Isolation and taxonomic and catabolic characterization of a 3,6-dimethylphenanthrene-utilizing strain of Sphingomonas sp

A bacterial strain capable of utilizing 3,6-dimethylphenanthrene (3,6-DMP) as its sole source of carbon and energy was isolated from a creosote-contaminated soil. The isolate was identified as a strain of Sphingomonas sp. and was designated strain JS1. Utilization of 3,6-DMP was demonstrated by an increase in bacterial biomass concomitant with a decrease in 3,6-DMP in a liquid mineral medium with this compound as its sole source of carbon and energy. Strain JS1 showed a high specificity in the use of the most abundant alkylderivatives of crude oils, such as alkylnaphthalenes and other alkylphenanthrenes, as the sole source of carbon and energy. It can also use several polycyclic aromatic hydrocarbons of three and four rings and their alkylated derivatives as growth substrates or transform them. The identification of several intermediate metabolites points to extensive metabolic activity, including the following: (i) aromatic ring oxidation and cleavage, (ii) methyl group oxidations, and (iii) methylenic oxidations. The metabolic actions of Sphingomonas sp. JS1 on the aromatic fraction extracted from a creosote-contaminated soil are also examined.     

Anaerobic oxidation of 2-chloroethanol under denitrifying conditions by<Emphasis Type="Italic"> Pseudomonas stutzeri</Emphasis> strain JJ

A bacterium that uses 2-chloroethanol as sole energy and carbon source coupled to denitrification was isolated from 1,2-dichloroethane-contaminated soil. Its 16 S rDNA sequence showed 98% similarity with the type strain of Pseudomonas stutzeri (DSM 5190) and the isolate was tentatively identified as Pseudomonas stutzeri strain JJ. Strain JJ oxidized 2-chloroethanol completely to CO(2) with NO(3)(- )or O(2) as electron acceptor, with a preference for O(2) if supplied in combination. Optimum growth on 2-chloroethanol with nitrate occurred at 30 degrees C with a mu(max) of 0.14 h(-1) and a yield of 4.4 g protein per mol 2-chloroethanol metabolized. Under aerobic conditions, the mu(max) was 0.31 h(-1). NO(2)(-) also served as electron acceptor, but reduction of Fe(OH)(3), MnO(2), SO(4)(2-), fumarate or ClO(3)(-) was not observed. Another chlorinated compound used as sole energy and carbon source under aerobic and denitrifying conditions was chloroacetate. Various different bacterial strains, including some closely related Pseudomonas stutzeri strains, were tested for their ability to grow on 2-chloroethanol as sole energy and carbon source under aerobic and denitrifying conditions, respectively. Only three strains, Pseudomonas stutzeri strain LMD 76.42, Pseudomonas putida US2 and Xanthobacter autotrophicus GJ10, grew aerobically on 2-chloroethanol. This is the first report of oxidation of 2-chloroethanol under denitrifying conditions by a pure bacterial culture.     

Mineralization of the cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine by Gordonia and Williamsia spp

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a cyclic nitroamine explosive that is a major component in many military high-explosive formulations. In this study, two aerobic bacteria that are capable of using RDX as the sole source of carbon and nitrogen to support their growth were isolated from surface soil. These bacterial strains were identified by their fatty acid profiles and 16S ribosomal gene sequences as Williamsia sp. KTR4 and Gordonia sp. KTR9. The physiology of each strain was characterized with respect to the rates of RDX degradation and [U-14C]RDX mineralization when RDX was supplied as a sole carbon and nitrogen source in the presence and absence of competing carbon and nitrogen sources. Strains KTR4 and KTR9 degraded 180 microM RDX within 72 h when RDX served as the only added carbon and nitrogen source while growing to total protein concentrations of 18.6 and 16.5 microg/ml, respectively. Mineralization of [U-14C]RDX to 14CO2 was 30% by strain KTR4 and 27% by KTR9 when RDX was the only added source of carbon and nitrogen. The addition of (NH4)2SO4- greatly inhibited KTR9's degradation of RDX but had little effect on that of KTR4. These are the first two pure bacterial cultures isolated that are able to use RDX as a sole carbon and nitrogen source. These two genera possess different physiologies with respect to RDX mineralization, and each can serve as a useful microbiological model for the study of RDX biodegradation with regard to physiology, biochemistry, and genetics.     

