Rhodobacter amnigenus sp. nov. and Rhodobacter ruber sp. nov., isolated from freshwater habitats.

Two bacterial strains, designated HSP-20T and CCP-1T, isolated from freshwater habitats in Taiwan, were characterized by polyphasic taxonomy. Both strains were Gram-stain-negative, aerobic, non-motile and rod-shaped. Cells of strains HSP-20T and CCP-1T formed pink and dark red coloured colonies, respectively. Both strains contained bacteriochlorophyll a, and showed optimum growth under anaerobic conditions by photoheterotrophy, but no growth by photoautotrophy. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences indicated that both strains belonged to the genus Rhodobacter. Analysis of 16S rRNA gene sequences showed that strains HSP-20T and CCP-1T shared 98.3 % sequence similarity and were closely related to Rhodobacter tardus CYK-10T (96.0 %) and Rhodobacter flagellatus SYSU G03088T (96.0 %), respectively. Both strains shared common chemotaxonomic characteristics including Q-10 as the major isoprenoid quinone, C18 : 1 ω7c as the predominant fatty acid, and phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine as the main polar lipids. The DNA G+C content of both strains was 66.2 mol%. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between these two novel isolates and their closest relatives were below the cut-off values of 95-96, 90 and 70 %, respectively, used for species demarcation. On the basis of phenotypic and genotypic properties and phylogenetic inference, both strains should be classified as novel species within the genus Rhodobacter, for which the names Rhodobacter amnigenus sp. nov. (=BCRC 81193T=LMG 31334T) and Rhodobacter ruber sp. nov. (=BCRC 81189T=LMG 31335T) are proposed.

Dysbiosis of the endometrial microbiota and its association with inflammatory cytokines in endometrial cancer.

The underlying molecular mechanisms involved in the pathogenesis of endometrial cancer (EC) are still not well understood. Our goal was to investigate the composition of the endometrial microbiota and the association with inflammatory cytokines in EC. Endometrial microbiota profiles of women with EC (n = 25) and benign uterine lesions (BUL, n = 25) were assessed by 16S ribosomal RNA gene amplicon sequencing. The expression levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-17 (IL-17) mRNA and protein in the endometrial tissues of the two groups were determined by real-time quantitative polymerase chain reaction and Western blot, respectively. There were significant differences in alpha diversity based on the observed operational taxonomic units (P = .002), Pielou evenness (P = .001), and Shannon index (P < .001) between EC and BUL groups. Significant differences were also found in Bray-Curtis (P = .001) and unweighted UniFrac (P = .001) beta diversity measures between the two groups. At the genus level, Micrococcus was more abundant in the EC group. Pseudoramibacter_Eubacterium, Rhodobacter, Vogesella, Bilophila, Rheinheimera, and Megamonas were enriched in the BUL group. There were no differences in IL-8 and IL-17 protein levels between the two groups, except IL-6 protein levels. However, the mRNA expression levels of IL-6, IL-8, and IL-17 were significantly different. Moreover, the relative abundances of Micrococcus was positively correlated with IL-6, and IL-17 mRNA levels. In conclusion, our results suggested that dysbiosis of endometrial microbiota and the inflammatory cytokines were associated with Micrococcus in EC patients, which might be useful for exploration of the mechanism between the endometrial microbiota and inflammatory responses in future studies.

Tabrizicola oligotrophica sp. nov. and Rhodobacter tardus sp. nov., two new species of bacteria belonging to the family Rhodobacteraceae.

