Emticicia oligotrophica gen. nov., sp. nov., a new member of the family 'Flexibacteraceae', phylum Bacteroidetes

Emticicia fluvialis sp. nov., a potential hormone-degrading bacterium isolated from Nakdong River, Republic of Korea

A novel species of the genus Emticicia, designated BHSR1T, was isolated from a water sample that was collected from the Nakdong River, Republic of Korea, and its taxonomic affiliation was studied using a polyphasic approach. This bacterium was Gram-stain-negative, non-motile, aerobic, curved, rod-shaped, and oxidase- and catalase-negative. The bacterium grew optimally at 37 °C, pH 7.5 and 0% (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain BHSR1T should be affiliated with the genus Emticicia, with a high similarity to Emticicia fontis KCTC 52248T (98.10%). Phylogenomic analysis also suggested that the strain represents a novel species in the genus Emticicia. The genomic G + C content was 41.9%. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization between strain BHSR1T and its closely related relatives in the genus Emticicia were in ranges of 71.1-75.8%, 69.4-77.5% and 18.6-19.9%, respectively. The gene cluster within BHSR1T contained genes encoding enzymes that could be involved in hormone degradation. The major cellular fatty acids (> 10%) were summed feature 3 (comprising C16:1ω6c and/or C16:1ω7c) and iso-C15:0. With regards to the polar lipid profile, phosphatidylethanolamine (PE), two unidentified aminolipids and three unidentified lipids were identified as the major compounds. The major respiratory quinone was menaquinone (MK)-7. Based on its phylogenetic, phenotypic, chemotaxonomic, and genomic features, strain BHSR1T should be considered a novel species in the genus Emticicia of the family Spirosomaceae, for which the name Emticicia fluvialis sp. nov. is proposed. The type strain was considered BHSR1T (= KCTC 92622T = GDMCC 1.3740T).

Biodegradation of p-nitrophenol by a member of the genus Brachybacterium, isolated from the river Ganges

A p-nitrophenol (PNP) degrading halotolerant, Gram-variable bacterial strain designated as DNPG3, was isolated from a water sample collected from the river Ganges in Hooghly, West Bengal (WB), India, by enrichment culture technique. Based on 16S rRNA gene sequence analysis (carried out at EzTaxon server and Ribosomal data base project site), the strain DNPG3 was identified as Brachybacterium sp., with B. zhongshanense strain JBT (97.08% identity) as it is nearest phylogenetic relative. The strain could tolerate up to 3 mM of PNP, while the optimal growth for the strain was recorded as 0.25 mM. The strain could carry out biodegradation of PNP with concomitant release of nitrite and p-benzoquinone (PBQ) was detected as a hydrolysis product. Under the catabolic condition, it could carry out 36% biodegradation of PNP within 144 h, while, under co-metabolic condition (with glucose), 100% biodegradation was achieved within 48 h at 30 °C. Calcium alginate bead-based cell immobilization studies (of the strain DNPG3) indicated complete biodegradation of PNP (under catabolic condition) within 26 h. This is the first report of PNP biodegradation by any representative strain of the genus Brachybacterium. The study definitely indicated that Brachybacterium sp. strain DNPG3 has biotechnological potential and the strain may be a suitable candidate for developing clean, green, eco-friendly, cost-effective bioremediation processes towards effective removal of PNP from the contaminated sites.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03263-7.

Oligotrophy vs. copiotrophy in an alkaline and saline habitat of Lonar Lake

We reported our comparative observations on oligotrophs vs. copiotrophs from a hyper-alkaline and hypersaline habitat, Lonar Lake, situated in the Buldhana district of Maharashtra, India. Cell numbers of oligotrophic and copiotrophic microbes from the sediment were enumerated by the three-tube most probable number (MPN) method using an array of nutrient-rich and oligotrophic (≈10–20 mg carbon L−1) media offering simulated natural conditions of pH and salinity. A total of 50 strains from 15 different genera and 30 different species were isolated from the highest positive dilutions of MPN to identify the taxa of oligotrophs and copiotrophic microorganisms dominating in Lonar Lake. We did not get any true oligotrophs due to their adaptation to higher carbon levels during the isolation procedure. On the contrary, several true copiotrophs, which could not adapt and survive on a low-carbon medium, were isolated. It is also observed that changes in medium composition and nutrient level altered the selection of organisms from the same sample. Our data indicate that copiotrophic microorganisms dominate the eutrophic Lonar Lake, which is also supported by the past metagenomics studies from the same site. We also reported that quick depletion of carbon from oligotrophic medium worked as a limiting factor, inducing cell death after 2–3 generations and preventing the development of visible colonies on plates and sufficient optical density in liquid medium. Therefore, a long-term supply of low levels of carbon, followed by isolation on enriched media, can serve as a good strategy in isolation of novel taxa of microorganism, with industrial or environmental importance.

