大亚湾裸甲藻种群动态及其关键调控因子

2008年1—12月对大亚湾养殖海域裸甲藻种群动态和主要环境因子进行了周年调查。结果表明,大亚湾海域裸甲藻类群以直径约为16～22μm的小型裸甲藻（Gymnodinium sp.）为主,另外米氏凯伦藻（Karenia mikimotoi）、链状裸甲藻（Gymnodnium catenatum）和血红哈卡藻（Akashiwo sanguinea）也有少量出现。裸甲藻种群密度呈现出明显的季节性变化特征：5月出现裸甲藻密度高峰,全年最大密度达到903 cells.mL-1,秋冬季节密度最小。不同站位裸甲藻密度也具有明显的空间分布差异,养殖及近岸海域密度普遍高于外海对照区。相关性分析结果表明,裸甲藻密度的关键调控因子包括温度、化学需氧量（COD）、可溶性有机氮（DON）和尿素浓度。裸甲藻高密度、高频率出现的温度范围在24～26℃,DON和尿素的质量浓度范围分别为N 156.38～187μg·L-1和N 17.4～38.9μg·L-1。在温度适宜的条件下,尿素等有机氮含量的增加可能成为裸甲藻赤潮的触发因子。     

Colonization of Penicillium oxalicum SL2 in Pb-contaminated paddy soil and its immobilization effect on soil Pb

Penicillium oxalicum SL2 (SL2) is a previously screened Pb-tolerant fungus that can promote crops growth. The relationship between SL2 colonization and Pb immobilization was studied to provide a theoretical basis for microbial remediation of Pb-contaminated paddy soil. In this study, green fluorescent protein (GFP) labeled SL2 was inoculated into different Pb-contaminated paddy soils (S1-S6). The Pb extracted from the soil by HNO₃, EDTA and CaCl₂ were used to characterize the available Pb. The results showed that the colonization of SL2 was divided into lag phase (0-7 days), growth phase (7-30 days), and mortality phase (30-90 days). SL2 colonized well in sandy soils rich in clay and total phosphorus with initial pH of 4.5-7.0. In addition, SL2 increased soil pH and decreased soil Eh, which was beneficial to immobilize Pb. In different soils, the highest percentages of CaCl₂-Pb, EDTA-Pb, and HNO₃-Pb immobilized by SL2 were 34.34%-40.53%, 17.05%-20.11%, and 7.39%-15.62%, respectively. Pearson correlation analysis showed that the percentages of CaCl₂-Pb and EDTA-Pb immobilized by SL2 were significantly positively correlated with the number of SL2 during the growth phase. SL2 mainly immobilized Pb in the growth phase and a higher peak number of SL2 was beneficial to the immobilization of Pb.     

温度、曝气和沉积物对绿潮硬毛藻分解的影响

为了解绿潮优势种——硬毛藻在温度、曝气和沉积物作用下的分解过程及三因素的效应大小,通过室内模拟研究了不同环境条件下硬毛藻早期分解过程中生物量、分解速率及藻体磷释放率的变化,分析了不同环境因子对藻体分解影响的效应大小.结果表明,高温(20~30℃)和添加沉积物均能促进硬毛藻的腐烂分解及藻体磷素释放,其中,30℃条件下含沉积物处理的最大分解速率可达12.13%·d-1,14 d后藻体磷释放率为90%以上.曝气一方面可通过扰动加速藻体生物量的损失和分解速率,另一方面提供了好氧环境,抑制了藻体生物分解和磷素释放,因而其影响效应较低.研究表明,高温和添加沉积物均可加速丝状硬毛藻的分解和藻体磷素释放,夏季应及时清除水体中滋生和衰亡的藻体.     

Optimized production of a novel bioflocculant M-C11 by Klebsiella sp. and its application in sludge dewatering

The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids（m/m）. A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration（SRF）decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity.     

