适用于分离人肠道中双歧杆菌的选择性培养基

【目的】比较并评价5种双歧杆菌选择性培养基对人源双歧杆菌的分离效果,试图筛选出一种适用于人肠道中双歧杆菌分离培养的选择性培养基。【方法】采集6份健康人粪便样品稀释涂布于5种选择性培养基上,厌氧培养后计数菌落并挑选单菌落进行鉴定。同时提取样品中细菌宏基因组DNA,应用变性梯度凝胶电泳技术(Denaturing Gel Gradient Electrophoresis,DGGE)和荧光定量PCR技术(Quantitative Polymerase Chain Reaction,q-PCR)揭示样品中双歧杆菌种类和数量,并以此为依据,客观评价上述5种选择性培养基的分离效果。【结果】BSM培养基和BLM培养基上双歧杆菌的计数结果与q-PCR的定量结果最为接近,并显著高于其它3种培养基。BLM培养基上分离到双歧杆菌的种类与DGGE图谱多样性分析的结果最为接近。【结论】BLM培养基是一种适用于人肠道中双歧杆菌分离培养的选择性培养基。     

贝壳砂改良土壤中反硝化细菌的分析

【目的】通过对一处经过长期使用贝壳砂进行改良的土壤中的反硝化细菌的多样性和细菌分离分析,研究该土壤中反硝化细菌的组成特征。【方法】采用454焦磷酸测序的方法分析了土壤样品中微生物群落的组成,选用Giltay培养基培养、鉴定从土壤中挑选的分离物的反硝化能力,并对具有反硝化能力的微生物进行了16S rRNA基因鉴定。【结果】该土壤样品中占据优势地位的为Proteobacteria、Acidobacteria、Bacteroidetes、Chloroflexi等门的微生物,属的水平上则有近70%尚未确立分类地位。所分离的细菌中,共得到12株厌氧条件下具有较高硝酸盐去除效率的微生物,分属Pseudomonas、Aeromonas、Serratia和Acinetobacter,均为γ变形菌纲的微生物。【结论】该土壤中具有较高的微生物多样性,包括很多未知类型的微生物和众多类型的反硝化细菌;分离到了11株具有反硝化能力的菌株,可用于该土壤的反硝化过程的进一步研究。     

一株好氧反硝化菌的分离鉴定及其除氮特性

【目的】生物除氮中反硝化菌具有重要的作用,需氧反硝化菌研究较少,有着很好的应用潜力,本研究主要从环境样品中分离具有高效去除铵氮和亚硝酸盐氮活性的好氧反硝化菌,并对其分类及除氮特性进行研究。【方法】以高效去除铵氮、除亚硝酸盐氮和好氧反硝化能力为主要指标,从富营养化的池塘淤泥水和工厂污泥样品中进行菌株分离筛选。通过生理生化特点以及16S rRNA序列分析对活性最好的菌株进行初步鉴定。在好氧条件下,分别以NO-3-N、NH+4-N和NO-2-N作为唯一氮源,考察菌株的好氧反硝化特性、去除铵氮和亚硝酸盐氮特性,以及不同初始pH值、温度、碳源、摇床转速对该菌去除铵氮和亚硝酸盐氮特性的影响。【结果】得到的细菌中,以菌株C-4的活性最好,其16S rRNA序列与不动杆菌的同源性达99%,结合生理生化特点,初步确定菌株C-4属于不动杆菌属(Acinetobacter sp.)。以柠檬酸钠作为碳源,30℃、120 r/min振荡培养,种龄为18 h,用初始pH为8.5的200 mg/L NH +4-N培养基和初始pH为7.5的100 mg/L NO -2-N培养基进行测定,分别培养15 h与12 h,净除氮率分别达到65.8%和47.8%。【结论】从鱼塘水样中分离到一株好氧反硝化菌C-4,初步鉴定为不动杆菌属的一个种(Acinetobacter sp.),具有较高的反硝化特性和高效去除铵氮与亚硝酸盐氮的能力,在处理实际池塘污水时中,净除氮率可达73.04%以上。     