Barley Rhizosphere Microbiome Transplantation – A Strategy to Decrease Susceptibility of Barley Grown in Soils With Low Microbial Diversity to Powdery Mildew

Beneficial bacteria in the rhizosphere are known to trigger faster and stronger plant immune responses to biotic and abiotic stressors. In the present study, we aimed to test the hypothesis that a rhizosphere microbiome transplant (RMT) may improve the immune response and reduce the disease rates of barley (Hordeum vulgare). This hypothesis was tested in a greenhouse system with the powdery mildew-causing fungus Blumeria graminis f. sp. hordei (Bgh). Detached rhizosphere microbiome from barley grown in a field soil was transplanted to barley seedlings grown in potting soil with reduced microbial diversity. Saline-treated plants served as control. At the three-leaf stage, barley was infected with Bgh. Decreased susceptibility to Bgh was observed for barley treated with the RMT as displayed by lower Bgh pustule counts in a detached leaf assay. A trend toward enhanced relative transcript abundances of the defense-related genes PR1b and PR17b was observed in leaves, 24 h after the Bgh challenge, when compared to the control. Moreover, 10 days after the Bgh challenge, the barley rhizosphere microbiome was harvested and analyzed by sequencing of 16S rRNA gene amplicons. The microbial community composition was significantly influenced by the RMT and displayed higher microbial diversity compared to the control. Furthermore, microbial beta-diversity and predicted functional profiles revealed a treatment-dependent clustering. Bacterial isolates from the RMT showed in vitro plant beneficial traits related to induced resistance. Our results showed that transplantation of a rhizosphere microbiome could be a sustainable strategy to improve the health of plants grown in potting soil with low microbial diversity under greenhouse conditions.

Acclimation of an algal consortium to sequester nutrients from anaerobic digestate

The objective of this research was to investigate the growth, community composition, and digestate treatment performance of a local algae consortium that was adapted to bacteria-pretreated digestate. The approach was to subculture a local consortium on pretreated dairy manure digestate and then municipal wastewater sludge digestate, allowing the community to adapt before assessing its performance. The adapted consortium was then tested for growth and nutrient removal performance on the digestates and compared to the model organism, Chlorella sorokiniana. Dramatic restructuring of the consortium took place when subcultured on the digestates with Scenedesmaceae and Chlorellaceae almost completely replacing Euglena. The consortium was consistently less productive than C. sorokiniana (184 vs. 248 mg/L/d in dairy digestate and 32 vs. 48 mg/L/d in municipal digestate, P < 0.01). Pretreatment increased growth by 81% and 500% for C. sorokiniana and the consortium, respectively, in dairy digestate (P < 0.01), and allowed for algal growth in municipal digestate.

Partitioning of nutrient removal contribution between granules and flocs in a hybrid granular activated sludge system

Sludge granulation in continuous-flow systems is an emerging technology to intensify existing activated sludge infrastructure for nutrient removal. In these systems, the nutrient removal contributions and partitioning of microbial functions between granules and flocs can offer insights into process implementations. To this end, a reactor system that simulates the continuous-flow environment using an equal amount of initial granule and floc biomass was investigated. The two operational strategies for maintaining granule growth in the continuous-flow system were (a) the higher solids retention time (SRT) for the granules versus flocs, as well as (b) selective feeding of carbon to the granules. The SRT of the large granule fractions (>425 µm, LG) and floc/small granule fractions (<425 µm, FSG) were controlled at 20 and 2.7-6.0 days, respectively. Long term operation of the hybrid granule/floc system achieved high PO₄^3- and NH₄⁺ removal efficiencies. Higher polyphosphate-accumulating organisms (PAO) activity was observed in the FSG than LG, while ammonia-oxidizing bacteria (AOB) activities were similar in the two biomass fractions. Nitrite shunt was observed in the FSG, possibly due to out-competition by the high NOB activity in LG. More importantly, washing out the FSG caused a reduction in LG's AOB and PAO activity, indicating a possible dependency of LG on FSG for maintaining its nutrient removal capacity. Our findings highlighted the partitioning and potential competition/cooperation of key microbial functional groups between LG and FSG, facilitating nutrient removal in a hybrid granular activated sludge system, as well as implications for practical application of the treatment platform.

Comparative study on the bacterial diversity and antibiotic resistance genes of urban landscape waters replenished by reclaimed water and surface water in Xi'an, China

Pathogenic bacteria and antibiotic resistance genes (ARGs) in urban landscape waters may pose a potential threat to human health. However, the investigation of their occurrence in the urban landscape waters replenished by reclaimed water (RW) and surface water (SW) is still insufficient. The water samples collected from six urban landscape waters replenished by RW or SW were used to analyze bacterial diversity using high-throughput sequencing of 16S rRNA gene and to detect 18 ARGs and 2 integron-integrase genes by means of quantitative PCR array. Results indicated that Proteobacteria was the dominant phylum in all six urban landscape waters. The bacterial species richness was lower in urban landscape waters replenished by RW than that by SW. Sulfonamide resistance genes (sulI and sulIII) were the major ARGs in these urban landscape waters. No significant difference in the relative abundance of sulfonamide resistance genes, tetracycline resistance genes, and most of beta-lactam resistance genes was observed between RW-replenished and SW-replenished urban landscape waters. By contrast, the relative abundance of bla_ampC gene and qnrA gene in RW-replenished urban landscape waters was significantly higher than that in SW-replenished urban landscape waters (p < 0.05), which suggested that use of RW may increase the amount of specific ARGs to urban landscape waters. Interestingly, among six urban landscape waters, RW-replenished urban landscape waters had a relatively rich variety of ARGs (12-15 of 18 ARGs) but a low relative abundance of ARGs (458.90-1944.67 copies/16S × 10⁶). The RW replenishment was found to have a certain impact on the bacterial diversity and prevalence of ARGs in urban landscape waters, which provide new insight into the effect of RW replenishment on urban landscape waters.