Biodegradation of pendimethalin by Bacillus subtilis Y3

A bacterium strain Y3,capable of efficiently degrading pendimethalin,was isolated from activated sludge and identified as Bacillus subtilis according to its phenotypic features and 16 S rRNA phylogenetic analysis.This strain could grow on pendimethalin as a sole carbon source and degrade 99.5%of 100 mg/L pendimethalin within 2.5 days in batch liquid culture,demonstrating a greater efficiency than any other reported strains.Three metabolic products,6-aminopendimethalin,5-amino-2-methyl-3-nitroso-4-(pentan-3-ylamino) benzoic acid,and 8-amino-2-ethyl-5-(hydroxymethyl)-1,2-dihydroquinoxaline-6-carboxylic acid,were identified by HPLC-MS/MS,and a new microbial degradation pathway was proposed.A nitroreductase catalyzing nitroreduction of pendimethalin to 6-aminopendimethalin was detected in the cell lysate of strain Y3.The cofactor was nicotinamide adenine dinucleotide phosphate(NADPH) or more preferably nicotinamide adenine dinucleotide(NADH).The optimal temperature and pH for the nitroreductase were 30℃ and 7.5,respectively.Hg~(2+),Ni~(2+),Pb~(2+),Co~(2+),Mn~(2+) Cu~(2+),Ag~+,and EDTA severely inhibited the nitroreductase activity,whereas Fe~(2+),Mg~(2+),and Ca~(2+) enhanced it.This study provides an efficient pendimethalin-degrading microorganism and broadens the knowledge of the microbial degradation pathway of pendimethalin.     

锰过氧化物酶的固态发酵及其对染料的脱色作用

采用稻壳作为基质,利用裂褶菌F17固态发酵产锰过氧化物酶(MnP),通过正交实验对发酵条件进行优化,并对5种不同结构类型的染料进行脱色.结果显示,含水率、温度、Mn2 、Cu2 对裂褶菌F17产MnP有显著影响;MnP发酵的最优化条件为稻壳27g、黄豆粉3g、MnSO40.4mg·g-1、含水率150%、接种量50%、培养温度22℃,pH不调节,优化后酶活达到16.39 U·g-1,比优化前的酶活9.20 U·g-1提高了78.2%.优化后的发酵体系对染料刚果红、茜素红、Poly R-478、中性红和结晶紫的24h脱色率分别达到92.6%、90.3%、93.1%、87.3%和95.6%.     

Biosorption of Cu(Ⅱ) on extracellular polymers from Bacillus sp.F19

Biosorption can be an effective process for the removal of heavy metals from aqueous solutions.The adsorption of Cu(Ⅱ) from aqueous solution on the extracellular polymers (EPS) from Bacillus sp.(named MBFF19) with respect to pH,incubation time,concentration of initial Cu(Ⅱ),and biosorbent dose was studied.Biosorption of Cu(Ⅱ) is highly pH dependent.The maximum uptake of Cu(Ⅱ) (89.62 mg/g) was obtained at pH 4.8.Biosorption equilibrium was established in approximately 10 min.The correlation coeffcient of mor...     

红球菌PR-1菌株破乳性能研究

利用乳化剂Span 80配制出一种稳定的煤油-水乳浊液作为模型乳浊液,进而从大港油田废水中筛选出1株破乳能力较强的红球菌PR-1.该菌株培养液在55℃下8h可以使模型乳浊液完全破乳,且在实验条件下比化学破乳剂DGF-01具有更强的破乳活性.研究发现,乳浊液的破乳为线性增长过程,冻融和高压灭菌对其破乳能力没有影响,菌体细胞是破乳的主要活性成分,经超声波破碎及有机溶剂处理后其破乳活性显著降低.菌体表面有很强的疏水性,其对烃的粘附率为84%,碳链长度范围在C₂₇～C₅₄的枝菌酸类物质是保持菌体细胞完整性和疏水性的关键,其对细胞的破乳活性也至关重要.PR-1菌株发酵液用于原油乳状液的破乳具有操作方便,破乳率高,应用面广,无毒无害等优点,且能完全脱出J9-19原油乳状液中的水,因此可作为原油乳状液或油田采出水的破乳剂.     

多效唑的生物降解性研究

利用从多效唑生产废水排放口土壤中富集获得的混合微生物和纯培养菌研究多效唑的生物降解性。结果表明，微生物生物量与多效唑相对浓度之间呈高度负相关（ｒ＝－０９３）。混合微生物降解多效唑较纯培养菌株快，降解的最适温度为３０℃，最适ｐＨ值为７０，对高ｐＨ值有耐受性。好氧和厌氧条件下微生物均能降解多效唑。富集培养物中的主要构成菌为假单孢菌属（Ｐｓｅｕｄｏｍｏｎａｓｓｐ）。降解动力学反应遵循Ｍｏｎｏｄ关系式。