Shewanella decolorationis sp. nov., a dye-decolorizing bacterium isolated from activated sludge of a waste-water treatment plant

Rhizobium borbori sp. nov., aniline-degrading bacteria isolated from activated sludge

Three aniline-degrading bacteria, strains DN316T, DN316-1 and DN365, were isolated from activated sludge. According to 16S rRNA gene sequence-based phylogenetic analysis, the isolates belonged to the genus Rhizobium, with Rhizobium ( = Agrobacterium) radiobacter LMG 140T as the closest relative, with 96.5 % sequence similarity. Phylogenetic analysis of the representative strain DN316T using sequences of the glnA, thrC and recA genes and the 16S–23S intergenic spacer region confirmed the phylogenetic arrangement obtained from analysis of the 16S rRNA gene. DNA–DNA relatedness between DN316T and R. radiobacter LMG 140T was 43.7 %, clearly indicating that the representative strain DN316T represents a novel species. Phenotypic and biochemical characterization of the isolates and insertion sequence-PCR fingerprinting patterns showed several distinctive features that differentiated them from closely related species. The major components of the cellular fatty acids were C18 : 1ω7c (57.10 %), C16 : 0 (11.31 %) and C19 : 0 cyclo ω8c (10.13 %). Based on our taxonomic analysis, the three isolates from activated sludge represent a novel species of the genus Rhizobium, for which the name Rhizobium borbori sp. nov. is proposed. The type strain is DN316T ( = CICC 10378T  = LMG 23925T).

Microbial community dynamics in mesophilic anaerobic co-digestion of mixed waste

This paper identifies key components of the microbial community involved in the mesophilic anaerobic co-digestion (AD) of mixed waste at Rayong Biogas Plant, Thailand. The AD process is separated into three stages: front end treatment (FET); feed holding tank and the main anaerobic digester. The study examines how the microbial community structure was affected by the different stages and found that seeding the waste at the beginning of the process (FET) resulted in community stability. Also, co-digestion of mixed waste supported different bacterial and methanogenic pathways. Typically, acetoclastic methanogenesis was the major pathway catalysed by Methanosaeta but hydrogenotrophs were also supported. Finally, the three-stage AD process means that hydrolysis and acidogenesis is initiated prior to entering the main digester which helps improve the bioconversion efficiency. This paper demonstrates that both resource availability (different waste streams) and environmental factors are key drivers of microbial community dynamics in mesophilic, anaerobic co-digestion.

In-situ Cr(VI) reduction with electrogenerated hydrogen peroxide driven by iron-reducing bacteria

Cr(VI) was reduced in-situ at a carbon felt cathode in an air-cathode dual-chamber microbial fuel cell (MFC). The reduction of Cr(VI) was proven to be strongly associated with the electrogenerated H(2)O(2) at the cathode driven by iron-reducing bacteria. At pH 2.0, only 42.5% of Cr(VI) was reduced after 12h in the nitrogen-bubbling-cathode MFC, while complete reduction of Cr(VI) was achieved in 4h in the air-bubbling-cathode MFC in which the reduction of oxygen to H(2)O(2) was confirmed. Conditions that affected the efficiency of the reduction of Cr(VI) were evaluated experimentally, including the cathodic electrolyte pH, the type of iron-reducing species, and the addition of redox mediators. The results showed that the efficient reduction of Cr(VI) could be achieved with an air-bubbling-cathode MFC.

Physiology and biochemistry of reduction of azo compounds by Shewanella strains relevant to electron transport chain

Azo dyes are toxic, highly persistent, and ubiquitously distributed in the environments. The large-scale production and application of azo dyes result in serious environmental pollution of water and sediments. Bacterial azo reduction is an important process for removing this group of contaminants. Recent advances in this area of research reveal that azo reduction by Shewanella strains is coupled to the oxidation of electron donors and linked to the electron transport and energy conservation in the cell membrane. Up to date, several key molecular components involved in this reaction have been identified and the primary electron transportation system has been proposed. These new discoveries on the respiration pathways and electron transfer for bacterial azo reduction has potential biotechnological implications in cleaning up contaminated sites.