Non-selective precultivation of bacteria able to degrade different polycyclic aromatic hydrocarbons (PAH)

The influence of the precultivation with different carbon sources on the ability of three different bacterial strains (Sphingomonas sp. strain BA2, Gordona sp. strain BP9, Mycobacterium sp. strain VF1) to grow on phenanthrene. anthracene, pyrene or fluoranthene as the sole source of carbon and energy were studied. The strains were found to maintain their ability to grow on two of the four PAH after 30 serial transfers in liquid nutrient broth medium without selective pressure. The ability to grow on these PAH as the sole carbon and energy source was also maintained after curing experiments with acridine orange. The high stability of the PAH-degradation phenotype suggests that the tested strains carry at least parts of the PAH-degradation pathway genes on the chromosome. The PAH-degradation versatility of the strains was also influenced by the carbon source being used for precultivation. Possible reasons for the particularly good impact of the precultivation on hexadecane on the PAH degradation are discussed in this paper.     

Isolation of phenanthrene-degrading bacteria and characterization of phenanthrene metabolites

Three aerobic bacterial consortia GY2, GS3 and GM2 were enriched from polycyclic aromatic hydrocarbon-contaminated soils with water-silicone oil biphasic systems. An aerobic bacterial strain utilizing phenanthrene as the sole carbon and energy source was isolated from bacterial consortium GY2 and identified as Sphingomonas sp. strain GY2B. Within 48 h and at 30°C the strain metabolized 99.1% of phenanthrene (100 mg/l) added to batch culture in mineral salts medium and the cell number increased by about 40-fold. Three metabolites 1-hydroxy-2-naphthoic acid, 1-naphthol and salicylic acid, were identified by gas chromatographic mass spectrometry and UV–visible spectroscopy analysis. A degradation pathway was proposed based on the identified metabolites. In addition to phenanthrene, strain GY2B could use other aromatic compounds such as naphthalene, 2-naphthol, salicylic acid, catechol, phenol, benzene and toluene as a sole source of carbon and energy.     

Plasmid Involvement in Linalool Metabolism by Pseudomonas fluorescens

A bacterial strain was isolated from a wastewater lagoon and identified as Pseudomonas fluorescens. This isolate was able to utilize linalool as a sole carbon and energy source. The ability was found to be encoded on a 60-megadalton transmissible plasmid, pSRQ60. The plasmid was also mated into a commercial waste treatment strain, which expanded its ability to utilize other isoprenoid compounds.     

Characterization of <Emphasis Type="Italic">Rhodococcus wratislaviensis</Emphasis> strain J3 that degrades 4-nitrocatechol and other nitroaromatic compounds

The bacterial strain J3 was isolated from soil by selective enrichment on mineral medium containing 4-nitrocatechol as the sole carbon and energy source. This strain was identified as Rhodococcus wratislaviensis on the basis of morphology, biochemical, physiological and chemotaxonomic characterization and complete sequencing of the 16S rDNA gene. The isolated bacterium could utilize 4-nitrocatechol, 3-nitrophenol and 5-nitroguaiacol as sole carbon and energy sources. Stoichiometric release of nitrites was measured during degradation of 4-nitrocatechol both in growing cultures and for stationary phase cells. The J3 strain was unable to degrade 4-nitroguaiacol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrobenzoic acid, 4,5-dimethoxy-2-nitrobenzoic acid and 2,3-difluoro-6-nitrophenol. The J3 strain is deposited in the Czech Collection of Microorganisms as CCM 4930.     

Xylitol Production by an Enterobacter Species

A xylose-utilizing bacterial strain was isolated from soil.

The strain, No. 553, was identified as Enterobacter liquefaciens from the result of the taxonomical studies. This bacterium grew well on D-xylose as a sole carbon source and accumulated pentitol extracellularly in shaking culture.

Pentitol produced was isolated from the culture broth and identified as xylitol.

