Description of Labrys sedimenti sp. nov., isolated from a diclofenac-degrading enrichment culture, and genome-based reclassification of Labrys portucalensis as a later heterotypic synonym of Labrys neptuniae

A Gram-stain-negative strain, designated as Zidic-5T, was isolated from diclofenac-degrading enrichment culture and characterized using a polyphasic approach to determine its taxonomic position. The 16S rRNA gene sequence analysis revealed that strain Zidic-5T belongs to the genus Labrys, with the highest 16S rRNA gene similarity to Labrys neptuniae LMG 23578T (99.13%), followed by Labrys portucalensis F11T (99.06%), Labrys methylaminiphilus JLW10T (98.58%) and Labrys okinawensis DSM 18385T (98.32%). The draft genome sequence of strain Zidic-5T is 7.64 Mb long, and the G+C content of the genome is 63.5 mol%. The orthologous average nucleotide identity and digital DNA-DNA hybridization relatedness values between strain Zidic-5T and its closest relatives were below the threshold values for species demarcation, confirming that strain Zidic-5T is distinctly separated from its closest relatives. Additionally, comparative whole-genome analysis of type strains of L. neptuniae and L. portucalensis indicated that they belong to the same genomic species, suggesting that L. portucalensis is a later heterotypic synonym of L. neptuniae. Cells of strain Zidic-5T were strictly aerobic, coccoid-shaped and non-motile. The predominant fatty acids (>10% of the total) of strain Zidic-5T were C18 : 1 ω7c, C16 : 0 and C19 : 0 cyclo ω7c. The major ubiquinone of strain Zidic-5T was Q-10, while the major polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and aminophospholipid. Based on the polyphasic study, it is concluded that strain Zidic-5T represents a novel species of the genus Labrys; thus, the name of Labrys sedimenti sp. nov. is proposed. The type strain of the species is strain Zidic-5T (=LMG 33565T=NCAIM B.02686T).

PFAS biodegradation by Labrys portucalensis F11: Evidence of chain shortening and identification of metabolites of PFOS, 6:2 FTS, and 5:3 FTCA

The biodegradation of three per- and polyfluoroalkyl substances (PFAS), namely perfluorooctane sulfonic acid (PFOS), 6:2-fluorotelomer sulfonic acid (6:2 FTS), and 5:3-fluorotelomer carboxylic acid (5:3 FTCA), were evaluated using Labrys portucalensis F11, an aerobic bacteria known to defluorinate fluorine-containing compounds. Cultures of L. portucalensis F11 were grown in minimal salts media and treated with 10,000 μg/L of individual PFAS as the sole carbon source in separate flasks. In PFOS-spiked media, several metabolites were detected, including perfluoroheptane sulfonic acid (PFHpS), perfluorohexane sulfonic acid (PFHxS), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA), and perfluoropropanoic acid (PFPrA). After 194-day incubation three de-fluorinated metabolites were identified: PFOS-F (m/z = 480.940, PFOS-2F (m/z = 462.980), and unsaturated PFOS-3F (m/z = 442.943). During the biodegradation of 5:3 FTCA, the following metabolites were observed: PFHxA, PFPeA, PFBA, PFPrA, and two fluorotelomer unsaturated carboxylic acids (5:3 FTUCA and 7:2 FTUCA). The biodegradation of 6:2 FTS was slower, with only 21 % decrease in concentration observed after 100 days, and subsequent formation of 4:2 FTS. On the contrary, 90 % of PFOS and 58 % of 5:3 FTCA were degraded after 100 days. These results indicate that L. portucalensis F11 can be potentially used for PFAS biodegradation in contaminated environments.

Removal of Ibuprofen in Water by Bioaugmentation with Labrys neptuniae CSW11 Isolated from Sewage Sludge-Assessment of Biodegradation Pathway Based on Metabolite Formation and Genomic Analysis

