Acidovorax benzenivorans sp. nov., a novel aromatic hydrocarbon-degrading bacterium isolated from a xylene-degrading enrichment culture.

A Gram-stain-negative strain, designated as D2M1T was isolated from xylene-degrading enrichment culture and characterized using a polyphasic approach to determine its taxonomic position. The 16S rRNA gene sequence analysis revealed that strain D2M1T belongs to the genus Acidovorax, with the highest 16S rRNA gene similarity to Acidovorax delafieldii DSM 64T (99.93 %), followed by Acidovorax radicis DSM 23535T (98.77 %) and Acidovorax kalamii MTCC 12652T (98.76 %). The draft genome sequence of strain D2M1T is 5.49 Mb long, and the G+C content of the genome is 64.2 mol%. Orthologous average nucleotide identity and digital DNA-DNA hybridization relatedness values between strain D2M1T and its closest relatives were below the threshold values for species demarcation confirming that strain D2M1T is distinctly separated from its closest relatives. The whole genome analysis of the strain revealed a phenol degradation gene cluster, encoding a multicomponent phenol hydroxylase (mPH) together with a complete meta-cleavage pathway including an I.2.C-type catechol 2,3-dioxygenase (C23O) gene. The strain was able to degrade benzene and ethylbenzene as sole sources of carbon and energy under aerobic and microaerobic conditions. Cells were facultatively aerobic rods and motile with a single polar flagellum. The predominant fatty acids (>10 % of the total) of strain D2M1T were summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). The major ubiquinone of strain D2M1T was Q8, while the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Based on polyphasic data, it is concluded that strain D2M1T represents a novel species of the genus Acidovorax, for which the name of Acidovorax benzenivorans sp. nov. is proposed. The type strain of the species is strain D2M1T (=DSM 115238T=NCAIM B.02679T).

Combined Omics Approach Reveals Key Differences between Aerobic and Microaerobic Xylene-Degrading Enrichment Bacterial Communities: Rhodoferax─A Hitherto Unknown Player Emerges from the Microbial Dark Matter.

Among monoaromatic hydrocarbons, xylenes, especially the ortho and para isomers, are the least biodegradable compounds in oxygen-limited subsurface environments. Although much knowledge has been gained regarding the anaerobic degradation of xylene isomers in the past 2 decades, the diversity of those bacteria which are able to degrade them under microaerobic conditions is still unknown. To overcome this limitation, aerobic and microaerobic xylene-degrading enrichment cultures were established using groundwater taken from a xylene-contaminated site, and the associated bacterial communities were investigated using a polyphasic approach. Our results show that the xylene-degrading bacterial communities were distinctly different between aerobic and microaerobic enrichment conditions. Although members of the genus Pseudomonas were the most dominant in both types of enrichments, the Rhodoferax and Azovibrio lineages were only abundant under microaerobic conditions, while Sphingobium entirely replaced them under aerobic conditions. Analysis of a metagenome-assembled genome of a Rhodoferax-related bacterium revealed aromatic hydrocarbon-degrading ability by identifying two catechol 2,3-dioxygenases in the genome. Moreover, phylogenetic analysis indicated that both enzymes belonged to a newly defined subfamily of type I.2 extradiol dioxygenases (EDOs). Aerobic and microaerobic xylene-degradation experiments were conducted on strains Sphingobium sp. AS12 and Pseudomonas sp. MAP12, isolated from the aerobic and microaerobic enrichments, respectively. The obtained results, together with the whole-genome sequence data of the strains, confirmed the observation that members of the genus Sphingobium are excellent aromatic hydrocarbon degraders but effective only under clear aerobic conditions. Overall, it was concluded that the observed differences between the bacterial communities of aerobic and microaerobic xylene-degrading enrichments were driven primarily by (i) the method of aromatic ring activation (monooxygenation vs dioxygenation), (ii) the type of EDO enzymes, and (iii) the ability of degraders to respire utilizing nitrate.

Flavobacterium hungaricum sp. nov. a novel soil inhabitant, cellulolytic bacterium isolated from plough field.

