RT-TGGE as a guide for the successful isolation of phosphonoacetate degrading bacteria

AIMS: Use of molecular techniques for the isolation of bacteria capable of phosphonoacetate mineralization as carbon, phosphorus and energy source. METHODS AND RESULTS: RNA extracts obtained at three different stages of an enrichment selecting for phosphonoacetate degrading bacteria were reverse transcribed using 16S rRNA-specific primers, amplified and analysed by temperature gradient gel electrophoresis (TGGE). This information was used to devise a strategy for the isolation of members of the enrichment that were otherwise difficult to obtain in pure culture. We were able to pull out, in total, four out of the six main microbial cultures that were detected by TGGE. Two of the isolates belonging to Mycobacterium and Agromyces genera were for the first time shown to grow in the presence of phosphonoacetate as sole carbon, phosphorus and energy source releasing almost equimolar levels of inorganic phosphate into the culture medium, and they were shown to exhibit phosphonoacetate hydrolase activity in vitro. CONCLUSIONS: The ubiquity of pseudomonad in degradation processes is more likely a consequence of our ignorance of bacterial requirements and physiology, rather than their possession of unique metabolic properties. SIGNIFICANCE AND IMPACT OF THE STUDY: RT-TGGE analysis can be used to guide the successful isolation of micro-organisms difficult to obtain by culture-dependent methods alone.     

两株高效苯酚降解菌的筛选、鉴定及生物强化-DTRO组合工艺初步验证

【目的】从煤化工废水中分离、筛选苯酚高效降解微生物,初步考察微生物与DTRO技术联用,构建含酚废水生物强化处理工艺的可行性。【方法】采用苯酚浓度梯度培养基对苯酚降解微生物进行分离和筛选;根据菌体形态电子显微镜观察、菌株生理生化特性考察和16S r RNA基因系统发育树构建,对菌株进行初步生物学鉴定;将筛选出的高效苯酚降解菌制备成相应的菌剂与碟管式反渗透(DTRO)技术组合形成"生物强化-DTRO"工艺,并试用于含酚废水的处理。【结果】共获得7株纯化细菌,其中Phe-03和Phe-05为高效苯酚降解菌;该2株菌均可以苯酚为唯一碳源生长。经鉴定Phe-03为壤霉菌属(Agromyces)菌株;Phe-05为棒杆菌属(Corynebacterium)菌株。到目前为止,壤霉菌属(Agromyces)菌株降解苯酚尚未见报道。在初始苯酚浓度达到1 300 mg/L条件下,Phe-03和Phe-05菌株44 h内对苯酚降解率均达到70%以上;76 h后苯酚降解率均超过90%。组合形成的"生物强化-DTRO"工艺不仅可以有效去除废水中的酚类化合物,而且还能减少反渗透膜污染,以及增加膜的通透性。【结论】研究表明微生物技术可与DTRO技术联用,构建含酚废水生物强化处理工艺,可为含酚废水处理技术研究提供一种选择思路。     

Further evidence for the phylogenetic coherence of actinomycetes with Group B-peptidoglycan and evidence for the phylogenetic intermixing of the genera Microbacterium and Aureobacterium as determined by 16S rDNA analysis

Abstract A 16S rDNA study was performed on at least two species, including the type strain of the type species, of each genus described to possess peptidoglycan of Group B. Analyses confirm that these actinomycetes form a phylogenetically coherent cluster within the arthrobacteria subline of descent. While members of the genera Agromyces, Clavibacter, Curtobacterium and Rathayibacter appear to be phylogenetically coherent, members of Microbacterium and Aureobacterium do not cluster according to their taxonomic affiliation but form one large cluster in which species of both genera are intermixed. Species with no taxonomic standing, i.e. "Corynebacterium aquaticum" , and "Brevibacterium helvolum" form three separate sublines of descent and can be considered nuclei of future novel genera.     

几株细菌的重金属抗性水平和吸附量

从堆积时间为80～100a的铅锌矿渣中分离了6株细菌,通过测定部分16S rRNA基因序列确定了它们的系统发育地位。结果表明有3株细菌属于节杆菌属(Arthrobacter),同A．nicotinovorans和A．histidinolovorans两个种关系密切。另外3株属于壤霉菌属(Agromyces),同Ag．mediolanus具有较近的亲缘关系。总体来看,这些菌株都对检测的5种重金属有高的最低抑菌浓度(minimal inhibitory concentration,MIC)。节杆菌对Zn、Co的耐受明显高于壤霉菌。此外,这些重金属高抗性菌株也对重金属有较强的吸附能力。在环境中有单一重金属离子的情况下,冻干的节杆菌对Ph的吸附率平均达到了约400mg／g干菌体,对Cd和zn的吸附也分别达到了近177和80mg/g干菌体,具有进一步开发为重金属吸附剂的潜力。