一株蒽降解菌的分离鉴定及其降解特性研究

从石油污染土壤中筛选出一株蒽的高效降解菌株JUST-1,JUST-1可在以蒽为唯一碳源的培养基中生长,能利用蒽的最高浓度为70mg/L左右。经形态学观察并进行ITS序列分析,初步判断菌株JUST-1属于尖镰孢菌(Fusarium oxysporum)或该菌的一个株系。JUST-1的菌丝呈白色或粉红色,并存在三类孢子,分别为小型分生孢子(microconidia)、大型分生孢子(macroconidia)和厚垣孢子(chlamydospores),但大孢子分隔数较少,隔膜1～2个。JUST-1菌株为好氧菌。投菌量、初始蒽浓度、pH和H_2O_2浓度是影响蒽降解效率的因素。JUST-1菌株对蒽的最适宜降解条件为:蒽浓度40mg/L,投菌量10%～20%,pH7.0～8.0。在此条件下,摇床培养5d后,葸去除率可达70%以上。

典型荧蒽降解菌的固定化方法优选及降解性能

为了对典型荧蒽降解菌(青霉素菌DTQ-HK1)固定化方法进行优选及其荧蒽的降解性能进行探究,比较菌种固定化后的耗氧速率及对荧蒽的短期降解效果,优选出最佳固定化方法,并对其进行液相和底泥中荧蒽长期降解实验.结果显示:粒径为10目玉米芯吸附固定化菌种后的耗氧速率最高为102 mg/(g·d),2%PVA+3%SA的载体包埋固定化后菌种的耗氧速率最高为82 mg/(g·d);对2种固定化方法中的最佳载体进行固定化菌对荧蒽的降解实验,14 d后吸附和包埋固定化菌对荧蒽的降解率分别为28.28%、23.49%,说明吸附固定化菌相对来说对荧蒽的降解和微生物活性更有利.菌种经过最佳固定化方法处理后对液相中荧蒽42 d连续降解实验可知,吸附固定化菌对荧蒽的降解率达到62.45%,比悬浮菌提高了10.23%;而吸附固定化菌对菖蒲根际底泥中荧蒽经过90 d降解实验,降解率达86.14%,比悬浮菌提高了5.56%.

蒽降解菌的分离鉴定与降解条件优化

[目的]研究蒽降解菌株的生长条件和降解特性。[方法]从长期被石油污染的土壤中筛选得到一株以蒽为唯一碳源的菌株A1,经16S rDNA分子鉴定后通过单因素试验和正交试验对菌株的培养条件和蒽降解条件进行研究。[结果]A1菌株的最佳培养条件为:接种量5.0%,pH 6.0,温度35℃,蒽初始浓度40 mg/L。菌株在pH 7～10,最适降解温度30℃,接种量5%时,生长率及降解率均达到最大。盐浓度为1.2%,蒽浓度为100 mg/L时,菌株降解率达到最大。[结论]该研究可为有机物污染土壤的生物修复研究提供理论依据。

蒽的高效降解菌的固定化小球的制备及其降解特性

旨在利用固定化高效降解菌小球去除水中蒽,充分发挥累托石的吸附和生物降解的协同作用,以累托石、聚乙烯醇(PVA)、海藻酸钠(SA)作为固定化载体材料,硼酸和氯化钙作为交联剂,将蒽的高效降解菌包埋制备固定化微生物小球。考察了累托石用量、PVA投加量、海藻酸钠用量、氯化钙用量、微生物包埋量和交联时间等因素对微生物小球活性的影响,通过正交实验确定了微生物小球的最佳制备条件。结果表明,制备固定化微生物小球的最佳条件为:累托石2.5%,PVA 12%,SA0.3%,CaCl24%,交联时间28 h,微生物包埋量10%。对40 mg/L的蒽溶液,游离微生物在50 h后开始发挥明显的降解作用,经过68 h蒽的去除率达到35.65%;而固定化微生物小球经过9 h即可使蒽的去除率达到81.8%,23 h后蒽的去除率可达100%。固定化微生物小球对水中蒽的去除机理与吸附-降解工艺的机理类似,即固定化微生物小球类似于一个一体化的微型反应器,经过迟滞期后,在该反应器内同时发生吸附和降解作用。