The xylitol production reached the maximum after the cessation of the cell growth with a yield of 33.3 mg per ml in a medium containing 10% D-xylose as a sole carbon source and no significant decline of the amount of xylitol was observed through the period of the cultivation.     

A new strain, Streptomyces venezuelae GY1, producing a poly(vinyl alcohol)-degrading enzyme

Summary An actinomycete strain, which could produce an extracellular poly(vinyl alcohol) (PVA)-degrading enzyme, was isolated from a PVA-contaminated soil sample using PVA as the sole carbon source. The strain was identified as Streptomyces venezuelae according to the whole-nucleotide-sequence analysis of 16S rDNA, the morphological and the physiological characteristics. The strain produced 120 U/l extracellular PVA-degrading enzyme when PVA was used as the sole carbon source. When glucose was used as the sole carbon source, however, the extracellular enzyme activity was very low (12 U/l). This is the first report showing that an actinomycete strain can produce a PVA-degrading enzyme.     

Perchlorate reduction by a novel chemolithoautotrophic,hydrogen-oxidizing bacterium

Water treatment technologies are needed that can remove perchlorate from drinking water without introducing organic chemicals that stimulate bacterial growth in water distribution systems. Hydrogen is an ideal energy source for bacterial degradation of perchlorate as it leaves no organic residue and is sparingly soluble. We describe here the isolation of a perchlorate-respiring, hydrogen-oxidizing bacterium (Dechloromonas sp. strain HZ) that grows with carbon dioxide as sole carbon source. Strain HZ is a Gram-negative, rod-shaped facultative anaerobe that was isolated from a gas-phase anaerobic packed-bed biofilm reactor treating perchlorate-contaminated groundwater. The ability of strain HZ to grow autotrophically with carbon dioxide as the sole carbon source was confirmed by demonstrating that biomass carbon (100.9%) was derived from CO2. Chemolithotrophic growth with hydrogen was coupled with complete reduction of perchlorate (10 mM) to chloride with a maximum doubling time of 8.9 h. Strain HZ also grew using acetate as the electron donor and chlorate, nitrate, or oxygen (but not sulphate) as an electron acceptor. Phylogenetic analysis of the 16S rRNA sequence placed strain HZ in the genus Dechloromonas within the beta subgroup of the Proteobacteria. The study of this and other novel perchlorate-reducing bacteria may lead to new, safe technologies for removing perchlorate and other chemical pollutants from drinking water.     

从白蚁中分离到具有纤维素酶活的贪噬菌

以黄胸散白蚁Reticulitermes flaviceps后肠为材料,分离培养具有降解纤维素能力的微生物,以进一步了解白蚁后肠微生物的种类。通过以羧甲基纤维素钠(CMC-Na)为唯一碳源的富集及选择培养基培养、筛选,获得一株具有纤维素酶活的菌株R3063。形态学鉴定、革兰氏染色观察及16S rDNA基因序列分析表明该菌株属于贪噬菌(Variovorax sp.)。目前尚未见贪噬菌具有纤维素酶活的报道。     

Degradation of petroleum hydrocarbons (C6-C40) and crude oil by a novel Dietzia strain

A novel bacterial strain, DQ12-45-1b, was isolated from the production water of a deep subterranean oil-reservoir. Morphological, physiological and phylogenetic analyses indicated that the strain belonged to the genus Dietzia with both alkB (coding for alkane monooxygenase) and CYP153 (coding for P450 alkane hydroxylase of the cytochrome CYP153 family) genes and their induction detected. It was capable of utilizing a wide range of n-alkanes (C6-C40), aromatic compounds and crude oil as the sole carbon sources for growth. In addition, it preferentially degraded short-chain hydrocarbons (?C25) in the early cultivation phase and accumulated hydrocarbons with chain-lengths from C23 to C27 during later cultivation stage with crude oil as the sole carbon source. This is the first study to report the different behaviors of a bacterial species toward crude oil degradation as well as a species of Dietzia degrading a wide range of hydrocarbons.     