Ibuprofen (IBP) is one of the most consumed drugs in the world. It is only partially removed in wastewater treatment plants (WWTPs), being present in effluent wastewater and sewage sludge, causing the widespread introduction of IBP as an emergent xenobiotic in different environmental compartments. This study describes the use of Labrys neptuniae CSW11, recently described as an IBP degrader, through bioaugmentation processes for the removal of IBP from water under different conditions (additional carbon sources, various concentrations of glucose and IBP). L. neptuniae CSW11 showed very good results in a wide range of IBP concentrations, with 100% removal in only 4 days for 1 and 5 mg L-1 IBP and 7 days for 10 mg L-1, and up to 48.4% removal in 28 days for IBP 100 mg L-1 when using glucose 3 g L-1 as an additional carbon source. Three IBP metabolites were identified during the biotransformation process: 1-hydroxyibuprofen (1-OH-IBP), 2-hydroxyibuprofen (2-OH-IBP), and carboxyibuprofen (CBX-IBP), whose concentrations declined drastically in the presence of glucose. IBP metabolites maintained a certain degree of toxicity in solution, even when IBP was completely removed. The results indicate that L. neptuniae CSW11 can be quite effective in degrading IBP in water, but the bioaugmentation method should be improved using CSW11 in consortia with other bacterial strains able to degrade the toxic metabolites produced. A genome-based analysis of L. neptuniae CSW11 revealed different enzymes that could be involved in IBP biodegradation, and a potential metabolic pathway was proposed based on the metabolites observed and genome analysis.

The Impact of Anti-Inflammatory Drugs on the Prokaryotic Community Composition and Selected Bacterial Strains Based on Microcosm Experiments

Non-steroidal anti-inflammatory drugs (NSAIDs) are increasingly recognized as potential environmental contaminants that may induce toxicity in aquatic ecosystems. This 3-week microcosm experiment explores the acute impacts of NSAIDs, including diclofenac (DCF), ibuprofen (IBU), and acetylsalicylic acid (ASA), on bacterial communities using a wide range of these substances (200-6000 ppm). The results showed that the NSAID-treated microcosms had higher cell count values than control samples, though the diversity of microbial communities decreased. The isolated heterotrophic bacteria mostly belonged to Proteobacteria, particularly Klebsiella. Next-generation sequencing (NGS) revealed that NSAIDs altered the structure of the bacterial community composition, with the proportion of Proteobacteria aligning with the selective cultivation results. Bacteria had higher resistance to IBU/ASA than to DCF. In DCF-treated microcosms, there has been a high reduction of the number of Bacteroidetes, whereas in the microcosms treated with IBU/ASA, they have remained abundant. The numbers of Patescibacteria and Actinobacteria have decreased across all NSAID-treated microcosms. Verrucomicrobia and Planctomycetes have tolerated all NSAIDs, even DCF. Cyanobacteria have also demonstrated tolerance to IBU/ASA treatment in the microcosms. The archaeal community structure was also impacted by the NSAID treatments, with Thaumarchaeota abundant in all microcosms, especially DCF-treated microcosms, while Nanoarchaeota is more typical of IBU/ASA-treated microcosms with lower NSAID concentrations. These results indicate that the presence of NSAIDs in aquatic environments could lead to changes in the composition of microbial communities.

Biodegradation and Metabolic Pathway of the Neonicotinoid Insecticide Thiamethoxam by Labrys portucalensis F11

Thiamethoxam (TMX) is an effective neonicotinoid insecticide. However, its widespread use is detrimental to non-targeted organisms and water systems. This study investigates the biodegradation of this insecticide by Labrys portucalensis F11. After 30 days of incubation in mineral salt medium, L. portucalensis F11 was able to remove 41%, 35% and 100% of a supplied amount of TMX (10.8 mg L^-1) provided as the sole carbon and nitrogen source, the sole carbon and sulfur source and as the sole carbon source, respectively. Periodic feeding with sodium acetate as the supplementary carbon source resulted in faster degradation of TMX (10.8 mg L^-1); more than 90% was removed in 3 days. The detection and identification of biodegradation intermediates was performed by UPLC-QTOF/MS/MS. The chemical structure of 12 metabolites is proposed. Nitro reduction, oxadiazine ring cleavage and dechlorination are the main degradation pathways proposed. After biodegradation, toxicity was removed as indicated using Aliivibrio fischeri and by assessing the synthesis of an inducible β-galactosidase by an E. coli mutant (Toxi-Chromo test). L. portucalensis F11 was able to degrade TMX under different conditions and could be effective in bioremediation strategies.