Shewanella indica sp. nov., isolated from sediment of the Arabian Sea

A Gram-negative, facultatively anaerobic, rod-shaped, catalase- and oxidase-positive bacterium, motile by means of a single polar flagellum and designated strain KJW27(T), was isolated from the marine sediment of Karwar jetty, west coast of India. The strain was β-haemolytic and grew with 0-10 % (w/v) NaCl, at 10-45 °C and at pH 6.5-10, with optimum growth with 2 % (w/v) NaCl, at 37 °C and at pH 7.5. The major fatty acids were iso-C₁₅:₀ (22.2 %), C₁₇:₁ω8c (21 %), summed feature 3 (comprising C₁₆:₁ω7c and/or C₁₆:₁ω6c; 10.2 %), C₁₆:₀ (7.1 %), iso-C₁₃:₀ (5.6 %) and C₁₇:₀ (4.4 %). The DNA G+C content was 51.2 mol%. Phylogenetic analysis based on 16S rRNA and gyrB gene sequences showed that strain KJW27(T) forms a lineage within the genus Shewanella and is closely related to Shewanella algae ATCC 51192(T) (98.8 %), Shewanella haliotis DW01(T) (98.8 %) and Shewanella chilikensis JC5(T) (98.2 %). Sequence identity with other members of this genus ranges from 92.2 to 96.4 %. The DNA-DNA relatedness of strain KJW27(T) with S. algae ATCC 51192(T), S. haliotis DW01(T) and S. chilikensis JC5(T) was 52, 44 and 33 %, respectively. The phenotypic, genotypic and DNA-DNA relatedness data indicate that strain KJW27(T) should be distinguished from S. algae ATCC 51192(T), S. haliotis DW01(T) and S. chilikensis JC5(T). On the basis of the data presented in this study, strain KJW27(T) represents a novel species, for which the name Shewanella indica sp. nov. is proposed. The type strain is KJW27(T) ( = KCTC 23171(T)  = BCC 41031(T)  = NCIM 5388(T)).

Effects of oxygen on Shewanella decolorationis NTOU1 electron transfer to carbon-felt electrodes

To clarify the major factor caused by oxygen-enhancing charge production of Shewanella decolorationis NTOU1 towards a polarized anode, a series of experimental runs (i.e., with/without ambient air flushing and with/without ammonia addition as nitrogen source) were conducted in this study. Within 6-day of operation at +0.4 V vs. Ag|AgCl and starting with 35 mM of lactate, consistently the electrical charge production under the aerobic condition was higher than that under the anaerobic condition. In all the experimental runs, the values of nicotinamide adenine dinucleotide (NADH) production were found to be correlated positively and significantly with the charge production, but the highest Coulombic efficiency of 18% was observed under the anaerobic conditions without ammonia addition while the lowest charge production occurred. Those results indicate that NADH production enhanced by oxygen is the leading cause of the increase of the charge production, but the biomass production and the oxygen reduction would both consume NADH electrons and lead to lower electron recoveries. In addition, whether under constant aerobic or anaerobic, or alternating aerobic/anaerobic conditions, chronoamperometric results made it possible to rule out other factors, like lactate uptake rate or cell growth, which might increase the charge production under aerobic conditions. By using high performance liquid chromatography, some diffusive flavins (e.g., 0.5 microM of riboflavin) were found under the aerobic condition, but were not found under the anaerobic one. However, from results of cyclic voltammetry (CV), the signals of flavins were found to be approximately the same under both conditions. Although it is inferred that oxygen renders the flavins secreted extracellularly, that is not the major effect of oxygen for boosting the charge production. Furthermore, bound flavins under anaerobic condition were found to be effectively electrocatalytic according to sigmoidal CV result.

Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (alpha-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of alpha-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe(2+)+alpha-FeOOH and the system of DIRB+alpha-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of alpha-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments.

Cloning, expression in Escherichia coli, and enzymatic properties of laccase from Aeromonas hydrophila WL-11

A strain WL-11 with high laccase activity was isolated from activated sludge collected from the effluent treatment plant of a textile and dyeing industry. It was identified as Aeromonas hydrophila by physiological test and 16S rDNA sequence analysis. A gene encoding of laccase from a newly isolated Aeromonas hydrophila WL-11 was cloned and characterized. Nucleotide sequence analysis showed an open reading frame of 1605 bp encoding a polypeptide comprised of 534 amino acids. The primary structure of the enzyme predicted the structural features characteristic of other laccases, including the conserved regions of four histidine-rich copper-binding sites. The predicted amino acid sequence showed a high homology (more than 60%) with bacterial laccases in the genome and protein databases and the highest degree of similarity (61% identity) was observed with the multicopper oxidase of Klebsiella sp. 601. When expressed in Escherichia coli, the recombinant enzyme was overproduced in the cytoplasm as soluble and active form. The purified enzyme had an optimum pH of 2.6 and 8.0 for ABTS (2,2'-azino-bis(3-ethylbenzthiazolinesulfonic acid) and DMP (2,6-dimethoxyphenol), respectively. The kinetic study on ABTS revealed a higher affinity of this enzyme to this substrate than DMP.