A Gram-negative bacterial strain, named Kb82, was isolated from agricultural soil and a polyphasic approach was used for characterisation and to determine its taxonomic position. Based on 16S rRNA gene sequence analysis, the highest similarity was found with Flavobacterium artemisiae SYP-B1015 (98.2%). The highest ANI (83.3%) and dDDH (26.5%) values were found with Flavobacterium ginsenosidimutans THG 01 and Flavobacterium fluviale HYN0086T, respectively. The isolate is aerobic with rod-shaped cells, positive for catalase and negative for oxidase tests. The DNA G+C content is 34.7 mol%. The only isoprenoid quinone is menaquinone 6 (MK-6). The major fatty acids are iso-C15:0, summed feature 3 (C16:1 ω7c/C16:1 ω6c) and iso-C17:0 3OH. The major polar lipid is phosphatidylethanolamine. On the bases of phenotypic characteristics and analysis of 16S rRNA gene sequences, it is concluded that strain Kb82T represents a novel species in the Flavobacterium genus, for which the name Flavobacterium hungaricum sp. nov. is proposed. The type strain of the species is strain Kb82T (= LMG 31576T = NCAIM B.02635T).

Pinisolibacter aquiterrae sp. nov., a novel aromatic hydrocarbon-degrading bacterium isolated from benzene-, and xylene-degrading enrichment cultures, and emended description of the genus Pinisolibacter.

Two Gram-reaction-negative strains, designated as B13T and MA2-2, were isolated from two different aromatic hydrocarbon-degrading enrichment cultures and characterized using a polyphasic approach to determine their taxonomic position. The two strains had identical 16S rRNA gene sequences and were most closely related to Pinisolibacter ravus E9T (97.36 %) and Siculibacillus lacustris SA-279T (96.33 %). Cells were facultatively aerobic rods and motile with a single polar flagellum. The strains were able to degrade ethylbenzene as sole source of carbon and energy. The assembled genome of strain B13T had a total length of 4.91 Mb and the DNA G+C content was 68.8 mol%. The predominant fatty acids (>5 % of the total) of strains B13T and MA2-2 were C18 : 1 ω7c/C18 : 1 ω6c, C16 : 1 ω7c/C16 : 1 ω6c and C16 : 0. The major ubiquinone of strain B13T was Q10, while the major polar lipids were phosphatidyl-N-methylethanolamine, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and a phospholipid. Based on phenotypic characteristics and phylogenetic data, it is concluded that strains B13T and MA2-2 are members of the genus Pinisolibacter and represent a novel species for which the name Pinisolibacter aquiterrae sp. nov. is proposed. The type strain of the species is strain B13T (=LMG 32346T=NCAIM B.02665T).

Microaerobic enrichment of benzene-degrading bacteria and description of Ideonella benzenivorans sp. nov., capable of degrading benzene, toluene and ethylbenzene under microaerobic conditions.

In the present study, the bacterial community structure of enrichment cultures degrading benzene under microaerobic conditions was investigated through culturing and 16S rRNA gene Illumina amplicon sequencing. Enrichments were dominated by members of the genus Rhodoferax followed by Pseudomonas and Acidovorax. Additionally, a pale amber-coloured, motile, Gram-stain-negative bacterium, designated B7T was isolated from the microaerobic benzene-degrading enrichment cultures and characterized using a polyphasic approach to determine its taxonomic position. The 16S rRNA gene and whole genome-based phylogenetic analyses revealed that strain B7T formed a lineage within the family Comamonadaceae, clustered as a member of the genus Ideonella and most closely related to Ideonella dechloratans CCUG 30977T. The sole respiratory quinone is ubiquinone-8. The major fatty acids are C16:0 and summed feature 3 (C16:1 ω7c/iso-C15:0 2-OH). The DNA G + C content of the type strain is 68.8 mol%. The orthologous average nucleotide identity (OrthoANI) and in silico DNA-DNA hybridization (dDDH) relatedness values between strain B7T and closest relatives were below the threshold values for species demarcation. The genome of strain B7T, which is approximately 4.5 Mb, contains a phenol degradation gene cluster, encoding a multicomponent phenol hydroxylase (mPH) together with a complete meta-cleavage pathway including a I.2.C-type catechol 2,3-dioxygenase (C23O) gene. As predicted by the genome, the type strain is involved in aromatic hydrocarbon-degradation: benzene, toluene and ethylbenzene are degraded aerobically and also microaerobically as sole source of carbon and energy. Based on phenotypic characteristics and phylogenetic analysis, strain B7T is a member of the genus Ideonella and represents a novel species for which the name Ideonella benzenivorans sp. nov. is proposed. The type strain of the species is strain B7T (= LMG 32,345T = NCAIM B.02664T).