滇池可培养好氧反硝化细菌多样性及其脱氮特性

【目的】氮污染已成为当今水体污染的一个重要因素,为了解滇池可培养好氧反硝化细菌的多样性,获得高效好氧反硝化细菌资源,为污染水体或浅层地下水的生物修复提供材料。【方法】采用富集培养方法从滇池沉积物和水体样品中分离好氧反硝化细菌,对好氧反硝化细菌的16S r RNA基因序列进行系统发育分析,并筛选其中的高效好氧反硝化细菌。【结果】分离出260株好氧反硝化菌,经16S rRNA基因序列分析,260株菌分属于2门13科14属的59个种。假单胞菌属(Pseudomonas)为优势细菌属,其次是不动杆菌属(Acinetobacter)、气单胞菌属(Aeromonas)和代尔夫特菌属(Delftia)。筛选到12株高效好氧反硝化细菌菌株,其中8株属于假单胞菌(Pseudomonas spp.),4株为不动杆菌(Acinetobacter spp.)。定量分析发现菌株N15-6-1的反硝化效果较好。对菌株N15-6-1的脱氮条件优化结果显示,在以蔗糖为碳源,温度为30–35℃、C/N=12、静止培养时,反硝化能力较强,其在48 h内硝态氮的去除率达到98.81%,总氮的去除率达96.27%。【结论】滇池存在着较丰富的可培养好氧反硝化细菌,好氧反硝化细菌的分离丰富了好氧反硝化菌的种类,其中的高效脱氮菌株为污染水体或浅层地下水的生物修复提供了初步的候选菌株。     

分离于河口区芦苇湿地1株好氧反硝化菌的鉴定及其反硝化特性

【目的】筛选高效脱氮且N_2O释放量少的好氧反硝化细菌,并对菌株的反硝化特性进行研究,可为河口湿地富营养化水体的生物修复提供技术支撑。【方法】经BTB培养基初筛和反硝化能力测定,从辽河河口区芦苇湿地土壤中分离得到1株具有较高反硝化能力的好氧反硝化菌C3。经形态观察、生理生化鉴定和16S rRNA序列分析,对菌株进行鉴定。研究温度、碳源、pH及C/N对其生长量、反硝化能力及N2O释放的影响。【结果】筛选得到的高效好氧反硝化细菌C3,经鉴定属于假单胞菌属(Pseudomonas sp.)。反硝化特性研究结果表明,该菌最适碳源为柠檬酸三钠,在温度为30°C、pH为7.0、C/N为10时生长速率和脱氮效率最高且N_2O释放量较少。在此条件下,该菌在36 h内使NO_3~–由179.55 mg/L降至5.08 mg/L,脱氮率高达97.17%。该菌株在整个反硝化过程中中间产物N_2O的最大累积量较低,为0.22 mg/L。【结论】从湿地土壤中分离所得好氧反硝化菌C3为假单胞菌属的1个种(Pseudomonas sp.),该菌株在高效除氮和低N_2O累积方面均具有明显优势,对后续河口湿地富营养化水体治理具有重要意义。     

广西北部湾茅尾海红树林生境放线菌分离培养基的比较

【背景】红树林生境拥有丰富的微生物资源,分离获得更多的纯培养放线菌为新型抗生素的发现提供菌种资源。【目的】使用新型放线菌分离培养基,发掘广西北部湾茅尾海红树林生境放线菌资源,评估新型放线菌分离培养基分离效果。【方法】设计出新型放线菌分离培养基——椰子汁-海藻糖培养基,对广西北部湾茅尾海红树林根际土壤和红树林根皮放线菌进行分离。基于分子生物学鉴定方法,对获得的纯培养放线菌进行多样性分析。【结果】从红树林根际土壤样品中分离获得65株放线菌,分布在5个目10个科15个属,使用YIM171培养基分离到7个属,MA培养基分离到5个属,椰子汁-海藻糖培养基分离到11个属,其中包括4株潜在新种;从红树林根皮样品中分离获得19株放线菌,分布在4个目7个科10个属,使用YIM171和椰子汁-海藻糖培养基分别分离到7个属,包括4株潜在新种;使用椰子汁-海藻糖培养基在红树林生境两类样品中获得3株潜在新种。【结论】广西北部湾茅尾海红树林根际土壤和根皮中放线菌多样性丰富,使用椰子汁-海藻糖培养基分离放线菌效果较佳,可用作放线菌的分离培养基。     