Identification of tissue-specific microbial profile of esophageal squamous cell carcinoma by full-length 16S rDNA sequencing

It was previously believed that the microbial community in the esophagus was relatively stable, but it has been reported that different esophageal diseases have different microbial community characteristics. In this study, we recruited patients with esophageal squamous cell carcinoma (ESCC) and collected 51 pairs of tumor and adjacent non-tumor tissues for full-length 16S rDNAsequencing and qPCR to compare the differences in microbial community structure. The results of sequencing in 19 pairs of tissues showed that Proteobacteria, Firmicutes, Bacteroidetes, Deinococcus-Thermus, and Actinobacteria were the main bacteria in tumor and adjacent non-tumor tissues. At the genus level, the bacteria with the highest relative proportion in tumor and adjacent non-tumor tissues were Streptococcus and Labrys, respectively. At the same time, it was observed that the complexity of microbial interactions in tumor tissues was weaker than that of adjacent non-tumor tissues. The results also found that the relative abundance of 24 taxa was statistically different between tumor and adjacent non-tumor tissues. The findings of qPCR in 32 pairs of tissues further evidence that the relative proportions of Blautia, Treponema, Lactobacillus murinus, Peptoanaerobacter stomatis, and Fusobacteria periodonticum were statistically different in tumor and adjacent non-tumor tissues. The findings of PIRCUSt2 indicated the lipopolysaccharide biosynthesis and biotin metabolism in the microbiome of cancer tissues are more significant. This study supplements the existing information on the structure, function, and interaction of microorganisms in the esophagus in situ and provides a direction for the further exploration of the relationship between esophageal in situ microorganisms and esophageal squamous cell carcinoma. KEY POINTS: • The structure of the microbial community in esophageal cancer tissue and adjacent non-tumor tissues at the phylum level is similar • Streptococcus and Labrys are the most important bacteria in esophageal tumor tissues and adjacent non-tumor tissues, respectively • Microbial interactions in tumor tissues are stronger than in adjacent non-tumor tissues.

Biorremediación de carbamazepina por hongos y bacterias en aguas residuales

La carbamazepina (CBZ), un fármaco psiquiátrico, antiepiléptico; mayormente utilizado en la actualidad para tratar enfermedades como la epilepsia y neuralgia del trigémino; es un contaminante emergente, considerado como una fuente importante de contaminación de fuentes hídricas, al no ser totalmente metabolizado por el organismo y ser excretado por vía urinaria y fecal, sin cambios o en forma de metabolitos conjugados. Estos contaminantes pasan por tratamientos de aguas residuales, sin embargo, los tratamientos convencionales no son capaces de degradarlo, produciendo daños a los seres vivos que habitan y necesitan de este recurso natural para poder sobrevivir. Frente a este problema, el objetivo de esta revisión fue identificar tratamientos biológicos con la utilización de microorganismos (bacterias y hongos) para la degradación de este compuesto recalcitrante. Los microorganismos identificados con mayor porcentaje de degradación de carbamazepina fueron Labrys portucalensis F11 y Trametes versicolor; la primera una bacteria que se adapta a diferentes fuentes de carbono; y el segundo un hongo denominado de pudrición de la madera, que presenta enzimas oxidativas que le permiten degradar una amplia gama de contaminantes emergentes. Trametes versicolor, es el microorganismo mayormente estudiado para los procesos de degradación de carbamazepina, con porcentajes de degradación de hasta el 94% a una temperatura de 25°C y un pH de 4.5.

Definition of Core Bacterial Taxa in Different Root Compartments of Dactylis glomerata, Grown in Soil under Different Levels of Land Use Intensity

Plant-associated bacterial assemblages are critical for plant fitness. Thus, identifying a consistent plant-associated core microbiome is important for predicting community responses to environmental changes. Our target was to identify the core bacterial microbiome of orchard grass Dactylis glomerata L. and to assess the part that is most sensitive to land management. Dactylis glomerata L. samples were collected from grassland sites with contrasting land use intensities but comparable soil properties at three different timepoints. To assess the plant-associated bacterial community structure in the compartments rhizosphere, bulk soil and endosphere, a molecular barcoding approach based on high throughput 16S rRNA amplicon sequencing was used. A distinct composition of plant-associated core bacterial communities independent of land use intensity was identified. Pseudomonas, Rhizobium and Bradyrhizobium were ubiquitously found in the root bacterial core microbiome. In the rhizosphere, the majority of assigned genera were Rhodoplanes, Methylibium, Kaistobacter and Bradyrhizobium. Due to the frequent occurrence of plant-promoting abilities in the genera found in the plant-associated core bacterial communities, our study helps to identify “healthy” plant-associated bacterial core communities. The variable part of the plant-associated microbiome, represented by the fluctuation of taxa at the different sampling timepoints, was increased under low land use intensity. This higher compositional variation in samples from plots with low land use intensity indicates a more selective recruitment of bacteria with traits required at different timepoints of plant development compared to samples from plots with high land use intensity.

