Isolation and characterization of a novel bacterium, <Emphasis Type="Italic">Sphingomonas bisphenolicum</Emphasis> strain AO1, that degrades bisphenol A

Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA), which is used as a synthetic resin material or a plasticizer, is a pollutant that␣possesses endocrine-disrupting activity. Bioremediation of BPA is used to decrease its polluting effects, and here we report a novel bacterial strain AO1, which is able to degrade BPA. This strain was isolated using enrichment cultivation from a soil sample from a vegetable-growing field; the sample was one of 500 soil samples collected across Japan. Strain AO1 degraded 100 mg/l BPA to an undetectable level within 6 h in MYPG medium (containing malt extract, yeast extract, peptone, and glucose) and within 48 h in minimum medium containing 1% glucose at 30°C. Strain AO1 can utilize BPA as a sole source of carbon and as an energy source under aerobic conditions. The estrogenic activity of BPA in MYPG medium was ultimately reduced by strain AO1, although the activity initially increased. Taxonomical analysis showed that strain␣AO1 is closely related to Sphingomonas chlorophenolicum and S. herbicidovorans, neither of which have a capacity for BPA degradation. DNA–DNA hybridization showed that strain AO1 is a novel species of the Sphingomonas genus, and we designated AO1 as S. bisphenolicum.     

Biodegradation of bisphenol A by cells and cell lysate from <Emphasis Type="Italic">Sphingomonas </Emphasis>sp. strain AO1

The capacity and pathway of bisphenol A [BPA; 2,2-bis(4-hydroxyphenyl)propane] degradation in Sphingomonassp. strain AO1, which was isolated from the soil of a vegetable-growing field in Japan, were investigated. The bacterial strain was able to grow in a basal mineral salt medium containing BPA as the sole carbon source (BSMB medium), and was able to degrade 115 gml^–1 BPA in 6h in L medium. Several BPA metabolites were detected in the culture supernatant by HPLC and then identified by GC-MS and LC-MS-MS. These compounds were confirmed to be the same as those reported for other BPA-degrading bacteria. BPA degradation by cells in the basal mineral salt medium was induced by BPA, and activity was detected only in the intracellular soluble fraction in the presence of coenzymes, such as NADH, NAD⁺ , NADPH or NADP⁺. The addition of metyrapone, a cytochrome P450 inhibitor, to BSMB medium resulted in a decrease in BPA degradation and cell growth. The BPA-degradation activity of the intracellular soluble fraction was also inhibited by the cytochrome P450 inhibitor. Carbon monoxide difference spectra indicated that cytochrome P450 was present in the cells and that the amount of cytochrome P450 corresponded to the cellular BPA-degradation activity. Our results provide evidence that the cytochrome P450 system is involved in BPA metabolism in Sphingomonassp. strain AO1.     

Isolation of a Xanthobacter sp. degrading dichloromethane and characterization of the gene involved in the degradation

A bacterial strain able to degrade dichloromethane (DCM) as the sole carbon source was isolated from a wastewater treatment plant receiving domestic and pharmaceutical effluent. 16S rDNA studies revealed the strain to be a Xanthobacter sp. (strain TM1). The new isolated strain when grown aerobically on DCM showed Luong type growth kinetics, with μ_max of 0.094 h⁻¹ and S _m of 1,435 mg l⁻¹. Strain TM1 was able to degrade other aromatic and aliphatic halogenated compounds, such as halobenzoates, 2-chloroethanol and dichloroethane. The gene for DCM dehalogenase, which is the key enzyme in DCM degradation, was amplified through PCR reactions. Strain TM1 contains type A DCM dehalogenase (dcmAa), while no product could be obtained for type B dehalogense (dcmAb). The sequence was compared against 12 dcmAa from other DCM degrading strains and 98% or 99% similarity was observed with all other previously isolated DCM dehalogenase genes. This is the first time a Xanthobacter sp. is reported to degrade DCM.     