Dyadobacter subterraneus sp. nov., isolated from hydrocarbon-polluted groundwater from an oil refinery in Hungary.

A Gram-stain-negative, aerobic, non-spore-forming, rod-shaped bacterial strain (UP-52T) was isolated from hydrocarbon-polluted groundwater located near an oil refinery in Tiszaujvaros, Hungary. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Dyadobacter in the family Cytophagaceae. Its closely related species are Dyadobacter frigoris (98.00 %), Dyadobacter koreensis (97.64 %), Dyadobacter psychrophilus (97.57 %), Dyadobacter ginsengisoli (97.56 %) and Dyadobacter psychrotolerans (97.20 %). The predominant fatty acids are summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω7c/C16 : 1 ω6c), C15 : 0 iso, C16 : 1 ω5c and C17 : 0 iso 3OH. The predominant respiratory quinone detected in strain UP-52T is quinone MK-7. The dominant polar lipids are glycolipid, phosphoaminolipid, phospholipid and aminolipid. The DNA G+C content is 40.0 mol%. Flexirubin-type pigment was present. Based on these phenotypic, chemotaxonomic and phylogenetic results, UP-52T represents a novel species of the genus Dyadobacter, for which the name Dyadobacter subterraneus sp. nov. is proposed. The type strain is UP-52T (=NCAIM B.02653T=CCM 9030T).

Cellvibrio polysaccharolyticus sp. nov., a cellulolytic bacterium isolated from agricultural soil.

A novel Gram-reaction-negative bacterial strain, designated Ka43T, was isolated from agricultural soil and characterised using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, the strain shows highest similarity (97.1 %) to Cellvibrio diazotrophicus E50T. Cells of strain Ka43T are aerobic, motile, short rods. The major fatty acids are summed feature 3 (C16 : 1 ω7c and/or iso-C15 : 0 2-OH), C18 : 1 ω7c and C16 : 0. The only isoprenoid quinone is Q-8. The polar lipid profile includes phosphatidylethanolamine, phosphatidylglycerol, four phospholipids, two lipids and an aminolipid. The assembled genome of strain Ka43T has a total length of 4.2 Mb and the DNA G+C content is 51.6 mol%. Based on phenotypic data, including chemotaxonomic characteristics and analysis of the 16S rRNA gene sequences, it was concluded that strain Ka43T represents a novel species in the genus Cellvibrio, for which the name Cellvibrio polysaccharolyticus sp. nov. is proposed. The type strain of the species is strain Ka43T (=LMG 31577T=NCAIM B.02637T).

Parvularcula mediterranea sp. nov., isolated from marine plastic debris from Zakynthos Island, Greece.

A Gram-negative, dark orange-pigmented, aerobic, non-spore-forming, coccoid-shaped bacterium designated as ZS-1/3T was isolated from a floating plastic litter (polypropylene straw) sample, collected from shallow seawater near the public beach of Laganas on Zakynthos island, Greece. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate is affiliated with the genus Parvularcula in the family Parvularculaceae. Its closest relatives are Parvularcula lutaonensis (98.09  %) and Parvularcula oceanus (95.89  %). The pH and temperature ranges for growth are pH 5-10 and 20-38 °C (optima, pH 7.0 and 28 °C). The predominant fatty acids are C18 : 1 ω7c (56.84  %), C16 : 0 (27.51  %), C18 : 0 (2.25  %) and C12 : 0 (1.42  %). The predominant respiratory quinone detected in strain ZS-1/3T is quinone-10 (Q10); the majority of detected polar lipids are glycolipid. The DNA G+C content is 62.5  mol%. Physiological and chemotaxonomic data further confirmed the distinctiveness of strain ZS-1/3T from other members of the genus Parvularcula. Thus, strain ZS-1/3T is considered to represent a novel species of the genus, for which the name Parvularcula mediterranea. sp. nov. is proposed. The type strain is ZS-1/3T (=NCAIM B 02654T=CCM 9032T).

Sphingobacterium hungaricum sp. nov. a novel species on the borderline of the genus Sphingobacterium.

