Biodegradation of hexabromocyclododecane by Rhodopseudomonas palustris YSC3 strain: A free-living nitrogen-fixing bacterium isolated in Taiwan.

The persistent organic pollutant, brominated flame retardant, hexabromocyclododecane (HBCD), identified as an emerging contaminant has been detected in various environmental matrix. The increased level of this toxic organic compound in the environment has been associated with serious human health risks. The results obtained from this study revealed that various Rhodopseudomonas palustris strains isolated from paddy soil in Taiwan possessed good HBCD biodegradation capability when they were cultured aerobically. Among these strains, YSC3 was considered as one of the most potential isolates for HBCD degradation. The optimum HBCD biodegradation occurred at neutral pH and at 35 °C in all our pH and temperature tests at an initial HBCD concentration of 1 ppm. HBCD degradation kinetics generally decreased with the increase of initial HBCD concentration. The study also suggested that the cultivation temperature played a vital role on YSC3 for its initiation of cellular HBCD degradation. The relative-molar ratio of the released bromide ions during the biodegradation of HBCD was observed in the range between 1 and 3.5, suggesting that the debromination reactions occurred. Concomitant with the loss of HBCD, there was a concurrent production of two metabolites, pentabromocyclododecanol and pentabromocyclododecene, which were determined by liquid chromatography and mass spectrometry techniques. On the basis of the obtained results, the possible biodegradation pathways were also proposed in this study.

Spike-in genomic DNA for validating performance of metagenomics workflows.

Shotgun metagenomics is a powerful platform to characterize human microbiomes. However, to translate such survey data into consumer-relevant products or services, it is critical to have a robust metagenomics workflow. We present a tool - spike-in DNA - to assess performance of metagenomics workflows. The spike-in is DNA from two organisms - Alivibrio fischeri and Rhodopseudomonas palustris, in a ratio of 4:1 added to samples before DNA extraction. With a valid workflow, the output ratio of relative abundances of these organisms should be close to 4. This expectation was tested in samples of varying diversities (n = 110), and the mean ratio was 4.73 (99% CI [4.0, 5.24]). We anticipate this tool to be a relevant community resource for assessing the quality of shotgun metagenomics workflows and thereby enable robust characterization of microbiomes.

Rhodopseudomonas telluris sp. nov., a phototrophic alphaproteobacterium isolated from paddy soil.

A strain of anoxygenic phototrophic bacteria isolated from paddy soil (designated strain TUT3615T) was studied taxonomically in comparison with Rhodopseudomonasstrain ATCC 17005 as its nearest phylogenetic relative. Strains TUT3615T and ATCC 17005 had budding rod-shaped cells and showed in vivo absorption maxima at 804 and 860 nm in the near infrared region, indicating the presence of bacteriochlorophyll a. The intracytoplasmic membrane system was of the lamellar type parallel to the cytoplasmic membrane. 16S rRNA gene sequence comparisons showed that strains TUT3615T and ATCC 17005 had a 99.7 % level of similarity to one another and were closest to Rhodopseudomonas palustris ATCC 17001T (98.6 % similarity) among the established species of the genus Rhodopseudomonas. Genomic DNA-DNA hybridization studies revealed that strains TUT3615T and ATCC 17005 had an average similarity level of 65 % to one another and of less than 40 % to the available type strains of Rhodopseudomonas species. Results of phenotypic studies showed that strains TUT3615T and ATCC 17005 could be differentiated from one another and from any previously described species of Rhodopseudomonas. The G+C contents of the genomic DNA of strain TUT3615T and ATCC 17005 were 66.3 and 66.5 mol%, respectively. Based on these data, we propose the name Rhodopseudomonas telluris sp. nov. for strain TUT3615T. The type strain is TUT3615T (=KCTC 23279T=NBRC 107609T). We suspend a proposal to reclassify strain ATCC 17005 as a novel species or subspecies until a genome-wide analysis provides more definite information on its taxonomic position.

Comparison of electrochemical performances and microbial community structures of two photosynthetic microbial fuel cells.

