Phylogenetic and metabolic bacterial diversity of <Emphasis Type="Italic">Phragmites australis</Emphasis> periphyton communities in two Hungarian soda ponds

Bacterial diversity of reed (Phragmites australis) periphyton communities of Kelemen-szék and Nagy-Vadas (two Hungarian soda ponds) was investigated using molecular cloning and cultivation-based techniques. The majority of the 80 Kelemen-szék and 72 Nagy-Vadas bacterial isolates proved to be moderately halophilic and alkaliphilic. A great proportion of the isolates showed phosphatase and urease activity, utilized aesculin, citrate and certain biopolymers (e.g., gelatine and tween 80). Partial 16S rDNA sequence analysis of 33 Kelemen-szék and 20 Nagy-Vadas ARDRA group representatives showed Gram-positive (Nesterenkonia, Cellulomonas, Dietzia, Bacillus and Planococcus) dominance at both sampling sites. Species of the genera Acidovorax, Hydrogenophaga (β-Proteobacteria) and Flavobacterium, Sphingobacterium (Bacteroidetes) were represented only from Kelemen-szék. Altogether 16 isolates showed low sequence similarity with yet described bacteria and may represent novel taxa. Screening of the 16S rRNA gene libraries of 129 Kelemen-szék and 158 Nagy-Vadas clones resulted in 30 and 28 different ARDRA groups, respectively. Sequence analysis revealed a Gram-negative (Rheinheimera, Aquimonas, Cellvibrio, Flavobacterium and Sphingobacterium) dominated phylogenetic diversity. A high number of the clones were affiliated with uncultured bacterial clones described from diverse environmental samples.     

微生物在镉污染土壤修复中的应用及其作用机理

土壤中镉（Cd）含量的超标导致了土壤生态系统的恶性发展,微生物作为土壤中的常见组分之一在缓解土壤镉污染中展现出巨大潜力。本文总结了微生物、微生物-植物和微生物-生物炭在镉污染土壤修复中的应用并阐述了相关的作用机理。芽孢杆菌（Bacillus）、不动杆菌（Acinetobacter）、荧光假单胞菌（Pseudomonas fluorescence）、丛枝菌根真菌（arbuscular mycorrhizal fungi,AMF）等微生物可以通过吸附、矿化、沉淀、溶解等方式改变镉的生物有效性,从而达到缓解镉污染的目的。pH值、温度、微生物生物量、镉初始浓度以及时间等对微生物降低镉的生物有效性方面有着显著的影响。假单胞菌、伯克霍尔德菌（Burkholderia）、黄杆菌（flavobacterium）等微生物可以通过促生、活化等作用促进超富集植物对Cd²⁺的吸收。生物炭作为一种土壤改良剂,其独有的理化性质可以作为微生物的庇护所。微生物-生物炭联合使用与单用生物炭相比可以进一步促进镉的残渣态的增加,降低土壤中有效态的比例。     

