Tahibacter aquaticus gen. nov., sp. nov., a new gammaproteobacterium isolated from the drinking water supply system of Budapest (Hungary)

Tahibacter soli sp. nov., isolated from soil and Tahibacter amnicola sp. nov., isolated from freshwater

Two Gram-stain-negative, facultative aerobic, catalase- and oxidase-positive, and non-motile rod bacteria, strains BL^T and W38^T, that were isolated from soil and freshwater, respectively, were taxonomically characterized. Both strains optimally grew at 30 °C and pH 7.0 in Reasoner's 2A medium and contained ubiquinone-8 as the sole respiratory quinone. As major fatty acids (>10 %), strain BL^T contained iso-C_15 : 0 and summed features 3 and 9 (comprising iso-C_15 : 0 2-OH and/or C_16 : 1  ω7c/ω6c and iso-C_17 : 1  ω9c and/or C_16 : 0 10-methyl, respectively), whereas strain W38^T contained iso-C_15 : 0, iso-C_16 : 0 and summed feature 9. Diphosphatidylglycerol and phosphatidylmonomethylethanolamine as major polar lipids and phosphatidylethanolamine and phosphatidylglycerol as minor polar lipids were detected in both strains. The DNA G+C contents of strains BL^T and W38^T were 68.3 and 65.3 %, respectively. Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that strains BL^T and W38^T formed a tight phylogenetic lineage with Tahibacter species, and they shared 98.8 % 16S rRNA gene sequence similarity and 75.5 % average nucleotide identity (ANI) and 16.6 % digital DNA-DNA hybridization (dDDH) values, indicating that they are different species. Strains BL^T and W38^T were most closely related to Tahibacter caeni BUT-6^T and Tahibacter aquaticus PYM5-11^T with 97.7 and 98.0 % 16S rRNA gene sequence similarities, respectively. ANI and dDDH values between strain BL^T and T. caeni BUT-6^T and between strain W38^T and T. aquaticus DSM 21667^T were 78.5 and 21.6% and 75.3 and 21.0 %, respectively. Based on their phenotypic, chemotaxonomic and genomic properties, strains BL^T and W38^T represent two different novel species of the genus Tahibacter, for which the names Tahibacter soli sp. nov. and Tahibacter amnicola sp. nov. are proposed. The type strains of T. soli and T. amnicola are BL^T (=KACC 22831^T=JCM 35402^T) and W38^T (=KACC 22832^T=JCM 35749^T), respectively.

Tahibacter harae sp. nov., isolated from pig farm soil in Guangdong, PR China

In the process of exploring the microbial diversity of pig farms, a Gram-stain-negative, aerobic, rod-shaped, non-spore-forming, non-motile bacterial strain, designated P2K^T, was isolated from soil sample collected at a pig farm, Guangdong Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain P2K^T belonged to the genus Tahibacter, with the highest sequence similarity to Tahibacter aquaticus PYM5-11^T (98.6%) and Tahibacter caeni BUT-6^T (98.3 %). The genome size of strain P2K^T was 6.0 Mb with a DNA G+C content of 68.3 mol%. Average nucleotide identity values between strain P2K^T and the type strains of the genus Tahibacter were 81.1-81.6 %. The digital DNA-DNA hybridization values between P2K^T and these relative species were 24.5-25.6%. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, an unknown aminolipids, two unknown lipids and three unknown phospholipids. The major respiratory quinone of strain P2K^T was ubiquinone Q-8, and the main fatty acids (>10.0 % of total fatty acids) of strain P2K^T were iso-C_15:0, iso-C_16:0 and summed feature 9 (C_16:0 10-methyl and/or iso-C_17:1 ω9c). Based on phenotypic and genotypic data, strain P2K^T represents a novel species within the genus Tahibacter, for which the name Tahibacter harae sp. nov. is proposed, with the type strain P2K^T (=GDMCC 1.3107^T=JCM 35231^T).