Microbial fuel cells (MFCs) have attracted intensive interest for their power generation and pollutants removal characteristics. Electrochemical performances and community structures of two algae cathode photosynthetic MFCs were investigated and compared. Microbial consortia of these two MFCs were taken from wetland sediment (named SMFC) and an up-flow anaerobic wastewater treatment reactor (named UMFC). Maximum power density of the SMFC and UMFC achieved 202.9 ± 18.1 mW/m2 and 158.2±15.1 mW/m2, respectively. The SMFC displayed higher columbic efficiency but lower chemical oxygen demand (COD) removal efficiency than that of UMFC. The results also revealed the addition of riboflavin (RF) and neutral red (NR) decreased the redox current of the SMFC but promoted that of UMFC. Community structure analysis showed the SMFC was dominated by photosynthetic genus Rhodopseudomonas (61.25%), while bacterial genera in the UMFC were more evenly distributed. The difference of electrochemical activities of the two MFCs was caused by the different roles of exoelectrogens such as Rhodopseudomonas spp. and Citrobacter spp. in the electron transfer process. Newly developed photosynthetic microbial fuel cells (PMFCs) provide a suitable process to generate power and remove pollutants. The consortia have a significant role in the performance and microbial community of the system.

Characterizations of purple non-sulfur bacteria isolated from paddy fields, and identification of strains with potential for plant growth-promotion, greenhouse gas mitigation and heavy metal bioremediation.

This study was aimed at selecting purple non-sulfur bacteria (PNSB) isolated from various paddy fields, including Cd- and Zn-contaminated paddy fields, based on their biofertilizer properties. Among 235 PNSB isolates, strain TN110 was most effective in plant growth-promoting substance (PGPS) production, releasing 3.2 mg/L of [Formula: see text] , 4.11 mg/L of 5-aminolevulinic acid (ALA) and 3.62 mg/L of indole-3-acetic acid (IAA), and reducing methane emission up to 80%. This strain had nifH, vnfG and anfG, which are the Mo, V and Fe nitrogenase genes encoded for key enzymes in nitrogen fixation under different conditions. This strain provided 84% and 55% removal of Cd and Zn, respectively. Another isolate, TN414, not only produced PGPS (1.30 mg/L of [Formula: see text] , 0.94 mg/L of ALA and 0.65 mg/L of IAA), but was also efficient in removing both Cd and Zn at 72% and 74%, respectively. Based on 16S rDNA sequencing, strain TN110 was identified as Rhodopseudomonas palustris, while strain TN414 was Rubrivivax gelatinosus. A combination of TN110 and TN414 could potentially provide a biofertilizer, which is a greener alternative to commercial/chemical fertilizers and an agent for bioremediation of heavy metals and greenhouse gas mitigation in paddy fields.

Arsenic resistance genes of As-resistant purple nonsulfur bacteria isolated from As-contaminated sites for bioremediation application.

This study aimed to identify arsenic resistant mechanisms in As-resistant purple nonsulfur bacteria (PNSB) by screening them for presence of As-resistance genes and related enzymes. Resistance to As(III) and As(V) of four As-resistant PNSB determined in terms of median inhibition concentration (IC50 values) were in the order of strains Rhodopseudomonas palustris C1 > R. palustris AB3 > Rubrivivax benzoatilyticus C31 > R. palustris L28 which corresponded to the presence of As-resistance genes in these bacteria. The strain C1 showed all As-marker genes; arsC, arsM, aioA, and acr3, while aioA was not detected in strain AB3. Strains C31 and L28 had only Arsenite-transporter gene, acr3. Translation of all these detected gene sequences of strain C1 to amino acid sequences showed that these proteins have vicinal cysteine; Cys126, Cys105, and Cys178 of Acr3, ArsC, AioA, respectively. Tertiary structure of proteins Acr3, ArsC, AioA, and ArsM showed strain C1 exhibits the high activities of arsenite oxidase and arsenate reductase enzymes that are encoded by aioA and arsC genes, respectively. Moreover, strain C1 with arsM gene produced volatile-methylated As-compounds; monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AsB) in the presence of either As(III) or As(V). In conclusion, the strain C1 has great potential for its application in bioremediation of As-contaminated sites.

Isolation and Characterization of a Purple Non-Sulfur Photosynthetic Bacterium Rhodopseudomonas faecalis Strain A from Swine Sewage Wastewater.