Shewanella xiamenensis sp. nov., isolated from coastal sea sediment

A Gram-negative, motile, rod-shaped bacterium, strain S4(T), was isolated from coastal sediment collected off Xiamen, China. The physiological and biochemical features of strain S4(T), determined using the API 20NE, API ZYM and Biolog GN2 systems, were similar to those of members of the genus Shewanella. Phylogenetic analyses based on 16S rRNA and gyrB gene sequences placed strain S4(T) in the genus Shewanella, and it was most closely related to Shewanella oneidensis and related species. DNA-DNA hybridization demonstrated only 11.9-30.4 % relatedness between S4(T) and the type strains of related Shewanella species. On the basis of phylogenetic and phenotypic characteristics, strain S4(T) is classified in the genus Shewanella as a representative of a distinct novel species, for which the name Shewanella xiamenensis sp. nov. is proposed. The type strain is S4(T) (=CCTCC M 209017(T) =JCM 16212(T)).

Effects of oxytetracycline and sulfachloropyridazine residues on the reductive activity of Shewanella decolorationis S12

Effects of oxytetracycline (OTC) and sulfachloropyridazine (SCP), two of the widely used antibiotics in livestock production, on beneficial environmental microorganisms were studied. Shewanella decolorationis S12 was selected as the target bacteria for the role in reduction of Fe(III) and dye under anaerobic conditions. The results showed that the antibiotics significantly inhibited Fe(III) reduction and dye decoloration in the reduction system. The rates of Fe(II) formed (-r) were 3.6 and 0.2 mg/L/day for the OTC concentrations of 0-1 mg/L and 1-50 mg/L, respectively, with 1 mg/L as the turning point of the inhibition effect. The turning point of inhibition effect was much higher for SCP treatments, at 4 mg/L. The results also showed higher production values for adsorbed Fe(II) than soluble Fe(II) in OTC treatments, but the reverse occurred in the SCP treatments. The difference between the treatments could be due to higher sorption coefficients of OTC as compared to SCP. Transmission electron micrographs showed changes in cell structures of S. decolorationis S12 grown in medium with OTC. Detached cell walls and large vacuoles in internal cell contents were found in OTC-treated cells. The results of the present study indicated that the inhibition of antibiotic on the reduction activity of S. decolorationis S12 may be due to a decrease in live S. decolorationis S12 population and/or damages of their cell structure in this reduction system.

Shewanella marina sp. nov., isolated from seawater

A motile, rod-shaped, pale-brown-pigmented bacterium, designated strain C4T, was isolated from seawater collected from the South Sea (Republic of Korea). Cells were Gram-negative, facultatively anaerobic, and catalase- and oxidase-positive. The major fatty acids were summed feature 3 (C16:1omega7c and/or iso-C15:0 2-OH; 19.4%), C16:0 (16.3%), C17:1omega8c (9.5%) and iso-C15:0 (7.7%). The DNA G+C content was 40.8 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain C4T formed a lineage within the genus Shewanella (92.7-96.1% sequence similarity to representative strains of the genus Shewanella) and was part of a distinct branch with the clade comprising Shewanella haliotis DW01T and Shewanella algae ATCC 51192T. Phenotypic characteristics enabled strain C4T to be distinguished from S. haliotis and S. algae. On the basis of the data presented in this study, strain C4T represents a novel species, for which the name Shewanella marina sp. nov. is proposed. The type strain is C4T (=KCTC 22185T=JCM 15074T).

Isolation and characterization of Pseudomonas otitidis WL-13 and its capacity to decolorize triphenylmethane dyes

Pseudomonas otitidis WL-13, which has a high capacity to decolorize triphenylmethane dyes, was isolated from activated sludge obtained from a wastewater treatment plant of a dyeing industry. This strain exhibited a remarkable color-removal capability when tested against several triphenylmethane dyes under both shaking and static conditions at high concentrations of dyes. More than 95% of Malachite Green and Brilliant Green was removed within 12 h at 500 micromol/L dye concentration under shaking conditions. Crystal Violet lost about 13% of its color under the same conditions tested. The rate of decolorization increased when the M9 medium was supplemented with yeast extract. The optimum pH and temperature for color removal were 7-9 and 35-40 degrees C, respectively. The observed changes in the visible spectra and the inspection of bacterial growth indicated the color-removal by the adsorption of dye to the cells during incubation with strains.