Two Gram-stain-negative, aerobic, non-motile bacteria, designated KMS-5T and CYK-10T, were isolated from freshwater environments. 16S rRNA gene sequence similarity results indicated that these two novel strains belong to the family Rhodobacteraceae. Strain KMS-5T is closely related to species within the genus Tabrizicola (96.1-96.8 % sequence similarity) and Cypionkella (96.5-97.0 %). Strain CYK-10T is closest to Rhodobacter thermarum YIM 73036T with 96.6 % sequence similarity. Phylogenetic analyses based on 16S rRNA gene sequences and an up-to-date bacterial core gene set showed that strain KMS-5T is affiliated with species in the genus Tabrizicola and strain CYK-10T is placed in a distinct clade with Rhodobacter blasticus ATCC 33485T, Rhodobacter thermarum YIM 73036T and Rhodobacter flagellatus SYSU G03088T. These two strains shared common chemotaxonomic features comprising Q-10 as the major quinone, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine as the principal polar lipids, and C18 : 1 ω7c as the main fatty acid. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between these two novel isolates and their closest relatives were below the cut-off values of 95-96, 90 and 70 %, respectively, used for species demarcation. The obtained polyphasic taxonomic data suggested that strain KMS-5T represents a novel species within the genus Tabrizicola, for which the name Tabrizicola oligotrophica sp. nov. is proposed with KMS-5T (=BCRC 81196T=LMG 31337T) as the type strain, and strain CYK-10T should represent a novel species of the genus Rhodobacter, for which the name Rhodobacter tardus sp. nov. is proposed with CYK-10T (=BCRC 81191T=LMG 31336T) as the type strain.

"Sporotan" a new fluorescent stain for identifying cryptic spores of Rhodobacter johrii.

We propose a new fluorescent stain "sporotan" and staining protocol which aid in the identification of cryptic endospores which are otherwise mistaken as poly-ß-hydroxyalkanoate granules.

Rhodobacter flagellatus sp. nov., a thermophilic bacterium isolated from a hot spring.

A thermophilic bacterium, designated SYSU G03088T, was isolated from Moincer hot spring, Tibet, PR China. Polyphasic taxonomic analyses and whole-genome sequencing were used to determine the taxonomic position and genomic profiles of the strain. Phylogenetic analysis using 16S rRNA gene sequence indicated that SYSU G03088T showed highest sequence similarity to Rhodobacter blasticus CGMCC 1.3365T (96.0 % sequence identity). The strain could be differentiated from most recognized species of the genus Rhodobacter by its slightly purple colony colour, distinct phenotypic characters and low ANI values. Cells were Gram-staining negative, and oval-to-rod shaped. Poly-ß-hydroxybutyrate and vesicular intracytoplasmic membrane structures were formed inside cells. Growth occurred optimally at 45 °C and pH 7.0. Ubiquinone 10 was the only respiratory quinone. The major fatty acids (>10 %) were C18 : 0, C18 : 1ω7c 11-methyl and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The detected polar lipids of SYSU G03088T included diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmethylethanolamine. The DNA G+C content of SYSU G03088T was 67.7 % (genome). On the basis of the differences in the phenotypic characteristics and phylogenetic analyses, SYSU G03088T is considered to represent a novel species of the genus Rhodobacter, for which the name Rhodobacter flagellatus sp. nov. is proposed. The type strain is SYSU G03088T (=CGMCC 1.16876T=KCTC 72354T).

Rhodobacter sediminicola sp. nov., isolated from a fresh water pond.

A phototrophic bacterium, designated as strain JA983T, was isolated from a freshwater pond in Gujarat, India. The strain was yellowish brown, catalase- and oxidase-positive, rod-to-oval shaped, Gram-stain-negative and motile. Growth was observed at 20-35 °C. NaCl was not required for optimum growth and up to 5 % was tolerated. Growth was observed at pH 6.0-8.0, with an optimum at pH 7.0. An unidentified glycolipid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminolipids (AL1, AL2) and two unidentified lipids (L1 and L2) are the polar lipids of JA983T. Q10 is the only quinone. C18 : 1 ω7c/C18 : 1 ω6c is the major fatty acid. JA983T showed highest 16S rRNA gene sequence similarity with the type strains of Rhodobacter sphaeroides (98.99%), Rhodobacter megalophilus (98.99 %), Rhodobacter johrii (98.99 %) and other members of the genus Rhodobacter with less than 98.7 % similarity. In a 16S rRNA gene sequence-based phylogenetic tree, JA983T formed a different sub-clade with its nearest phylogenetic members of genus Rhodobacter. Phenotypic, chemotaxonomic, phylogenetic and genomic [average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) differences indicated that JA983T is significantly different from other species of the genus Rhodobacter and thus represents a novel species of the genus for which the name Rhodobacter sediminicola sp. nov. is proposed. The type strain is JA983T (=KCTC 15782T=NBRC 113843T).