A purple non-sulfur photosynthetic bacterium (PNSB), PSB Strain A was isolated from swine sewage wastewater. Phylogenetic analysis revealed that PSB Strain A was most closely related to Rhodopseudomonas faecalis. Growth of the isolate under anaerobic-light conditions with a variety of carbon sources was investigated. Both PSB Strain A and the standard strain showed good growth with acetic acid, propionic acid, and n-butyric acid at a concentration of 20 mM. At the high concentration of 200 mM, PSB Strain A showed better growth in pyruvate, acetate, propionate, succinate and malate. By applying PSB Strain A to treat swine sewage wastewater, the concentration of VFAs, which were acetic acid and propionic acid, decreased from 158.0 mM to 120.2±2.9 mM, and 14.9 mM to 9.3±0.9 mM, respectively, after 216-h incubation. After 330-h incubation, the concentrations of TOC and ammonia nitrogen dropped from 4508.0 mg/L to 3104.0±451.5 mg/L, and 629.7 mg/L to 424.1±7.4 mg/L, respectively. The isolated PSB Strain A showed almost the same efficiency compared with the standard strain on the removal of VFAs and TOC. The results suggest the possibility of using the isolated strain to treat swine sewage wastewater.

[Isolation, Identification and Characteristics of a Rhodopseudomonas with High Ammonia-nitrogen Removal Efficiency].

A strain of photosynthetic bacterium named psb1 capable of ammonia-nitrogen degradation was isolated from a swamp in Yunnan. The psb1 was similar to Rhodopseudomonas sp. according to its cell morphological properties and absorption spectrum analysis of living cells. The alignment result of 16S rDNA amplification sequence with specific primers of photosynthetic bacteria showed that the homology between strain psb1 and Rhodopseudomonas sp. was 99%, and the alignment results of protein sequences of bacterial chlorophyll Y subunit showed that the strain psb1 and Rhodopseudomonas palustris were the most similar, with a similarity of 99%. But there was a great difference in the biological properties of the strains psb1 and Rhodopseudomonas palustris according to physiological biochemical characteristics and main fatty acid analysis. For example, strain psb1 could not utilize glucose and mannitol as carbon source, and had specific fatty acid C18:1ω6c. The results of single factor test showed that:the optimal growth was obtained at pH 7.0 and 40℃, the optimal nitrogen source was yeast extract. The optimal conditions for ammonia nitrogen biodegradation were as following:anaerobic, light, initial pH 6.0-7.0, temperature 30℃, inoculation volume 0.4%. Under that cultural condition, the degradation rate of ammonia nitrogen in wastewater could reach 99%. The results indicated that strain psb1 might be a novel bacterium in genus Rhodopseudomonas with high ammonia removal efficiency, and can be applied in the bioremediation of polluted landscape water.

Genomics and Ecophysiology of Heterotrophic Nitrogen-Fixing Bacteria Isolated from Estuarine Surface Water.

UNLABELLED: The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing heterotrophic organisms are widespread in marine bacterioplankton, but their autecology and ecological significance are unknown. Here, we report genomic and ecophysiology data in relation to N2 fixation by three environmentally relevant heterotrophic bacteria isolated from Baltic Sea surface water: Pseudomonas stutzeri strain BAL361 and Raoultella ornithinolytica strain BAL286, which are gammaproteobacteria, and Rhodopseudomonas palustris strain BAL398, an alphaproteobacterium. Genome sequencing revealed that all were metabolically versatile and that the gene clusters encoding the N2 fixation complex varied in length and complexity between isolates. All three isolates could sustain growth by N2 fixation in the absence of reactive N, and this fixation was stimulated by low concentrations of oxygen in all three organisms (≈ 4 to 40 µmol O2 liter(-1)). P. stutzeri BAL361 did, however, fix N at up to 165 µmol O2 liter(-1), presumably accommodated through aggregate formation. Glucose stimulated N2 fixation in general, and reactive N repressed N2 fixation, except that ammonium (NH4 (+)) stimulated N2 fixation in R. palustris BAL398, indicating the use of nitrogenase as an electron sink. The lack of correlations between nitrogenase reductase gene expression and ethylene (C2H4) production indicated tight posttranscriptional-level control. The N2 fixation rates obtained suggested that, given the right conditions, these heterotrophic diazotrophs could contribute significantly to in situ rates. IMPORTANCE: The biological process of importing atmospheric N2 is of paramount importance in terrestrial and aquatic ecosystems. In the oceans, a diverse array of prokaryotes seemingly carry the genetic capacity to perform this process, but lack of knowledge about their autecology and the factors that constrain their N2 fixation hamper an understanding of their ecological importance in marine waters. The present study documents a high variability of genomic and ecophysiological properties related to N2 fixation in three heterotrophic isolates obtained from estuarine surface waters and shows that these organisms fix N2 under a surprisingly broad range of conditions and at significant rates. The observed intricate regulation of N2 fixation for the isolates indicates that indigenous populations of heterotrophic diazotrophs have discrete strategies to cope with environmental controls of N2 fixation. Hence, community-level generalizations about the regulation of N2 fixation in marine heterotrophic bacterioplankton may be problematic.

