利用固定化菌半连续生产微生物絮凝剂的研究

利用多孔聚酯泡沫为载体,进行了微生物絮凝剂产生菌的固定化条件优化和半连续生产絮凝剂的研究。研究发现,利用多孔聚酯可吸附固定XN1菌丝细胞,且能够较长时间保持高的活性。选择载体颗粒0.5cm×0.5 cm×0.5 cm,固液比为6 g/L,接种量105个孢子/mL培养基可达到较好的固定化和产絮凝剂效果。利用最佳固定化条件进行絮凝剂的摇瓶半连续生产实验发现,在最佳条件下,固定化XN1菌产絮凝剂可连续达12批次,且絮凝活性均在90%以上,说明利用多孔聚酯泡沫颗粒作为固定化载体,连续生产絮凝剂的方法是可行的。且和游离菌生产絮凝剂相比,生产效率可提高77.78%。     

微生物絮凝剂产生菌固定化条件的优化

采用多种固定化方法及载体,进行了微生物絮凝剂产生菌M09固定化方法及条件的研究,并对其所产絮凝剂在不同存储条件下絮凝活性的稳定性进行探讨。结果表明,选用粒径为0.5 cm×0.5 cm×0.5 cm的多孔聚氨酯泡沫为固定化载体,4 g/L的固液比,使用初始蔗糖浓度为2%,NaNO3为0.4%的培养基,28℃振荡培养60 h可获得较高活性的固定化细胞,发酵上清液能够保持较高的絮凝率。研究还发现,在室温条件下,利用此工艺所产高絮凝活性发酵液在含有菌体的反应器内自然静置,发酵液絮凝率仍可缓慢持续上升,维持较高水平达数日,具有较高的稳定性。     

螺旋纤维床固定化生物反应器同时产酶降解壳聚糖的研究

采用多孔聚酯泡沫固定里氏木霉,在鼓泡柱固定化反应器中同时产酶降解壳聚糖。结果表明通过控制降解时间可以得到不同平均聚合度的降解产物。在28℃,pH4.8,通气量3vvm条件下,利用固定化反应器,在30d内连续进行10批同时产酶降解试验,结果发现壳聚糖酶活力和壳聚糖降解率能保持稳定。每批产生的壳聚糖酶活力平均达到0.15u/mL以上,壳聚糖平均降解率为73%。     

一株絮凝剂产生菌的筛选及其絮凝特性研究

目的:筛选并研究对有毒物质有一定耐受性的絮凝剂产生菌。方法:利用含苯酚、邻苯二甲酸二丁酯和Pb2(SO4)3的分离培养基从土壤和活性污泥中分离筛选絮凝剂产生菌,对所得的菌种进行摇瓶发酵试验,分别考察其产絮凝剂的周期、絮凝活性分布以及对有毒物质的耐受性等特征,通过提取絮凝剂,将其絮凝活性与其它絮凝剂进行比较。结果:得到一株对苯酚具有一定耐受性的絮凝剂产生菌B2(Serratiasp.),其产絮凝剂的最佳培养时间为48h,絮凝率高于80%。苯酚浓度达0.6g/L时,B2菌的絮凝活性仍高于70%。其90%的絮凝物质集中于菌体,且热稳定性好,对多种悬浊液的絮凝活性高于硫酸铝、PAC。结论:新型絮凝剂产生菌B2对苯酚耐受性强,且絮凝剂提取简便,具有重要的研究价值。     

微生物絮凝剂产生菌的筛选及培养条件的优化

目的:从好氧活性污泥、土壤和河泥中分离筛选具有较高活性的絮凝剂产生菌,并优化其培养条件;方法:通过常规分离获得目的菌株,运用单因素法考察培养时间、培养温度、发酵液初始pH值及摇床转速对菌株絮凝活性的影响;结果:得到了絮凝活性较高的菌株,经过优化得出,其最佳培养时间和温度分别为48h和30℃,发酵液最佳初始pH值为7.0,最佳摇床转速为120r/min,在最佳培养条件下,RF-32对高岭土悬浊液絮凝率为84.32%。结论:从活性污泥中可筛选出较高活性的絮凝剂产生菌,研究发现,菌株的絮凝活性与其生长量呈同步增长趋势,并在一段时间后达到一稳定值。培养时间、培养温度、发酵液初始pH值及摇床转速均能通过一定的作用因素对菌株生长情况产生影响,进而影响其絮凝活性。     