深海沉积物高效脱氮菌筛选分离及其脱氮特性研究

【背景】深海海域具有高压、低温、无光等环境条件,蕴含着丰富而独特的微生物资源。【目的】从深海沉积物中定向分离、筛选脱氮效率高的好氧脱氮菌株资源,并揭示其脱氮特性,为开发水体脱氮微生物技术提供物质基础。【方法】以东太平洋、南大西洋、西南印度洋共10个站位的深海沉积物为研究材料,在28°C下使用无机氮源连续进行两轮富集培养,然后定性筛选可以脱除氨氮、亚硝态氮和硝态氮的菌株,并通过形态学和16S rRNA基因序列分析进行初步分类鉴定;对优选得到的功能菌株,分别采用以氨氮、亚硝态氮、硝态氮为唯一氮源的培养基定量研究其生长和脱氮性能。【结果】从10份大洋深海沉积物样品中共分离得到49株好氧反硝化菌,其中3株在有氧条件下反硝化效率较高,分别命名为Pseudomonassp.G111、Pseudomonassp.G112和Dietziamaris W023a,其中菌株G111和G112与模式菌株博岑假单胞菌Pseudomonas bauzanensis BZ93T的16S rRNA基因序列相似度为99.2%,菌株W023a与模式菌株海洋迪茨氏菌DietziamarisATCC35013T的16SrRNA基因序列相似度为99.9%。菌株G111、G112和W023a培养48h后,对氨氮的脱除率分别为98.0%、85.2%和97.6%;对亚硝态氮的脱除率分别为71.9%、67.5%和34.7%;对硝态氮的脱除率分别为66.0%、52.6%和56.3%。菌株G111、G112和W023a均为异养硝化-好氧反硝化菌,可通过好氧反硝化作用将亚硝态氮和硝态氮还原为含氮气体,也可通过异养硝化-好氧反硝化作用将氨氮转化为含氮气体。【结论】从深海沉积物中分离筛选得到3株高效好氧反硝化菌,所获得的菌株在水体净化、污水处理、生态系统修复等领域具有应用潜力。     

不同分离方法对子实体形成和粘细菌分离的影响

【目的】基于模拟原位环境策略、可培养粘细菌的营养策略及细菌互作网络,改良分离培养基,以提高分离粘细菌的多样性。【方法】通过添加土壤浸提液、使用不同种类的诱导菌和改变诱导菌的接种方式设置分离方法,同时以传统的分离方法作对照。【结果】改良的分离方法比对照组诱导出了更多粘细菌子实体种类,采自4个地区的9份样品共分离纯化出40株粘细菌,按形态学和分子生物学,将其归类于原囊菌属(Archangium)、珊瑚菌属(Corallococcus)、软骨霉状菌属(Chondromyces)、粘球菌属(Myxococcus)、侏囊菌属(Nannocystis)、多囊菌属(Polyangium)、匣状球菌属(Pyxidicoccus)。【结论】与传统分离方法相比,添加土壤浸提液,诱导菌点接法能大大提高诱导出的粘细菌子实体种类的数目,革兰氏阳性菌和革兰氏阴性菌作为诱导菌对子实体种类影响较小,但是也发现革兰氏阳性菌特异性诱导出的子实体。虽然本研究通过对分离培养基的改良大大增加了子实体种类,但是纯化出的粘细菌种类远少于观察到的子实体种类,说明除改良分离方法外,还需进一步研究粘细菌的纯化方法,提高分离所得粘细菌的多样性,获取更多粘细菌新资源。     