A Gram-reaction-negative bacterial strain, designated Kb22T, was isolated from agricultural soil and characterized using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, the strain shows highest similarity (94.39 %) to Sphingobacterium nematocida M-SX103T. The highest average nucleotide identity value (71.83 %) was found with Sphingobacterium composti T5-12T, and the highest amino acid identity value (66.65 %) was found with Sphingobacterium olei HAL-9T. Cells are aerobic, non-motile rods. The isolate was found to be positive for catalase and oxidase tests. The assembled genome of strain Kb22T has a total length of 4,06 Mb, the DNA G+C content is 38.1 mol%. The only isoprenoid quinone is menaquinone 7 (MK-7). The major fatty acids are iso-C15:0 (28.4%), summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH) (25.7 %) and iso-C17:0 3-OH (19.7 %). Based on phenotypic characteristics and phylogenetic results, it is concluded that strain Kb22T is a member of the genus Sphingobacterium and represents a novel species for which the name Sphingobacterium hungaricum sp. nov. is proposed. The type strain of the species is strain Kb22T (=LMG 31574T=NCAIM B.02638T).

Sphingobacterium pedocola sp. nov. a novel halotolerant bacterium isolated from agricultural soil.

A Gram-reaction-negative halotolerant bacterial strain, designated Ka21T, was isolated from agricultural soil and characterised using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, highest similarity was found with Sphingobacterium alkalisoli Y3L14T (96.72%). Cells were observed to be aerobic, non-motile rods. The isolate was found to be able to grow between 0 and 10% of NaCl concentration. The assembled genome of strain Ka21T has a total length of 5.2 Mb with a G + C content of 41.0 mol%. According to the genome analysis, Ka21T encodes several glycoside hydrolases that may play a role in the degradation of accumulated plant biomass in the soil. Based on phenotypic characteristics and phylogenetic analysis, it is concluded that strain Ka21T represents a novel species in the Sphingobacterium genus for which the name Sphingobacterium pedocola sp. nov. is proposed. The type strain of the species is strain Ka21T (= LMG 31575T = NCAIM B.02636T).

Genome analysis provides insights into microaerobic toluene-degradation pathway of Zoogloea oleivorans BucT.

Zoogloea oleivorans, capable of using toluene as a sole source of carbon and energy, was earlier found to be an active degrader under microaerobic conditions in aquifer samples. To uncover the genetic background of the ability of microaerobic toluene degradation in Z. oleivorans, the whole-genome sequence of the type strain BucT was revealed. Metatranscriptomic sequence reads, originated from a previous SIP study on microaerobic toluene degradation, were mapped on the genome. The genome (5.68 Mb) had a mean G + C content of 62.5%, 5005 protein coding gene sequences and 80 RNA genes. Annotation predicted that 66 genes were involved in the metabolism of aromatic compounds. Genome analysis revealed the presence of a cluster with genes coding for a multicomponent phenol-hydroxylase system and a complete catechol meta-cleavage pathway. Another cluster flanked by mobile-element protein coding genes coded a partial catechol meta-cleavage pathway including a subfamily I.2.C-type extradiol dioxygenase. Analysis of metatranscriptomic data of a microaerobic toluene-degrading enrichment, containing Z . oleivorans as an active-toluene degrader revealed that a toluene dioxygenase-like enzyme was responsible for the ring-hydroxylation, while enzymes of the partial catechol meta-cleavage pathway coding cluster were responsible for further degradation of the aromatic ring under microaerobic conditions. This further advances our understanding of aromatic hydrocarbon degradation between fully oxic and strictly anoxic conditions.

Microaerobic conditions caused the overwhelming dominance of Acinetobacter spp. and the marginalization of Rhodococcus spp. in diesel fuel/crude oil mixture-amended enrichment cultures.