Identification of an uptake hydrogenase for hydrogen-dependent dissimilatory azoreduction by Shewanella decolorationis S12

Shewanella decolorationis S12, a representative dissimilatory azo-reducing bacterium of Shewanella genus, can grow by coupling the oxidation of hydrogen to the reduction of azo compounds as the sole electron acceptor, indicating that an uptake hydrogenase is an important component for electron transfer for azoreduction. For searching to the uptake hydrogenase in the genome of S. decolorationis, two operons, hyd and hya, were cloned and sequenced, which encode periplasmically oriented Fe-only hydrogenase and a Ni-Fe hydrogenase, respectively, according to the homologous comparison with other bacterial hydrogenases. In order to assess the roles of these two enzymes in hydrogen-dependent azoreduction and growth, hyd- and hya-deficient mutants were generated by gene replacement. Hya was found to be required for hydrogen-dependent reduction of azo compound by resting cell suspensions and to be essential for growth with hydrogen as electron donor and azo compound as electron acceptor. Hyd, in contrast, was not. These findings suggest that Hya is an essential respiratory hydrogenase of dissimilatory azoreduction in S. decolorationis.

Brachybacterium zhongshanense sp. nov., a cellulose-decomposing bacterium from sediment along the Qijiang River, Zhongshan City, China

A cellulose-decomposing bacterium, strain JBT, was isolated from sediments along the Qijiang River, Zhongshan City, China. Results of morphological, biochemical and chemotaxonomic characterization and 16S rRNA gene sequence analysis revealed that strain JBT belonged to the genus Brachybacterium. Insertion sequence-PCR fingerprinting patterns, DNA base ratio analysis and DNA-DNA hybridization data showed that strain JBT differed from recognized species of the genus Brachybacterium. Based on polyphasic analysis, strain JBT represents a novel species of the genus Brachybacterium, for which the name Brachybacterium zhongshanense sp. nov. is proposed. The type strain is JBT (=LMG 23926T=CGMCC 1.6508T=DSM 18832T).

Ecology and biotechnology of the genus Shewanella

The shewanellae are aquatic microorganisms with worldwide distribution. Their hallmark features include unparalleled respiratory diversity and the capacity to thrive at low temperatures. As a genus the shewanellae are physiologically diverse, and this review provides an overview of the varied roles they serve in the environment and describes what is known about how they might survive in such extreme and harsh environments. In light of their fascinating physiology, these organisms have several biotechnological uses, from bioremediation of chlorinated compounds, radionuclides, and other environmental pollutants to energy-generating biocatalysis. The ecology and biotechnology of these organisms are intertwined, with genomics playing a key role in our understanding of their physiology.

Shewanella haliotis sp. nov., isolated from the gut microflora of abalone, Haliotis discus hannai

A motile, rod-shaped, pink–orange pigmented bacterium, designated strain DW01T, was isolated from the gut microflora of abalone collected from the South Sea (Republic of Korea). Cells were Gram-negative, facultatively anaerobic, catalase- and oxidase-positive. The major fatty acids were iso-C15 : 0 (17.7 %), C16 : 0 (13.4 %), iso-C15 : 0 2-OH and/or C16 : 1 ω7c (12.5 %) and C17 : 1 ω8c (10.7 %). The DNA G+C content was 53.7 mol%. A phylogenetic tree based on the 16S rRNA gene sequences showed that strain DW01T forms a lineage of the genus Shewanella and is closely related to Shewanella algae ATCC 51192T (98.3 % sequence similarity) and to other members of the genus Shewanella (91.0–94.9 %). The phenotypic characteristics and DNA–DNA hybridization relatedness data indicate that strain DW01T should be distinguished from S. algae ATCC 51192T. On the basis of the data presented in this study, strain DW01T represents a novel species, for which the name Shewanella haliotis sp. nov. is proposed. The type strain is DW01T (=KCTC 12896T=JCM 14758T).

Biodegradation of textile azo dye by Shewanella decolorationis S12 under microaerophilic conditions

The complete biodegradation of azo dye, Fast Acid Red GR, was observed under microaerophilic conditions by Shewanella decolorationis S12. Although the highest decolorizing rate was measured under anaerobic condition and the highest biomass was obtained under aerobic condition, a further biodegradation of decolorizing products can only be achieved under microaerophilic conditions. Under microaerophilic conditions, S. decolorationis S12 could use a range of carbon sources for azo dye decolorization, including lactate, formate, glucose and sucrose, with lactate being the optimal carbon source. Sulfonated aromatic amines were not detected during the biotransformation of Fast Acid Red GR, while H(2)S formed. The decolorizing products, aniline, 1,4-diaminobenzene and 1-amino-2-naphthol, were followed by complete biodegradation through catechol and 4-aminobenzoic acid based on the analysis results of GC-MS and HPLC.