Physicochemical and Microbial Diversity Analyses of Indian Hot Springs

In the present study, physicochemical and microbial diversity analyses of seven Indian hot springs were performed. The temperature at the sample sites ranged from 32 to 67°C, and pH remained neutral to slightly alkaline. pH and temperature influenced microbial diversity. Culture-independent microbial diversity analysis suggested bacteria as the dominant group (99.3%) when compared with the archaeal group (0.7%). Alpha diversity analysis showed that microbial richness decreased with the increase of temperature, and beta diversity analysis showed clustering based on location. A total of 131 strains (divided into 12 genera and four phyla) were isolated from the hot spring samples. Incubation temperatures of 37 and 45°C and T5 medium were more suitable for bacterial isolation. Some of the isolated strains shared low 16S rRNA gene sequence similarity, suggesting that they may be novel bacterial candidates. Some strains produced thermostable enzymes. Dominant microbial communities were found to be different depending on the culture-dependent and culture-independent methods. Such differences could be attributed to the fact that most microbes in the studied samples were not cultivable under laboratory conditions. Culture-dependent and culture-independent microbial diversities suggest that these springs not only harbor novel microbial candidates but also produce thermostable enzymes, and hence, appropriate methods should be developed to isolate the uncultivated microbial taxa.

Emticicia agri sp. nov., a novel member of the family Cytophagaceae

A bacterial strain, 17J42-9^T, was isolated from a soil sample collected on Jeju Island, Republic of Korea. Cells were observed to be Gram-stain negative and rod-shaped. Colonies were observed to be orange in colour on R2A agar. Analysis of 16S rRNA gene sequences showed that high levels of 16S rRNA sequence similarity were shared between 17J42-9^T and Emticicia fontis IMCC1731^T (98.2 %), Emticicia ginsengisoliGsoil 085^T (98.2 %) and Emticicia soli ZZ-4^T (97.8 %). Growth of strain 17J42-9^T was observed at 10-37 °C, pH 6.0-8.5 and in the presence of 0-0.5 % NaCl. The genomic G+C content was calculated to be 38.6 mol%. The predominant respiratory quinone of the isolate was found to be MK-7; the major fatty acids were identified as summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) (34.1 %), C_15 : 0iso (23.4 %) and C_17 : 0iso 3-OH (10.8 %). The major polar lipids were found to be phosphatidylethanolamine, two unidentified aminolipids and an unidentified lipid. The phenotypic and chemotaxonomic data support the affiliation of strain 17J42-9^T with the genus Emticicia. However, the DNA-DNA relatedness between the isolate and its closest phylogenetic neighbours was lower than 46 %. The results of 16S rRNA gene sequence similarity analysis, DNA-DNA hybridization analysis and the observed differentiating phenotypic properties from other closely related taxa clearly indicate that strain 17J42-9^T represents a novel species in the genus Emticicia, for which the name Emticiciaagri sp. nov. is proposed. The type strain is 17J42-9^T (=KCTC 62270^T=JCM 33056^T).

Comparative metagenomic analyses of a high-altitude Himalayan geothermal spring revealed temperature-constrained habitat-specific microbial community and metabolic dynamics

Metagenomic surveys across microbial mat (~ 55 °C) samples of high-altitude (1760 m above sea level) Himalayan geothermal springs have revealed specialized community enriched with niche-specific functions. In this study, we have performed metagenomic sequence-based analyses to get insights into taxonomic composition and functional potential of hyperthermophiles in water (~ 95 °C) and sediment samples (78-98 °C). Community analyses revealed predominance of thermophilic bacterial and archeal genera dwelling in water in contrast to microbial mats (55 °C), namely Methylophilus, Methyloversatilis, Emticicia, Caulobacter, Thermus, Enhydrobacter and Pyrobaculum. Sediment samples having surface temperature (~ 78 °C) were colonized by Pyrobaculum and Chloroflexus while genus Massilia was found to be inhabited in high-temperature sediments (~ 98 °C). Functional analyses of metagenomic sequences revealed genetic enrichment of genes such as type IV secretion system, flagellar assembly and two-component system in contrast to mats. Furthermore, inter-sample comparison of enriched microbial diversity among water, sediment and microbial mats revealed habitat-specific clustering of the samples within same environment highlighting the role of temperature dynamics in modulating community structure across different habitats in same niche. However, function-based analysis demonstrated site-specific clustering among sediment, microbial mat and water samples. Furthermore, a novel thermophilic genotype of the genus Emticicia (designated as strain MM) was reconstructed from metagenome data. This is a correlative study between three major habitats present in geothermal spring environment, i.e., water, sediment and microbial mats revealing greater phylogenetic and functional dispersion emphasizing changing habitat-specific dynamics with temperature.