Carbamazepine is degraded by the bacterial strain Labrys portucalensis F11

The occurrence of pharmaceuticals in the environment is a topic of concern. Carbamazepine (CBZ) is a widespread antiepileptic drug and due to its physical-chemical characteristics minimal removal is achieved in conventional water treatments, and thus has been suggested as a molecular marker of wastewater contamination in surface water and groundwater. The present study reports the biotransformation of CBZ by the bacterial strain Labrys portucalensis F11. When supplied as a sole carbon source, a 95.4% biotransformation of 42.69 μM CBZ was achieved in 30 days. In co-metabolism with acetate, complete biotransformation was attained at a faster rate. Following a target approach, the detection and identification of 14 intermediary metabolites was achieved through UPLC-QTOF/MS/MS. Biotransformation of CBZ by the bacterial strain is mostly based on oxidation, loss of -CHNO group and ketone formation reactions; a biotransformation pathway with two routes is proposed. The toxicity of untreated and treated CBZ solutions was assessed using Vibrio Fischeri and Lepidium sativum acute toxicity tests and Toxi-Chromo Test. The presence of CBZ and/or its degradations products in solution resulted in moderate toxic effect on Vibrio Fischeri, whereas the other organisms were not affected. To the best of our knowledge this is the first report that proposes the metabolic degradation pathway of CBZ by a single bacterial strain.

Aerobic degradation of 2- and 3-fluoroaniline in mixed culture systems and microbial community analysis

Among three monofluoroanilines, 2-fluoroaniline (2-FA) and 3-fluoroaniline (3-FA) exhibit relatively poor biodegradability. This work examined their degradation characteristics in a mixed culture system and also analyzed the microorganism community. After acclimation for 58 d and 43 d, the high removal efficiency of 100% of 2-FA and 95.3% of 3-FA was obtained by adding 25 mg L^-1 of 2-FA or 3-FA to the two reactors, respectively. In addition, the high defluorination rates of 2-FA and 3-FA were observed to be 87.0% and 89.3%, respectively. The degradation kinetics showed that the maximum specific degradation rates of 2-FA and 3-FA were (21.23 ± 0.91) mg FA (g•VSS·h)^-1, and (11.75 ± 0.99) mg FA (g•VSS·h)^-1, respectively. PCR-DGGE analysis revealed that the unique bacteria degrading 2-FA were mainly composed of six genera (Novosphingobium, Bradyrhizobium, Aquaspirillum, Aminobacter, Ochrobactrum, and Labrys), and five genera that degraded 3-FA (Ochrobactrum, Aquaspirillum, Lachnobacterium, Bradyrhizobium, and Variovorax). Analysis of the key catabolic enzyme activities indicated that the simultaneous hydroxylation and dehalogenation were involved in monooxygenase elimination of 2-FA and conversion of 3-FA to 4-fluorocatechol by dioxygenase, indicating that enriched mixed cultures were effective to metabolize 2-FA or 3-FA by unconventional pathways to prevent the accumulation of toxic metabolites.

A novel environmental fate of graphene oxide: Biodegradation by a bacterium Labrys sp. WJW to support growth

Graphene oxide (GO) is a new type of nanomaterial with unique physicochemical properties and diverse applications, whereas it poses potential risk to human and environment. By screening from natural soil exposed to GO in the laboratory, we successfully obtained a novel bacterium, Labrys sp. WJW, which was able to use GO as the sole carbon source for growth. Within 8 days, cell numbers increased 16.76 ± 3.21 folds using 100 mg/L GO as the carbon source by qPCR analysis. The bacterial biodegradation which resulted in formation of holes and functional group changes of GO was proved by Raman spectroscopy, atomic force microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy analyses. Aromatic intermediates with structures of benzoic acid and phenol were identified using gas chromatograph-mass spectrometry and liquid chromatography/time-of-flight/mass spectrometry. Combination of genomic and proteomic analyses were performed to explore the proteins associated with GO degradation. A total of 644 proteins were significantly shifted. Bioinformatics analysis indicated that part of the up-regulated proteins were related to oxidation, ring cleavage and intermediates transmembrane processes, and GO was supposed to be degraded to benzoate and further degraded for downstream processes. This study enriches our understanding and provides new insights into the environmental fate of GO.