一株耐盐的卓贝儿氏菌(Zobellella sp.)的分离鉴定及其硝酸盐还原能力

【背景】好氧反硝化是指在有氧条件下进行反硝化作用,使得硝化和反硝化过程能够在同一反应器中同时发生,是废水脱氮最具竞争力的技术。红树林湿地中蕴藏着丰富的微生物资源,分布着大量好氧反硝化微生物。【目的】了解耐盐微生物的脱氮机制,为含盐废水生物脱氮的工程实践提供理论依据,对一株分离于红树林湿地中的耐盐好氧细菌A63的硝酸盐异化还原能力进行分析。【方法】利用形态学特征及16S rRNA基因序列测定分析,对其种属进行了鉴定,采用单因子实验测定该菌在不同环境因子下的硝酸盐还原能力,并对其反硝化脱氮条件进行了优化。【结果】初步判定该菌株为卓贝儿氏菌(Zobellellasp.),其能在盐度0%-10%、pH5.0-10.0、温度20-40°C范围内进行反硝化脱氮和硝酸盐异化还原为氨(dissimilatorynitratereductiontoammonium,DNRA)作用。菌株A63最适生长碳源为柠檬酸钠(1.2 g/L),适宜脱氮盐度为3%、pH 7.0-7.5、温度30-35°C,且C/N为10。在最适脱氮条件下,该菌株12h内能将培养基中208.8mg/L硝态氮降至0,且仅有少量铵态氮生成,无亚硝态氮积累,脱氮率高达99%。此外,该菌株在高盐度、低C/N比、弱酸性和低温等不利生境中DNRA作用显著。【结论】细菌A63生长范围宽,脱氮效率显著,适用于海水养殖废水处理。研究为今后开发高效含盐废水生物脱氮工艺奠定了基础,对于加深氮素转化规律的认识、丰富生物脱氮理论有着重要意义。     

耐低温好氧反硝化菌Aeromonas sp.的分离鉴定及脱氮条件优化

【目的】从冬季活性污泥和河水底泥中分离筛选得到耐低温好氧反硝化菌，并对影响脱氮的关键因子进行优化，以提高低温条件下的脱氮效果。【方法】采用富集纯化法分离筛选耐低温好氧反硝化菌株。通过形态观察和16S rRNA基因系统发育分析等方法对筛选菌株进行菌种鉴定。以NO3–-N去除率为响应目标，采用Box-Behnken试验设计及响应面回归分析法优化影响脱氮效果的关键因子（C/N、温度、pH和摇床转速），确定最佳培养条件。【结果】从东北寒冷地区冬季河水底泥样品中分离得到的一株耐低温好氧反硝化菌Z6，菌落呈白色半透明圆形，菌体细胞为短杆状，大小为（0.8–1.6）μm×（0.6–0.8）μm，革兰氏染色阴性。与气单胞菌属（Aeromonas）的16S rRNA基因序列高度同源，鉴定该菌为气单胞菌。采用响应面分析方法得到菌株Aeromonas sp. Z6的最佳脱氮条件为：C/N 5.9，温度12°C,pH 6.8，摇床转速155 r/min，在此条件下对NO₃^–-N的去除率为89.72%，与预测值（90.34%）无显著差别。【结论】首次报道气单胞菌（Ae...     

Development of group-specific PCR-DGGE fingerprinting for monitoring structural changes of Thauera spp. in an industrial wastewater treatment plant responding to operational perturbations

A Thauera-specific nested-PCR denaturing gradient gel electrophoresis (DGGE) method was developed, and its usefulness was demonstrated by monitoring the structural shifts of Thauera spp. in an anaerobic-anoxic-oxic fixed-biofilm coking wastewater treatment plant (WWTP) responding to operational perturbations. The specificity of the PCR method was confirmed by the fact that all 16 S rRNA gene sequences, cloned from the amplicons of a biofilm sample, belonged to Thauera genus. 16 S rRNA gene V3 region was then amplified from the first round Thauera-specific PCR product and applied for DGGE analysis. All Thauera clones, with 13 different V3 regions, migrated into 10 positions on DGGE gel, which demonstrated the high resolution of this DGGE method. When the WWTP experienced a gradual deterioration in chemical oxygen demand (COD) removal function due to a mechanical failure of the recirculation pump, biofilm samples were collected from the reactor and analyzed by this method. Principal component analysis (PCA) of the DGGE fingerprinting data showed that the composition of Thauera group exhibited a time related trajectory when the plant's COD removal rate decreased from 84.1+/-2.7% in the first 4 weeks to less than 75% at week 5 and 6, suggesting a concomitant shift of Thauera composition and the system's COD removal function. This group-specific PCR DGGE fingerprinting technology has the potential to be a profiling tool for monitoring structural shifts of Thauera spp. in industrial WWTPs.     