Climate and Soil Properties Influence Species Diversity of Soil Bacillus Community in India

Bacillus is an important genus as it is a source for antibiotics, enzymes, and probiotics. Therefore, several studies are targeted on this genus in order to understand its diversity abundance in different soil environments. In present study, we investigated the diversity of Bacillus at species level using culturable approach in soils collected at different climatic zones of India and identified 20 prominent members of genus Bacillus species that are able to grow in different media types under same culture conditions. Results also showed that the species diversity of Bacillus changes according to the soil microenvironment under the influence of different climatic conditions. As a pilot study using culturable approach, we made an attempt to investigate the shift in Bacillus species diversity present in the Indian soils experiencing a climatic gradient over a large geographic area.

Assessing the cellulase enzyme heterogeneity of bacterial strains and their feedback to cattle manure degradation in a greenhouse model of in vivo pond ecosystem

The responses of cellulase enzymes of three bacterial isolates and their impacts on cattle manure decomposition were assessed in a greenhouse model in vivo pond ecosystem. Fifty grams of fresh cattle manure was placed in a fastened nylon bag (mesh size ~ 50 μm dia.) and placed in triplicate in a plastic bucket with 10 l of pond water which was hung inside the enclosed polyhouse, semi-closed and open systems for 4 weeks. Samples of manure residue directly from nylon bag and water from manure leached bucket water, water, and soil from the enclosed polyhouse were collected for enzymatic assays, enumeration of aerobic cellulose decomposing and heterotrophic bacteria, and determination of water and soil quality parameters. Responses of cellulases to different temperatures in situ were also elucidated. The values of test bacteria, endoglucanase, exoglucanase and β-glucosidase, and organic carbon were significantly (P ˂ 0.05) higher in the closed system compared to semi-closed or open system. Priming of all the enzymes coupled with the peak of aerobic cellulose decomposing bacteria and heterotrophic bacterial populations occurred on the day 14 or 21 in vivo. Since the peaks of three cellulases of bacterial isolates (KUPH1, KUPH6, and KUPH8) were demonstrated between 35 and 40 °C, and that temperature coincided with temperature of the greenhouse model, this temperature range appeared to favor the growth of cellulose decomposing bacterial populations and involved cellulase enzymes.

A halotolerant Enterobacter sp. displaying ACC deaminase activity promotes rice seedling growth under salt stress

Agricultural productivity is proven to be hampered by the synthesis of reactive oxygen species (ROS) and production of stress-induced ethylene under salinity stress. One-aminocyclopropane-1-carboxylic acid (ACC) is the direct precursor of ethylene synthesized by plants. Bacteria possessing ACC deaminase activity can use ACC as a nitrogen source preventing ethylene production. Several salt-tolerant bacterial strains displaying ACC deaminase activity were isolated from rice fields, and their plant growth-promoting (PGP) properties were determined. Among them, strain P23, identified as an Enterobacter sp. based on phenotypic characteristics, matrix-assisted laser desorption ionization-time of flight mass spectrometry data and the 16S rDNA sequence, was selected as the best-performing isolate for several PGP traits, including phosphate solubilization, IAA production, siderophore production, HCN production, etc. Enterobacter sp. P23 was shown to promote rice seedling growth under salt stress, and this effect was correlated with a decrease in antioxidant enzymes and stress-induced ethylene. Isolation of an acdS mutant strain enabled concluding that the reduction in stress-induced ethylene content after inoculation of strain P23 was linked to ACC deaminase activity.

Microbiological studies of hot springs in India: a review

The earliest microbiological studies on hot springs in India date from 2003, a much later date compared to global attention in this striking field of study. As of today, 28 out of 400 geothermal springs have been explored following both culturable and non-culturable approaches. The temperatures and pH of the springs are 37-99 °C and 6.8-10, respectively. Several studies have been performed on the description of novel genera and species, characterization of different bio-resources, metagenomics of hot spring microbiome and whole genome analysis of few isolates. 17 strains representing novel species and many thermostable enzymes, including lipase, protease, chitinase, amylase, etc. with potential biotechnological applications have been reported by several authors. Influence of physico-chemical conditions, especially that of temperature, on shaping the hot spring microbiome has been established by metagenomic investigations. Bacteria are the predominant life forms in all the springs with an abundance of phyla Firmicutes, Proteobacteria, Actinobacteria, Thermi, Bacteroidetes, Deinococcus-Thermus and Chloroflexi. In this review, we have discussed the findings on all microbiological studies that have been carried out to date, on the 28 hot springs. Further, the possibilities of extrapolating these studies for practical applications and environmental impact assessment towards protection of natural ecosystem of hot springs have also been discussed.