Isolation of a heavy metal-resistant 4-Chloronitrobenzene degrader Cupriavidus sp. D4 and cloning of its cnb genes

Strain D4 was isolated from the sludge of the wastewater treating system of a 4-Chloronitrobenzene (4-CNB) manufacturer. It was able to utilize 4-CNB as the sole carbon and nitrogen source for growth. Strain D4 was preliminarily identified as Cupriavidus sp. based on its physiological & biochemical characteristics and 16S rRNA gene sequence analysis. It could completely degrade 300 mg L⁻¹ of 4-CNB within 25 h under the condition of 30 °C and pH 7.0. Strain D4 could also degrade 4-CNB in presence of heavy metals including Co²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Mn²⁺and so on, therefore it was an excellent candidate for the bio-treatment of 4-CNB and heavy metals co-contaminated environments. The main 4-CNB degrading related genes (cnb A, B, Cab, D, G, Z) and arsenate resistance gene fragment of strain D4 were cloned, sequenced and analyzed, which showed high similarity with the corresponding genes of a reported 4-CNB-degrader, strain CNB-1. The cnb genes of strain D4 were located on two plasmids. This is the first report on the degradation of 4-CNB by the strain from the genus of Cupriavidus sp.     

Identification of a flavobacterium strain virulent against Giardia lamblia cysts

We have isolated from a Kentucky stream a bacterial strain capable of killing the cyst form of Giardia lamblia. This bacterium, designated Sun4, is a Gram-negative, aerobic rod which produces a yellow pigment, but not of the flexirubin-type. Although true gliding motility has not been observed in Sun4, this strain does exhibit a spreading colony morphology when grown on R2A agar. Strain Sun4 has been identified by 16S rRNA sequencing and phylogenetic analysis as belonging to the genus Flavobacterium, and is most closely related to Cytophaga sp. strain Type 0092 and associated Flavobacterium columnare strains. Lipid analysis also identified fatty acids characteristic of the Cytophaga–Flavobacterium group of bacteria. In culture, Sun4 is able to degrade casein and cellulose, but not chitin, gelatin, starch, or agar. Degradation of Giardia cysts by Sun4 appears to require direct cellular contact as neither cell-free extracts nor cells separated from the cysts by dialysis membranes showed any activity against cysts. Activity against Giardia cysts is rapid, with Sun4 killing over 90% of cysts within 48 h. Strain Sun4 requires elevated levels of Ca²⁺ for optimal growth and degradative activity against Giardia cysts. We propose that bacterial strains such as Sun4 could be used as biological control agents against Giardia cysts in drinking water treatment systems.     

<Emphasis Type="Italic">Anoxybacillus rupiensis</Emphasis> sp. Nov., a novel thermophilic bacterium isolated from Rupi basin (Bulgaria)

Three strains of a novel thermophilic, strictly aerobic, Gram-positive, spore-forming hemo-organotrophic bacterium were isolated from three hot springs in the region of Rupi basin, Bulgaria as producers of amylolytic enzymes. Their 16S rRNA gene sequences (first 500 nucleotides) were very similar (99.8%). Strains were able to ferment a wide spectrum of carbohydrates such as sugars, polyols, and polysaccharides like xylan, glycogen and starch. Optimal growth was observed at 55–58°C, and pH at 6.0–6.5. Phylogenetic analysis of the whole 16S rRNA gene sequence clustered the strain R270^T with the representatives of the genus Anoxybacillus and with Geobacillus tepidamans. The G + C content of the genomic DNA was 41.7%. DNA–DNA hybridization analysis revealed low homology with the closest relatives (32.0 mol% homology to Geobacillus tepidamans). Fatty acid profile (major fatty acids iso-C15:0 and iso-C17:0) confirmed the affiliation of the strain to the genus Anoxybacillus. On the basis of the data presented here, we propose that strain R270^T, represents a new species of the genus Anoxybacillus for which, we recommend the name Anoxybacillus rupiensis sp. nov. (=DSM 17127^T = NBIMCC 8387^T). The 16S rRNA gene sequence data of a strain R270^T have been deposited in the EMBL databases under the accession number AJ879076.     

Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic,extremely salt-tolerant,obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium <Emphasis Type="Italic">Thioalkalibacter halophilus</Emphasis> gen. nov., sp. nov. from South-Western Siberian soda lakes

A chemolithoautotrophic sulfur-oxidizing bacterium (SOB) strain ALCO 1 capable of growing at both near-neutral and extremely alkaline pH was isolated from hypersaline soda lakes in S-W Siberia (Altai, Russia). Strain ALCO 1 represents a novel separate branch within the halothiobacilli in the Gammaproteobacteria, which, so far, contained only neutro-halophilic SOB. On the basis of its unique phenotypic properties and distant phylogeny, strain ALCO 1 is proposed as a new genus and species Thioalkalibacter halophilus gen. nov. sp. nov. ALCO 1 was able to grow within a broad range of salinity (0.5–3.5 M of total sodium) with an optimum at around 1 M Na⁺, and pH (7.2–10.2, pH_opt at around 8.5). Na⁺ was required for sulfur-dependent respiration in ALCO 1. The neutral (NaCl)-grown chemostat culture had a much lower maximum growth rate (μ_max), respiratory activity and total cytochrome c content than its alkaline-grown counterpart. The specific concentration of osmolytes (ectoine and glycine-betaine) produced at neutral pH and 3 M NaCl was roughly two times higher than at pH 10 in soda. Altogether, strain ALCO 1 represents an interesting chemolithoautotrophic model organism for comparative investigations of bacterial adaptations to high salinity and pH. Nucleotide sequence accession number: The GenBank/EMBL accession number of the 16S rRNA gene sequence of strain ALCO1^T is EU124668.     

Characterization of a strain of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> isolated from agricultural soil that degrades cadusafos (an organophosphorus pesticide)

Bacteria capable of degrading the pesticide, cadusafos, were isolated from agricultural soil using an enrichment method. In this way, five distinct cadusafos-degrading strains of Pseudomonas putidia were isolated, and were characterized using morphological and biochemical analysis, as well as 16S rRNA sequencing. Strain PC1 exhibited the greatest cadusafos degradation rate and was consequently selected for further investigation. Degradation of cadusafos by strain PC1 was rapid at 20 and 37°C, but was greatly reduced (~1.5-fold) by the presence of carbon sources. Strain PC1 was able to effectively degrade cadusafos in sterilized soil using low inoculum levels. The maximum degradation rate of cadusafos (V _max ) was calculated as 1.1 mg l⁻¹ day⁻¹, and its saturation constant (K _s ) was determined as 2.5 mg l⁻¹. Bacteria such as strain PC1, that use cadusafos as a carbon source, could be employed for the bioremediation of sites contaminated with pesticides.     

Isolation and characterization of phenol-degrading yeasts from an oil refinery wastewater in Brazil

This study investigated the aerobic degradation of phenol by yeast strains isolated from an oil refinery wastewater from the Northeast of Brazil. The samples displayed low fungal diversity, as only yeast colonies were detected on Sabouraud dextrose agar containing chloramphenicol 0.05% (w/v). Among the isolates, three yeast strains were selected to be evaluated for their potential for degrading high phenol concentrations. These species were identified through morphological and biochemical characteristics as Candida tropicalis, C. rugosa, and Pichia membranaefaciens. Although the strains were able to degrade the phenol concentration present in the wastewater, which was 7 mg l⁻¹, only C. tropicalis was capable of growing at high concentrations of phenol such as 500 mg l⁻¹ and 1,000 mg l⁻¹ in a mineral medium containing this pollutant as the only carbon source. C. rugosa and P. membranaefaciens were inhibited in the presence of 500 mg l⁻¹ of phenol. However, a longer incubation time was needed for C. tropicalis strain to degrade 1,000 mg l⁻¹ of phenol compared to the time required to degrade 500 mg l⁻¹. Moreover, the strain released a significant amount of polysaccharide biosurfactant in the medium probably to minimize the toxic effect of the high phenol concentration. When challenged with 1,500 and 2,000 mg l⁻¹ of phenol, C. tropicalis was unable to grow at the tested conditions. The results indicate that this strain of C. tropicalis can be considered both a good phenol-degrader and biosurfactant-producer. Application of this strain might be useful in bioremediation activities or treatment of phenol-polluted wastewater.     

