerobically incubated microcosms for 120 d. The applied treatments aimed at enhancing PAH removal from the heavily contaminated soils are: (i) bioaugmentation by adding aged PAH-contaminated soil (ACS) containing activated indigenous degraders; and (ii) combined bioaugmentation/biostimulation by incorporating sewage sludge compost (SSC) and decaying rice straw (DRS). The adopted treatments produced higher PAH dissipation rates than those observed in unamended PAH-spiked soils, especially for ANT and PYR in the presence of DRS or ACS (>96%). However, B[a]P was the most recalcitrant hydrocarbon to biodegradation. Extracellular enzyme investigation revealed the existence of ligninolytic activities in all soil treatments, including control but no relationship could be found with PAH dissipation. The ecotoxicological assessment indicated that regardless of applied treatment, PAH-spiked soils were chronically lethal to ostracod Heterocypris incongruens and confirmed the sensitivity of the microcrustacean to the concomitant presence of these three hydrocarbons. Lettuce root elongation inhibition was correlated with PAH level but the presence of SSC conferred a strong phytotoxic capacity to PAH-spiked soils. DRS amendment may constitute a cost-effective alternative for hydrocarbon bioremediation as it has impacted positively on soil microbial activity and enhanced PAH removal with no apparent changes in soil physico-chemical properties.     

Homogeneous inoculation vs. microbial hot spots of isolated strain and microbial community: What is the most promising approach in remediating 1,2,4-TCB contaminated soils?

We investigated the effectiveness of different inoculation approaches in enhancing the mineralization of [U-¹⁴C] labeled 1,2,4-trichlorobenzene (1,2,4-TCB) in soil. Inoculation was conducted with a soil-borne 1,2,4-TCB mineralizing microbial community (MC) as well as the Bordetella sp. strain F2 originally isolated from this community as the key degrader organism (IS). Both were applied either via liquid medium (LM) or attached on clay particles (CP). Fluorescence in-situ hybridization in combination with ¹⁴C-1,2,4-TCB mineralization measurements as well as measurements of ¹⁴C-residues in soil were used to investigate the bioaugmentation efficiency of the different approaches. Bordetella sp. cell numbers increased about 2-5 times during the incubation process, indicating that the bacteria could survive and develop in the new soil habitat. While the native soil showed negligible 1,2,4-TCB mineralization rates, soil inoculated with the MC attached on CP showed the highest 1,2,4-TCB mineralization rate per Bordetella cell, whereas the other inoculum approaches showed an increased but lower contaminant mineralization. Additionally, the MC-CP approach showed the highest cumulative 1,2,4-TCB mineralization as well as the highest formation of bound ¹⁴C-residues which is most likely equivalent to ¹⁴C incorporated into the microbial biomass. Thus, our results allow the conclusion that the application of a specific microbe-clay-particle-complex is the most promising approach for an accelerated in-situ mineralization of chemicals in agricultural soils.     

油污土壤降解细菌的分离鉴定及其生物强化研究

从大庆油田长期石油污染的土壤中分离出高效降解石油烃的菌株5种,通过生理生化分析和16Sr D-NA全序列分析,初步确定为Pseudomonas sp.(假单胞菌属)、Pseudomonas aeruginosa(铜绿假单胞菌属)、Aci-netobacter junii(琼氏不动杆菌属)、Microbacterium oxydans(微杆菌属)、Pseudomonas aeruginosa(铜绿假单胞菌属)。在摇瓶培养和土壤固体培养条件下的石油烃降解率都远远高出了对照组。同时通过改变初始盐浓度、N源和P源,初步探测了各菌株的最适生长和降解条件,为本土微生物强化的生物修复方法提供了新的菌种资源和信息,对进一步有效实现本土微生物强化具有重要意义。     