Effect of blue light on growth and exopolysaccharides production in phototrophic Rhodobacter sp. BT18 isolated from brackish water.

Rhodobacter sp. BT18, a phototrophic salt-resistant bacterium, was isolated from brackish water and screened for the production of exopolysaccharides (EPS). The effect of different light sources on the growth of Rhodobacter sp. BT18 was investigated. The effect on the growth order was found to be blue > white > green > red > yellow > dark. Based on Box-Behnken design, the studied variables (pH 7.0, 35 °C, and 30% of sucrose concentration under 60 h of incubation with blue light illumination) were found to be ideal for the maximum production of EPS (582.5 mg/L). Scanning electron microscopy images revealed the porous nature of EPS. Fourier transform spectroscopy and X-ray diffraction were applied to study the functional groups and the crystalline nature of the EPS, respectively. The emulsification index of the EPS was >75% and the maximum flocculating activity was about 75.4% at 30 mg/L concentration of EPS. In addition, EPS showed effective arsenic (64%) and lead (51%) chelating activities in liquid solutions. The multiple environmental applications of the EPS produced by Rhodobacter sp. BT18 make it be a promising alternative for emulsification, flocculation and metal removal in various industries.

Elucidation of the microbial diversity in rivers in south-west Victoria, Australia impacted by rural agricultural contamination (dairy farming).

We assessed the water quality of south-west Victorian rivers impacted by the dairy industry using traditional water quality assessment together with culture-dependent (colilert/enterolert) and also culture-independent (next generation sequencing) microbial methods. The aim of the study was to identify relationships/associations between dairy farming intensity and water contamination. Water samples with high total and faecal coliforms (>1000 MPN cfu/100 ml), and with high nitrogen levels (TN) were observed in zones with a high proportion of dairy farming. Members of the genus Nitrospira, Rhodobacter and Rhodoplanes were predominant in such high cattle density zones. Samples from sites in zones with lower dairy farming activities registered faecal coliform numbers within the permissible limits (<1000 MPN cfu/100 ml) and showed the presence of a wide variety of microorganisms. However, no bacterial pathogens were found in the river waters regardless of the proportion of cattle. The data suggests that using the spatially weighted proportion of land used for dairy farming is a useful way to target at-risk sub-catchments across south west Victoria; further work is required to confirm that this approach is applicable in other regions.

Rhodobacter thermarum sp. nov., a novel phototrophic bacterium isolated from sediment of a hot spring.

An ovoid to rod-shaped, phototrophic, purple non-sulfur bacterium was isolated from a sediment sample of a hot spring in Tibet, China. Cells of strain YIM 73036T were Gram-stain negative, non-motile and multiplied by binary fission. Strain YIM 73036T grew optimally at pH 7.0-7.5 at 37-45 °C. Growth occurred in 0.5-3.5% (w/v) NaCl. Vitamins were not required for growth. The presence of photosynthesis genes pufL and pufM were shown and photosynthesis pigments were formed. Bacteriochlorophyll α, the bacteriopheophytin and carotenoids were present as photosynthetic pigments. Internal cytoplasmic membranes were of the lamellar type. The organism YIM 73036T was able to grow chemo-organoheterophically, chemo-lithoautotrophically and photo-organoheterotrophically but photo-lithoautotrophic and fermentative growth were not demonstrated. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain YIM 73036T is closely related to Rhodobacter blasticus ATCC 33485T (96.65% sequence similarity) and clustered with species of the genus Rhodobacter of the family Rhodobacteraceae. Whole-genome sequence analyses based on the average nucleotide BLAST identity (ANI < 82%) indicated that this isolate belongs to a novel species. The genomic DNA G+C content of organism YIM 73036T was determined to be 66.0 mol%. Strain YIM 73036T contained Q-10 as the predominant ubiquinone and C18:1ω7c, C18:1ω7c 11-methyl and C18:0 as the major fatty acids. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and unidentified phospholipid. Differential phenotypic and chemotaxonomic properties, together with the phylogenetic distinctiveness, demonstrated that strain YIM 73036T is distinguishable from other species of the genus Rhodobacter. On the basis of the data presented, strain YIM 73036T is considered to represent a novel species of the genus Rhodobacter, for which the name Rhodobacter thermarum sp. nov. [type strain YIM 73036T (= KCTC 52712T = CCTCC AB 2016298T)] is proposed.