Chemotaxis of a Ralstonia sp. SJ98 toward co-metabolizable nitroaromatic compounds

We have earlier reported chemotaxis of a Gram-negative, motile Ralstonia sp. SJ98 towards p-nitrophenol (PNP), 4-nitrocatechol (NC), o-nitrobenzoate (ONB), p-nitrobenzoate (PNB), and 3-methyl-4-nitrophenol (MNP) that also served as sole source of carbon and energy to the strain [S.K. Samanta, B. Bhushan, A. Chauhan, R.K. Jain, Biochem. Biophy. Res. Commun. 269 (2000) 117; B. Bhushan, S.K. Samanta, A. Chauhan, A.K. Chakraborti, R.K. Jain, Biochem. Biophy. Res. Commun. 275 (2000) 129]. In this paper, we report chemotaxis of a Ralstonia sp. SJ98 toward seven different nitroaromatic compounds (NACs) by drop assay, swarm plate assay, and capillary assay. These NACs do not serve as sole carbon and energy source to strain SJ98 but are partially transformed in the presence of an alternate carbon source such as succinate. This is the first report showing chemotaxis of a bacterial strain toward co-metabolizable NACs.     

烟碱降解细菌的分离、鉴定及其降解性能的初步研究

从福建三明地区的土壤中分离得到一株能够高效降解烟碱的菌株 ,编号为DN2。该菌经常规的形态、生理生化分析以及 16SrDNA序列同源性分析 ,鉴定为Ochrobactrumintermedium ,属于α_变形杆细菌纲。该菌在 30℃～4 0℃和pH 6 . 0～ 9. 0范围内具有较高的降解活性 ,其最适值分别为 30℃和 6 5 ,烟碱的耐受浓度在无机盐培养基中可达到 4 0 0 0mg L。该菌能够以烟碱为唯一碳源生长 ,对于 5 0 0mg L烟碱的降解速率为 15mg L·h ,36h烟碱降解率为97. 6 5 %。该菌在烟草工业和环境保护上可能具有应用前景。     

Mineralization of the Cyclic Nitramine Explosive Hexahydro-1,3,5-Trinitro-1,3,5-Triazine by Gordonia and Williamsia spp.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a cyclic nitroamine explosive that is a major component in many military high-explosive formulations. In this study, two aerobic bacteria that are capable of using RDX as the sole source of carbon and nitrogen to support their growth were isolated from surface soil. These bacterial strains were identified by their fatty acid profiles and 16S ribosomal gene sequences as Williamsia sp. KTR4 and Gordonia sp. KTR9. The physiology of each strain was characterized with respect to the rates of RDX degradation and [U-¹⁴C]RDX mineralization when RDX was supplied as a sole carbon and nitrogen source in the presence and absence of competing carbon and nitrogen sources. Strains KTR4 and KTR9 degraded 180 μM RDX within 72 h when RDX served as the only added carbon and nitrogen source while growing to total protein concentrations of 18.6 and 16.5 μg/ml, respectively. Mineralization of [U-¹⁴C]RDX to ¹⁴CO₂ was 30% by strain KTR4 and 27% by KTR9 when RDX was the only added source of carbon and nitrogen. The addition of (NH₄)₂SO₄ greatly inhibited KTR9's degradation of RDX but had little effect on that of KTR4. These are the first two pure bacterial cultures isolated that are able to use RDX as a sole carbon and nitrogen source. These two genera possess different physiologies with respect to RDX mineralization, and each can serve as a useful microbiological model for the study of RDX biodegradation with regard to physiology, biochemistry, and genetics.     

Bacterial metabolism of 3-chloroacrylic acid.

Two bacterial strains were isolated with 3-chloroacrylic acid (CAA) as sole source of carbon and energy. Strain CAA1, a Pseudomonas cepacia sp., was capable of growth with only the cis-isomer of CAA. Strain CAA2, a coryneform bacterium, utilized both isomers of CAA as sole source of carbon and energy. Strain CAA1 contained cis-CAA hydratase and strain CAA2 contained two hydratases, one with cis-CAA hydratase activity and one with trans-CAA hydratase activity. The product of the hydratase activities with CAA was malonate semialdehyde. In both strains malonate semialdehyde was subsequently decarboxylated by a cofactor-independent decarboxylase yielding acetaldehyde and CO2.     