Skatole remediation potential of Rhodopseudomonas palustris WKU-KDNS3 isolated from an animal waste lagoon.

UNLABELLED: Skatole (3MI) is a major contributor to the malodor emission resulting from ruminant and human faeces. The remediation of malodor has been a major challenge for the animal production industry. In this investigation, a pure culture of purple nonsulphur bacterium capable of degrading 3MI was isolated from a swine waste lagoon using an enrichment technique and identified as Rhodopseudomonas palustris WKU-KDNS3 based on 16S rRNA analysis and UV-visible spectroscopy. The cell structure of the organism was confirmed by transmission electron microscopy. Growth profile and 3MI removal pattern were determined using media supplemented with 0.1 µmol 3MI under short-term and long-term aerobic growth conditions. The organism grew on 3MI media as luxuriantly as control (without 3MI). Growth of R. palustris WKU-KDNS3 demonstrated a significant reduction in the level of 3MI (>48%) in 72 h. The level of 3MI dropped further by >93% of the total concentration present in the medium in 21 days. Skatole remediation potential of R. palustris WKU-KDNS3 can be judiciously utilized in various animal and industrial waste treatment systems. SIGNIFICANCE AND IMPACT OF THE STUDY: Odour pollution is a serious environmental problem, particularly in the agriculture industry, and technologies based on chemical remediation are less effective and cost prohibitive. In this study, the newly isolated Rhodopseudomonas palustris strain WKU-KDNS3 causes biodegradation of 3-methylindole (skatole), which is one of the most offensive odorants present in wastewater lagoons. Aerobic degradation of this widely spread aromatic pollutant by Rhodopseudomonas strain is a significant finding that enhances the present understanding about metabolic versatility of purple photosynthetic nonsulphur bacteria. The remediation potential of R. palustris WKU-KDNS3 can also be gainfully utilized in various waste treatment facilities.

Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., isolated from paddy soils.

Two strains (JA575(T) and JA576(T)) of orange- to pink-pigmented, rod-shaped, motile and budding phototrophic bacteria were isolated from paddy soils. Both strains contained bacteriochlorophyll a and carotenoids of spirilloxanthin series. Both strains had C(18 : 1)ω7c as the major cellular fatty acid, ubiquinone-10 (Q(10)) as the main quinone, and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine as polar lipids. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that both strains clustered with species of the genus Rhodopseudomonas in the class Alphaproteobacteria. Strains JA575(T) and JA576(T) were genotypically (<35 % DNA-DNA relatedness) and phenotypically distinct from each other. Further, both strains showed less than 48 % DNA-DNA relatedness with the type strains of all recognized species of the genus Rhodopseudomonas. The molecular evidence is supported by phenotypic evidence. It is proposed that strains JA575(T) and JA576(T) be classified as representing two novel species of the genus Rhodopseudomonas with the species names Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., respectively. The type strains of the proposed novel species are JA575(T) (= NBRC 108862(T) = KCTC15143(T)) and JA576(T) (= NBRC 108863(T) = KCTC 15144(T)), respectively.

Factors influencing the production of hydrogen by the purple non-sulphur phototrophic bacterium Rhodopseudomonas acidophila KU001.

Rhodopseudomonas acidophila KU001 was isolated from leather industry effluents and the effect of different cultural conditions on hydrogen production was studied. Anaerobic light induced more hydrogen production than anaerobic dark conditions. Growing cells produced more amounts of hydrogen between 96 and 144 h of incubation. Resting and growing cells preferred a pH of 6.0 ± 0.24 for hydrogen production. Succinate was the most preferred carbon source for the production of hydrogen while citrate was a poor source of carbon. Acetate and malate were also good carbon sources for hydrogen production under anaerobic light. Among the nitrogen sources, R. acidophila preferred ammonium chloride followed by urea for production of hydrogen. L-tyrosine was the least preferred nitrogen source by both growing and resting cells.

[Photosynthetic bacteria of Rhodopseudomonas palustris isolated from river sediment].