Rhodobacter alkalitolerans sp. nov., isolated from an alkaline brown pond.

An alkali-tolerant, Gram-stain-negative, motile, rod-to-oval-shaped, yellowish brown-colored, phototrophic bacterium, designated as strain JA916T, was isolated from an alkaline brown pond in Gujarat, India. The DNA G + C content of the strain JA916T was 65.1 mol%. Strain JA916T grew well at pH 10. Respiratory quinone was Q-10 and major fatty acid was C18:1ω7c/C18:1ω6c, with significant quantities of C15:02OH observed. Strain JA916T shared the highest 16S rRNA gene sequence similarity with the type strains of Rhodobacter johrii (98.4%), followed by Rhodobacter megalophilus (98.3%), Rhodobacter sphaeroides (98.3%), Rhodobacter azotoformans (97.9%) and other members of the genus Rhodobacter (< 97%). 16S rRNA gene-based phylogenetic tree shows that strain JA916T formed a distinct sub-clade with Rhodobacter johrii, Rhodobacter megalophilus, Rhodobacter sphaeroides and Rhodobacter azotoformans. Further, rpoB-based phylogenetic analysis showed lower similarity with closely related species (≤ 93.0%) of the genus Rhodobacter, which suggests that JA916T is a novel species of the genus Rhodobacter. DNA-DNA hybridization values between strain JA916T and related type strains were less than 40%. Phenotypic, chemotaxonomical and phylogenetic differences showed that strain JA916T was distinct from other species of the genus Rhodobacter, suggesting strain JA916T represents a new species of the genus for which the name Rhodobacter alkalitolerans sp. nov. is proposed. Type strain is JA916T (= KCTC 15473T = LMG 28749T).

Description of Rhodobacter azollae sp. nov. and Rhodobacter lacus sp. nov.

Three strains (JA826T, JA912T and JA913), which were yellowish brown colour, rod to oval shaped, Gram-stain-negative, motile, phototrophic bacteria with a vesicular architecture of intracytoplasmic membranes, were isolated from different pond samples. The DNA G+C content of the three strains was between 64.6 and 65.5 mol%. The highest 16S rRNA gene sequence similarity of all three strains was with the type strains of the genus Rhodobacter sensu stricto in the family Rhodobacteraceae. Strain JA826T had highest sequence similarity with Rhodobacter maris JA276T (98.5 %), Rhodobacter viridis JA737T (97.5 %) and other members of the genus Rhodobacter (<97 %). Strain JA912T had highest sequence similarity with Rhodobacter viridis JA737T (99.6 %), Rhodobacter sediminis N1T (99.3 %), Rhodobacter capsulatus ATCC 11166T (98.8 %) and less than 97 % similarity with other members of the genus Rhodobacter. The 16S rRNA gene sequence similarity between strains JA826T and JA912T was 96.9 %. DNA-DNA hybridization showed that strains JA826T and JA912T (values among themselves and between the type strains of nearest members <44 %) did not belong to any of the nearest species of the genus Rhodobacter. However, strains JA912T and JA913 were closely related (DNA-DNA hybridization value >90 %). The genomic distinction was also supported by differences in phenotypic and chemotaxonomic characteristics in order to propose strains JA826T (=KCTC 15478T=LMG 28758T) and JA912T (=KCTC 15475T=LMG 28748T) as new species in the genus Rhodobacter sensu stricto with the names Rhodobacter lacus and Rhodobacter azollae, respectively.

Highly complex substrates lead to dynamic bacterial community for polyhydroxyalkanoates production.