S5 Lipase: an organic solvent tolerant enzyme

In this study, an organic solvent tolerant bacterial strain was isolated. This strain was identified as Pseudomonas sp. strain S5, and was shown to degrade BTEX (Benzene, Toluene, Ethyl-Benzene, and Xylene). Strain S5 generates an organic solvent-tolerant lipase in the late logarithmic phase of growth. Maximum lipase production was exhibited when peptone was utilized as the sole nitrogen source. Addition of any of the selected carbon sources to the medium resulted in a significant reduction of enzyme production. Lower lipase generation was noted when an inorganic nitrogen source was used as the sole nitrogen source. This bacterium hydrolyzed all tested triglycerides and the highest levels of production were observed when olive oil was used as a natural triglyceride. Basal medium containing Tween 60 enhanced lipase production to the most significant degree. The absence of magnesium ions (Mg2+) in the basal medium was also shown to stimulate lipase production. Meanwhile, an alkaline earth metal ion, Na+, was found to stimulate the production of S5 lipase.     

Biodegradation of bis(2-chloroethyl) ether by Xanthobacter sp. strain ENV481

Degradation of bis(2-chloroethyl) ether (BCEE) was observed to occur in two bacterial strains. Strain ENV481, a Xanthobacter sp. strain, was isolated by enrichment culturing of samples from a Superfund site located in the northeastern United States. The strain was able to grow on BCEE or 2-chloroethylethyl ether as the sole source of carbon and energy. BCEE degradation in strain ENV481 was facilitated by sequential dehalogenation reactions resulting in the formation of 2-(2-chloroethoxy)ethanol and diethylene glycol (DEG), respectively. 2-Hydroxyethoxyacetic acid was detected as a product of DEG catabolism by the strain. Degradation of BCEE by strain ENV481 was independent of oxygen, and the strain was not able to grow on a mixture of benzene, ethylbenzene, toluene, and xylenes, other prevalent contaminants at the site. Another bacterial isolate, Pseudonocardia sp. strain ENV478 (S. Vainberg et al., Appl. Environ. Microbiol. 72:5218-5224, 2006), degraded BCEE after growth on tetrahydrofuran or propane but was not able to grow on BCEE as a sole carbon source. BCEE degradation by strain ENV478 appeared to be facilitated by a monooxygenase-mediated O-dealkylation mechanism, and it resulted in the accumulation of 2-chloroacetic acid that was not readily degraded by the strain.     

Plasmid-mediated mineralization of carbofuran by Sphingomonas sp. strain CF06.

A bacterial strain (CF06) that mineralized both the carbonyl group and the aromatic ring of the insecticide carbofuran and that is capable of using carbofuran as a sole source of carbon and nitrogen was isolated from a soil in Washington state. Phospholipid fatty acid and 16S rRNA sequencing analysis indicate that CF06 is a Sphingomonas sp. CF06 contains five plasmids, at least some of which are required for metabolism of carbofuran. Loss of the plasmids induced by growth at 42 degrees C resulted in the inability of the cured strain to grow on carbofuran as a sole source of carbon. Introduction of the plasmids confers on Pseudomonas fluorescens M480R the ability to use carbofuran as a sole source of carbon for growth and energy. Of the five plasmids, four are rich in insertion sequence elements and contain large regions of overlap. Rearrangements, deletions, and loss of individual plasmids that resulted in the loss of the carbofuran-degrading phenotype were observed following introduction of Tn5.     

Degradation of polycyclic aromatic hydrocarbons by a newly discovered enteric bacterium, Leclercia adecarboxylata

A bacterial strain, PS4040, capable of degrading polycyclic aromatic hydrocarbons for use as the sole carbon source was isolated from oily-sludge-contaminated soil. The 16S rRNA gene showed 98.8% homology to that of Leclercia adecarboxylata. Comparative molecular typing with the clinical strain of L. adecarboxylata revealed that there were few comigrating and few distinct amplimers among them.