Inhibitory properties of Enterococcus spp. isolated from faeces of healthy dogs

The aim of the present study was to evaluate the inhibitory effect by the cross-streak method of nine Enterococcus faecium strains isolated from faeces of healthy dogs and their treated and non-treated cell-free supernatant (CFS) by the well-diffusion test on the growth of potentially pathogenic bacteria isolated from clinical cases and aflatoxigenic Aspergillus section Flavi and the consequent aflatoxin B₁ (AFB₁) production. Results obtained from the cross-strake assay showed that E. faecium MF1, GJ18 and GJ40 presented the major inhibitory activity against all pathogenic strains assayed; E. faecium GJ40 produced the larger inhibitory zones (26–27 mm). Well-diffusion test results showed that the majority of the enterococci strains CFS had antimicrobial activity against the pathogenic microorganisms, especially on Gram negative indicators. Cell-free supernatant of E. faecium GJ40 was the one that produced the largest inhibition zones (14 to 21 mm) in the majority of the indicator microorganisms assayed. All supernatants treated with 10 N NaOH (pH6) showed no inhibitory effect on the indicator strain assayed. With respect to fungal inhibition, any of the CFS assayed significantly inhibited the Aspergillus strains growth. But, in general, all CFS reduced AFB₁ production from 8 to 87%. The results demonstrate that enterococci isolated from healthy dog feaces produce substances with the capacity to inhibit some potential pathogenic bacteria growth and the capacity of inhibiting or reducing the AFB₁ production in vitro.     

柠檬酸中和废水回用技术研究

本文研究了柠檬酸中和废水回用工艺技术。中和废水经碱（ＮａＯＨ）沉淀和酸（Ｈ２ＳＯ４）中和预处理措施,直接用于发酵配料。实验用菌株Ｃ－９８自黑曲霉ＣＢＸ－１２分离获得。最佳发酵条件：总还原糖１４％～１６％,麦麸２．５％,初始ｐＨ６．５,乙醇１．５％。同传统的柠檬酸废水处理工艺比较,该工艺在投资和运转成本方面具有潜在的优势。     

曲霉WZ-2对染料脱色研究

从废水池污泥中分离到一株染料脱色曲霉ＷＺ－２,它对不同染料均有较好的脱色效果。在３３￣４０℃温度范围内ＷＺ－２对活性桃红ＫＤ－８Ｂ的脱色率为８４％￣９８％,最佳脱色温度为３３℃,ｐＨ值在４．０￣７．０范围内ＷＺ－２对直接耐晒翠蓝ＧＬ的脱色率为８３％￣９６％,最佳脱色ｐＨ为６．０,碳源、氮源及接种量对其脱色率均有影响,染料脱色物的紫外－可见光谱分析表明,可见光区５２０ｎｍ处的吸收峰完全消失,而紫外光     

黑曲霉吸附弱酸性艳蓝RAWL机理研究

考察了黑曲霉对染料吸附性能的pH响应模式,红外光谱表征了菌体表面的主要官能团组成,化学修饰定量研究了不同官能团的染料吸附贡献.结果显示,在低pH条件下,菌体表现出最优的染料吸附特性:随着pH值由2.0升至6.0,染料吸附量由39.6mg/g降至9.3mg/g.菌体表面含有氨基、羧基和磷酸根.高pH下,羧基和磷酸根电离导致菌体表面带负电并与染料发生静电斥力,使得染料吸附量下降;低pH下,氨基的质子化使得菌体带正电并通过静电吸引提高染料吸附.甲基化氨基在酸性条件下仍然可以质子化,故氨基甲基化修饰后染料吸附性能不变;乙酰化氨基在酸性体系中失去质子化能力,乙酰化修饰菌体染料吸附性能下降51.6%.氨基质子化引起的菌体正电性和染料负电性之间的静电引力是染料吸附的重要机制.图6参10     

Bioremediation of metal contamination

A study was initiated to evaluate the use of the fungus Aspergillus niger for bioleaching and then todetermine the effect of process steps, the tailingsconcentration and type of substrate. An oxidized miningtailing containing mainly copper (7240 mg kg^-1 tailings) was studied. A sucrose and mineral salts medium was initially used to produce citric and gluconic acids by A. niger atvarious concentrations of tailings (1, 5, 7, 10 and 15% w/v).Maximal removal of up to 60% of the copper was obtained forthe 5% tailings when the organic acid supernatant was addedto the tailings. In a single step process, A. niger wasthen grown in the presence of mining tailings at variousconcentrations. Maximum copper solubilization (63%) occurredwith 10% mining tailings using sucrose as the substrate.Other substrates were then evaluated including molasses, corncobs and brewery waste (10% mining tailings). Sucrose gavethe best results for copper removal, followed by molasses,corn cobs and brewery waste. Other experiments usingultrasound as a pretreatment showed that 80% removal of thecopper could be obtained for a 5% tailings concentration. Inconclusion, leaching of copper from mining tailings istechnically feasible using A. niger but furtherresearch will be required to increase the economic feasibilityof the process.     