Reproducibility of Aerobic Granules in Treating Low-Strength and Low-C/N-Ratio Wastewater and Associated Microbial Community Structure

Long-term stability of the aerobic granular sludge system is essentially based on the microbial community structure of the biomass. In this study, the physicochemical and microbial characteristics of sludge and wastewater treatment performance were investigated regarding formation, maturation, and long-term maintenance of granules in two parallel sequencing batch reactors (SBR), R1 and R2, under identical conditions. The aim was to explore the linkage between microbial community structure of the aerobic granules, their long-term stability, as well as the reproducibility of granulation and long-term stability. The two reactors were operated with a COD concentration of 400 mg/L and a chemical oxygen demand to nitrogen (COD/N) ratio of 4:1 under anoxic–oxic conditions. It was found that although SVI30, sludge size, and distributions in R1 and R2 were different, aerobic granules were formed, and they maintained long-term stability in both reactors for 320 days, implying that a certain level of randomness of granulation does not affect the long-term stability and performance for COD and N removal. In addition, a significant reduction in the richness and diversity of microbial production was observed after the sludge was converted from inoculum or flocs to granules, but this did not negatively affect the performance of wastewater treatment. Among the predominant microbial species in aerobic granules, Zoogloea was identified as the most important bacteria present during the whole operation with the highest abundance, while Thauera was the important genus in the formation and maturation of the aerobic granules, but it cannot be maintained long-term due to the low food-to-microorganisms ratio (F/M) in the system. In addition, some species from Ohtaekwangia, Chryseobacterium, Taibaiella, and Tahibacter were found to proliferate strongly during long-term maintenance of aerobic granules. They may play an important role in the long-term stability of aerobic granules. These results demonstrate the reproducibility of granulation, the small influence of granulation on long-term stability, and the robustness of aerobic granulation for the removal of COD and N. Overall, our study contributes significantly to the understanding of microbial community structure for the long-term stability of aerobic granular sludge in the treatment of low-COD and low-COD/N-ratio wastewater in practice.

Constructed wetlands for rural domestic wastewater treatment: A coupling of tidal strategy, in-situ bio-regeneration of zeolite and Fe(Ⅱ)-oxygen denitrification

Constructed wetlands (CWs) offer a promising method to treat domestic wastewater in rural areas, but CWs usually limiting in nitrogen removal and large area. In this study, zeolite and pyrite were used to construct tidal wetlands to address the problems of insufficient oxygen supply and carbon source. The results show that the fully drained wetland achieved the highest ammonia removal load of 34.67 ± 1.72 g/(m²·d) with 8.57 ± 1.13 mg/L of effluent. Pyrite was found to compensate for the lack of carbon source in the denitrification process in half-drained wetland, which achieved a 78.36 ± 5.3% TN removal rate with 7.09 ± 1.85 mg/L effluent concentration. Pyrite released Fe(II) to promote nitrate reduction for denitrification in the subsequent flooded period. Microbial community analysis indicates that the tidal flow constructed wetlands simultaneously achieved nitrification and denitrification by the coupling of in-situ zeolite regeneration and Fe(II) oxidation denitrification.

Impacts of antimony and arsenic co-contamination on the river sedimentary microbial community in an antimony-contaminated river

Antimony (Sb) and arsenic (As) are toxic elements that occur widely in trace soil concentrations. Expansion of mining activities has increased Sb and As pollution, thus posing a severe threat to human welfare and ecological systems worldwide. Knowledge regarding the composition and adaptation of the microbial communities in these metal(loid) contaminated sites is still limited. In the current study, samples along a river flowing through the world's largest Sb mining area (Xikuangshan) were selected to investigate the microbial response to different Sb or As species. A comprehensive analysis of geochemical parameters, high-throughput sequencing, and statistical methods were applied to reveal the different effects of Sb and As on sedimentary microorganisms. Results suggested that the majority of the Sb and As fractions were not bioavailable. The Sb extractable fraction had a stronger effect on the microbial community compared with its As counterpart. Random forest analyses indicated that the easily exchangeable Sb fraction and specifically sorbed surface-bound fraction were the two most selective variables shaping microbial community diversity. A total of 11 potential keystone phyla, such as bacteria associated with the Bacteroidetes, Proteobacteria, and Firmicutes, were identified according to a molecular ecological network analysis. Strong correlations (|R| > 0.7, P < 0.05) were identified among the indigenous microbial community and pH (negative), sulfate (negative), and exchangeable Sb fraction (positive). Bacteria associated with the genera Geobacter, Phormidium, Ignavibacterium, Desulfobulbus, Ferruginibacter, Fluviicola, Methylotenera, and Scytonema, were predicted to tolerate or metabolize the Sb extractable fraction.