基于可培养方法分析云南腾冲小空山火山谷芽胞杆菌分布特征

【目的】为了解云南腾冲小空山火山谷土壤中可培养芽胞杆菌种类分布特征。【方法】采用可培养手段对小空山火山谷阳坡、谷底和阴坡土壤中的芽胞杆菌进行分离培养,根据16S rRNA基因序列同源性对分离菌株进行鉴定,并分析系统发育地位。利用Canoco5软件分析采样点芽胞杆菌种类分布特征与土壤样品理化性质的相关性。【结果】从火山谷土壤样品中共分离获得180株芽胞杆菌,16S rRNA基因测序鉴定结果表明分离菌株隶属于芽胞杆菌纲2个科(芽胞杆菌科和类芽胞杆菌科)、6个属、34个种,其中芽胞杆菌属(Bacillus) 11个种,类芽胞杆菌属(Paenibacillus) 14个种,短芽胞杆菌属(Brevibacillus)3个种,赖氨酸芽胞杆菌属(Lysinibacillus)4个种,嗜冷芽胞杆菌属(Psychrobacillus)1个种和绿芽胞杆菌属(Viridibacillus)2个种,其中7个菌株与其最近模式菌株16SrRNA相似性低于种的界定阈值(98.65%),为芽胞杆菌潜在新物种。优势属为芽胞杆菌属和类芽胞杆菌属,优势种为蕈状芽胞杆菌(Bacillusmycoides),图瓦永芽胞杆菌(Bacillustoyonensis),蜡状芽胞杆菌(Bacilluscereus),解木糖赖氨酸芽胞杆菌(Lysinibacillusxylanilyticus),蜂房类芽胞杆菌(Paenibacillusalvei)和沙地绿芽胞杆菌(Viridibacillus arenosi)。其中16个种分离自阳坡,29个种分离自阴坡,9个种分离自谷底,三者共同种类为6种。阳坡、谷底和阴坡的芽胞杆菌种群分布Bray-Curtis相似性为62.4%,多样性分析结果表明,Shannon指数(H′)大小次序为阴坡阳坡谷底。环境因子分析发现,芽胞杆菌种群分布多样性特征与其土壤的海拔高度、碳氮比和硫含量呈负相关,而和碳源和氮源含量呈正相关。【结论】从以上结果得出,云南腾冲火山谷有着较为丰富的芽胞杆菌资源,且还存在可分离培养的芽胞杆菌的潜在新物种,为利用火山微生物资源提供了保障。     

Effect of chelating agents and respiratory inhibitors on regulation of the cadA gene in Escherichia coli

The cadA gene that encodes lysine decarboxylase in Escherichia coli is induced by low pH and – during anaerobic growth – by the substrate, lysine. We used operon fusions of cadA to lacZ to investigate the effects of aeration on cadA regulation. When an insertion mutation in osmZ (= hns) was introduced, a cadA-lacZ fusion was derepressed in the presence of air to approximately the same level as seen during anaerobic growth. However, the pH-dependent regulation of cadA was not affected by osmZ. Introduction of mutations in rpoS, fur, or fnr had no significant effect on cadA expression. However, defects in arcB or arcA largely abolished expression of cadA during anaerobic growth. Nonetheless, strains defective in both arcB and osmZ showed the same high cadA-lac expression in air as seen in the single osmZ derivatives. Blocking the respiratory chain with mutations or chemical inhibitors also caused derepression of a cadA-lacZ fusion in air, while agents affecting the proton gradient had no effect. Derepression of cadA in air was also mediated by several chelating agents, in particular by methoxyindole carboxylic acid. Addition of Fe²⁺ overcame this effect. Chelating agents also abolished the expression during aerobic growth of several genes known to be under arcAB control and which are normally repressed during anaerobic growth but induced in the presence of air. This implies that the effect of chelating agents on cadA expression is mediated via the arcAB regulatory system. Received: 16 August 1996 / Accepted: 12 November 1996     

Cellulolytic bacteria from soils in harsh environments

It is believed that the exposure of organisms to harsh climate conditions may select for differential enzymatic activities, making the surviving organisms a very promising source for bioprospecting. Soil bacteria play an important role in degradation of organic matter, which is mostly due to their ability to decompose cellulose-based materials. This work focuses on the isolation and identification of cellulolytic bacteria from soil found in two environments with stressful climate conditions (Antarctica and the Brazilian semi-arid caatinga). Cellulolytic bacteria were selected using enrichments at high and low temperatures (4 or 60°C) in liquid media (trypic soy broth—TSB and minimum salt medium—MM) supplemented with cellulose (1%). Many of the isolates (119 out of 254—46.9%) displayed the ability to degrade carboxymethyl-cellulose, indicating the presence of endoglucolytic activity, while only a minority of these isolates (23 out of 254—9.1%) showed exoglucolytic activity (degradation of avicel). The obtained isolates revealed a preferential endoglucolytic activity according to the temperature of enrichments. Also, the identification of some isolates by partial sequencing of the 16S rRNA gene indicated that the Bacteroidetes (e.g., Pedobacter, Chryseobacterium and Flavobacterium) were the main phylum of cellulolytic bacteria isolated from soil in Antarctica; the Firmicutes (e.g., Bacillus) were more commonly isolated from samples from the caatinga; and Actinobacteria were found in both types of soil (e.g., Microbacterium and Arthrobacter). In conclusion, this work reports the isolation of bacteria able to degrade cellulose-based material from soil at very low or very high temperatures, a finding that should be further explored in the search for cellulolytic enzymes to be used in the bioenergy industry.     