Characterization of a simple bacterial consortium for effective treatment of wastewaters with reactive dyes and Cr(VI)

A microbial consortia consisting of three bacteria isolated from tanning and textile wastewaters revealed high capacity to simultaneously bioaccumulate dye and Cr(VI). The identity of the bacteria were determined by 16S rRNA gene analysis to be closely related to Ochrobactrium sp., Salmonella enterica and Pseudomonas aeruginosa. Dependence of initial pH values and range of concentrations of the dye Reactive Black B (33.2-103.1 mg l(-1)) and Cr(VI) (19.9-127.6 mg l(-1)) were examined to find the effect of pH on the dye and Cr(VI) bioaccumulation. Optimal pH for growth of the consortia in media containing 35 mg l(-1) dye and 50 mg l(-1) Cr(VI) was determined to be around 8. The Cr(VI) bioaccumulation by the consortia was rapid in media containing molasses with or without reactive dye with a maximum Cr(VI) bioaccumulation yield ranging from 90% to 99% within a 2-4d period. A slightly lower yield for the dye bioaccumulation was measured with a maximum dye bioaccumulation of 80% at 59.3 mg l(-1) dye and 69.8 mg l(-1) Cr(VI). The highest specific Cr uptake value was obtained as 76.7 mg g(-1) at 117.1 mg l(-1) Cr(VI) and 50.8 mg l(-1) dye concentration. This ability to bioaccumulate dye and Cr(VI) was more efficient than the enriched sludge from which they were isolated.

Effects of electron donors and acceptors on anaerobic reduction of azo dyes by Shewanella decolorationis S12

Shewanella decolorationis S12 was able to reduce various azo dyes in a defined medium with formate, lactate, and pyruvate or H(2) as electron donors under anaerobic conditions. Purified membranous, periplasmic, and cytoplasmic fractions from strain S12 analyzed, respectively, only membranous fraction was capable of reducing azo dye in the presence of electron donor, indicating that the enzyme system for anaerobic azoreduction was located on cellular membrane. Respiratory inhibitor Cu(2+), dicumarol, stigmatellin, and metyrapone inhibited anaerobic azoreduction by purified membrane fraction, suggesting that the bacterial anaerobic azoreduction by strain S12 was a biochemical process that oxidizes the electron donors and transfers the electrons to the acceptors through a multicompound system related to electron transport chain. Dehydrogenases, cytochromes, and menaquinones were essential electron transport components for the azoreduction. The electron transport process for azoreduction was almost fully inhibited by O(2), 6 mM of NO3-, and 0.9 mM of NO2-, but not by 10 mM of Fe(3+). The inhibition may be a result from the competition for electrons from electron donors. These findings impact on the understanding of the mechanism of bacterial anaerobic azoreduction and have implication for improving treatment methods of wastewater contaminated by azo dyes.

Reduction and partial degradation mechanisms of naphthylaminesulfonic azo dye amaranth by Shewanella decolorationis S12

Reduction and biodegradation mechanisms of naphthylaminesulfonic azo dye amaranth using a newly isolated Shewanella decolorationis strain S12 were investigated. Under anaerobic conditions, amaranth was reduced by strain S12, and a stoichiometric amount of two reduction products RP-1 and RP-2 were generated. UV/visible spectrophotometric and high performance liquid chromatography (HPLC) analysis indicated that RP-1 and RP-2 were 1-aminenaphthylene -4-sulfonic acid and 1-aminenaphthylene-2-hydroxy-3, 6-disulfonic acid. The result strongly supports a mechanism of azo dye reduction by the process via the reductive cleavage of the azo bond to form corresponding aromatic amines. The result of HPLC analyses revealed that these aromatic amines were not able to be mineralized by strain S12 under anaerobic conditions. But after re-aeration of the decolorized culture, RP-2 was mineralized completely by this microorganism, but the consumption of RP-1 was not observed. Ames test showed that amaranth had mutagenic but no cytotoxic potential. The mutagenic potential was relieved after the anaerobic treatment with strain S12 as the mutagenic effect of the two reduction products from amaranth was not detected by Ames test. Thus, the ability of strain S12 to reduce and partially mineralize the naphthylaminesulfonic azo dye efficiently was demonstrated, which can potentially be used to biodegrade and detoxify wastewater containing azo dyes using an alternating anaerobic/aerobic treatment procedure.