微生物絮凝剂产生菌的筛选和发酵条件研究

设计了微生物絮凝剂产生菌菌种筛选模型,并从土壤和活性污泥中筛选到５１株絮凝剂产生菌,经复筛获得两株絮凝活性较高的菌株,分别定名为Ｎｏｃａｒｄｉａ,ＪＩＭ－８９和ＪＩＭ－１２７。对两株菌的发酵条件,特别是培养基组成,进行了初步研究。两株菌所产生的絮凝剂,对大肠杆菌悬液２０ｍｉｎ的絮凝活性在１０００ｕ／ｍｌ,最高可达１２４８ｕ／ｍｌ。     

假单细菌GX_4-1利用鱼粉废水产絮凝剂的研究

研究了假单胞菌 (Pseudomonassp .)GX4 1利用鱼粉废水产生絮凝剂的条件 ,结果表明 ,适宜条件为废水COD浓度为 1 0g/L左右、初始pH为 7～ 9、培养温度为 30℃、摇床转速为 1 0 0～ 2 50r/min ,此时的絮凝率可高达 99 5%。同时发现在废水培养基不灭菌的条件下 ,该菌仍能产生高效的絮凝剂。该菌利用鱼粉废水产生的絮凝剂对高岭土悬液、土壤悬液和细活性炭粉末悬液和电瓷厂污水均有较好的絮凝作用。     

提高复合型产絮菌F2-F6产絮能力的驯化方法

为了提高复合型产絮菌F1-F6的产絮能力,采用贫富营养交替的方法,利用发酵法生物制氢反应器排放的废液连续驯化复合型产絮菌F1-R。试验结果表明,此驯化方法可以有效地促进复合型产絮菌F1-R利用生物制氢废液产絮,絮凝率由11.4％提高到92．4％。调节高岭土悬浊液pH值的顺序对絮凝率有较大影响,后调节pH值比先调可以获得更高的絮凝率。生物絮凝剂与无机絮凝剂AlCl3结合有更好的絮凝效果。     

生物絮凝剂絮凝活性评价方法的探讨

对生物絮凝剂絮凝活性的评价方法进行了探讨。研究发现,在固定絮凝剂添加量的情况下仅仅比较絮凝率大小,从而对絮凝活性进行评价的方法是不科学的。絮凝剂絮凝活性应以絮凝率和絮凝剂最适添加量两个指标为其活性评价参数,在有较高絮凝率的情况下,絮凝剂添加量越少则絮凝活性越高。     

假单细菌GX4-1利用鱼粉废水产絮凝剂的研究

研究了假单胞菌 (Pseudomonassp .)GX4 1利用鱼粉废水产生絮凝剂的条件 ,结果表明 ,适宜条件为废水COD浓度为 1 0g/L左右、初始pH为 7～ 9、培养温度为 30℃、摇床转速为 1 0 0～ 2 50r/min ,此时的絮凝率可高达 99 5%。同时发现在废水培养基不灭菌的条件下 ,该菌仍能产生高效的絮凝剂。该菌利用鱼粉废水产生的絮凝剂对高岭土悬液、土壤悬液和细活性炭粉末悬液和电瓷厂污水均有较好的絮凝作用。     

Characterization of bioflocculants from biologically aerated filter backwashed sludge and its application in dying wastewater treatment

In this study, the feasibility of bioflocculant extraction from backwashing sludge to reduce its production costs was investigated. Results showed that ultrasound and base treatment could significantly enhance bioflocculant extraction efficiency, however, flocculating activity was affected. It was observed that bioflocculants extracted from sludge of pH 11.0 had no flocculating activity. In contrast, bioflocculants extracted from sludge of pH 5.0, named as M-1, had good flocculating activity. To further study the flocculating activity of M-1, factors such as bioflocculant dosage, temperature and pH of the reaction solution were tested. The optimal conditions were 6.0 mg/l bioflocculant dosage and pH 5.0, at a temperature of 10 °C. Under these conditions, the flocculating rate of kaolin clay was 92.67%. The effectiveness of such bioflocculants in the decolorization of synthetically dyed wastewater was then examined. In flocculating methylene blue and fast blue in aqueous solutions, decolorization efficiency levels were 82.9% and 77.8%, respectively.     