Biodegradability of bacterial surfactants

This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO₂ evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO₂ emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.     

Influence of short chain fatty acids and lysine on Salmonella typhimurium cadA expression

In Salmonella typhimurium, cadA has a role in virulence expression and is an inducible gene that responds to external lysine concentration. In this study, a strain of S. typhimurium carrying a cadA: lacZ fusion was used to determine if the induction of cadA occurred under different lysine concentrations and mildly acid conditions in the presence of short chain fatty acids. Aliquots of an 18-h culture of S. typhimurium were placed on fresh media containing different lysine concentrations at pH 5.8 adjusted by addition of HCl or by 1 M short chain fatty acids (SCFA, acetic, propionic and butyric acid) stock solution. After an induction period of 2 h, -galactosidase activities were assayed. Expression of cadA in rich medium was significantly higher than that of minimal medium at neutral pH and different lysine concentrations. In contrast, at pH 5.8, there was a significant increase in cadA expression, particularly when pH was adjusted using HCl at all lysine levels. Addition of a mixture of organic acids yielded an overall lower cadA expression at all lysine levels studied when compared to HCl. However, each SCFA challenge (individual or as a mixture) caused a high level of expression, both at neutral and acidic pH. Based on these results it is apparent that in the presence of external lysine, SCFA and nutrient availability can influence cadA expression in S. typhimurium.     

High Diversity among Feather-Degrading Bacteria from a Dry Meadow Soil

The aim of this study was to determine the diversity of cultivable bacteria able to degrade feathers and present in soil under temperate climate. We obtained 33 isolates from soil samples, which clustered in 13 ARDRA groups. These isolates were able to grow on solid medium with pigeon feathers as sole carbon and nitrogen source. One representative isolate of each ARDRA group was selected for identification and feather degradation tests. The phylogenetic analysis of 16S rDNA gene fragments revealed that only 4 isolates were gram positives. Two other isolates belonged to the Cytophaga–Flavobacterium group, and the remaining to Proteobacteria. High keratinolysis activity was found for strains related to Bacillus, Cytophagales, Actinomycetales, and Proteobacteria. The 13 selected strains showed variable efficiency in degrading whole feathers and 5 strains were able to degrade maximum 40% to 98% of the whole feathers. After 4 weeks incubation, five strains grown on milled feathers produced more than 0.5 U keratinase per mL. Keratinase activities across the 13 strains were positively correlated with the percentage of feather fragmentation and protein concentration.     

Genomic Analysis and Comparative Hexavalent Chromium Reduction Potential of Predominant Bacillus species Isolated from Chromite Mine Soil

Ten predominant bacteria (CSB 1-10), isolated from chromite mine soil of Sukinda, Odisha, were characterized by means of biochemical and 16S rRNA gene sequencing. All of the bacterial isolates were Gram-positive, spore-forming, and motile rods with diameter ranging from 1.57–2.79 μm and identified as Bacillus species. Based on 16S rRNA gene sequencing and phylogenetic tree construction, 10 Bacillus species were grouped into two clusters: Bacillus subtilis cluster with four species (two of B. amyloliquefaciens, and one each of B. tequilensis and B. mojavensis); and Bacillus cereus cluster containing six species of B. cereus. Secondary rRNA structure predicted for all 10 bacteria using 16S rRNA sequences revealed some degree of genetic variations among the species. Among the isolated bacteria, CSB-9 was found to be the most efficient chromate reducing strain (0.8 × 10^?4 mg mg^?1 h^?1) in comparison to the others. Chromate reduction of the bacteria was associated with the contribution of extracellular enzyme production, and highest enzyme activity (0.9 ± 0.09 U mL^?1) was observed in CSB-9 (B. amyloliquefaciens). The present study revealed the dominance of Bacillus species in the chromite mine soil and their potential for bioremediation of hexavalent chromium from the polluted environments.     