The aim of the present study was to reveal how different microbial communities evolve in diesel fuel/crude oil-contaminated environments under aerobic and microaerobic conditions. To investigate this question, aerobic and microaerobic bacterial enrichments amended with a diesel fuel/crude oil mixture were established and analysed. The representative aerobic enrichment community was dominated by Gammaproteobacteria (64.5%) with high an abundance of Betaproteobacteriales (36.5%), followed by Alphaproteobacteria (8.7%), Actinobacteria (5.6%), and Candidatus Saccharibacteria (4.5%). The most abundant alkane monooxygenase (alkB) genotypes in this enrichment could be linked to members of the genus Rhodococcus and to a novel Gammaproteobacterium, for which we generated a high-quality draft genome using genome-resolved metagenomics of the enrichment culture. Contrarily, in the microaerobic enrichment, Gammaproteobacteria (99%) overwhelmingly dominated the microbial community with a high abundance of the genera Acinetobacter (66.3%), Pseudomonas (11%) and Acidovorax (11%). Under microaerobic conditions, the vast majority of alkB gene sequences could be linked to Pseudomonas veronii. Consequently, results shed light on the fact that the excellent aliphatic hydrocarbon degrading Rhodococcus species favour clear aerobic conditions, while oxygen-limited conditions can facilitate the high abundance of Acinetobacter species in aliphatic hydrocarbon-contaminated subsurface environments.

Aerobic and oxygen-limited naphthalene-amended enrichments induced the dominance of Pseudomonas spp. from a groundwater bacterial biofilm.

In this study, we aimed at determining the impact of naphthalene and different oxygen levels on a biofilm bacterial community originated from a petroleum hydrocarbon-contaminated groundwater. By using cultivation-dependent and cultivation-independent approaches, the enrichment, identification, and isolation of aerobic and oxygen-limited naphthalene degraders was possible. Results indicated that, regardless of the oxygenation conditions, Pseudomonas spp. became the most dominant in the naphthalene-amended selective enrichment cultures. Under low-oxygen conditions, P. veronii/P. extremaustralis lineage affiliating bacteria, and under full aerobic conditions P. laurentiana-related isolates were most probably capable of naphthalene biodegradation. A molecular biological tool has been developed for the detection of naphthalene 1,2-dioxygenase-related 2Fe-2S reductase genes of Gram-negative bacteria. The newly developed COnsensus DEgenerate Hybrid Oligonucleotide Primers (CODEHOP-PCR) technique may be used in the monitoring of the natural attenuation capacity of PAH-contaminated sites. A bacterial strain collection with prolific biofilm-producing and effective naphthalene-degrading organisms was established. The obtained strain collection may be applicable in the future for the development of biofilm-based bioremediation systems for the elimination of PAHs from groundwater (e.g., biofilm-based biobarriers).

Planktonic and Benthic Bacterial Communities of the Largest Central European Shallow Lake, Lake Balaton and Its Main Inflow Zala River.

Lake Balaton is the largest European shallow lake, which underwent cultural eutrophication in the '70-80s. Therefore, strict pollution control measures were introduced and the water quality has become meso-eutrophic since the millennium. Due to the touristic significance and change in trophic levels of the lake, numerous ecological studies were carried out, but none of them was focused on both benthic and planktonic microbial communities at the same time. In our study, an attempt was made to reveal the spatial bacterial heterogeneity of the Lake Balaton and Zala River by 16S rDNA terminal restriction fragment length polymorphism fingerprinting and Illumina amplicon sequencing methods in the summer of 2017. According to the molecular biology results, mostly well-known freshwater microorganisms, adapted to nutrient-poor conditions were found in the pelagic water column. The LD12 subclade member Fonsibacter ubiquis, the cyanobacterial Synechococcus sp. and unknown Verrucomicrobia species were abundant in the less nutrient-dense basins, while the hgcI clade members showed various distribution. In the estuary and in the nutrient-dense western part of the lake, some eutrophic conditions preferring cyanobacteria (filamentous Anabaena and Aphanizomenon species) were also detectable. The benthic microbial community showed higher diversity, according to the observed appearance of microorganisms adapted to the deeper, less aerated layers (e.g. members of Desulfobacteraceae, Nitrosomonadaceae).

Hydrogenophaga aromaticivorans sp. nov., isolated from a para-xylene-degrading enrichment culture, capable of degrading benzene, meta- and para-xylene.