高效微生物絮凝剂D6对屠宰废水的应用研究

筛选出一株针对屠宰废水有高效絮凝活性的微生物絮凝剂产生菌,并对其所产微生物絮凝剂D6进行单因子絮凝条件优化和正交试验优化得到最佳絮凝条件。絮凝条件包括:微生物絮凝剂D6投加量、pH、金属离子种类、1%CaCl₂投加量。试验中发现碱性环境是微生物絮凝剂D6发挥絮凝活性的前提,表明微生物絮凝剂D6分子链的充分伸展对絮凝作用起决定因素,因此微生物絮凝剂D6的絮凝机理为吸附架桥作用。其最佳絮凝条件为微生物絮凝剂D6的投加量为25mL·L^-1,1%CaCl₂投加量55mL·L^-1,pH为8。在最佳絮凝条件下,絮凝率为96.6%,浊度去除率为97.8%,SS去除率为92.6%。     

Production and characterization of a bioflocculant by Proteus mirabilis TJ-1

A bioflocculant TJ-F1 with high flocculating activity, produced by strain TJ-1 from a mixed activated sludge, was investigated with regard to its production and characterization. By 16S rDNA sequence and biochemical and physiological characteristics, strain TJ-1 was identified as Proteus mirabilis. The most preferred carbon source, nitrogen source and C/N ratio (w/w) for strain TJ-1 to produce the bioflocculant were found to be glucose, peptone and 10, respectively. TJ-F1 production could be greatly stimulated by cations Ca(2+), Mg(2+) and Fe(3+). The optimal conditions for TJ-F1 production were inoculum size 2 per thousand (v/v), initial pH 7.0, culture temperature 25 degrees C, and shaking speed 130r/min, under which the flocculating activity of the bioflocculant reached 93.13%. About 1.33 g of the purified bioflocculant, whose molecular weight (MW) was 1.2 x 10(5) Da, could be recovered from 1.0 l of fermentation broth. Chemical analysis of bioflocculant TJ-F1 indicated that it contained protein (30.9%, w/w) and acid polysaccharide (63.1%, w/w), including neutral sugar, glucuronic acid and amino sugar as the principal constituents in the relative weight proportions of 8.2:5.3:1. Scanning electron microscopy (SEM) image of the purified solid-state TJ-F1 showed that it had a crystal-linear structure. Spectroscopic analysis of the bioflocculant by Fourier-transform infrared (FTIR) spectrometry indicated the presence of carboxyl, hydroxyl and amino groups preferred for the flocculation process.     

Study on the flocculability of the Arthrobacter sp., an actinomycete resuscitated from the VBNC state

A bioflocculant with high flocculating activity, LC13-SF, produced by strain LC13^T which was in a viable but nonculturable (VBNC) state, and which was woken up by Rpf (resuscitation promoting factor), was systematically investigated with regard to its fermentation conditions and flocculating activity. The key parameters influencing the bioflocculant LC13-SF were investigated through measuring the optical density at 660 (OD₆₆₀) of the fermentation liquid and the optical density at 550 (OD₅₅₀) of the centrifugal supernatant. The flocculating efficiency and the Zeta potentials were chosen as the response variables for the study of the flocculating activity. The results showed that the optimal conditions for bioflocculant LC13-SF production were a fermentation time of 72 h, an initial pH of 7.0, a fermentation temperature of 30°C and a shaking speed of 150 r/min. The optimized flocculating process was as follows: a final volume percentage of bioflocculant LC13-SF and 0.5% (w/w) CaCl₂ were 1.5 and 5%, respectively in a 4 g/L Kaolin suspension, and the system pH was adjusted to 8.0. Under these conditions, the flocculating efficiency and the absolute value of the Zeta potential reached 94.83% and 4.37, respectively.     

Bioflocculant production by Bacillus sp. Gilbert isolated from a marine environment in South Africa

In our previous study we reported on the bioflocculant production by a Bacillus species isolated from sediment samples of Algoa Bay in the Eastern Cape Province of South Africa. In the current study we carried out further evaluation on the effect of different culture conditions on the bioflocculant production, as well as characterised the bioflocculant produced in detail. The bacteria produced bioflocculant optimally under the following conditions: using sodium carbonate (95.2% flocculating activity) and potassium nitrate (76.6% flocculating activity) as carbon and nitrogen sources, respectively; inoculum size of 3% (v/v); initial pH 9.0; and Al³⁺ as coagulant aid. The crude bioflocculant retained 44.2% residual flocculating activity after heating at 100°C for 15 min. Chemical analysis of the Bacillus sp. Gilbert purified bioflocculant demonstrated that it was composed mainly of polysaccharide. Fourier transform infrared spectroscopy analysis revealed the presence of hydroxyl, carboxyl and methylene groups in the bioflocculant and energy-dispersive X-ray analysis detected the elemental composition in mass proportion (% w/w) of C, N, O, S and P as 4.12:7.40:39.92:3.00:13.91. Scanning electron micrograph image of the bioflocculant revealed an amorphous compound.     