佳西热带雨林土壤芽胞杆菌分离与多样性分析

采用热处理法从海南省佳西热带雨林土壤中分离到147株芽胞杆菌,并利用16S rDNA PCR-RFLP与序列分析技术对其遗传多样性进行了研究。16S rDNA PCR-RFLP酶切图谱UPGMA聚类分析结果表明,在100%的相似性水平上,这些芽胞杆菌分属13个遗传类群。不同遗传类型代表菌株的16S rRNA基因序列分析结果显示,它们分布在Bacillaceae、Planococcaceae和Paenibacillaceae科的Bacillus、Lysinibacillus、Paucisalibacillus、Bhargavaea和Paenibacillus五个属,其中Bacillus为优势属(占50%);有3株芽胞杆菌的16S rRNA基因序列与数据库中相应模式菌株的最大相似性在98.3%~98.9%之间。结果表明,佳西热带雨林土壤中芽胞杆菌有着较为丰富的遗传多样性。     

<Emphasis Type="Italic">Bacillus deserti</Emphasis> sp. nov., a novel bacterium isolated from the desert of Xinjiang,China

A Gram-positive, rod-shaped, motile and spore-forming bacterium, designated ZLD-8^T, was isolated from a desert soil sample collected from Xinjiang Province in north-west China, and subjected to a polyphasic taxonomic analysis. This isolate grew optimally at 30°C and pH 7.0. It grew with 0–4% NaCl (optimum, 0–1%). Comparative 16S rRNA gene sequence analysis showed that strain ZLD-8^T was closely related to members of the genus Bacillus, exhibiting the highest 16S rRNA gene sequence similarity to Bacillus kribbensis DSM 17871^T (98.0%). The levels of 16S rRNA gene sequence similarity with respect to other Bacillus species with validly published names were less than 96.3%. The DNA G + C content of strain ZLD-8^T was 40.1 mol%. The strain contained MK-7 as the predominant menaquinone. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids (>5% of total fatty acids) were anteiso-C15:0 (39.56%), iso-C14:0 (25.69%), C16:1 ω7c alcohol (10.13%) and iso-C15:0 (5.27%). These chemotaxonomic results supported the affiliation of strain ZLD-8^T to the genus Bacillus. However, low DNA–DNA relatedness values and distinguishing phenotypic characteristics allowed genotypic and phenotypic differentiation of strain ZLD-8^T from recognized Bacillus species. On the basis of the polyphasic evidence presented, strain ZLD-8^T is considered to represent a novel species of the genus Bacillus, for which the name Bacillus deserti sp. nov. is proposed. The type strain is ZLD-8^T (=CCTCC AB 207173^T = KCTC 13246^T).     

Transfer of megaplasmid pKB1 from the rubber-degrading bacterium <Emphasis Type="Italic">Gordonia westfalica</Emphasis> strain Kb1 to related bacteria and its modification