Bifidobacterial diversity and the development of new microbial source tracking indicators

Many studies suggest a close relationship between species of Bifidobacterium and their hosts. Thus, species such as B. adolescentis and B. thermacidophilum subsp. porcinum have been proposed as potential indicators of human and porcine fecal pollution. The diversity of bifidobacteria in wastewaters (human and animal) and slurries is analyzed using nested PCR followed by denaturant gradient gel electrophoresis (DGGE). The sewage samples showed similar DGGE patterns. The predominant bands were recognized as B. adolescentis, B. longum, and two unidentified species related to B. adolescentis. A single band detected in poultry samples was identified as B. saeculare. Bifidobacterial diversity was higher within porcine and bovine samples. The main bands in porcine samples were identified as B. minimum, an unknown species, and B. thermophilum/B. thermacidophilum subsp. porcinum. The latter species was also identified among the main bands in bovine samples together with B. pseudolongum and B. ruminantium. We then attempted to isolate the host-specific strains. DGGE bands were examined to develop specific probes to screen environmental samples by colony hybridization and further isolation of strains from positively hybridized colonies. Bifidobacterial strains that are host associated by DGGE bands to human and pig were successfully isolated from the environment: B. adolescentis from human sewage samples and the unidentified species related to pig from slurries and slaughterhouse wastewater. Neither the poultry-associated B. saeculare nor the ruminant-associated B. pseudolongum could be isolated with the current methodology, suggesting either a low prevalence in the samples or failure of the culture to grow in the media used.     

农村生活污水处理厂中阿米巴原虫的定量检测

【目的】自由生活的棘阿米巴属(Acanthamoeba spp.)和哈曼属原虫(Hartmannella vermiformis)普遍存在于自然界的土壤和各种水体中,这两个属中的某些种类被认为对人和动物具有潜在的致病性,应用染料法实时荧光定量PCR技术建立特异性强、灵敏度高及重复性好的快速检测阿米巴虫的方法具有实际意义。【方法】采用非培养方法选择适合低拷贝基因检测的荧光染料BRYT Green? dye用于农村生活污水处理厂不同工艺阶段水样中Acanthamoeba spp.和H. Vermiformis 18S rRNA基因的检测和定量分析。【结果】在整个处理工艺流程中均检测到Acanthamoeba spp.和H. Vermiformis,并呈现出不同的变化趋势,进水中分别达到8.70×105拷贝/L和1.84×106拷贝/L。与进水相比,调节池、好氧池和膜池中阿米巴原虫的数量均降低了1?2个数量级,但是出水中Acanthamoeba spp. 则出现增加趋势。【结论】对阿米巴原虫可能造成的潜在健康危害应引起重视,并有必要作为污水处理达标的补充标准。     

Development of a selective myclobutanil agar (MBA) medium for the isolation of Fusarium species from asparagus fields

A new selective myclobutanil agar medium for the detection of Fusarium, species is proposed. Ten media formulations based on various selective agents (pentachloronitrobenzene (PCNB), Rose Bengal, malachite green, sodium hypochlorite, captan, benomyl, chlorotalonil, myclobutanil, thiram, and cupric sulfate) were compared. First, mycelium growth and colony appearance of Alternaria alternata, Aspergillus flavus, Cladosporium cladosporioides, Epicoccum nigrum, Fusarium sp., Fuisarium solani, Fusarium moniliforme, Fusarium oxysporum f.sp. dianthi, Penicillium sp., and Trichoderma viride isolates were compared. Second, the ability of the different media to isolate and enumerate fusaria from asparagus fields was evaluated. The myclobutanil-based medium showed the highest selectivity to Fusarium spp. growth but required a slightly longer incubation time (>5 d) than peptone-pentachloronitrobenzene-based agar (PPA) (< 5 d). PPA allowed a faster fusaria growth but also permited the growth of other moulds. The other media were less selective and did not allow to isolate fusaria or to differenciate them from other growing fungi.     