OBJECTIVE: One strain of photosynthetic bacteria associated with highly removal capability of pollutant was isolated, and investigated about its growth. METHODS: By using an enrichment culture and plate dilution method, one strain of bacteria, named VOTO1-G, was isolated from river sediment mainly received domestic wastewater. The VOTO1-C bacteria was researched about its growth law, and identified by molecular biology method, and further used to test its ability in the removing of nitrogen, phosphorus and organic compound from eutrophic water by 0.05 per thousand, 0.1 per thousand and 0.2 per thousand. RESULTS: By checking the individual morphology, colony culture characteristics, DNA sequencing and 16S rDNA gene bank, VOTO1-G was identified as Rhodopseudomonas palustris. The isolated bacteria strain had some nitrogen, phosphorus and organic compound removal ability. CONCLUSION: One strain of photosynthetic bacteria was successfully isolated from sewage sediments. Its removal capacity of nitrogen, phosphorus and organic compound from eutrophic water was good, which removed COD 12%, TP 25%, TN 13%.

Descriptions of Rhodopseudomonas parapalustris sp. nov., Rhodopseudomonas harwoodiae sp. nov. and Rhodopseudomonas pseudopalustris sp. nov., and emended description of Rhodopseudomonas palustris.

Four strains (JA310(T), JA531(T), JA447 and JA490) of red to reddish brown pigmented, rod-shaped, motile and budding phototrophic bacteria were isolated from soil and freshwater sediment samples from different geographical regions of India. All strains contained bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The major cellular fatty acid of strains JA310(T) and JA531(T) was C(18:1)ω7c, the quinone was Q-10 and polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an aminohopanoid and an unidentified aminolipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that all strains clustered with species of the genus Rhodopseudomonas in the class Alphaproteobacteria. Strains JA531(T), JA447 and JA490 were genotypically (>80% related based on DNA-DNA hybridization) and phenotypically closely related to each other and the three strains were distinct from strain JA310(T) (33% related). Furthermore, all four strains had less than 48% relatedness (DNA-DNA hybridization) with type strains of members of the genus Rhodopseudomonas, i.e. Rhodopseudomonas palustris ATCC 17001(T), Rhodopseudomonas faecalis JCM 11668(T) and Rhodopseudomonas rhenobacensis DSM 12706(T). The genomic DNA G+C contents of strains JA310(T) and JA531(T) were 63.8 and 62.4 mol%, respectively. On the basis of phenotypic, chemotaxonomic and molecular genetic evidence, it is proposed that strains JA310(T) ( = NBRC 106083(T) = KCTC 5839(T)) and JA531(T) ( = NBRC 107575(T) = KCTC 5841(T)) be classified as the type strains of two novel species of the genus Rhodopseudomonas, Rhodopseudomonas parapalustris sp. nov. and Rhodopseudomonas harwoodiae sp. nov., respectively. In addition, we propose that strain DSM 123(T) ( = NBRC 100419(T)) represents a novel species, Rhodopseudomonas pseudopalustris sp. nov., since this strain differs genotypically and phenotypically from R. palustris ATCC 17001(T) and other members of the genus Rhodopseudomonas. An emended description of R. palustris is also provided.

[Biodegradation of o-chlorophenol by photosynthetic bacteria under co-metabolism].

Photosynthetic bacterial strain PSB-1D cannot utilize o-chlorophenol (2-CP) as the sole carbon source for energy. In this paper, different carbon sources (malic acid, sodium propionate, sodium acetate, sodium citrate, phenol, glucose, and soluble starch) were taken as the co-metabolism substrates to study their effects on PSB-1D growth and 2-CP degradation under the condition of aerobic culture in darkness. Among the substrates, glucose was most efficient, which promoted the reproduction of PSB-1D, enhanced the 2-CP degradation efficiency, and shortened the degradation period. The optimization experiment of added concentration of glucose showed that when the added glucose concentration was 3 g x L(-1), the PSB-1D cell concentration deltaD560 after 168 h culture was 1.749, the half-time of 2-CP was shortened to 3.9 d, and the degradation rate constant was increased to 0.00864 h(-1). The SDS-PAGE analysis on the total microbial cellular protein showed that taking glucose as the co-metabolism substrate, PSB-1D could induce a specific 2-CP-degrading enzyme.

Anaerobic utilization of phenanthrene by Rhodopseudomonas palustris.

A phenanthrene-utilizing bacterium was anaerobically isolated and identified as Rhodopseudomonas palustris. It tolerated up to 100 mg phenanthrene l(-1) and degraded 50% of 50 mg phenanthrene l(-1) over 10 days. The presence of phenanthrene caused a prolonged lag phase (2-3 days) in cell growth and affected the photopigments biosynthesis, while DMSO (the solvent for phenanthrene) had no impact on cell growth. The cell surface hydrophobicity of the isolate was also increased.