Fe(III)-enhanced Azo Reduction by Shewanella decolorationis S12

Shewanella decolorationis S12 is capable of high rates of azo dye decolorization and dissimilatory Fe(III) reduction. Under anaerobic conditions, when Fe(III) and azo dye were copresent in S12 cultures, dissimilatory Fe(III) reduction and azo dye biodecolorization occurred simultaneously. Furthermore, the dye decolorization was enhanced by the presence of Fe(III). When 1 mM Fe(III) was added, the methyl red decolorizing efficiency was 72.1% after cultivation for 3 h, whereas the decolorizing efficiency was only 60.5% in Fe(III)-free medium. The decolorizing efficiencies increased as the concentration of Fe(III) was increased from 0 to 6 mM. Enzyme activities, which mediate the dye decolorization and Fe(III) reduction, were not affected by preadaption of cells to Fe(III) and azo dye nor by the addition of chloramphenicol. Both the Fe(III) reductase and the azo reductase were membrane associated. The respiratory electron transport chain inhibitors metyrapone, dicumarol, and stigmatellin showed significantly different effects on Fe(III) reduction than on azo dye decolorization.

Respiration and growth of Shewanella decolorationis S12 with an Azo compound as the sole electron acceptor

The ability of Shewanella decolorationis S12 to obtain energy for growth by coupling the oxidation of various electron donors to dissimilatory azoreduction was investigated. This microorganism can reduce a variety of azo dyes by use of formate, lactate, pyruvate, or H(2) as the electron donor. Furthermore, strain S12 grew to a maximal density of 3.0 x 10(7) cells per ml after compete reduction of 2.0 mM amaranth in a defined medium. This was accompanied by a stoichiometric consumption of 4.0 mM formate over time when amaranth and formate were supplied as the sole electron acceptor and donor, respectively, suggesting that microbial azoreduction is an electron transport process and that this electron transport can yield energy to support growth. Purified membranous, periplasmic, and cytoplasmic fractions from S12 were analyzed, but only the membranous fraction was capable of reducing azo dyes with formate, lactate, pyruvate, or H(2) as the electron donor. The presence of 5 microM Cu(2+) ions, 200 microM dicumarol, 100 microM stigmatellin, and 100 microM metyrapone inhibited anaerobic azoreduction activity by both whole cells and the purified membrane fraction, showing that dehydrogenases, cytochromes, and menaquinone are essential electron transfer components for azoreduction. These results provide evidence that the microbial anaerobic azoreduction is linked to the electron transport chain and suggest that the dissimilatory azoreduction is a form of microbial anaerobic respiration. These findings not only expand the number of potential electron acceptors known for microbial energy conservation but also elucidate the mechanisms of microbial anaerobic azoreduction.

Shewanella spongiae sp. nov., isolated from a marine sponge

A psychrophilic bacterium, designated strain HJ039T, was isolated from a marine sponge collected in the East Sea of Korea (also known as the Sea of Japan). Cells were Gram-negative, motile and rod-shaped (1.8–3.54 μm×0.27–0.73 μm). Growth was observed between 5 and 26 °C (optimum 15 °C), at pH 5.0–8.5 (optimum pH 6.0–6.5) and in the presence of 0–6.0 % NaCl (optimum 2.0 %). The 16S rRNA gene sequence of strain HJ039T showed high levels of similarity (93.7–95.4 %) with members of the genus Shewanella, especially with Shewanella gaetbuli TF-27T (95.2 %), Shewanella decolorationis S12T (94.9 %), Shewanella putrefaciens LMG 26268T (94.6 %), Shewanella hafniensis P010T (94.6 %), Shewanella algae ATCC 51192T (94.5 %) and Shewanella kaireitica c931T (94.5 %). However, phylogenetic analysis revealed that strain HJ039T shared a phyletic line with S. algae and Shewanella amazonensis. The major respiratory quinone was Q-8. The DNA G+C content was 52.8 mol%. The major fatty acids were i-13 : 0 (8.5 %), 15 : 0 (4.2 %), i-15 : 0 (23.2 %), i-15 : 1 (7.9 %), 16 : 0 (8.7 %), 16 : 1ω7 (21.0 %) and 17 : 1ω8 (6.4 %). From this polyphasic taxonomic evidence, strain HJ039T is considered to represent a novel species of the genus Shewanella, for which the name Shewanella spongiae sp. nov. is proposed. The type strain is HJ039T (=KCCM 42304T=JCM 13830T).