Nitrate-removal activity of a biofilm attached to a perlite carrier under continuous aeration conditions

The nitrate-removal activity of a biofilm attached to a perlite carrier from an aerobic bioreactor used for treating dairy farm wastewater was examined by batch experiments under continuous aeration conditions. Despite aeration, the biofilm removed nitrate at a rate of 114.4 mg-N/kg-perlite/h from wastewater containing cow milk and manure. In a clone library analysis of the biofilm, bacteria showing high similarity to the denitrifying bacteria Thauera spp. were detected.     

Bacterial community dynamics in long‐term operation of a pilot plant using aerobic granular sludge to treat pig slurry

Aerobic granular sludge represents an interesting approach for simultaneous organic matter and nitrogen removal in wastewater treatment plants. However, the information about microbial communities in aerobic granular systems dealing with industrial wastewater like pig slurry is limited. Herein, bacterial diversity and dynamics were assessed in a pilot scale plant using aerobic granular sludge for organic matter and nitrogen elimination from swine slurry during more than 300 days. Results indicated that bacterial composition evolved throughout the operational period from flocculent activated sludge, used as inoculum, to mature aerobic granules. Bacterial diversity increased at the beginning of the granulation process and then declined due to the application of transient organic matter and nitrogen loads. The operational conditions of the pilot plant and the degree of granulation determined the microbial community of the aerobic granules. Brachymonas, Zoogloea and Thauera were attributed with structural function as they are able to produce extracellular polymeric substances to maintain the granular structure. Nitrogen removal was justified by partial nitrification (Nitrosomonas) and denitrification (Thauera and Zoogloea), while Comamonas was identified as the main organic matter oxidizing bacteria. Overall, clear links between bacterial dynamics and composition with process performance were found and will help to predict their biological functions in wastewater ecosystems improving the future control of the process. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1212–1221, 2016     

Biodegradation of 1,4-dioxane by a <Emphasis Type="Italic">Flavobacterium</Emphasis>

A dioxane-degrading consortium was enriched from soil obtained from a contaminated groundwater plume. The enriched consortium did not use dioxane as the sole source of carbon and energy but co-metabolized dioxane in the presence of tetrahydrofuran (THF). THF and dioxane concentrations up to 1000 ppm were degraded by the enriched consortium in about 2 weeks with a longer lag phase observable at 1000 ppm. Three colonies from the enriched consortium were then obtained on agar plates containing basal salts and glucose as the carbon source. Only one of the three colonies was capable of dioxane degradation. Further enrichment of this colony in liquid media led to a pure culture that grew on glucose and co-metabolically degraded dioxane after THF degradation. The rate and extent of dioxane degradation of this isolate increased with increasing THF concentration. This isolate was subsequently identified as a Flavobacterium by 16S rDNA sequencing. Using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analysis of microbial populations, Flavobacterium was determined to be the dominant species in the enriched consortium and was distinct from the two other colonies that did not degrade dioxane. This is the first report of a dioxane-degrading Flavobacterium which is phylogenetically distinct from any previously identified dioxane degrader.     

Diversity and functional analysis of bacterial communities associated with natural hydrocarbon seeps in acidic soils at Rainbow Springs, Yellowstone National Park

In this paper we describe the bacterial communities associated with natural hydrocarbon seeps in nonthermal soils at Rainbow Springs, Yellowstone National Park. Soil chemical analysis revealed high sulfate concentrations and low pH values (pH 2.8 to 3.8), which are characteristic of acid-sulfate geothermal activity. The hydrocarbon composition of the seep soils consisted almost entirely of saturated, acyclic alkanes (e.g., n-alkanes with chain lengths of C15 to C30, as well as branched alkanes, predominately pristane and phytane). Bacterial populations present in the seep soils were phylogenetically characterized by 16S rRNA gene clone library analysis. The majority of the sequences recovered (>75%) were related to sequences of heterotrophic acidophilic bacteria, including Acidisphaera spp. and Acidiphilium spp. of the alpha-Proteobacteria. Clones related to the iron- and sulfur-oxidizing chemolithotroph Acidithiobacillus spp. were also recovered from one of the seep soils. Hydrocarbon-amended soil-sand mixtures were established to examine [14C]hexadecane mineralization and corresponding changes in the bacterial populations using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. Approximately 50% of the [14C]hexadecane added was recovered as 14CO2 during an 80-day incubation, and this was accompanied by detection of heterotrophic acidophile-related sequences as dominant DGGE bands. An alkane-degrading isolate was cultivated, whose 16S rRNA gene sequence was identical to the sequence of a dominant DGGE band in the soil-sand mixture, as well as the clone sequence recovered most frequently from the original soil. This and the presence of an alkB gene homolog in this isolate confirmed the alkane degradation capability of one population indigenous to acidic hydrocarbon seep soils.     

