Biodegradation of benzo[a]pyrene in soil by Mucor sp. SF06 and Bacillus sp. SB02 co-immobilized on vermiculite

Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons （PAHs） were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a] pyrene （BaP）. The characteristics of BaP degradation by both free and co-immobilized microorganism were then investigated and compared. The removal rate using the immobilized bacterial-fungal mixed consortium was higher than that of the freely mobile mixed consortium. 95.3% of BaP was degraded using the co-immobilized system within 42 d, which was remarkably higher than the removal rate of that by the free strains. The optimal amount of inoculated co-immobilized system for BaP degradation was 2%. The immobilized bacterial-fungal mixed consortium also showed better water stability than the free strains. Kinetics of BaP biodegradation by co-immobilized SF06 and SB02 were also studied. The results demonstrated that BaP degradation could be well described by a zero-order reaction rate equation when the initial BaP concentration was in the range of 10--200 mg/kg. The scanning electronic microscope （SEM） analysis showed that the co-immobilized microstructure was suitable for the growth of SF06 and SB02. The mass transmission process of co-immobilized system in soil is discussed. The results demonstrate the potential for employing the bacterial-fungal mixed consortium, co-immobilized on vermiculite, for in situ bioremediation of BaP.     

胶质芽孢杆菌对印度芥菜富集土壤Cd及土壤pH的影响

采用根袋法盆栽试验,研究接种活菌量浓度分别为1×1010 cfu·kg-1 (T1)和2×1010 cfu·kg-1(T2)的胶质芽孢杆菌,对印度芥菜富集土壤Cd、土壤有效态Cd含量及土壤pH的影响.结果表明,以不接种菌液作为对照,处理T1、T2地上部分生物富集系数分别为13.58、16.83,与对照相比分别提高42.95％、77.16％;地下部分生物富集系数分别为4.35、4.83,分别比对照提高24.64％、38.40％;土壤的净化率分别是对照的1.73、2.20倍.对照组土壤有效态Cd含量随着时间的延长而降低,根际和非根际土壤分别降低32.93％和45.54％;但T1和T2处理中,根际、非根际土壤有效态Cd含量分别提高15.15％、31.73％和36.54％、45.28％.收获时,处理T1、T2根际土壤pH降低率分别是对照的1.08、1.10倍.不同浓度胶质芽孢杆菌处理下土壤pH与有效态Cd含量均呈显著负线性关系.综上,胶质芽孢杆菌主要是通过改变土壤pH来影响土壤Cd生物有效性,从而促进超富集植物的修复效果.本研究可为微生物辅助植物修复重金属污染土壤提供一定理论依据和实践指导.     

铁铝复合氧化物对两种细菌的吸附作用研究

铁铝氧化物是土壤的重要组分之一,其对土壤中有机无机组分的迁移具有重要影响.本文以枯草芽孢杆菌和荧光假单胞菌为研究对象,通过批吸附实验和DLVO理论,探究铁铝复合氧化物对细菌的粘附作用及其作用机制.结果表明,铁铝复合氧化物对细菌的粘附随着平衡浓度的增加而增加,吸附过程可用Langmuir方程拟合.铁铝1∶3复合氧化物对枯草芽孢杆菌和荧光假单胞菌的最大吸附量分别为3717.43和2792.29 mg·g~(-1),铁铝3∶1复合氧化物对枯草芽孢杆菌和荧光假单胞菌的最大吸附量分别为3455.58和2760.33 mg·g~(-1).随着pH值的增大,两种铁铝复合氧化物对两种细菌的吸附量均呈下降趋势.铁铝1∶3复合氧化物对两种细菌的吸附量均大于铁铝3∶1复合氧化物.静电吸引力是铁铝复合氧化物与细菌之间相互作用的主要因素之一.     