Biodegradation of ethylthionocarbamates by a mixed culture of iron-reducing bacteria enriched from tailings dam sediments

Ethylthionocarbamates （ETC）, which is the most widely used as collectors in the flotation of sulfide, is known to cause serious pollution to soil and groundwater. The potential biodegradation of ETC was evaluated by applying a mixed culture of iron-reducing bacteria （IRB） enriched from tailings dam sediments. The results showed that ETC can be degraded by IRB coupled to Fe（III） reduction, both of which can be increased in the presence of anthraquinone-2,6-disulfonate （AQDS）. Moreover, Fe（III）-EDTA was found to be a more favorable terminal electron acceptor compared to α-Fe2O3, e.g., within 30 d, 72% of ETC was degraded when α-Fe2O3＋AQDS was applied, while it is 82.67% when Fe（III）-EDTA＋AQDS is added. The dynamic models indicated that the kETC degradation was decreased in the order of Fe（III）-EDTA＋AQDS〉α-Fe2O3＋AQDS〉Fe（III）-EDTA〉α-Fe2O3, with the corresponding maximum biodegradation rates being 2.6, 2.45, 2.4 and 2.0 mg/（L·d）, respectively, and positive parallel correlations could be observed between kFe（III） and kETC. These findings demonstrate that IRB has a good application prospect in flotation wastewater.

Bacterial degradation of anthraquinone dyes

Anthraquinone dyes,which contain anthraquinone chromophore groups,are the second largest class of dyes after azo dyes and are used extensively in textile industries.The majority of these dyes are resistant to degradation because of their complex and stable structures;consequently,a large number of anthraquinone dyes find their way into the environment causing serious pollution.At present,the microbiological approach to treating printing and dyeing wastewater is considered to be an economical and feasible method,and reports regarding the bacterial degradation of anthraquinone dyes are increasing.This paper reviews the classification and structures of anthraquinone dyes,summarizes the types of degradative bacteria,and explores the possible mechanisms and influencing factors of bacterial anthraquinone dye degradation.Present research progress and existing problems are further discussed.Finally,future research directions and key points are presented.

Potential of the White-Rot Fungus Pleurotus pulmonarius F043 for Degradation and Transformation of Fluoranthene

Fluoranthene, a four-ring polycyclic aromatic hydrocarbon that is possible genotoxic in nature, has been used as an indicator for assessing polycyclic aromatic hydrocarbon （PAH）-containing pollutants. Microbial degradation is one of the promising methods in removing up PAH-contaminated environments. White-rot fungi have showed the ability to degrade a wide range of PAHs. This study aimed to investigate enzyme production, fungal biomass, and glucose utilization during the biodegradation process of fiuoranthene by a white-rot fungus Pleurotus pulmonarius F043 and to identify the metabolites produced in the degradation process. The extracellular ligninolytic enzyme system of the fungi, producing laccases and peroxidases, was directly linked to the biodegradation of fiuoranthene. The production of ligninolytic enzymes during fluoranthene degradation was related to an increase in the biomass of Pleurotus pulmonarius F043. Fluoranthene removal decreased with an increase in fluoranthene concentrations. The highest biomass production of Pleurotus pulmonarius F043 （〉 4 400 mg L-1） was found in the 10 mg L-1 fluoranthene culture after 30 d of incubation. Two fluoranthene metabolites, naphthalene-l,8-dicarboxylic acid and phthalic acid, were found in the process of fluoranthene degradation. Laccase was revealed as the major enzyme that played an important role in degradation process. Suitable conditions must be found to promote a successful fungal biotransformation augmentation in liquid culture.