Mixed microbial cultures (MMC) and waste/surplus substrates, as hardwood spent sulfite liquor, are being used to decrease polyhydroxyalkanoates' (PHA) production costs. The process involves two or three steps, being the selection step a crucial one. For the industrial implementation of this strategy, reactor stability in terms of both performance and microbial community presence has to be considered. A long-term operation of a sequencing batch reactor under feast/famine conditions was performed along with microbial community identification/quantification using FISH and DGGE. The community was found to be extremely dynamic, dominated by Alphaproteobacteria, with Paracoccus and Rhodobacter present, both PHA-storing microorganisms. 16S rRNA gene clone library further revealed that side populations' non-PHA accumulators were able to strive (Agrobacterium, Flavobacteria, and Brachymonas). Nevertheless, reactor performance in terms of PHA storage was stable during operation time. The monitoring of the MMC population evolution provided information on the relation between community structure and process operation.

Rhodobacter sediminis sp. nov., isolated from lagoon sediments.

Two Gram-stain-negative, rod-shaped phototrophic bacteria (designated strains N1T and C7) were isolated from lagoon sediments. Both strains were positive for catalase and oxidase activity. Casein, starch, urea and Tween 20 were hydrolysed by both strains while chitin, gelatin and Tween 80 were not. In both strains, C16 : 0, C18 : 0,C16 : 1ω6c/C16 : 1ω7c and C18 : 1ω6c/ C18 : 1ω7c were the predominant fatty acids, with minor amounts of C8 : 0 3-OH, anteiso-C14 : 0, C17 : 0, C14 : 1ω5c, C17 : 1 10-methyl and C18 : 1ω5c. Strains N1T and C7 contained phosphatidylglycerol and phosphatidylethanolamine as major polar lipids with minor amounts of phosphatidylcholine, unidentified lipids and an unidentified phospholipid. The mean genomic DNA G+C content was 70.6±1 mol% and the two strains were closely related (mean DNA-DNA hybridization >90 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that the two strains clustered with species of the genus Rhodobacter belonging to the family Rhodobacteraceae of the class Alphaproteobacteria. Strain N1T has a 16S rRNA gene sequence similarity of 99.2 % with Rhodobacter capsulatus ATCC 11166T, 99.1 % with Rhodobacter viridis JA737T and <96.6 % with other members of the genus Rhodobacter. Strain N1T and C7 shared 100 % 16S rRNA gene sequence similarity. DNA- DNA hybridization values between strain N1T and the type strains of the nearest species were clearly below the 70 % threshold. On the basis of phenotypic and genotypic data, it is proposed that strain N1T represents a novel species of the genus Rhodobacter, for which the name Rhodobacter sediminis sp. nov. is proposed. The type strain is N1T (=KEMB 563-471T=JCM 31175T), and strain C7 is an additional strain of the species.

Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization.

Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria.

Photo-fermentational hydrogen production of Rhodobacter sp. KKU-PS1 isolated from an UASB reactor

Background In this study, the detection of nifH and nifD by a polymerase chain reaction assay was used to screen the potential photosynthetic bacteria capable of producing hydrogen from five different environmental sources. Efficiency of photo-hydrogen production is highly dependent on the culture conditions. Initial pH, temperature and illumination intensity were optimized for maximal hydrogen production using response surface methodology with central composite design. Results Rhodobacter sp. KKU-PS1 (GenBank Accession No. KC478552) was isolated from the methane fermentation broth of an UASB reactor. Malic acid was the favored carbon source while Na-glutamate was the best nitrogen source. The optimum conditions for simultaneously maximizing the cumulative hydrogen production (Hmax) and hydrogen production rate (Rm) from malic acid were an initial of pH 7.0, a temperature of 25.6°C, and an illumination intensity of 2500 lx. Hmax and Rm levels of 1264 ml H2/l and 6.8 ml H2/L-h were obtained, respectively. The optimum initial pH and temperature were further used to optimize the illumination intensity for hydrogen production. An illumination intensity of 7500 lx gave the highest values of Hmax (1339 ml H2/l) and Rm (12.0 ml H2/L-h) with a hydrogen yield and substrate conversion efficiency of 3.88 mol H2/mol malate and 64.7%, respectively. Conclusions KKU-PS1 can produce hydrogen from at least 8 types of organic acids. By optimizing pH and temperature, a maximal hydrogen production by this strain was obtained. Additionally, by optimizing the light intensity, Rm was increased by approximately two fold and the lag phase of hydrogen production was shortened.