<Emphasis Type="Italic">Halorubrum cibi</Emphasis> sp. nov., an extremely halophilic archaeon from salt-fermented seafood

Strain B31^T is a Gram-staining-negative, motile, and extremely halophilic archaeon that was isolated from salt-fermented seafood. Its morphology, physiology, biochemical features, and 16S rRNA gene sequence were determined. Phylogenetic analysis of its 16S rRNA gene sequence and composition of its major polar lipids placed this archaeon in the genus Halorubrum of the family Halobacteriaceae. Strain B31^T showed 97.3, 97.2, and 96.9 % 16S rRNA similarity to the type strains of Halorubrum alkaliphilum, Hrr. tibetense, and Hrr. vacuolatum, respectively. Its major polar lipids were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and sulfated diglycosyl diether (S-DGD). Genomic DNA from strain B31^T has a 61.7 mol% G+C content. Analysis of 16S rRNA gene sequences, as well as physiological and biochemical tests, identified genotypic and phenotypic differences between strain B31^T and other Halorubrum species. The type strain of the novel species is B31^T (=JCM 15757^T =DSM 19504^T).     

Isolation of a methyl parathion-degrading strain <Emphasis Type="Italic">Stenotrophomonas</Emphasis> sp. SMSP-1 and cloning of the <Emphasis Type="Italic">ophc2</Emphasis> gene

A rod-shaped, gram-negative bacterium Stenotrophomonas sp. SMSP-1 was isolated from the sludge of a wastewater treating system of a pesticide manufacturer. Strain SMSP-1 could hydrolyze methyl parathion to p-nitrophenol (PNP) and dimethyl phosphorothioate but could not degrade PNP further. Strain SMSP-1 was able to hydrolyze other organophosphate pesticides, including fenitrothion, ethyl parathion, fenthion, and phoxim, but not chlorpyrifos. A 4395-bp DNA fragment, including an organophosphorus hydrolase encoding gene ophc2, was cloned from the chromosome of strain SMSP-1 using the shotgun technique. Its sequence analysis showed that ophc2 was associated with a typical mobile element ISPpu12 consisting of tnpA (encoding a transposase), lspA (encoding a lipoprotein signal peptidase), and orf1 (encoding a CDF family heavy metal/H⁺ antiporter). The ophc2 gene was effectively expressed in E. coli. This is the second report of cloning the ophc2 gene and the first report of this gene from the genus of Stenotrophomonas.     

Isolation and characterization of a new carbendazim-degrading <Emphasis Type="Italic">Ralstonia</Emphasis> sp. strain

A bacterial strain 1-1 capable of utilizing carbendazim was isolated from carbendazim-treated Qiyang red soils Hunan Province, China. It is gram-negative, rod-shaped, motile with peritrichous flagella, which formed round, smooth, convex and transparent colonies of about 1.1 mm diameter after 3 days of incubation on the isolation and purification medium using carbendazim as the sole carbon and energy sources. The degradation ratios of carbendazim by strain 1-1 were 19.16 and 95.96 in the carbendazim (500 mg/l)-degrading medium and the carbendazim (500 mg/l)-degrading medium supplemented with yeast extract (150 mg/l) within 24 days, respectively. Strain 1-1 was identified as Ralstonia sp. (β-Proteobacteria) based on the results of phenotypic features, G+C mol and phylogenetic analysis of 16S rDNA. Strain 1-1 could become a new bacterial resource for biodegrading carbendazim and might play a bioremediation role for soils contaminated by carbendazim.     