Because engineering of the 101.016-bp megaplasmid pKB1 of Gordonia westfalica Kb1 failed due to the absence of an effective transfer system, pKB1 was transferred by conjugation from G. westfalica Kb1 to a kanamycin-resistant mutant of Rhodococcus opacus PD630 at a frequency of about 6.2 × 10⁻⁸ events per recipient cell. Furthermore, pKB1 was transferred to G. polyisoprenivorans strains VH2 and Y2K and to Mycobacterium smegmatis by electroporation at frequencies of 5.5 × 10³, 1.9 × 10³, and 8.3 × 10² transformants per microgram plasmid DNA. The pKB1-encoded cadmium resistance gene cadA was used for selection in these experiments. Recombinant pKB1-containing G. polyisoprenivorans VH2 and M. smegmatis were then used to engineer pKB1. A kanamycin resistance cassette was inserted into the pKB1-encoded cadA gene, ligated to suicide plasmid pBBR1MCS-5, and the resulting plasmid was electroporated into plasmid-harboring strains. Homologous recombination between cadA on suicide plasmid and the respective sequence in pKB1 led to its integration into pKB1. Thus, two selection markers were accommodated in pKB1 to monitor plasmid transfer into Gordonia and related taxa for analysis of genes essential for rubber degradation and others. In this study, two transfer methods for large plasmids and strategies for engineering of pKB1 were successfully applied, thereby, extending the tool box for Gordonia.     

Shift in microbial population in response to crystalline cellulose degradation during enrichment with a semi-desert soil

Addition of crystalline cellulose to semi-desert soil shifts the microbial population; this was assessed by following the 16S rRNA gene, glycosyl hydrolase, and measuring its functional diversity in the bacterial population. Quantification of the glycosyl hydrolase gene showed an increase from 1 × 10⁴ g⁻¹ of unamended soil to 3 × 10⁴ g⁻¹ of crystalline-cellulose-amended soil by the 15th day of crystalline cellulose utilization. The indigenous glycosyl hydrolase community in unamended soil was dominated by the clone families that were closely related to the glycosyl hydrolases from Betaproteobacteria and Firmicutes. The addition of crystalline cellulose induced a shift in the glycosyl hydrolase population toward an increase in the relative abundance of the glycosyl hydrolase that was consistent with those of Bacteroidetes and Flavobacteria. The population shift of glycosyl hydrolase was also supported by the comparison of the 16S rRNA gene families in unamended and crystalline-cellulose-amended soil libraries. The most abundant 16S rRNA gene sequences retrieved in the unamended soil were identical to Pseudomonas, Massilia, Paenibacillus, and Bacillus spp., while Cytophaga and Flavobacterium spp. dominated in crystalline-cellulose-amended soil.     

Detection of aerolysin gene in <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis> isolated from fish and pond water

Aerolysin is a hemolytic toxin encoded by aerolysin gene (1482 bp) that plays a key role in the pathogenesis of Aeromonas hydrophila infection in fish. New speciesspecific primers were designed to amplify 326 bp conserved region of aerolysin gene for A. hydrophila. Twenty-five isolates of A. hydrophila recovered from fish and pond water were studied for detection of aerolysin gene. Aerolysin gene was detected in 85% of the isolates during the study. The designed primers were highly specific and showed no cross reactivity with Escherichia coli, Aeromonas veronii, Vibrio cholerae, Flavobacterium spp., Chyseobacterium spp. and Staphylococcus aureus. The sensitivity limit of primers for detection of aerolysin gene in the genomic DNA of A. hydrophila was 5 pg.     

<Emphasis Type="Italic">Bacillus kyonggiensis</Emphasis> sp. nov., isolated from soil of a lettuce field

A Gram-positive, rod-shaped, motile, endospore-forming bacterial strain, designated NB22^T, was isolated from soil of a lettuce field in Kyonggi province, South Korea, and was characterized by using a polyphasic taxonomic approach. This novel isolate grew optimally at 30–37°C and pH 8–9. It grew in the presence of 0–4% NaCl (optimum, 1–2%). Comparative 16S rRNA gene sequence analysis showed that strain NB22^T was closely related to members of the genus Bacillus and fell within a coherent cluster comprising B. siralis 171544^T (98.1%) and B. korlensis ZLC-26^T (97.3%). The levels of 16S rRNA gene sequence similarity with respect to other Bacillus species with validly published names were less than 96.4%. Strain NB22^T had a genomic DNA G+C content of 36.3 mol% and the predominant respiratory quinone was MK-7. The peptidoglycan contained meso-diaminopimelic acid. The major cellular fatty acids were iso-C_15:0, anteiso-C_15:0, C_14:0, and C_16:0. These chemotaxonomic results supported the affiliation of strain NB22^T to the genus Bacillus, and the low DNA-DNA relatedness values and distinguishing phenotypic characteristics allowed genotypic and phenotypic differentiation of strain NB22^T from recognized Bacillus species. On the basis of the evidence presented, strain NB22^T is considered to represent a novel species of the genus Bacillus, for which the name Bacillus kyonggiensis sp. nov. is proposed. The type strain is NB22^T (=KEMB 5401-267^T =JCM 17569^T).     