细菌絮凝剂与沸石对模拟重金属废水的吸附作用

以含Fe3+、Cd2+的模拟废水为例,利用细菌絮凝剂和沸石两种吸附剂,分析了两种吸附剂单独及联合使用对模拟重金属废水的处理效果。结果表明,在处理高浓度含Fe3+废水时细菌絮凝剂表现出较好的吸附效果,在处理高浓度含Cd2+废水时,沸石处理效果明显,两种吸附剂联合处理废水可弥补各自吸附特性的不足,细菌絮凝剂能促进天然沸石颗粒物沉降。     

3株溶藻细菌溶藻特性的初步研究

对3株溶藻细菌L7、L8和L18溶解水华鱼腥藻(Anabaena flos-aquae FACHB-245)的溶藻方式、溶藻活性代谢产物的溶藻特性进行了研究。3株菌都为间接溶藻,产生具有热稳定性的、对水华鱼腥藻有较强溶藻效果的活性代谢产物。L8的溶藻效果与藻液中投加溶藻活性代谢产物的浓度呈正相关。处于衰减期的L8,其溶藻活性代谢产物的溶藻效果好于对数生长期和稳定期。在不同pH值条件下进行溶藻实验,当pH值为8.5±0.1时,L7溶藻活性代谢产物的去除率达到85.78%;当pH值为10±0.2时,L8和L18溶藻活性代谢产物的去除率分别达到92.84%和78.72%;由7×108cells/mL的L8菌液获得的无菌滤液,当投加量<30%时,对水华鱼腥藻的生长具有促进作用。     

Combination e ect of pH and acetate on enzymatic cellulose hydrolysis

The productivity and e ciency of cellulase are significant in cellulose hydrolysis. With the accumulation of volatile fatty acids (VFAs), the pH value in anaerobic digestion system is reduced. Therefore, this study will find out how the pH and the amount of acetate influence the enzymatic hydrolysis of cellulose. The e ects of pH and acetate on cellulase produced from Bacillus coagulans were studied at various pH 5–8, and acetate concentrations (0–60 mmol/L). A batch kinetic model for enzymatic cellulose hydrolysis was constructed from experimental data and performed. The base hypothesis was as follows: the rates of enzymatic cellulose hydrolysis rely on pH and acetate concentration. The results showed that the suitable pH range for cellulase production and cellulose hydrolysis (represents e ciency of cellulase) was 2.6–7.5, and 5.3–8.3, respectively. Moreover, acetate in the culture medium had an e ect on cellulase production (KI = 49.50 mmol/L, n = 1.7) less than cellulose hydrolysis (KI = 37.85 mmol/L, n = 2.0). The results indicated that both the pH of suspension and acidogenic products influence the enzymatic hydrolysis of cellulose in an anaerobic environment. To enhance the cellulose hydrolysis rate, the accumulated acetate concentration should be lower than 25 mmol/L, and pH should be maintained at 7.     

一株硝化脱氮除臭菌的筛选鉴定及其多途径氮代谢功能的研究

从江门某污水处理厂活性污泥中分离出一株能够高效脱除氨气的菌株JN-4.通过菌株形态观察、生理生化及16SrDNA分子鉴定,发现菌株JN-4与枯草芽孢杆菌(Bacillus subtilis)亲缘关系最为接近,同源性达到99%,认为JN-4为一株枯草芽孢杆菌(Bacillus subtilis).好氧培养条件下,以葡萄糖为碳源,JN-4在32h内对NH4+-N和NO2--N的总削减率能够达98.51%和84.50%,体系中总氮的削减率达到63.1%和16.9%,N2的产生量分别为3.72mmol·L-1和0.62mmol·L-1.好氧培养条件下,以KNO3为唯一氮源,NO3--N初始浓度为82.47mg·L-1,32h内体系中NO3--N的总削减率达到96.54%,体系中总氮的削减率达49.6%,产生1.44mmol·L-1的N2,反应中检测到有NH4+-N迅速积累,但会随着时间进行同步转化,可见JN-4不仅能够高效硝化脱氨,同时具有高效好氧反硝化的能力.JN-4在厌氧以及乙酸钠作为碳源的条件下,利用NH4+-N效率大大降低,但是能够在NO3--N存在时进行NO3--N还原(反硝化).JN-4能够进行多途径氮代谢,为一株异养硝化-好氧反硝化偶联的菌株,具有重要的应用价值.     