Biodegradation of malachite green by strain <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. K9 and cloning of the <Emphasis Type="Italic">tmr2</Emphasis> gene associated with an IS<Emphasis Type="Italic">Ppu12</Emphasis>

A bacterial strain K9 capable of degrading malachite green was isolated from the sludge of the wastewater treatment system of a chemical plant. It was identified preliminarily as Pseudomonas sp. Strain K9 was also able to degrade other triphenylmethane dyes, such as Crystal Violet and Basic Fuchsin. The gene tmr2, encoding the triphenylmethane reductase, was cloned from strain K9, and functionally expressed in E. coli. A 5946-bp DNA fragment including the tmr2 gene was cloned from the genomic DNA of strain K9 by chromosome walking. Its sequence analysis showed that tmr2 was associated with a typical mobile element ISPpu12 consisting of tnpA (encoding a transposase), lspA (encoding a lipoprotein signal peptidase) and orf1 (encoding a putative MerR family regulator), orf2 (encoding a CDF family heavy metal/H⁺ antiporter). This association was also found in another malachite green-degrading strain Pseudomonas sp. MDB-1, which indicated that the tmr2 gene might be a horizontally transferable gene.     

Rhodococcus sp. strain TM1 plays a synergistic role in the degradation of piperidine by Mycobacterium sp. strain THO100

Mycobacterium sp. strain THO100 and Rhodococcus sp. strain TM1 were isolated from a morpholine-containing enrichment culture of activated sewage sludge. Strain THO100, but not strain TM1, was able to degrade alicyclic amines such as morpholine, piperidine, and pyrrolidine. The mixed strains THO100 and TM1 showed a better growth on piperidine as the substrate than the pure strain THO100 because strain TM1 was able to reduce the level of glutaraldehyde (GA) produced during piperidine degradation. GA was toxic to strain THO100 (IC₅₀ = 28.3 μM) but less toxic to strain TM1 (IC₅₀ = 215 μM). Strain THO100 possessed constitutive semialdehyde dehydrogenases, namely Sad1 and Sad2, whose activities toward succinic semialdehyde (SSA) were strongly inhibited by GA. The two isozymes were identified as catalase–peroxidase (KatG = Sad1) and semialdehyde dehydrogenase (Sad2) based on mass spectrometric analyses of tryptic peptides and database searches of the partial DNA sequences of their genes. In contrast, strain TM1 containing another constitutive enzyme Gad1 could oxidize both SSA and GA. This study suggested that strain TM1 possessing Gad1 played a synergistic role in reducing the toxic and inhibitory effects of GA produced in the degradation of piperidine by strain THO100.     

Taxonomic identification,phenanthrene uptake activity,and membrane lipid alterations of the PAH degrading <Emphasis Type="Italic">Arthrobacter</Emphasis> sp. strain Sphe3

This report describes phenanthrene uptake as well as the effect of phenanthrene on the membrane phospholipid and fatty acid composition in a newly isolated bacterial strain, Sphe3, that we taxonomically identified as Arthrobacter sp. Strain Sphe3 is able to utilize phenanthrene as a carbon source at high rates and appears to internalize phenanthrene with two mechanisms: a passive diffusion when cells are grown on glucose, and an inducible active transport system when cells are grown on phenanthrene as a sole carbon source. Active transport followed Michaelis-Menten kinetics, and it was amenable to inhibition by 2,4-dinitrophenol and sodium azide. Evidence provided here indicates that apart from inducing an active PAH uptake, the presence of phenanthrene elicits significant changes in membrane fluidity.     