The Frequency of Eubacterium-to-Eukaryote Lateral Gene Transfers Shows Significant Cross-Taxa Variation Within Amoebozoa

Single-celled bacterivorous eukaryotes offer excellent test cases for evaluation of the frequency of prey-to-predator lateral gene transfer (LGT). Here we use analysis of expressed sequence tag (EST) data sets to quantify the extent of LGT from eubacteria to two amoebae, Acanthamoeba castellanii and Hartmannella vermiformis. Stringent screening for LGT proceeded in several steps intended to enrich for authentic events while at the same time minimizing the incidence of false positives due to factors such as limitations in database coverage and ancient paralogy. The results were compared with data obtained when the same methodology was applied to EST libraries from a number of other eukaryotic taxa. Significant differences in the extent of apparent eubacterium-to-eukaryote LGT were found between taxa. Our results indicate that there may be substantial inter-taxon variation in the number of LGT events that become fixed even between amoebozoan species that have similar feeding modalities. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Martin Kreitman]     

Biodegradation of 2-Nitrotoluene by <Emphasis Type="Italic">Micrococcus</Emphasis> sp. strain SMN-1

A bacterial consortium capable of degrading nitroaromatic compounds was isolated from pesticide-contaminated soil samples by selective enrichment on 2-nitrotoluene as a sole source of carbon and energy. The three different bacterial isolates obtained from bacterial consortium were identified as Bacillus sp. (A and C), Bacillus flexus (B) and Micrococcus sp. (D) on the basis of their morphological and biochemical characteristics and by phylogenetic analysis based on 16S rRNA gene sequences. The pathway for the degradation of 2-nitrotoluene by Micrococcus sp. strain SMN-1 was elucidated by the isolation and identification of metabolites, growth and enzymatic studies. The organism degraded 2-nitrotoluene through 3-methylcatechol by a meta-cleavage pathway, with release of nitrite.     

Matching population diversity of rhizobial nodA and legume NFR5 genes in plant–microbe symbiosis

We hypothesized that population diversities of partners in nitrogen‐fixing rhizobium–legume symbiosis can be matched for “interplaying” genes. We tested this hypothesis using data on nucleotide polymorphism of symbiotic genes encoding two components of the plant–bacteria signaling system: (a) the rhizobial nodA acyltransferase involved in the fatty acid tail decoration of the Nod factor (signaling molecule); (b) the plant NFR5 receptor required for Nod factor binding. We collected three wild‐growing legume species together with soil samples adjacent to the roots from one large 25‐year fallow: Vicia sativa, Lathyrus pratensis, and Trifolium hybridum nodulated by one of the two Rhizobium leguminosarum biovars (viciae and trifolii). For each plant species, we prepared three pools for DNA extraction and further sequencing: the plant pool (30 plant indiv.), the nodule pool (90 nodules), and the soil pool (30 samples). We observed the following statistically significant conclusions: (a) a monotonic relationship between the diversity in the plant NFR5 gene pools and the nodule rhizobial nodA gene pools; (b) higher topological similarity of the NFR5 gene tree with the nodA gene tree of the nodule pool, than with the nodA gene tree of the soil pool. Both nonsynonymous diversity and Tajima's D were increased in the nodule pools compared with the soil pools, consistent with relaxation of negative selection and/or admixture of balancing selection. We propose that the observed genetic concordance between NFR5 gene pools and nodule nodA gene pools arises from the selection of particular genotypes of the nodA gene by the host plant.     

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.