中试清水池水力条件对氯消毒效率的影响

以枯草杆菌黑色变种芽孢为目标微生物,以紫外线消毒后的炭滤池出水为进水,在中试清水池模型中模拟氯消毒过程,通过改变清水池导流板数目获得不同的水力条件,研究清水池水力条件对氯消毒效率的影响.结果表明,在本试验中,不同水力条件下以Ct10值计算的NaClO对枯草杆菌黑色变种芽孢的灭活系数之间相互一致,而不同水力条件下以CT值计算的NaClO对枯草杆菌黑色变种芽孢的灭活系数之间相差很大,表明Ct10是评价清水池消毒效率的合理指标;在Ct10=(100~300)mg.min/L的范围内,NaClO对枯草杆菌黑色变种芽孢的灭活系数为0.0016 L/(mg.min),与其他研究者的结果具有很好的一致性;清水池水力条件的改善可以提高消毒效率,在CT=(100~700)mg.min/L的范围内,当CT值固定时,随着清水池内导流板数增多,水力条件得到改善,t10增加,目标菌种的灭活率显著提高.     

Surface reaction of Bacillus cereus biomass and its biosorption for lead and copper ions

In this study, the surface chemical functional groups of Bacillus cereus biomass were identified by Fourier transform infrared （FTIR） analytical technique. It had been shown that the B. cereus cells mainly contained carboxyl, hydroxyl, phosphate, amino and amide functional groups. The potentiometric titration was conducted to explain the surface acid-base properties of aqueous B. cereus biomass. The computer program FITEQL 4.0 was used to perform the model calculations. The optimization results indicated that three sitesthree pKas model, which assumed the cell surface to have three distinct types of surface organic functional groups based on the IR analysis results, simulated the experimental results very well. Moreover, batch adsorption experiments were performed to investigate biosorption behavior of Cu（Ⅱ） and Pb（Ⅱ） ions onto the biomass. Obviously, the adsorption equilibrium data for the two ions were reasonably described by typical Langmuir isotherm.     

Removal of ammonium-N from ammonium-rich sewage using an immobilized Bacillus subtilis AYC bioreactor system

A self-design bioreactor system employing a fixed bed operation process with immobilized Bacillus subtilis AYC beads for NH4 +-N removal from slightly polluted water was proposed. Polyvinyl alcohol and Na-alginate were used as a gel matrix to entrap Bacillus subtilis AYC to form the immobilized beads. The NH4 +-N removal process was studied in a intermittent operation mode to examine the start-up and steady state behaviors of the immobilized AYC in the reactor. The results indicated that the reactor was in the start-up state during the first week. NH4 +-N began to be steadily removal since the second week, and the nitrogen removal rate was between 84.61% and 96.19% when the hydraulic retention time (HRT) was 30 min. To apply Bacillus subtilis AYC to develop a practical nitrogen removal system and further understand its nitrogen removal ability, the bioreactor was continuously operated under different experimental perameters. The results showed that under the optimum conditions of an HRT of 20 min and DO of 3.77–5.80 mg/L, the NH4 +-N removal rate reached 99.55%. The NH4 +-N removal rate increased as the C/N ratio increased. However, a high C/N may cause a high residual carbon level in the effluent, therefore, the most suitable C/N ratio was 10. In addition, the results showed that the bioreactor system could remove many types of nitrogen such as NH4 +-N, NO3??-N and organic-N, and had a good performance for inorganic nitrogen removal from sewage.