Biodegradation of aged residues of atrazine and alachlor in a mix-load site soil

A selected microbial consortium (SMC) capable of degrading two specific herbicides, alachlor (2-chloro-2′,6′-diethyl-N-[methoxymethyl]-acetanilide; AL) and atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT) was isolated from a pesticide-contaminated mix-load site soil. Evaluation of bioaugmentation as a feasible bioremediation strategy for this mix-load site soil (Site 5A) was initiated in standard laboratory biometer flasks utilizing the isolated SMC. The biometer flasks were monitored for CO₂ evolution and pesticide degradation. The total amount of CO₂ evolved from the treated biometer flasks was significantly different from the control flasks. The rate of CO₂ evolution was 2.6 times faster in the treated soil (0.0123 mM CO₂ d⁻¹ vs. 0.0048 mM CO₂ d⁻¹). The total net CO₂ produced in the treated biometer flasks was 0.9481 mM, representing mineralization of approximately 10% of the AT and AL initially present. Forty-eight percent of AT and 70% of AL was degraded in the inoculated biometer flasks. The first-order rate constants were 0.0064 d⁻¹ and 0.1331 d⁻¹ for AT and AL, respectively. The calculated half-life of AT was 108 d while a 50% decrease in AL occurred by Day 5. In just 2 d, 20% of the AT was degraded while only 10% of the AL disappeared. The initial fast degradation rate of AT was followed by a much slower, more gradual degradation rate period that lasted about 35 d. Alternatively, the rate of AL degradation increased after the second day resulting in 60% of the AL being transformed by the end of the first week. Alachlor degradation appeared to be dependent upon AT degradation especially during the first several days of the incubation period. Complete disappearance of the herbicides over the study time was not achieved.     

Water quality and phytoplankton stability in response to application frequency of bioaugmentation agent in shrimp ponds

Splitting the recommended weekly dosage of bioaugmentation agent and applied at varying frequencies were tested to determine its effects on water quality and phytoplankton stability in tiger shrimp (Penaeus monodon) grow-out ponds. The supplier's recommended weekly dosage was followed but at varying application frequencies namely: once per week, twice per week, and four times per week for the duration of 120 culture days. A treatment with no bioaugmentation was added as control. Results showed that ammonia and particulate organic matter levels were significantly lower and plankton die-off was greatly minimized if the product was applied four times a week application compared with twice a week and weekly applications. Significant reduction in the number of luminous Vibrio species was observed in ponds with more frequent applications than those with less. For shrimp, survival and production were significantly higher in ponds with twice and four times per week applications compared to the weekly application and the control (P < 0.05). Results of this study indicate that splitting the weekly dosage of bioaugmentation agent and applying it four times per week is highly beneficial and ideal for shrimp culture.     

Microbial intervention for better fish health in aquaculture: the Indian scenario

Aquaculture has evolved as the fastest growing food-producing sector and developed as an important component in food security. To keep a sustainable growth pattern, health management strategies must go beyond antibiotics and chemotherapeutics, which create resistant bacteria and immunosuppression in the host. Besides development of drug resistant bacteria and pathogens, the adverse effect of antibiotics is caused by their influence on the aquatic microflora, and the retention of harmful residues in aquatic animals. On the other hand, the microbes with their unique structure and cell wall components can trigger immunity, and thus exposure plays an important role in the evolution. Microbial intervention through an environmentally friendly approach is an alternative method of health management. India is endowed with a bounty of varied climatic conditions, microbial diversity and fish fauna and aquaculture systems offering challenges in biological and environmental pursuits. Producing about 4.4% of world’s fish and ranking third in global fish production, India trades about 2.4% in global fish market with the annual export earning being over $1311 million. Use of microbes for beneficial purposes is increasingly recognized as a valuable input for sustainable and responsible aquaculture. Microbial intervention in aquaculture can be broadly water/environment based through bioaugmentation, biostimulation, biocontrol measures, or (to generate) host response through probiotics, immunostimulants, and vaccines. Also, application of molecular methods such as polymerase chain reaction (PCR) and nucleic acid techniques are making increasing inroads into aquatic microbiological research in India. This paper elucidates all these aspects of microbial intervention in aquaculture, high-lighting Indian research and accomplishments.     

石油污染盐碱土壤生物修复模式

石油污染盐碱土壤的生物修复从机理上看,最主要的作用是微生物的降解能力,而植物和其他措施则主要起着辅助和刺激土壤微生物发挥效用的作用.因此,将石油污染盐碱土壤的生物修复模式划分为生物强化、生物刺激以及生物强化和生物刺激组合的三大类.生物强化主要强调石油污染物降解的直接加强措施,使该作用成为修复的主流或强势;而生物刺激则强调环境因素的改变,使生物强化效果提高的各种间接措施.在实际应用过程中,生物强化和生物刺激联合模式是提高石油污染物快速降解转化的主要生物修复模式.目前国内外的研究结果表明,在降解率方面,生物刺激＜生物强化＜生物强化和生物刺激的组合.根据污染土壤的具体情况,一般采用的生物刺激手段越丰富,降解效果越好.一般地,影响石油降解的顺序为营养＞表面活性剂＞电子受体.因此,生物强化是生物修复的主体,辅助以适当的生物刺激手段是石油污染盐碱土壤生物修复模式的首选.而成本有限时,应优先考虑营养刺激.