Emticicia soli sp. nov., a novel member of the family 'Flexibacteraceae', isolated from tetrabromobisphenol A-contaminated soil

Bacterial strain ZZ-4T, a Gram-stain-negative, aerobic, non-spore-forming, non-motile, non-flagellated, rod-shaped bacterium, was isolated from tetrabromobisphenol A-contaminated soil in PR China. The taxonomic position of this strain was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZZ-4T was a member of the genus Emticicia and showed the highest sequence similarity to Emticicia fontis IMCC1731T (98.0 %) and Emticicia ginsengisoli Gsoil 085T (97.2 %), and lower (<97 %) sequence similarity to other known Emticicia species. Chemotaxonomic analysis revealed that strain ZZ-4T possessed menaquinone MK-7 as the major isoprenoid quinone; and iso-C15 : 0, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7), iso-C17 : 0 3-OH and C16 : 1ω5c were the predominant fatty acids. Strain ZZ-4T showed low DNA-DNA relatedness with E. fontis IMCC1731T (39.8±3.1 %) and E. ginsengisoli Gsoil 085T (44.51±1.5 %). The DNA G+C content was 38.3 mol%. Based on the phylogenetic and phenotypic characteristics, chemotaxonomic data and DNA-DNA hybridization results, strain ZZ-4T is considered to represent a novel species of the genus Emticicia, for which the name Emticicia soli sp. nov. is proposed. The type strain is ZZ-4T (=KCTC 52344T=CCTCC AB 2016137T).

Arcticibacterium luteifluviistationis gen. nov., sp. nov., isolated from Arctic seawater

A Gram-staining-negative, aerobic, non-motile and yellow-pigmented bacterium, designated strain SM1504T, was isolated from Arctic seawater. It hydrolysed aesculin and gelatin but did not reduce nitrate to nitrite. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain SM1504T constituted a distinct phylogenetic line within the family Cytophagaceae and was closely related to species of the genera Lacihabitans, Emticicia, Fluviimonas and Leadbetterella, with respect to which low sequence similarities between 88.9 and 91.6 % were observed. The major fatty acids of strain SM1504T were summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 : 0 2-OH) and iso-C15 : 0. The predominant polar lipids of strain SM1504T were phosphatidylethanolamine and one unidentified lipid. The only respiratory quinone detected in strain SM1504T was MK7. The DNA G+C content of strain SM1504T was 40.8 mol%. On the basis of the phylogenetic, chemotaxonomic and phenotypic characterization in this study, strain SM1504T is considered to represent a novel species in a new genus of the family Cytophagaceae, for which the name Arcticibacterium luteifluviistationis gen. nov., sp. nov. is proposed. The type strain is SM1504T (=KCTC 42716T=CCTCC AB 2015348T).

Emticicia aquatilis sp. nov., isolated from a freshwater sample

A Gram-stain-negative, facultatively anaerobic, non-motile, rod-shaped and yellow-pigmented bacterium, designated strain THG-DN6.14T, was isolated from a freshwater sample near Donghaksa temple in Daejeon, South Korea. On the basis of the results of 16S rRNA gene sequence comparisons, THG-DN6.14T was found to be most closely related to Emticicia sediminis JBR12T (99.1 % sequence similarity), Emticicia oligotrophica DSM 17448T (97.6 %), Emticicia aquatica HMF2925T (96.5 %), and Emticicia ginsengisoliGsoil 085T (94.4 %). The DNA-DNA relatedness between THG-DN6.14T and its phylogenetically closest neighbours was below 65.0 %. The DNA G+C content was 43.3 mol%. The major polar lipids were found to be phosphatidylethanolamine, an unidentified glycolipid and an unidentified aminoglycolipid. The major fatty acids were identified as C16 : 0, iso-C15 : 0, iso-C17 : 0 3-OH, and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The respiratory quinone was menaquinone MK-7. These data supported the affiliation of THG-DN6.14T to the genus Emticicia. THG-DN6.14Tcould be distinguished from related species of the genus Emticicia by physiological and biochemical tests. Therefore, the novel isolate represents a novel species, for which the name Emticicia aquatilis sp. nov. is proposed, with THG-DN6.14T (=KACC 18540T=CGMCC 1.15958T) as the type strain.

Genome-Based Taxonomic Classification of Bacteroidetes

The bacterial phylum Bacteroidetes, characterized by a distinct gliding motility, occurs in a broad variety of ecosystems, habitats, life styles, and physiologies. Accordingly, taxonomic classification of the phylum, based on a limited number of features, proved difficult and controversial in the past, for example, when decisions were based on unresolved phylogenetic trees of the 16S rRNA gene sequence. Here we use a large collection of type-strain genomes from Bacteroidetes and closely related phyla for assessing their taxonomy based on the principles of phylogenetic classification and trees inferred from genome-scale data. No significant conflict between 16S rRNA gene and whole-genome phylogenetic analysis is found, whereas many but not all of the involved taxa are supported as monophyletic groups, particularly in the genome-scale trees. Phenotypic and phylogenomic features support the separation of Balneolaceae as new phylum Balneolaeota from Rhodothermaeota and of Saprospiraceae as new class Saprospiria from Chitinophagia. Epilithonimonas is nested within the older genus Chryseobacterium and without significant phenotypic differences; thus merging the two genera is proposed. Similarly, Vitellibacter is proposed to be included in Aequorivita. Flexibacter is confirmed as being heterogeneous and dissected, yielding six distinct genera. Hallella seregens is a later heterotypic synonym of Prevotella dentalis. Compared to values directly calculated from genome sequences, the G+C content mentioned in many species descriptions is too imprecise; moreover, corrected G+C content values have a significantly better fit to the phylogeny. Corresponding emendations of species descriptions are provided where necessary. Whereas most observed conflict with the current classification of Bacteroidetes is already visible in 16S rRNA gene trees, as expected whole-genome phylogenies are much better resolved.