Biodegradation of Diclofenac by the bacterial strain Labrys portucalensis F11

Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory pharmaceutical which is detected in the environment at concentrations which can pose a threat to living organisms. In this study, biodegradation of DCF was assessed using the bacterial strain Labrys portucalensis F11. Biotransformation of 70% of DCF (1.7-34 μM), supplied as the sole carbon source, was achieved in 30 days. Complete degradation was reached via co-metabolism with acetate, over a period of 6 days for 1.7 µM and 25 days for 34 μM of DCF. The detection and identification of biodegradation intermediates was performed by UPLC-QTOF/MS/MS. The chemical structure of 12 metabolites is proposed. DCF degradation by strain F11 proceeds mainly by hydroxylation reactions; the formation of benzoquinone imine species seems to be a central step in the degradation pathway. Moreover, this is the first report that identified conjugated metabolites, resulting from sulfation reactions of DCF by bacteria. Stoichiometric liberation of chlorine and no detection of metabolites at the end of the experiments are strong indications of complete degradation of DCF by strain F11. To the best of our knowledge this is the first report that points to complete degradation of DCF by a single bacterial strain isolated from the environment.

Natural production of fluorinated compounds and biotechnological prospects of the fluorinase enzyme

Fluorinated compounds are finding increasing uses in several applications. They are employed in almost all areas of modern society. These compounds are all produced by chemical synthesis and their abundance highly contrasts with fluorinated molecules of natural origin. To date, only some plants and a handful of actinomycetes species are known to produce a small number of fluorinated compounds that include fluoroacetate (FA), some ω-fluorinated fatty acids, nucleocidin, 4-fluorothreonine (4-FT), and the more recently identified (2R3S4S)-5-fluoro-2,3,4-trihydroxypentanoic acid. This largely differs from other naturally produced halogenated compounds, which totals more than 5000. The mechanisms underlying biological fluorination have been uncovered after discovering the first actinomycete species, Streptomyces cattleya, that is capable of producing FA and 4-FT, and a fluorinase has been identified as the enzyme responsible for the formation of the C-F bond. The discovery of this enzyme has opened new perspectives for the biotechnological production of fluorinated compounds and many advancements have been achieved in its application mainly as a biocatalyst for the synthesis of [¹⁸F]-labeled radiotracers for medical imaging. Natural fluorinated compounds may also be derived from abiogenic sources, such as volcanoes and rocks, though their concentrations and production mechanisms are not well known. This review provides an outlook of what is currently known about fluorinated compounds with natural origin. The paucity of these compounds and the biological mechanisms responsible for their production are addressed. Due to its relevance, special emphasis is given to the discovery, characterization and biotechnological potential of the unique fluorinase enzyme.

Bacterial degradation of moxifloxacin in the presence of acetate as a bulk substrate

Fluoroquinolones constitute a group of emerging pollutants and their occurrence in different environmental compartments is becoming object of increasing public concern due to their ecotoxicological effects and the potential to develop resistant bacteria. This study aimed to investigate the biodegradation of moxifloxacin (MOX), for which studies in the literature are very scarce. An activated sludge (AS) consortium and three bacterial strains able to degrade fluoroaromatic compounds - strains F11, FP1 and S2 - were tested. Biodegradation studies were conducted using acetate as a bulk carbon source. Strain F11 showed the highest biodegradation capacity, being able to completely consume and dehalogenate 7.5 μM of the target antibiotic when daily co-supplemented with acetate present as a readily degradable organic substrate in wastewaters. MOX could be used by strain F11 as a sole nitrogen source but the presence of an external nitrogen source in the culture medium was essential for complete biodegradation. Strain F11 was capable of completely consuming MOX in a range between 2 and 11 μM, although stoichiometric fluoride release was not obtained for the highest tested concentration. The antibacterial activity of residual MOX and of the metabolic products potentially resultant from the biodegradation process was investigated by agar diffusion tests, demonstrating that MOX biodegradation is associated with the elimination of the antibacterial properties of the target antibiotic and of the produced metabolites, which is an important result, as the activity of antibiotics and/or their metabolites in the environment, even at low levels, may lead to the development of resistant bacterial strains. Overall, the results obtained in this study suggest that strain F11 is a promising microorganism for the treatment of waters contaminated with MOX, where it could be used for bioaugmentation/bioremediation purposes. To the best of our knowledge, this is the first study reporting complete removal and dehalogenation of MOX by a single microorganism.