Shewanella irciniae sp. nov., a novel member of the family Shewanellaceae, isolated from the marine sponge Ircinia dendroides in the Bay of Villefranche, Mediterranean Sea

Strain UST040317-058T, comprising non-pigmented, rod-shaped, facultatively anaerobic, Gram-negative cells that are motile by means of single polar flagella, was isolated from the surface of a marine sponge (Ircinia dendroides) collected from the Mediterranean Sea. Comparative 16S rRNA gene sequence-based phylogenetic analysis placed the strain in a separate cluster with the recognized bacterium Shewanella algae IAM 14159T, with which it showed a sequence similarity of 95.0 %. The sequence similarity between strain UST040317-058T and its other (six) closest relatives ranged from 91.6 to 93.8 %. Strain UST040317-058T showed oxidase, catalase and gelatinase activities. The typical respiratory quinones for shewanellas, menaquinone MK-7 and ubiquinones Q-7 and Q-8, were also detected. The predominant fatty acids in strain UST040317-058T were i15 : 0, 16 : 0, 17 : 1ω8c and summed feature 3 (comprising i15 : 0 2-OH and/or 16 : 1ω7c), altogether representing 56.9 % of the total. The DNA G+C content was 39.9 mol%. The strain could be differentiated from other Shewanella species by its inability to reduce nitrate or produce H2S and by 10–22 additional phenotypic characteristics. On the basis of the phylogenetic and phenotypic data presented in this study, strain UST040317-058T represents a novel species in the genus Shewanella, for which the name Shewanella irciniae sp. nov. is proposed. The type strain is UST040317-058T (=JCM 13528T=NRRL B-41466T).

Shewanella loihica sp. nov., isolated from iron-rich microbial mats in the Pacific Ocean

A novel marine bacterial strain, PV-4(T), isolated from a microbial mat located at a hydrothermal vent of Loihi Seamount in the Pacific Ocean, has been characterized. This micro-organism is orangey in colour, Gram-negative, polarly flagellated, facultatively anaerobic and psychrotolerant (temperature range, 0-42 degrees C). No growth was observed with nitrate, nitrite, DMSO or thiosulfate as the electron acceptor and lactate as the electron donor. The major fatty acid detected in strain PV-4(T) was iso-C(15 : 0). Strain PV-4(T) had ubiquinones consisting mainly of Q-7 and Q-8, and possessed menaquinone MK-7. The DNA G+C content of the strain was 53.8 mol% and the genome size was about 4.5 Mbp. Phylogenetic analyses based on 16S rRNA gene sequences placed PV-4(T) within the genus Shewanella. PV-4(T) exhibited 16S rRNA gene sequence similarity levels of 99.6 and 97.5 %, respectively, with respect to the type strains of Shewanella aquimarina and Shewanella marisflavi. DNA from strain PV-4(T) showed low mean levels of relatedness to the DNAs of S. aquimarina (50.5 %) and S. marisflavi (8.5 %). On the basis of phylogenetic and phenotypic characteristics, the bacterium was classified in the genus Shewanella within a distinct novel species, for which the name Shewanella loihica sp. nov. is proposed. The type strain is PV-4(T) (=ATCC BAA-1088(T)=DSM 17748(T)).

Bowmanella denitrificans gen. nov., sp. nov., a denitrifying bacterium isolated from seawater from An-Ping Harbour, Taiwan

A heterotrophic, non-fermentative, denitrifying isolate, designated strain BD1T, was obtained from a seawater sample collected in the shallow coastal region of An-Ping Harbour, Tainan, Taiwan. The cells of strain BD1T were Gram-negative. Cells grown in broth cultures were curved rods that were motile by means of a single polar flagellum. Growth occurred between 10 and 40 °C, with an optimum at 30–35 °C. Strain BD1T grew in NaCl levels of 0–10 %, with better growth occurring at 1–3 %. It grew aerobically and could achieve anaerobic growth by adopting a denitrifying metabolism with nitrate or nitrous oxide as the terminal electron acceptor. The major fatty acids were C16 : 0, C18 : 1 ω7c and summed feature 3 (C16 : 1 ω7c and/or C15 : 0 iso 2-OH). The polar lipids consisted of phosphatidylethanolamine (56.6 %) and phosphatidylglycerol (43.4 %). The isoprenoid quinones were Q-8 (81.5 %), Q-9 (11.1 %) and Q-10 (7.4 %). The DNA G+C content was 50.0 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain BD1T formed a distinct lineage in the Gammaproteobacteria and that it exhibited the highest level of sequence similarity with species of the genera Alteromonas (92.8–93.7 %), Aestuariibacter (93.0 %), Glaciecola (90.4–92.7 %) and Salinimonas (91.8 %). Strain BD1T was distinguishable from species of these genera by the presence of Q-9 and Q-10. Phenotypically, strain BD1T was also distinguishable from species of these genera in that it did not require NaCl for growth and was capable of denitrification. On the basis of the polyphasic data from this study, the isolate represents a novel species within a novel genus, for which the name Bowmanella denitrificans gen. nov., sp. nov. is proposed. The type strain of Bowmanella denitrificans is BD1T (=BCRC 17491T=JCM 13378T).