[Characterization of a new strain of a purple nonsulfur bacterium from a thermal spring].

A new budding nonsulfur purple bacterium of the genus Rhodobacter (strain Ku-2) was isolated from a mat of a moderately thermal spring (Baikal rift zone, Buryat Republic, Russia). The bacterium had lamellar photosynthetic membranes, which are typica of only one Rhodobacter species, Rba. blasticus. The cells contined spheroidene carotenoids and bacteriochlorophyll a (Bchl a). In vivo absorption spectrum of the cells had the major maximum at 863 nm and an additional peak at 887 nm, which is characteristic of the pigment-protein complexes of Bchl a-containing membranes. The previously described Rba. blasticus strains did not exhibit a 887-nm maximum. The new isolate was photoheterotrophic, with optimal growth occurring at 35 degrees C, 3 g/L NaCl, and pH 7-8. The DNA G+C content was 64.4 mol %. The similarity between the 16S rRNA gene sequences of strain Ku-2 and the Rba. blasticus type strain was 98.7%. The similarity between the PufM amino acid sequences of strain Ku-2 and the previously studied Rba. blasticus strain was 89.0%. Thus, the bacterial strain Ku-2 belonged to the genus Rhodobacter and was phylogenetically related to Rba. blasticus.

Rhodobacter viridis sp. nov., a phototrophic bacterium isolated from mud of a stream.

A green phototrophic bacterium (strain JA737(T)), which was oval- to rod-shaped, Gram-negative and motile, was isolated from mud of a stream in the Western Ghats of India. Strain JA737(T) contained bacteriochlorophyll a, and the major carotenoid was neurosporene. The major quinone was Q-10 and the polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified aminolipid, two unidentified phospholipids and five unidentified lipids. Phylogenetic analysis showed that the strain clustered with members of the genus Rhodobacter belonging to the family Rhodobacteraceae of the class Alphaproteobacteria. Based on 16S rRNA gene sequence analysis, strain JA737(T) had highest sequence similarity with Rhodobacter capsulatus ATCC 11166(T) (98.8 %), Rhodobacter maris JA276(T) (97 %), Rhodobacter aestuarii JA296(T) (96.7 %) and other members of the genus Rhodobacter (<96 %). However, strain JA737(T) showed 22-55 % DNA-DNA relatedness with the above type strains. On the basis of phenotypic, chemotaxonomic and molecular genetic evidence, strain JA737(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter viridis sp. nov. is proposed. The type strain is JA737(T) ( = KCTC 15167(T) = MTCC 11105(T) = NBRC 108864(T)).

Transient response of microbial communities in a water well field to application of an impressed current.

Deterioration of water wells due to clogging and corrosion over time is a common problem where solutions may be costly and ineffective. Pilot studies have suggested that impressed current or cathodic protection may be used to reduce microbially-induced declines in water well performance. Two water wells in an alluvial aquifer close to the North Saskatchewan River were selected to study the response of subsurface microbial communities to the application of an impressed current as an anti-fouling technology. The treated well was exposed to an impressed current while the untreated well was used as a reference site. Biofilms grown on in situ coupons under the influence of the impressed current were significantly (p < 0.05) thicker (mean thickness = 67.3 µm) when compared to the biofilms (mean thickness = 19.3 µm) grown outside the electric field. Quantitative PCR analyses showed significantly (p < 0.05) higher numbers of total bacteria, iron- and nitrate-reducers in the electrified zone. Molecular analysis revealed that the predominant bacteria present in biofilms grown under the influence of the impressed current belonged to Rhodobacter spp., Sediminibacterium spp. and Geobacter spp. In addition to favouring the growth of biofilms, direct microscopic and ICP-AES analyses revealed that the impressed current also caused the deposition of iron and manganese on, and in the vicinity of, the well screen. Together, these factors contributed to rapid clogging leading to reduced specific pumping capacities of the treated well. The study revealed that the impressed current system was not effective as an anti-fouling technology but actually promoted both microbial growth and physical clogging in this aquifer.