<Emphasis Type="Italic">Tindallia texcoconensis</Emphasis> sp. nov., a new haloalkaliphilic bacterium isolated from lake Texcoco,Mexico

A new alkaliphilic and moderately halophilic, strictly anaerobic, fermentative bacterium (strain IMP-300^T) was isolated from a groundwater sample in the zone of the former soda lake Texcoco in Mexico. Strain IMP-300^T was Gram-positive, non-sporulated, motile and rod-shaped. It grew within a pH range from 7.5 to 10.5, and an optimum at 9.5. The organism was obligately dependent on the presence of sodium salts. Growth showed an optimum at 35°C with absence of growth above 45°C. It fermented peptone and a few amino acids, preferentially arginine and ornithine, with production of acetate, propionate, and ammonium. Its fatty acid pattern was mainly composed of straight chain saturated, unsaturated, and cyclopropane fatty acids. The G + C content of genomic DNA was 40.0 mol%. Analysis of the 16S rRNA gene sequence indicated that the new isolate belongs to the genus Tindallia, in the low G + C Gram-positive phylum. Phylogenetically, strain IMP-300^T has Tindallia californiensis, as closest relative with a 97.5% similarity level between their 16S rDNA gene sequences, but the DNA–DNA re-association value between the two DNAs was only 42.2%. On the basis of differences in genotypic, phenotypic, and phylogenetic characteristics, strain IMP-300^T is proposed as a new species of the genus Tindallia, T. texcoconensis sp. nov. (type strain IMP-300^T = DSM 18041^T = JCM 13990^T).     

Growth and survival of Pseudomonas cepacia DBO1(pRO101) in soil amended with 2,4-dichlorophenoxyacetic acid

The 2,4-dichlorophenoxyacetic acid (2,4-D) degrading pseudomonad, Pseudomonas cepacia DBO1(pRO101), was inoculated at approximately 10⁷ CFU/g into sterile and non-sterile soil amended with 0, 5 or 500 ppm 2,4-D and the survival of the strain was studied for a period of 44 days. In general, the strain survived best in sterile soil. When the sterile soil was amended with 2,4-D, the strain survived at a significantly higher level than in non-amended sterile soil. In non-sterile soil either non-amended or amended with 5 ppm 2,4-D the strain died out, whereas with 500 ppm 2,4-D the strain only declined one order of magnitude through the 44 days.The influence of 0,0.06, 12 and 600 ppm 2,4-D on short-term (48 h) survival of P. cepacia DBO1(pRO101) inoculated to a level of 6×10⁴, 6×10⁶ or 1×10⁸ CFU/g soil was studied in non-sterile soil. Both inoculum level and 2,4-D concentration were found to have a positive influence on numbers of P. cepacia DBO1(pRO101). At 600 ppm 2,4-D growth was significant irrespective of the inoculation level, and at 12 ppm growth was stimulated at the two lowest inocula levels. P. cepacia DBO1(pRO101) was able to survive for 15 months in sterile buffers kept at room temperature. During this starvation, cells shrunk to about one third the volume of exponentially growing cells.Abbreviations AODC acridine orange direct count - CFU colony forming units - PTYG-Agar peptone, tryptone, yeast & glucose agar - TET tetracycline - LB Luria Bertani medium     

Amphibacillus fermentum sp. nov. and Amphibacillus tropicussp. nov., New Alkaliphilic,Facultatively Anaerobic,Saccharolytic Bacilli from Lake Magadi

New alkaliphilic, saccharolytic, rod-shaped, gram-positive bacteria resistant to heating and drying and phylogenetically affiliated to the Bacilluslineage were isolated under strictly anaerobic conditions from sediments of the alkaline and highly mineralized Lake Magadi. Strain Z-7792 forms endospores; in strain Z-7984, endospore formation was not revealed. The strains are capable of both anaerobic growth (at the expense of fermentation of glucose and certain mono- and disaccharides with the formation of formate, ethanol, and acetate) and aerobic growth. Among polysaccharides, the strains hydrolyze starch, glycogen, and xylan. Yeast extract or methionine are required for growth. The strains are strict alkaliphiles exhibiting obligate requirement for Na⁺and carbonate ions, but not for Cl^–ions. Growth occurs at a total mineralization as high as 3.3–3.6 M Na⁺, with an optimum at 1–1.7 M Na⁺. Strain Z-7792 is an obligate alkaliphile with a pH growth range of 8.5–11.5 and an optimum of 9.5–9.7. Strain Z-7984 grows in a pH range of 7.0–10.5 with an optimum at 8.0–9.5. Both strains are mesophiles having a growth optimum at 37–38°C. The G+C contents of the DNA of strains Z-7792 and Z-7984 are 39.2 and 41.5 mol %, respectively. These isolates of facultatively anaerobic, strictly alkaliphilic, Na⁺-dependent bacilli can be considered representatives of the ecological group adapted to life at drying-up shoals of soda lakes. Because of their independence of NaCl and lack of obligate dependence on sodium carbonates, the isolates are to be assigned to athalassophilic organisms. According to their physiological and phylogenetic characteristics, they taxonomically belong to group 1 of the species of bacilli with a low G+C content and occupy a position intermediate between the genera Amphibacillusand Gracilibacillus.The isolates are described as new species of Amphibacillus: A. fermentum(type strain, Z-7984^T) and A. tropicus(type strain, Z-7792^T).     