Emticiciafontis sp. nov., isolated from a freshwater pond

A bacterial strain, designated IMCC1731T, was isolated from an eutrophic freshwater pond and characterized using a polyphasic taxonomic approach. Cellular growth occurred at pH 6-9 (optimum, pH 8.0), at 10-30 °C (optimum, 25 °C) and with 0-1 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain IMCC1731T belonged to the genus Emticicia in the family Cytophagaceae and was most closely related to Emticicia ginsengisoli Gsoil 085T (98.1 %) followed by Emticicia paludis HMF3850T (95.0 %), Emticicia oligotrophica DSM 17448T (94.7 %), Emticicia aquatica HMF2925T (94.4 %) and Emticicia sediminis JBR12T (94.0 %). The DNA-DNA relatedness between strain IMCC1731T and E. ginsengisoli Gsoil 085T was 47±4 %. The DNA G+C content of strain IMCC1731T was 37.7 mol%. The predominant cellular fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and iso-C15 : 0. Based on the physiological and chemotaxonomic characteristics, DNA-DNA relatedness and 16S rRNA gene phylogeny, stain IMCC1731T is considered to represent a novel species of the genus Emticicia, for which the name Emticicia fontis sp. nov. is proposed. The type strain is IMCC1731T (=KCTC 52248T=JCM 31373T).

Emticicia paludis sp. nov., isolated from wetland freshwater

A novel bacterium, designated HMF3850T, was isolated from freshwater collected from the Gyeong-an wetland, Republic of Korea. Cells were Gram-stain-negative, aerobic, straight rods, non-motile, and oxidase- and catalase-positive. Growth was observed at pH 6.0-8.0 and at 10-30 °C on R2A agar. Comparative analysis of 16S rRNA gene sequences revealed that strain HMF3850T is a member of the genus Emticicia, sharing highest sequence similarities with Emticicia aquatica HMF2925T (96.7 % 16S rRNA gene sequence similarity), Emticicia sediminis JBR12T (95.0 %), Emticicia ginsengisoliGsoil 085T (94.9 %) and Emticicia oligotrophica DSM 17448T (94.7 %). The major fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The predominant respiratory quinone was MK-7. The major polar lipids were phosphatidylethanolamine, phosphatidylinositol, one unidentified aminophospholipid, two unidentified aminolipids and eight unidentified polar lipids. The DNA G+C content was 38.5 mol %. On the basis of the evidence presented in this study, strain HMF3850T represents a novel species of the genus Emticicia, for which the name Emticicia paludis sp. nov. is proposed. The type strain is HMF3850T (=KCTC 42851T=CECT 9087T).

Microbiological mechanism of the improved nitrogen and phosphorus removal by embedding microbial fuel cell in Anaerobic-Anoxic-Oxic wastewater treatment process

Anaerobic-Anoxic-Oxic (AA/O) wastewater treatment process is a widely used wastewater treatment process for simultaneous nitrogen and phosphorus removal. Microbial fuel cell (MFC) can generate electricity and treat the organic wastewater simultaneously. Our previous research showed that embedding MFC in AA/O wastewater treatment process could enhance the pollutants removal efficiency. However, the mechanism was not clear. In this study, a lab-scale corridor-style AA/O reactor with MFC embedded was operated and both the total nitrogen and total phosphorus removal efficiencies were enhanced. DGGE and Illumina Miseq results demonstrated that both the microbial community structures on the surface of the cathode and in the suspensions of cathode chamber have been changed. The percentage of Thauera and Emticicia, identified as denitrifying bacteria, increased significantly in the suspension liquid when the MFC was embedded in the AA/O reactor. Moreover, the genus Rheinheimera were significantly enriched on the cathode surface, which might contribute to both the nitrogen removal enhancement and electricity generation.

Chemotaxis and degradation of organophosphate compound by a novel moderately thermo-halo tolerant Pseudomonas sp. strain BUR11: evidence for possible existence of two pathways for degradation

An organophosphate (OP) degrading chemotactic bacterial strain BUR11 isolated from an agricultural field was identified as a member of Pseudomonas genus on the basis of its 16S rRNA gene sequence. The strain could utilize parathion, chlorpyrifos and their major hydrolytic intermediates as sole source of carbon for its growth and exhibited positive chemotactic response towards most of them. Optimum concentration of parathion for its growth was recorded to be 200 ppm and 62% of which was degraded within 96 h at 37 °C. Growth studies indicated the strain to be moderately thermo-halo tolerant in nature. Investigation based on identification of intermediates of parathion degradation by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography mass spectrometry (LC-MS/MS) provided evidence for possible existence of two pathways. The first pathway proceeds via 4-nitrophenol (4-NP) while the second proceeds through formation of 4-aminoparathion (4-APar), 4-aminophenol (4-AP) and parabenzoquinone (PBQ). This is the first report of chemotaxis towards organophosphate compound by a thermo-halo tolerant bacterium.