Microbial degradation of fluorinated drugs: biochemical pathways, impacts on the environment and potential applications

Since the discovery over 60 years ago of fluorocortisone's biological properties (9-α-Fluoro derivatives of cortisone and hydrocortisone; Fried J and Sabo EF, J Am Chem Soc 76: 1455-1456, 1954), the number of fluorinated drugs has steadily increased. With the improvement in synthetic methodologies, this trend is likely to continue and will lead to the introduction of new fluorinated substituents into pharmaceutical compounds. Although the biotransformation of organofluorine compounds by microorganisms has been well studied, specific investigations on fluorinated drugs are relatively few, despite the increase in the number and variety of fluorinated drugs that are available. The strength of the carbon-fluorine bond conveys stability to fluorinated drugs; thus, they are likely to be recalcitrant in the environment or may be partially metabolized to a more toxic metabolite. This review examines the research done on microbial biotransformation and biodegradation of fluorinated drugs and highlights the importance of understanding how microorganisms interact with this class of compound from environmental, clinical and biotechnological perspectives.

Labrys soli sp. nov., isolated from the rhizosphere of ginseng

In this study, we describe strain DCY64T that was isolated from the rhizosphere of three-year-old Korean ginseng root. Cells were Gram-reaction negative, oxidase- and catalase-positive, strictly aerobic, capsulated, non-motile, non-sporulating and spherical to short rod-shaped. Multiplicative budding cells were produced. Vesicles covered the surface of cells. Phylogenetic analysis placed strain DCY64T within the genus Labrys with the highest similarity to Labrys monachus VKM B-1479T (97.6 % 16S rRNA gene sequence similarity), followed by Labrys okinawensis MAFF 210191T (97.5 %), Labrys miyagiensis G24103T (97.4) and Labrys portucalensis F11T (97.0 %). The genomic DNA G+C content was 63 mol%. The presences of summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C19 : 1 cyclo ω8c and C16 : 0 as major fatty acids; phosphatidylmonomethylethanolamine, phosphatidylglycerol, phosphatidylcholine and diphosphatidylglycerol as major polar lipids; ubiquinone Q-10 as the predominant quinone and sym-homospermidine as the dominant polyamine were found in strain DCY64T. These chemotaxonomic results were in accordance with those of members of the genus Labrys. However, the absence of C16 : 0 2-OH, C16 : 0 3-OH and C18 : 1 2-OH from the fatty acids profile and differences in minor polar lipids and phenotypic characteristics distinguished strain DCY64T from the closest type strains. The discrimination was also supported by unique enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) fingerprints, as well as DNA-DNA hybridization values ( ≤ 48 %) between strain DCY64T and related type strains. Therefore, we propose that strain DCY64T represents a novel species of the genus Labrys. The name Labrys soli sp. nov. is proposed, with DCY64T ( = KCTC 32173T = JCM 19895T) as the type strain.

Responses of microbial communities to single-walled carbon nanotubes in phenol wastewater treatment systems

The expanding use of single-walled carbon nanotubes (SWCNTs) raises environmental concerns. Wastewater treatment systems are potential recipients of SWCNTs containing influent, yet the impacts of SWCNTs on these systems are poorly documented. In this study, the microbial responses to SWCNTs in simulated phenol wastewater treatment systems were investigated. The phenol removal rates were improved in all SWCNTs-treated sequencing batch reactors during the first 20 days, but when facing higher phenol concentration (1000 mg/L) after 60 days, reactors with the highest concentration (3.5 g/L) of SWCNTs exhibited a notably decreased phenol removal capacity. Cell viability tests, scanning electron microscopy analysis and DNA leakage data suggested that SWCNTs protected microbes from inactivation, possibly by producing more bound extracellular polymeric substances (EPS), which could create a protective barrier for the microbes. Illumina sequencing of 16S rRNA gene amplicons revealed that the bacterial diversity did not change significantly except for a minor reduction after the immediate addition of SWCNTs. Bacterial community structure significantly shifted after SWCNTs addition and did not recover afterward. Zoogloea increased significantly upon SWCNTs shocking. At the final stage, Rudaea and Mobilicoccus increased, while Burkholderia, Singulisphaera, Labrys and Mucilaginibacter decreased notably. The shifts of these dominant genera may be associated with altered sludge settling, aromatic degradation and EPS production. This study suggested that SWCNTs exerted protective rather than cytotoxic effects on sludge microbes of phenol wastewater treatment systems and they affected the bacterial community structure and diversity at test concentrations. These findings provide new insights into our understanding of the potential effects of SWCNTs on wastewater treatment processes.