Characterization of Desulfomicrobium escambium sp. nov. and proposal to assign Desulfovibrio desulfuricans strain Norway 4 to the genus Desulfomicrobium

A sulfate-reducing bacterium, designated strain ESC1, was isolated and found to be a new species. Strain ESC1 is a strictly anaerobic, gram-negative, non-sporeforming, motile, short, round-ended rod often occurring in pairs. Of 31 fermentative substrates tested, only pyruvate was utilized. Sulfate enhanced growth with pyruvate and allowed growth with ethanol, lactate, formate and hydrogen. Both sulfate and thiosulfate were reduced. Lactate was incompletely oxidized to acetate and CO₂. The strain was desulfoviridin negative. The G+C content is 59.9%. These data suggested placement of strain ESC1 in the genus Desulfomicrobium. Comparative 16S rRNA analysis showed that strain ESC1 shares 98% rRNA sequence similarity with Desulfomicrobium baculatum and Desulfovibrio desulfuricans strain Norway 4. The latter two strains shared greater than 99% 16S rRNA sequence similarity. Strain ESC1 has been designated as the new species Desulfomicrobium escambium. We also recommend that D. desulfuricans strain Norway 4 be considered for reclassification as a Desulfomicrobium species.     

Isolation and Characterization of a Pseudomonas putida Strain able to Grow with Trimethyl-1,2-dihydroxy-propyl-ammonium as Sole Source of Carbon, Energy and Nitrogen

Trimethyl-1,2-dihydroxypropyl-ammonium (TM) originates from the hydrolysis of the parent esterquat surfactant, which is widely used as softener in fabric care. Based on test procedures mimicking complex biological systems, TM is supposed to degrade completely when reaching the environment. However, no organisms able to degrade TM were isolated nor has the degradation pathway been elucidated so far. We isolated a Gram-negative rod able to grow with TM as sole source of carbon, energy and nitrogen. The strain reached a maximum specific growth rate of 0.4 h^–1 when growing with TM as the sole source of carbon, energy and nitrogen. TM was degraded to completion and surplus nitrogen was excreted as ammonium into the growth medium. A high percentage of the carbon in TM (68% in continuous culture and 60% in batch culture) was combusted to CO₂ resulting in a low yield of 0.54 mg cell dry weight per mg carbon during continuous cultivation and 0.73 mg cell dry weight per mg carbon in batch cultures. Choline, a natural structurally related compound, served as a growth substrate, whereas a couple of similar other quaternary aminoalcohols also used in softeners did not. The isolated bacterium was identified by 16S-rDNA sequencing as a strain of Pseudomonas putida with a difference of only one base pair to P. putida DSM 291^T. Despite their high identity, the reference strain P. putida DSM 291^T was not able to grow with TM and the two strains differed even in shape when growing on the same medium. This is the first microbial isolate able to degrade a quaternary ammonium softener head group to completion. Previously described strains growing on quaternary ammonium surfactants (decyltrimethylammonium, hexadecyltrimethylammonium and didecyldimethylammonium) either excreted metabolites or a consortium of bacteria was required for complete degradation.