阿特拉津降解菌株的分离、鉴定和工业废水生物处理试验

用液体无机盐培养基富集培养法和无机盐平板直接分离法, 从生产阿特拉津的农药厂的废水和污泥混合物中分离到13个能以阿特拉津为唯一氮源生长的细菌菌株。通过16S rRNA基因序列分析, 11个菌株被鉴定为Arthrobacter spp., 2个菌株被鉴定为Pseudomonas spp.。对阿特拉津降解活力最高的Arthrobacter sp. AD30和Pseudomonas sp. AD39的降解基因组成和降解特性进行了详细研究。降解基因的PCR扩增表明, AD30和AD39都含有trzN-atzBC基因, 能将有毒的阿特拉津降解成无毒的氰尿酸。降解实验表明, 向阿特拉津浓度为200 mg/L的无机盐培养基中分别接种等量的AD30、AD39和这两个菌株的混合菌液, 30°C振荡培养48 h以后, 阿特拉津去除率分别为92.5%、97.9%和99.6%, 表明混合菌的降解效果好于单菌。用AD30和AD39的混合菌液接种阿特拉津浓度为176 mg/L的工业废水, 30°C振荡培养72 h以后, 99.1%的阿特拉津被去除, 表明混合菌株在阿特拉津工业废水的生物处理中有很好的应用潜力。     

蜘蛛抱蛋属植物内生细菌的多样性及其抗菌活性筛选

【背景】药用植物中蕴含多样性丰富的内生菌资源,这些微生物产生的多种新型物质在制药领域表现出较好的应用前景。【目的】研究蜘蛛抱蛋属(Aspidistra Ker-Gawl.)植物内生细菌的多样性,探索药用植物内生细菌在药用活性产物方面的开发潜力,以期发现具有抗菌活性的次级代谢产物。【方法】对9种13株新鲜的蜘蛛抱蛋植物进行表面消毒,采用5种分离培养基分离内生细菌;根据菌落形态特征排除重复菌株,并测定其16S rRNA基因序列,构建系统进化树分析内生细菌多样性;将菌株分别用2种培养基发酵,使用耻垢分枝杆菌(Mycobacterium smegmatis ATCC 700044)、水稻白叶枯菌(Xanthomonas oryzae PXO99A)、白色念珠菌(Candidaalbicans ATCC 10231)、肺炎雷伯菌(Klebsiella pneumoniae ATCC 700603)和耐药粪肠球菌HH22(Enterococcus faecalis HH22)5种检定菌对分离菌株的发酵液进行抑菌活性筛选。【结果】从植物组织中分离得到了234株内生细菌,根据形态初步排重得到156株植物内生细菌;基于16S rRNA基因序列构建的系统进化树显示它们分属于3门10目22科29属,其中链霉菌属(Streptomyces)、芽孢杆菌属(Bacillus)、微杆菌属(Microbacterium)、类芽孢杆菌属(Paenibacillus)和根瘤菌属(Rhizobium)的菌株广泛地分布在不同种的蜘蛛抱蛋植株中,且占据一定优势;发现可能的潜在新分类单元6个;156株内生细菌中38株菌的发酵液具有抑菌活性,初筛阳性率为23.7%。【结论】蜘蛛抱蛋植物组织中含有种类多样的内生细菌,它们可能是抗菌生物活性次级代谢产物的有效来源。