Culturable Rhodobacter and Shewanella species are abundant in estuarine turbidity maxima of the Columbia River.

Measurements of dissolved, ascorbate-reducible and total Mn by ICP-OES revealed significantly higher concentrations during estuarine turbidity maxima (ETM) events, compared with non-events in the Columbia River. Most probable number (MPN) counts of Mn-oxidizing or Mn-reducing heterotrophs were not statistically different from that of other heterotrophs (10³ -104 cells ml⁻¹) when grown in defined media, but counts of Mn oxidizers were significantly lower in nutrient-rich medium (13 cells ml⁻¹). MPN counts of Mn oxidizers were also significantly lower on Mn(III)-pyrophosphate and glycerol (21 cells ml⁻¹). Large numbers of Rhodobacter spp. were cultured from dilutions of 10⁻² to 10⁻5, and many of these were capable of Mn(III) oxidation. Up to c. 30% of the colonies tested LBB positive, and all 77 of the successfully sequenced LBB positive colonies (of varying morphology) yielded sequences related to Rhodobacter spp. qPCR indicated that a cluster of Rhodobacter isolates and closely related strains (95-99% identity) represented approximately 1-3% of the total Bacteria, consistent with clone library results. Copy numbers of SSU rRNA genes for either Rhodobacter spp. or Bacteria were four to eightfold greater during ETM events compared with non-events. Strains of a Shewanella sp. were retrieved from the highest dilutions (10⁻5) of Mn reducers, and were also capable of Mn oxidation. The SSU rRNA gene sequences from these strains shared a high identity score (98%) with sequences obtained in clone libraries. Our results support previous findings that ETMs are zones with high microbial activity. Results indicated that Shewanella and Rhodobacter species were present in environmentally relevant concentrations, and further demonstrated that a large proportion of culturable bacteria, including Shewanella and Rhodobacter spp., were capable of Mn cycling in vitro.

Description of Catellibacterium caeni sp. nov., reclassification of Rhodobacter changlensis Anil Kumar et al. 2007 as Catellibacterium changlense comb. nov. and emended description of the genus Catellibacterium.

A novel non-sporulating, non-motile, catalase- and oxidase-positive, strictly aerobic, Gram-negative, rod-shaped bacterial strain, designated DCA-1(T), was isolated from activated sludge collected from a butachlor wastewater treatment facility. The strain was able to degrade about 85 % of 100 mg butachlor l(-1) within 5 days of incubation. Growth occurred in the presence of 0-6 % (w/v) NaCl [optimum, 1 % (w/v) NaCl] and at pH 5.5-9.0 (optimum, pH 7.0) and 15-35 °C (optimum, 25-30 °C). Vesicular internal membrane structures and photoheterotrophic growth were not observed. The major respiratory quinone was ubiquinone 10 (Q-10) and the major cellular fatty acids were C(18 : 1)ω7c and 11-methyl C(18 : 1)ω7c. The genomic DNA G+C content of strain DCA-1(T) was 62.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain DCA-1(T) was a member of the family Rhodobacteraceae and was related most closely to the type strain of Catellibacterium aquatile (96.5 % sequence similarity). The combination of phylogenetic analysis, phenotypic characteristics and chemotaxonomic data supports the suggestion that strain DCA-1(T) represents a novel species of the genus Catellibacterium, for which the name Catellibacterium caeni sp. nov. is proposed. The type strain is DCA-1(T) ( = CGMCC 1.7745(T)  = DSM 21823(T)). In addition, based on the characterization data obtained in this study, it is proposed that Rhodobacter changlensis should be reclassified as Catellibacterium changlense comb. nov. (type strain JA139(T)  = DSM 18774(T)  = CCUG 53722(T)  = JCM 14338(T)). An emended description of the genus Catellibacterium is also presented.