A benzene, para- and meta-xylene-degrading Gram-stain-negative, aerobic, yellow-pigmented bacterium, designated as D2P1T, was isolated from a para-xylene-degrading enrichment culture. Phylogenetic analyses based on 16S rRNA genes showed that D2P1T shares a distinct phyletic lineage within the genus Hydrogenophaga and shows highest 16S rRNA gene sequence similarity to Hydrogenophaga taeniospiralis NBRC 102512T (99.2 %) and Hydrogenophaga palleronii NBRC 102513T (98.3 %). The draft genome sequence of D2P1T is 5.63 Mb long and the genomic DNA G+C content is 65.5 %. Orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) analyses confirmed low genomic relatedness to its closest relatives (OrthoANI <86 %; dDDH <30 %). D2P1T contains ubiquinone 8 (Q-8) as the only respiratory quinone and phospholipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol as major polar lipids. The main whole-cell fatty acids of D2P1T are summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). The polyphasic taxonomic results indicated that strain D2P1T represents a novel species of the genus Hydrogenophaga, for which the name Hydrogenophaga aromaticivorans sp. nov. is proposed. The type strain is D2P1T (=LMG 31780T=NCAIM B 02655T).

Sphingobium aquiterrae sp. nov., a toluene, meta- and para-xylene-degrading bacterium isolated from petroleum hydrocarbon-contaminated groundwater.

A Gram-negative, aerobic, slightly yellow-pigmented bacterium, designated as SKLS-A10T, was isolated from groundwater sample of the 'Siklós' petroleum hydrocarbon contaminated site (Hungary). Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain SKLS-A10T formed a distinct phyletic lineage within the genus Sphingobium. It shared the highest 16S rRNA gene homology with Sphingobium abikonense DSM 23268T (97.29 %), followed by Sphingobium lactosutens DSM 23389T (97.23 %), Sphingobium phenoxybenzoativorans KCTC 42448T (97.16 %) and Sphingobium subterraneum NBRC 109814T (96.74 %). The predominant fatty acids (>5 % of the total) are C18 : 1ω7c, C14 : 0 2-OH, C16 : 1ω7c/iso C15 : 0 2-OH, C17 : 1ω6c and C16 : 0. The major ubiquinone is Q-10. The predominant polyamine is spermidine. The major polar lipids are sphingoglycolipid and diphosphatidylglycerol. The DNA G+C content of strain SKLS-A10T is 65.9 mol%. On the basis of evidence from this taxonomic study using a polyphasic approach, strain SKLS-A10T represents a novel species of the genus Sphingobium for which the name Sphingobiumaquiterrae sp. nov. is proposed. The type strain is SKLS-A10T (=DSM 106441T=NCAIM B. 02634T).

Xylanibacillus composti gen. nov., sp. nov., isolated from compost.

A novel Gram-stain-positive bacterial strain, designated as K13T, was isolated from compost and characterized using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, the strain showed highest similarity (93.8 %) to Paenibacillus nanensis MX2-3T. Cells of strain K13T were aerobic, motile rods. The major fatty acids were anteiso C15 : 0 (34.4 %), iso C16 : 0 (17.3 %) and C16 : 0 (10.0 %). The major menaquinone was MK-7, the polar lipid profile included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and an aminophospholipid. The DNA G+C content was 52.3 %. Based on phenotypic, including chemotaxonomic characteristics and analysis of the 16S rRNA gene sequences, it was concluded that strain K13T represents a novel genus, for which the name Xylanibacillus gen. nov., sp. nov. is proposed. The type species of the genus is Xylanibacillus composti, the type strain of which is strain K13T (=DSM 29793T=NCAIM B.02605T).

Aflatoxin B1 and Zearalenone-Detoxifying Profile of Rhodococcus Type Strains.

Aflatoxin B1 (AFB1) and zearalenone (ZON) are dangerous mycotoxins due to their carcinogenicity or oestrogenicity. To alleviate negative effects on humans and animals, successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins can be an effective way in food and feed industry enhancing food safety. Several Rhodococcus strains are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology. In this study, we investigated the AFB1 and ZON detoxification ability of 42 type strains of Rhodococcus species. Samples were analysed by high-performance liquid chromatograph equipped with fluorescence detector for mycotoxin concentration and SOS-chromotest was used for monitoring remaining genotoxicity. Out of the 42 Rhodococcus strains, 18 could eliminate more than 90% of the applied AFB1 and the genotoxicity was ceased by 15 strains in 72 h (R. imtechensis JCM 13270T, R. erythropolis JCM 3201T, R. tukisamuensis JCM 11308T, R. rhodnii JCM 3203T, R. aerolatus JCM 19485T, R. enclensis DSM 45688T, R. lactis DSM 45625T, R. trifolii DSM 45580T, R. qingshengii DSM 45222T, R. artemisiae DSM 45380T, R. baikonurensis DSM 44587T, R. globerulus JCM 7472T, R. kroppenstedtii JCM 13011T, R. pyridinivorans JCM 10940T, R. corynebacterioides JCM 3376T). In case of ZON, only R. percolatus JCM 10087T was able to degrade more than 90% of the compound and to reduce the oestrogenicity with 70%.