Harvest of Scenedesmus sp. with bioflocculant and reuse of culture medium for subsequent high-density cultures

The optimal flocculating conditions for harvesting high-density cultures of Scenedesmus sp. were investigated using inorganic coagulants and the bioflocculant produced by Paenibacillus polymyxa AM49. The flocculated medium as nutrients for subsequent algal cultivation was also tested. Consecutive treatment with 8.5 mM CaCl(2) and 0.2 mM FeCl(3) as coagulants and 1% bioflocculant from the culture broth of P. polymyxa AM49 showed the highest flocculating activity of up to 95% for high density algal cultures. The medium flocculated with the coagulants and bioflocculant showed less than 8% decrease in the growth yield in the subsequent algal cultivation. Furthermore, a 20% or 50% fresh BG11 medium supplement allowed the flocculated medium to maintain a high growth yield in subsequent algal cultivation. These results suggest that the flocculation method presented here is efficient and bio-friendly, and allows the reuse of the flocculated medium, thereby contributing to the economic cultivation and harvest of microalgae.     

Production of an exopolysaccharide bioflocculant by Sorangium cellulosum

AIMS: To isolate a new exopolysaccharide bioflocculant produced by the myxobacterium Sorangium cellulosum NUST06, and to characterize its chemical composition and expolysaccharide production relative to carbon source. METHODS AND RESULTS: Exopolysaccharide levels and biomass production by S. cellulosum NUST06 were analysed relative to carbon source. Glucose in the medium at a level of 3 g l(-1) completely inhibited cell growth and exopolysaccharide production, but low concentrations of glucose (1-2 g l(-1)) could stimulate cell utilization of starch. The chemical composition and flocculating activity of the NUST06 exopolysaccharide was investigated. The flocculant comprised 38.3% proteins and 58.5% carbohydrates, of which glucose, mannose and glucuronic acid were present at 51.3%, 39.2% and 10.5%, respectively. The flocculating activity of the NUST06 flocculant depended strongly on cations. CONCLUSIONS: It is feasible to produce an exopolysaccharide bioflocculant by the strain NUST06 in a mineral salts medium using starch as a carbon source. SIGNIFICANCE AND IMPACT OF THE STUDY: This strain may be advantageous for commercial bioflocculant production and may enrich existing knowledge of myxobacteria.     

一种富集高温栅藻Desmodesmus sp. F51的新型生物絮凝剂

[背景]海科贝特氏菌(Cobetia marina)可产生大量具有絮凝活性的胞外产物,可视为一种新型的生物絮凝剂。高温栅藻(Desmodesmus sp.F51)是一种具有较高叶黄素含量的微藻,被认为是一种新兴的叶黄素来源,但利用该生物絮凝剂高效富集高温栅藻的相关研究迄今尚未见报道。[目的]以高温栅藻为对象,研究该新型生物絮凝剂的絮凝效率,并对絮凝机理进行初步探讨。[方法]探索在不同生长阶段微藻培养液添加生物絮凝剂、添加量、絮凝时间、pH对絮凝效率的影响,分析生物絮凝剂的功能基团,并测定在不同pH条件下添加生物絮凝剂前后高温栅藻的Zeta电位变化,以及在显微镜下分析藻细胞在添加生物絮凝剂前后的形态。[结果]在高温栅藻生长至稳定期(pH 8.0)添加2 mL生物絮凝剂,絮凝15 min絮凝效果最佳,达82.1%。傅里叶红外光谱(fourier transform infrared spectroscopy,FTIR)显示了多糖及酰胺结构的特征吸收峰,由此推测生物絮凝剂主要是多糖的混合物,含有少量蛋白质。根据Bradford法测定絮凝剂中蛋白含量约为0.4%(质量比),通过苯酚-硫酸法测定总糖质量分数约为34.5%(质量比),与FTIR分析结果基本相符。生物絮凝剂在pH 4.0-11.0保持60%以上的絮凝效率,说明无论是酸性或是碱性条件下絮凝效率都较高,结合Zeta电位的分析表明,推测生物絮凝剂对高温栅藻的絮凝机理中占主导地位的可能是吸附架桥作用。[结论]该研究对微藻生物絮凝具有重要的理论和实践意义。     

Production of a novel bioflocculant by fed-batch culture of Citrobacter sp.

Production of a novel bioflocculant by a fed-batch culture of Citrobacter sp. TKF04 was investigated using acetic acid as a sole carbon source. Synthesis of the bioflocculant was favored by dissolved O₂ tension at 20% of air saturation and C/N ratio (mol acetic acid/mol ammonium) of 10:1 in the feed solution. Under optimal conditions, 4.6 g crude bioflocculant per liter broth was produced, whose flocculating activity was 22 300 units. This activity was 9 times higher than that of the control (only acetic acid was supplied).