Zobellella denitrificans gen. nov., sp. nov. and Zobellella taiwanensis sp. nov., denitrifying bacteria capable of fermentative metabolism

Two denitrifying strains of heterotrophic, facultatively anaerobic bacteria, designated ZD1T and ZT1T, were isolated from sediment samples collected from mangrove ecosystems in Taiwan. The isolates were Gram-negative. Cells grown in broth cultures were straight rods that were motile by means of a single polar flagellum. The isolates grew optimally in 1–3 % NaCl, but NaCl was not an absolute requirement for growth; only strain ZT1T grew in 13–14 % NaCl. Both isolates grew between 10 and 45 °C, with optimum growth at 30–35 °C. They were capable of anaerobic growth by denitrifying metabolism using nitrate or nitrous oxide as terminal electron acceptors or, alternatively, by fermenting glucose, sucrose or mannitol as substrates. C18 : 1 ω7c was the most abundant fatty acid (32.6–35.7 %). The other major fatty acids included C16 : 1 ω7c (27.5–29.4 %) and C16 : 0 (20.1–22.0 %). The two isolates had 16S rRNA gene sequence similarity of 96.8 % and shared 94.1–96.8 % sequence similarity with the most closely related species, Oceanimonas doudoroffii, Oceanimonas baumannii, Oceanimonas smirnovii and Oceanisphaera litoralis. They could be distinguished from these species in that they were capable of fermentative metabolism, had relatively high DNA G+C contents (62.0–64.0 mol%) and contained C18 : 1 ω7c instead of C16 : 1 ω7c as the most abundant fatty acid. Characterization data accumulated in this study revealed that the two denitrifying isolates could be classified as representatives of two novel species in a new genus, Zobellella gen. nov., with Zobellella denitrificans sp. nov. (type strain ZD1T=BCRC 17493T=JCM 13380T) as the type species and Zobellella taiwanensis sp. nov. (type strain ZT1T=BCRC 17494T=JCM 13381T) as a second species.

Decolorization of anthraquinone dye by Shewanella decolorationis S12

A new species of genus Shewanella, Shewanella decolorationis S12, from activated sludge of a textile-printing wastewater treatment plant, can decolorize Reactive Brilliant Blue K-GR, one kind of anthraquinone dye, with flocculation first. Although S. decolorationis displayed good growth in an aerobic condition, color removal was the best in an anaerobic condition. For color removal, the most suitable pH values and temperatures were pH 6.0-8.0 and 30-37 degrees C under anaerobic culture. More than 99% of Reactive Brilliant Blue K-GR was removed in color within 15 h at a dye concentration of 50 mg/l. Lactate was the suitable carbon source for the dye decolorization. A metal compound, HgCl(2), had the inhibitory effect on decolorization of Reactive Brilliant Blue K-GR, but a nearly complete decolorization also could be observed at a HgCl(2) concentration of 10 mg/l. The enzyme activities, which mediate the tested dye decolorization, were not significantly affected by preadaptation of the bacterium to the dye.

Decolorization of triphenylmethane, azo, and anthraquinone dyes by a newly isolated Aeromonas hydrophila strain

A broad-spectrum dye-decolorizing bacterium, strain DN322, was isolated from activated sludge of a textile printing wastewater treatment plant. The strain was characterized and identified as a member of Aeromonas hydrophila based on Gram staining, morphology characters, biochemical tests, and nearly complete sequence analysis of 16S rRNA gene and the gyrase subunit beta gene (gyrB). Strain DN322 decolorized a variety of synthetic dyes, including triphenylmethane, azo, and anthraquinone dyes. For color removal, the most suitable pH and temperature were pH 5.0-10.0 and 25-37 degrees C, respectively. Triphenylmethane dye, e.g., Crystal Violet, Basic Fuchsin, Brilliant Green, and Malachite Green (50 mg l(-1)) were decolorized more than 90% within 10 h under aerobic culture condition and Crystal Violet could be used as sole carbon source and energy source for cell growth. The color removal of triphenylmethane dyes was due to a soluble cytosolic enzyme, and the enzyme was an NADH/NADPH-dependent oxygenase; For azo and anthraquinone dyes, e.g., Acid Amaranth, Great Red GR, Reactive Red KE-3B, and Reactive Brilliant Blue K-GR (50 mg l(-1)) could be decolorized more than 85% within 36 h under anoxic condition. This strain may be useful for bioremediation applications.