Unexpected Diversity and High Abundance of Putative Nitric Oxide Dismutase (Nod) Genes in Contaminated Aquifers and Wastewater Treatment Systems.

It has recently been suggested that oxygenic dismutation of NO into N2 and O2 may occur in the anaerobic methanotrophic "Candidatus Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1. It may represent a new pathway in microbial nitrogen cycling catalyzed by a putative NO dismutase (Nod). The formed O2 enables microbes to employ aerobic catabolic pathways in anoxic habitats, suggesting an ecophysiological niche space of substantial appeal for bioremediation and water treatment. However, it is still unknown whether this physiology is limited to "Ca Methylomirabilis oxyfera" and HdN1 and whether it can be coupled to the oxidation of electron donors other than alkanes. Here, we report insights into an unexpected diversity and remarkable abundance of nod genes in natural and engineered water systems. Phylogenetically diverse nod genes were recovered from a range of contaminated aquifers and N-removing wastewater treatment systems. Together with nod genes from "Ca Methylomirabilis oxyfera" and HdN1, the novel environmental nod sequences formed no fewer than 6 well-supported phylogenetic clusters, clearly distinct from canonical NO reductase (quinol-dependent NO reductase [qNor] and cytochrome c-dependent NO reductase [cNor]) genes. The abundance of nod genes in the investigated samples ranged from 1.6 × 107 to 5.2 × 1010 copies · g-1 (wet weight) of sediment or sludge biomass, accounting for up to 10% of total bacterial 16S rRNA gene counts. In essence, NO dismutation could be a much more widespread physiology than currently perceived. Understanding the controls of this emergent microbial capacity could offer new routes for nitrogen elimination or pollutant remediation in natural and engineered water systems. IMPORTANCE: NO dismutation into N2 and O2 is a novel process catalyzed by putative NO dismutase (Nod). To date, only two bacteria, the anaerobic methane-oxidizing bacterium "Ca Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1, are known to harbor nod genes. In this study, we report efficient molecular tools that can detect and quantify a wide diversity of nod genes in environmental samples. A surprisingly high diversity and abundance of nod genes were found in contaminated aquifers as well as wastewater treatment systems. This evidence indicates that NO dismutation may be a much more widespread physiology in natural and man-made environments than currently perceived. The molecular tools presented here will facilitate further studies on these enigmatic microbes in the future.

Rhodococcus sovatensis sp. nov., an actinomycete isolated from the hypersaline and heliothermal Lake Ursu.

A Gram-stain-positive, strictly aerobic, mesophilic bacterium, designated H004T, was isolated from a water sample of the hypersaline and heliothermal Lake Ursu, Sovata, Romania. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain H004T formed a distinct phyletic lineage within the genus Rhodococcus. It shared the highest 16S rRNA gene sequence similarity with Rhodococcus yunnanensis YIM 70056T (98.80 %), followed by Rhodococcus fascians LMG 3623T (98.73 %), Rhodococcus cercidiphylli YIM 65003T (98.73 %), Rhodococcus cerastii C5T (98.58 %) and Rhodococcus kyotonensis DS472T (98.53 %). The alkB-based phylogenetic analysis further confirmed that this strain constitutes a highly unique lineage within the genus. Chemotaxonomic characteristics, including the predominant fatty acids acids C15 : 0, C18 : 1ω9c, C19 : 1ω11c/C19 : 1ω9c and C16 : 1ω7c/iso-C15 : 0 2-OH, the major quinone MK-8(H2), the presence of mycolic acids and cell-wall chemotype IV were also consistent with the properties of members of the genus Rhodococcus. The DNA G+C content of strain H004T was 65.4 mol%. The results of DNA-DNA hybridization analyses with the closest relatives, in combination with the alkB-based phylogenetic analysis, as well as the chemotaxonomic and physiological data, demonstrated that isolate H004T represents a novel species of the genus Rhodococcus, for which the name Rhodococcus sovatensissp. nov. is proposed. The type strain is H004T (=DSM 102881T=NCAIM B.02632T).