鼠李糖脂对土壤中原油降解的促进

从辽河油田石油污染的土壤中筛选、驯化得到三株对辽河原油具有较高降解效果的菌种(H1,H2,H3),选取对原油降解率最高的菌株H1为供试菌种,以受原油污染的天津滨海地区典型土壤(淤泥质粉质粘土夹粉砂)为供试土样,考察了不同浓度下鼠李糖脂对菌种H1生长、原油增溶和降解效果的影响.结果表明,鼠李糖脂对菌种H1无毒性,其对原油增溶效果明显,原油溶解度随着鼠李糖脂浓度的增加而增加.降解动力学实验结果表明,原油的降解符合指数常数模型.鼠李糖脂能明显促进土壤中原油的降解,缩短降解周期,大大提高修复效率.     

人工湿地填料有机堵塞问题的化学溶脱法室内模拟

用化学溶脱法解决人工湿地填料的有机堵塞,结果表明:用碱类、酸类、强氧化剂和洗涤剂可以使有效孔隙率和渗透系数均有不同程度的增加,以强氧化剂类(次氯酸钠)最为明显,可以使渗透系数恢复到原来的69%;三种溶液都对基质中的微生物类群和基质酶产生了伤害,但是经过7d可以基本恢复,说明解决人工湿地有机堵塞的问题可以借鉴和尝试"溶脱法".     

Mechanical Property and Biodegradability of Cast Films Prepared from Blends of Oppositely Charged Biopolymers

Biodegradable cast films of about 50 m thickness were fabricated by blending oppositely charged biopolymers such as anionic starch–chitosan, and cationic starch–pectin. The tensile strength and elongation at break (%) of films were evaluated as well as their capacity to degrade in compost. Films recovered from soil every 48 h showed consistent degradation (weight loss), diminution of the polymers characteristic peak absorbance in the carbohydrate fingerprint region of the FTIR, and changes in the surface morphology via scanning electron microscopy (SEM). Anionic starch–chitosan films had much superior tensile strength and elongation compared to cationic starch–pectin, suggesting that the ionic bonds formed between anionic-starch and positively charged groups in chitosan polymer were much more stable and stronger. Initially, both films lost about 36% weight within 96 h, which also correlated well with the loss in the characteristic absorption peaks in the region of the infrared spectrum typical of biopolymers. The total mineralization of films by microorganisms in compost soil was also measured using respirometric techniques. Though the rate of mineralization differed for two formulations, total mineralization (extent) for both films were achieved within 45 days.     

Polycyclic aromatic hydrocarbon biodegradation and extracellular enzyme secretion in agitated and stationary cultures of Phanerochaete chrysosporium

The extracellular enzyme secretion and biodegradation of polycyclic aromatic hydrocarbons (PAHs) were studied in agitated and shallow stationary liquid cultures of Phanerochaete chrysosporium. Veratryl alcohol and Tween80 were added to cultures as lignin peroxidase (LIP) and manganese peroxidase (MnP) inducer, respectively. Shallow stationary cultures were suitable for the production of enzyme, whereas agitated cultures enhanced overall biodegradation by facilitating interphase mass transfer of PAHs into aqueous phases. The use of a LIP stimulator, veratryl alcohol, did not increase PAH degradation but significantly enhanced LiP activity. In contrast, Tween80 increased both MnP secretion and PAH degradation in shallow stationary cultures. On the other hand, high PAH degradation was observed in agitated cultures in the absence of detectable LIP and MnP activities. The results suggested that extracellular peroxidase activities are not directly related to the PAH degradation, and the increased solubility rather than enzyme activity may be more important in the promotion of PAH degradation.     

绿脓杆菌S6产表面活性剂对PAHs增溶效果研究

文章以超声取-高效液相色谱法研究铜绿似单细胞S6菌产生物表面活性剂在浓度、pH值、温度及时间下对萘、蒽.芘、苯并蒽的增溶效果,结果表明:一定浓度范围内,表面活性剂浓度越高,萘、蒽、芘、苯并蒽的溶解度越大;固定生物表面活性剂浓度下,在对萘、蒽、苯并蒽及芘进行增溶时,pH值应控制在6～8之间,最好设置pH值为8;在对萘、蒽...     

Effect of fungicides on plant growth promoting activities of phosphate solubilizing Pseudomonasputida isolated from mustard (Brassica compestris) rhizosphere

This study was navigated to examine the effects of fungicide-stress on the activities of plant-growth-promoting rhizobacterium Pseudomonasputida with inherent phosphate solubilizing activity. The fungicide-tolerant and phosphate solubilizing P.putida strain PS9 was isolated from the mustard rhizosphere and tentatively identified following standard morphological, physiological and biochemical tests. To further consolidate the identity of the strain PS9, the 16S rDNA sequence analysis was performed. Following the BLAST program, the strain PS9 was identified as P.putida. In the presence of the varying concentrations (0-3200 μg mL⁻¹; at a two fold dilution interval) of four fungicides of different chemical families (tebuconazole, hexaconazole, metalaxyl and kitazin) amended in minimal salt agar medium, the P.putida strain PS9 showed a variable tolerance levels (1400-3200 μg mL⁻¹) against the tested fungicides. The strain PS9 produced plant-growth-promoting (PGP) substances in significant amount in the absence of fungicides. In general, fungicides applied at the recommended, two and three times of the recommended rates, decreased the PGP attributes of P.putida the strain PS9 and affected the PGP activities in concentration-dependent manner. Fungicides at the recommended dose had minor reducing effect while the doses higher than the recommended dose significantly reduced the PGP activities (phosphate solubilization, salicylic acid, 2,3-dihydroxy benzoic acid, and indole-3-acetic acid production except exo-polysaccharides, hydrogen cyanate and ammonia production). Of the four fungicides, tebuconazole generally, showed maximum toxicity to the PGP activities of the strain PS9. This study inferred that fungicides must be examined in vitro for their possible adverse effects on soil micro flora before their application in agricultural fields. Moreover, the results also suggested the prerequisite of application of fungicide-tolerant PGPR strains as bioinoculants so that their PGP activities may not be suppressed under fungicide stress.