Emticicia aquatica sp. nov., a species of the family Cytophagaceae isolated from fresh water

A Gram-staining-negative, non-gliding, orange-pigmented bacterial strain, designated HMF2925T, was isolated from fresh water in Korea. The phylogenetic tree based on 16S rRNA gene sequences showed that strain HMF2925T formed a distinct lineage within the genus Emticicia. Strain HMF2925T was closely related to Emticicia oligotrophica DSM 17448T (95.5 %) and Emticicia ginsengisoli Gsoil 085T (94.1 %). The major fatty acids of strain HMF2925T were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), iso-C15 : 0, C16 : 1ω5c and C16 : 0.The major polar lipids of strain HMF2925T were phosphatidylethanolamine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid, two unidentified amino lipids and three unidentified polar lipids. The DNA G+C content of strain HMF2925T was 36.5 mol%. On the basis of the evidence presented in this study, strain HMF2925T represents a novel species of the genus Emticicia, for which the name Emticicia aquatica sp. nov. is proposed. The type strain is HMF2925T ( = KCTC 42574T = CECT 8858T).

Impact of manufactured TiO2 nanoparticles on planktonic and sessile bacterial communities

In the present study, we conducted a 2 week microcosm experiment with a natural freshwater bacterial community to assess the effects of titanium dioxide nanoparticles (TiO2-NPs) at various concentrations (0, 1, 10 and 100 mg/L) on planktonic and sessile bacteria under dark conditions. Results showed an increase of planktonic bacterial abundance at the highest TiO2-NP concentration, concomitant with a decrease from that of sessile bacteria. Bacterial assemblages were most affected by the 100 mg/L TiO2-NP exposure and overall diversity was found to be lower for planktonic bacteria and higher for sessile bacteria at this concentration. In both compartments, a 100 mg/L TiO2-NPs exposure induced a decrease in the ratio between the Betaproteobacteria and Bacteroidetes. For planktonic communities, a decrease of Comamonadaceae was observed concomitant with an increase of Oxalobacteraceae and Cytophagaceae (especially Emticicia). For sessile communities, results showed a strong decrease of Betaproteobacteria and particularly of Comamonadaceae.

Emticicia sediminis sp. nov. isolated from sediment of a shallow stream

A novel bacterial strain, designated JBR12T, was isolated from sediment of a shallow stream in Cheonan, Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JBR12T belongs to the genus Emticicia, and indicated that its closest relatives are Emticicia oligotrophica DSM 17448T (97.8 % sequence similarity) and E. ginsengisoli Gsoil 085T (94.3%). A DNA-DNA hybridization experiment revealed < 70 % genomic relatedness between strain JBR12T and E. oligotrophica DSM 17448T. The major fatty acids (>5% of the total) were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 3-OH, anteiso-C15 : 0 and iso-C15 : 0 3-OH. The DNA G+C content of strain JBR12T was 37.7 mol%. According to data from the present polyphasic taxonomic study, strain JBR12T represents a novel species of the genus Emticicia, for which the name Emticicia sediminis sp. nov. is proposed. The type strain is JBR12T ( = KACC 17466T = JCM 19321T).

Fluviimonas pallidilutea gen. nov., sp. nov., a new member of the family Cytophagaceae isolated from a freshwater river

A bacterial strain designated TQQ6T was isolated from a freshwater river in Taiwan and characterized using a polyphasic taxonomy approach. Cells of strain TQQ6T were strictly aerobic, Gram-staining-negative, poly-β-hydroxybutyrate-containing, non-motile, non-spore-forming, long rods surrounded by a thick capsule and forming pale orange colonies. Growth occurred at 20–40 °C (optimum, 25 °C), at pH 7.0–9.0 (optimum, pH 8.0) and with 0–0.5 % NaCl (optimum, 0 %). The predominant fatty acids were iso-C15 : 0, summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), iso-C17 : 0 3-OH, C16 : 1ω5c and C16 : 0. The major isoprenoid quinone was MK-7 and the DNA G+C content was 42.2 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylcholine, two uncharacterized aminophospholipids and three uncharacterized phospholipids. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain TQQ6T represents a distinct phyletic line that reflects a novel generic status within the family Cytophagaceae with relatively low sequence similarities (less than 90 %) to members of other genera with validly published names. On the basis of the genotypic and phenotypic data, strain TQQ6T represents a new genus and novel species of the family Cytophagaceae , for which the name Fluviimonas pallidilutea gen. nov., sp. nov. is proposed. The type strain is TQQ6T ( = BCRC 80447T = LMG 27056T = KCTC 32035T).