Microcystin-LR-induced changes of hepatopancreatic transcriptome, intestinal microbiota, and histopathology of freshwater crayfish (Procambarus clarkii)

As a hepatotoxin, microcystin-LR (MC-LR) poses a great threat to aquatic organisms. In this research, the hepatopancreatic transcriptome, intestinal microbiota, and histopathology of Procambarus clarkii (P. clarkii) in response to acute MC-LR exposure were studied. RNA-seq analysis of hepatopancreas identified 372 and 781 differentially expressed genes (DEGs) after treatment with 10 and 40 μg/L MC-LR, respectively. Among the DEGs, 23 genes were immune-related and 21 genes were redox-related. GO functional enrichment analysis revealed that MC-LR could impact nuclear-transcribed mRNA catabolic process, cobalamin- and heme-related processes, and sirohydrochlorin cobaltochelatase activity of P. clarkii. In addition, the only significantly enriched KEGG pathway induced by MC-LR was galactose metabolism pathway. Meanwhile, sequencing of the bacterial 16S rRNA gene demonstrated that MC-LR decreased bacterial richness and diversity, and altered the intestinal microbiota composition. At the phylum level, after 96 h, the abundance of Verrucomicrobia decreased after treatment with 10 and 40 μg/L MC-LR, while Firmicutes increased in the 40 μg/L MC-LR-treated group. At the genus level, the abundances of 15 genera were significantly altered after exposure to MC-LR. Our research demonstrated that MC-LR exposure caused histological alterations such as structural damage of hepatopancreas and intestines. This research provides an insight into the mechanisms associated with MC-LR toxicity in aquatic crustaceans.

Arenimonas subflava sp. nov., isolated from a drinking water network, and emended description of the genus Arenimonas

A strain designated PYM3-14T was isolated from the drinking water network of Budapest (Hungary) and was studied by polyphasic taxonomic methods. The straight-rod-shaped cells stained Gram-negative, were aerobic and non-motile. Phylogenetic analysis of the 16S rRNA gene sequence of strain PYM3-14T revealed a clear affiliation with members of the family Xanthomonadaceae within the class Gammaproteobacteria. The 16S rRNA gene sequence of strain PYM3-14T showed the closest sequence similarities to Arenimonas daechungensis CH15-1T (96.2 %), Arenimonas oryziterrae YC6267T (95.2 %) and Lysobacter brunescens UASM DT (94.4 %). The DNA G+C content of strain PYM3-14T, measured by two different methods (52.0 mol% and 55.9 mol%, respectively), was much lower than that of any member of the genus Arenimonas. The predominant fatty acids (>8 %) were iso-C16:0, iso-C15:0, iso-C14:0, iso-C17:1ω9c and C16:1ω7c alcohol. Strain PYM3-14T contained Q-8 as the major ubiquinone and phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylmonomethylethanolamine as the major polar lipids. According to phenotypic and genotypic data strain PYM3-14T represents a novel species of the genus Arenimonas, for which the name Arenimonas subflava sp. nov. is proposed. The type strain is PYM3-14T ( = NCAIM B 02508T = DSM 25526T). On the basis of new data obtained in this study, an emended description of the genus Arenimonas is also proposed.

Tahibacter caeni sp. nov., isolated from activated sludge

A Gram-reaction-negative, aerobic, rod-shaped, non-spore-forming, non-motile bacterial strain, designated BUT-6T, was isolated from activated sludge of a wastewater-treatment facility. The strain grew at 15–35 °C (optimum 30 °C), pH 4.0–10.0 (optimum pH 7.0) and 0–3.0 % (w/v) NaCl (optimum 1.0 %). Phylogenetic analysis based on 16S rRNA sequences showed that strain BUT-6T was most closely related to Tahibacter aquaticus PYM5-11T (98.6 % similarity). However, the DNA–DNA relatedness between strain BUT-6T and T. aquaticus PYM5-11T was 47.1 %. The major fatty acids (>10 % of total fatty acids) of strain BUT-6T were iso-C15 : 0, iso-C17 : 1ω9c and iso-C17 : 0. The major respiratory quinone was ubiquinone Q-8. The profile of polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, an unidentified aminophospholipid, three unknown aminolipids and unidentified phospholipids. The DNA G+C content of strain BUT-6T was 71.7 mol%. On the basis of the data from the polyphasic taxonomic study presented, strain BUT-6T is considered to represent a novel species of the genus Tahibacter , for which the name Tahibacter caeni sp. nov. is proposed. The type strain is BUT-6T ( = CCTCC AB 2013266T = KACC 17139T).

List of new names and new combinations previously effectively, but not validly, published

The purpose of this announcement is to effect the valid publication of the following effectively published new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send three copies of the pertinent reprint or photocopies thereof, or an electronic copy of the published paper to the IJSEM Editorial Office for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries. It should be noted that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in the nomenclature of prokaryotes. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.