氧化乐果曲霉降解特性和中间产物的研究

在氧化乐果和葡萄糖共基质条件下,曲霉G21优先利用葡萄糖作为碳源,葡萄糖耗尽后开始快速降解氧化乐果,高浓度氧化乐果抑制了曲霉G21的生物降解活性.GC-MS分析表明,曲霉G21降解氧化乐果的主要中间产物为O,O,S-三甲基磷酸酯,氧化乐果降解率提高不会导致该有毒中间产物的累积效应.     

利用响应面法优化生物淋滤飞灰处理条件的研究

利用响应面法进行试验设计,选定蔗糖初始浓度、黑曲霉孢子浓度、投加的飞灰浓度以及飞灰投加时间作为影响因素,对生物淋滤城市生活垃圾焚烧飞灰的处理条件进行优化.通过响应面法,得到飞灰中Cd、Cr、Fe、Mn、Zn及重金属总量与4种因素之间的非线性回归方程,确定了生物淋滤的最适条件范围:蔗糖初始浓度为114~126g/L;黑曲霉孢子浓度为(1.6~2.1)×107个/mL;飞灰浓度为29~39g/L;飞灰投加时间为3.6~4.4d.在最适条件下,70g/L飞灰经20d生物淋滤后,溶出重金属总浓度降为901mg/L,占飞灰中重金属总量的41%,处理后飞灰的重金属浸出毒性远低于国家标准.     

复合菌利用酱油废液制备生物絮凝剂及其絮凝特性分析

利用酱油曲霉(Aspergillus sojae)和毕赤酵母(Pichia membranifaciens)复合菌以酱油酿造废液作为培养基生产生物絮凝剂,研究了外加碳源、外加氮源、培养基的初始pH值以及酱油酿造废液浓度等因素对絮凝剂产量及絮凝剂活性的影响,并考察了所制备絮凝剂的絮凝特性.结果表明,酱油酿造废液稀释1倍,加入5g/L乙醇作为补充碳源,不需添加氮源,调节pH值至5.0左右,培养30h,生物絮凝剂的产量可达到5.92g/L.实验制备的生物絮凝剂具有较好的絮凝效果,对高岭土悬浊液的去除率达到98.3%;对酱油废水、酿酒废水、生活污水、乳品废水等实际废水的浊度的去除率78.2%~92.3%,COD去除率为64.2%~85.2%.     

不同粒径曲霉-好氧颗粒污泥的微环境对脱氮除磷能力影响

针对目前实验室好氧颗粒污泥颗粒化慢,稳定性差等问题。以自发成球的曲霉为核心,开发了絮状污泥的快速颗粒化技术,提高体系运行稳定性。对形成的大 (3.0 mm<d≤5.0 mm) 、中 (1.5 mm<d≤3.0 mm) 、小 (d≤1.5 mm) 3种尺寸的曲霉-好氧颗粒污泥 (Aspergillus-AGS) 进行了性能对比,然后结合脱氮除磷性能实验监测数据,对曲霉投加后菌群结构的演变进行分析。大尺寸的Aspergillus-AGS是最优选,能促进胞外多聚物的分泌,从而有利于颗粒化性能提高,维持颗粒稳定结构,并且提高了污染物去除效率。在投加不同粒径的反应器中,通过菌群分析,曲霉Aspergillus作为优势载体菌种在对照组絮状污泥、大、中和小尺寸反应器中占比分别是4.17%、85.67%、47.20%和58.00%。此外,大尺寸颗粒反应器中,细菌种类NOB、PAO占比相比其他反应器明显更高,其中反硝化菌Ferruginibacter、Castellaniella等丰度较高,脱氮除磷有明显优势,L-AGS体系6 h内氨氮的去除率为77.2%,总氮去除率为52.8%,总磷的去除率为49.2%,硝酸盐的去除率为93.9%。     

黑曲霉固态发酵三七渣产纤维素酶

考察了硫酸铵添加量、磷酸二氢钾添加量、三七渣粒径、培养基含水率等因素对黑曲霉固态发酵三七渣产纤维素酶的影响,并采用正交实验对培养基制备条件进行了优化。研究结果表明,三七渣作为发酵培养基用于生产纤维素酶是可行的;含水率、硫酸铵添加量、磷酸二氢钾添加量以及三者之间的交互作用对实验结果的影响极显著(P 含水率> 磷酸二氢钾添加量> 交互作用;优化的培养基制备条件为:采用过80目的筛三七渣,硫酸铵添加量为40 mg/g干药渣,磷酸二氢钾添加量为10 mg/g干药渣,初始含水率为55%,pH值自然,在此条件下发酵,所产CMC酶活可达73.23 IU/g湿物料。