Production, purification and characterization of a novel thermotolerant endoglucanase (CMCase) from Bacillus strain isolated from cow dung

In an attempt to screen out cellulase producing bacteria from herbivorous animal fecal matter it was possible to isolate a potent bacterium from cow dung. The bacterium was identified as Bacillus sp. using 16S rDNA based molecular phylogenetic approach. The effect of different agricultural wastes, paper wastes and carboxymethyl cellulose on endoglucanase production was tested and was found to produce maximally at 8% carboxymethyl cellulose. The endoglucanase was precipitated by ammonium sulfate saturation and purified by DEAE- Sepharose column. The purification was achieved 8.5 fold from the crude extract with a yield of 68.1%. The molecular weight of the protein was determined to be 97 kDa by SDS-PAGE. The enzymatic activity was moderately reduced by detergents (SDS, Tween-80), metal ions (MnCl₂, ZnCl₂) and EDTA. The endoglucanase was stable between pH 5.0 – 9.0 and temperature between 20−70°C with optimal activity at pH 7.0 and temperature 50°C. The apparent Km value of the enzyme for the substrate carboxymethyl cellulose was recorded to be 0.25 mg/ml. The endoglucanase was stable in the presence of commercial detergents such as Ariel, Surf Excel and Tide, indicated might be of potential applications in detergent industry. The enzyme from this strain could also be applied in bioconversion of lignocellulosic biomass into fermentable sugars.

Complete genome sequence of Leadbetterella byssophila type strain (4M15)

Leadbetterella byssophila Weon et al. 2005 is the type species of the genus Leadbetterella of the family Cytophagaceae in the phylum Bacteroidetes. Members of the phylum Bacteroidetes are widely distributed in nature, especially in aquatic environments. They are of special interest for their ability to degrade complex biopolymers. L. byssophila occupies a rather isolated position in the tree of life and is characterized by its ability to hydrolyze starch and gelatine, but not agar, cellulose or chitin. Here we describe the features of this organism, together with the complete genome sequence, and annotation. L. byssophila is already the 16^th member of the family Cytophagaceae whose genome has been sequenced. The 4,059,653 bp long single replicon genome with its 3,613 protein-coding and 53 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.

Endosymbiotic bacteria in the parasitic ciliate Ichthyophthirius multifiliis

Endosymbiotic bacteria were identified in the parasitic ciliate Ichthyophthirius multifiliis, a common pathogen of freshwater fish. PCR amplification of DNA prepared from two isolates of I. multifiliis, using primers that bind conserved sequences in bacterial 16S rRNA genes, generated an approximately 1,460-bp DNA product, which was cloned and sequenced. Sequence analysis demonstrated that 16S rRNA gene sequences from three classes of bacteria were present in the PCR product. These included Alphaproteobacteria (Rickettsiales), Sphingobacteria, and Flavobacterium columnare. DAPI (4',6-diamidino-2-phenylindole) staining showed endosymbionts dispersed throughout the cytoplasm of trophonts and, in most, but not all theronts. Endosymbionts were observed by transmission electron microscopy in the cytoplasm, surrounded by a prominent, electron-translucent halo characteristic of Rickettsia. Fluorescence in situ hybridization demonstrated that bacteria from the Rickettsiales and Sphingobacteriales classes are endosymbionts of I. multifiliis, found in the cytoplasm, but not in the macronucleus or micronucleus. In contrast, F. columnare was not detected by fluorescence in situ hybridization. It likely adheres to I. multifiliis through association with cilia. The role that endosymbiotic bacteria play in the life history of I. multifiliis is not known.

Flavobacterium indicum sp. nov., isolated from warm spring water in Assam, India

A polyphasic taxonomic approach was employed to characterize a strain designated GPTSA100-9T, which was isolated from water sampled from a warm spring. The micro-organism, comprising Gram-negative, strictly aerobic rods, could not grow on nutritionally rich media such as tryptic soy broth. Analysis of the 16S rRNA gene sequence (1396 nt) of strain GPTSA100-9Trevealed that it is a member of the genusFlavobacterium, sharing 99.8 % sequence similarity with the CFB group bacterium strain A0653 (AF236016), 93.4 % with ‘[Flexibacter]aurantiacussubsp.excathedrus’ and 93.2–92.0 % withFlavobacterium saliperosum,Flavobacterium soli,Flavobacterium aquatileandFlavobacterium columnare. The G+C content of the genomic DNA was 31.0 mol%. The major fatty acids of the strain grown on modified R2A agar were iso-C15 : 0(18.5 %), iso-C15 : 1G (18.0 %), summed feature 3 (iso-C15 : 02-OH and/or C16 : 1ω7c, 16.6 %) and iso-C17 : 03-OH (9.0 %). On the basis of phenotypic and genotypic characteristics, strain GPTSA100-9Trepresents a novel species of the genusFlavobacterium, for which the nameFlavobacterium indicumsp. nov. is proposed. The type strain is GPTSA100-9T(=MTCC 6936T=DSM 17447T).