Enantioselective biodegradation of fluoxetine by the bacterial strain Labrys portucalensis F11

Fluoxetine (FLX) is a chiral fluorinated pharmaceutical indicated mainly for the treatment of depression and is one of the most dispensed drugs in the world. There is clear evidence of environmental contamination with this drug and its active metabolite norfluoxetine (NFLX). In this study the enantioselective biodegradation of racemic FLX and of its enantiomers by Labrys portucalensis strain F11 was assessed. When 2μM of racemic FLX was supplemented as sole carbon source, complete removal of both enantiomers, with stoichiometric liberation of fluoride, was achieved in 30d. For racemic FLX concentration of 4 and 9μM, partial degradation of the enantiomers was obtained. In the presence of acetate as an additional carbon source, at 4, 9 and 21μM of racemic FLX and at 25μM of racemic FLX, (S)-FLX or (R)-FLX, complete degradation of the two enantiomers occurred. At higher concentrations of 45 and 89μM of racemic FLX, partial degradation was achieved. Preferential degradation of the (R)-enantiomer was observed in all experiments. To our knowledge, this is the first time that enantioselective biodegradation of FLX by a single bacterium is reported.

Biology of fluoro-organic compounds

Investigations on diverse aspects of fluoro-organic compounds have rapidly increased during the past decades. Because natural sources of fluoro-organic compounds are extremely rare, the industrial synthesis of fluorinated organic compounds and production of fluorinated natural product derivatives have greatly expanded in recent years because of their increasing importance in the agrochemical and pharmaceutical industries. Due to structural complexity or instability, synthetic modification is often not possible, and various biofluorination strategies have been developed in recent years for applications in the anti-cancer, anti-viral and anti-infection fields. Despite the industrial importance of fluorinated compounds, there have been serious concerns worldwide over the levels and synthetic routes of certain fluorinated organic compounds, in particular perfluorinated chemicals (PFCs). PFCs are emerging and recalcitrant pollutants which are widely distributed in the environment and have been detected in humans and wildlife globally. PFCs have been demonstrated to be potentially carcinogenic, adversely affect the neuroendocrine and immune systems, and produce neurotoxicity, heptatotoxicity and endocrine disrupting effects in vertebrate animals. Here, we provide an overview of recent advances in our understanding of the biology of various fluoro-organic compounds and perspectives for new enzymes and metabolic pathways for bioremediation of these chemicals.

Labrys wisconsinensis sp. nov., a budding bacterium isolated from Lake Michigan water, and emended description of the genus Labrys

Two facultatively anaerobic, budding bacterial strains, designated W1215-PCA4(T) and SRNK-1, were isolated from water from Lake Michigan, USA. The two strains showed identical ERIC-PCR-generated genomic fingerprints and shared 99.9 % 16S rRNA gene sequence similarity. Strain W1215-PCA4(T) showed highest 16S rRNA gene sequence similarities to Labrys monachus VKM B-1479(T) (95.8 %), Labrys methylaminiphilus DSM 16812(T) (95.1 %), Labrys okinawensis MAFF 210191(T) (96.0 %), Labrys miyagiensis G24103(T) (95.4 %), Labrys neptuniae BCRC 17578(T) (95.7 %) and Labrys portucalensis DSM 17916(T) (95.8 %). Data suggested that the two strains were members of a single novel species of the genus Labrys. The major cellular fatty acids of the two isolates were C(18 : 1)omega7c, C(19 : 0) cyclo omega8c and C(16 : 0). Their polar lipid profiles were highly similar to that of Labrys monachus DSM 5896(T). The primary quinone was ubiquinone Q-10, with minor amounts of Q-9 and Q-11. sym-Homospermidine was the predominant polyamine, with putrescine present in moderate amounts. The two strains were identical in terms of their biochemical and physiological traits, but were distinguishable from other species of the genus Labrys. Hence, the description of a novel species in this genus appears to be justified. The name Labrys wisconsinensis sp. nov. is proposed; the type strain is W1215-PCA4(T) (=DSM 19619(T)=NRRL B-51088(T)).