[Biological characteristics and phylogenetic analysis of a denitrifying photosynthetic bacterium].

OBJECTIVE: Nitrite accumulation in aquaculture water is toxic to reared animals. One of the solutions to this problem is to apply denitrifying bacteria. This paper is intended to get a strain of phototrophic bacteria for efficient removal of nitrite from aquaculture water. METHODS: We used soft agar to isolate and purify phototrophic bacteria. We investigated biological characteristics of the isolate by means of light and electronic observations, physical and chemical tests. We analyzed its phylogenetical position based on the sequences of 16S rDNA and the gene that codes for photosynthetic reaction center subunit M (pufM). RESULTS: A photosynthetic bacterial strain, named wps, showing high removal efficiency of nitrite, was isolated from the freshwater ponds. Cells were Gram-negative, rod-shaped, slightly curved, 0.4 - 0.6 x 1.5 - 4.0 microm, motile by means of polar multiple flagella. Intracellular membranes were of the lamellar type. It grew under facultative anaerobic conditions in the light with bacteriochlorophyll a and carotenoid of sppirilloxanthin series as photosynthetic pigment. The optimum growth was obtained at pH 5.5 - 8.5, in a range of 0 - 2% salinity and at 25 - 38 degrees C. The similarity of 16S rDNA between strain wps and Rhodopseudomonas palustris was 98.9% and 94.9% for pufM gene. However, there are significant differences between them in the morphological and physiological characteristics, i. e. grew at pH 5.5; no growth photoautotrophicaly with sodium hydrogen carbonate; could not utilize citrate or formate as only carbon source; required thiamine hydrochloride and calcium pantothenate as growth factors. CONCLUSION: Strain wps may represent a novel species in genus Rhodopseudomonas and possibly find its application in the bioremediation of polluted aquaculture water.

[Biodegradation characteristics of o-chlorophenol with photosynthetic bacteria PSB-1D].

A strain of photosynthetic bacteria named PSB-1D with degradation of o-chlorophenol (2-CP) was isolated and screened from the shallow substrate sludge in downstream side of the sewage outfall of an insecticide factory. The PSB-1D is identified preliminarily as Rhodopseudomonas sp. according to its colony and cell morphological properties, physiological biochemical characteristics and absorption spectrum analysis of living cells. The experiments results of relationship between PSB-1D growth and o-chlorophenol degradation showed that the degradation rate of o-chlorophenol was up to 57.26% after 7 days cultural time. The main environmental factors including way of illumination and oxygen, initial pH, cultural temperature, illumination intensity had distinctly influenced on the o-chlorophenol degradation with PSB-1D. The results showed that the optimum conditions were as following: an anaerobic light, pH 7.0, temperature 30 degrees C, illumination intensity 4000 lx,initial o-chlorophenol concentration 50 mg/L. Under that cultural condition, the degradation rate of o-chlorophenol could reach to 62.08%. The degradation kinetic data fitted the Andrews model well. In addition, the biodegradation process of o-chlorophenol can be well described by enzymatic reaction of high concentration inhibition, with the maximum substrate utilization rate 0.309 d(-1), Michaelis-Menten constant 2.733 mg/L, inhibitory constant 230.15 mg/L respectively.

Phototropic H2 production by a newly isolated strain of Rhodopseudomonas palustris.

Rhodopseudomonas palustris TN1 was isolated from Songkhla Lake, Thailand. It phototrophically generates H(2) from the predominant volatile fatty acids (VFAs) produced from microbial dark-fermentations of palm oil milling effluent; yields from 20 mM butyrate, acetate and propionate were 4.7, 2.5, and 1.7 mol H(2) mol VFA(-1) with light efficiencies of 1.8, 1, and 0.2%, respectively. Optimum conditions were pH 7 and 3000 lux, although production was reduced by only 33% at 1000 lux. CO(2) evolution never exceeded 9 mmol mol VFA(-1).

Anaerobic phototrophic nitrite oxidation by Thiocapsa sp. strain KS1 and Rhodopseudomonas sp. strain LQ17.

In anaerobic enrichment cultures for phototrophic nitrite-oxidizing bacteria from different freshwater sites, two different cell types, i.e. non-motile cocci and motile, rod-shaped bacteria, always outnumbered all other bacteria. Most-probable-number (MPN) dilution series with samples from two freshwater sites yielded only low numbers (