Isolation and characterization of Novosphingobium aquae sp. nov. and Novosphingobium anseongense sp. nov., isolated from freshwater

Two novel Gram-stain-negative, aerobic, heterotrophic, non-motile bacterial strains, designated as AS3R-12T and PS1R-30T, were isolated from freshwater in South Korea. To determine their taxonomic positions, the strains were thoroughly characterized. Genomic analyses, based on 16S rRNA gene and draft genome sequence data, revealed that the two novel isolates, AS3R-12T and PS1R-30T, belonged to the genus Novosphingobium. AS3R-12T showed the highest 16S rRNA gene similarity (97.7%) with Novosphingobium flavum UCT-28T. In addition, PS1R-30T showed 97.9% 16S rRNA gene similarity with Novosphingobium lentum NBRC 107847T. The draft genome of strains AS3R-12T and PS1R-30T consisted of 4 149 275 and 4 969 838 bps, with DNA G+C content of 63.1 and 66.1 mol%, respectively. The average nucleotide identity between two strains and other related species was below 76.2%, and the digital DNA-DNA hybridization values with closely related species were below 20.8%, both lower than the species delineation threshold. Strains AS3R-12T and PS1R-30T contained the ubiquinone Q-10 as the major quinone and displayed a polyamine pattern with spermidine as the predominant polyamine. Additionally, their major fatty acids were characterized by C16:1  ω7c/C16:1  ω6c (summed feature 3) and C18:1  ω7c/C18:1  ω6c (summed feature 8). The major polar lipids of AS3R-12T and PS1R-30T were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), sphingoglycolipid (SGL) and phosphatidylcholine (PC). Moreover, physiological and biochemical results allowed the phenotypic and genotypic differentiation of strains AS3R-12T and PS1R-30T from their closest and other species of the genus Novosphingobium with validly published names. Therefore, AS3R-12T and PS1R-30T represented novel species of the genus Novosphingobium, for which the names Novosphingobium aquae sp. nov. (type strain AS3R-12T=KACC 23096T=LMG 32950T) and Novosphingobium anseongense sp. nov. (type strain PS1R-30T=KACC 23097T=LMG 32951T) are proposed.

Unique gel-like colony forming bacterium Novosphingobium pituita sp. nov., isolated from a membrane bioreactor (MBR) treating sewage

A novel, gelatinous, colony-forming, rod-shaped bacterial strain, designated IK01T was isolated from biofilms formed on the membrane surface of a sewage-treating membrane bioreactor (MBR). Strain IK01T produced gelatinous and almost transparent colonies at lower medium concentrations. Fourier transform infrared analysis of the gelatinous colony matrix showed that the matrix could be a biofilm substance. This suggests that strain IK01T is a fouling-causing bacteria in the MBR. Furthermore, 16S rRNA gene sequence analysis showed that strain IK01T was phylogenetically placed in the genus Novosphingobium. The average nucleotide identity values for IK01T and the other 50 species of the genus Novosphingobium ranged from 78.5 to 83.9 %. Correspondingly, the estimated digital DNA-DNA hybridization values ranged from 20.8 to 24.4 %. The genomic DNA G + C content was 66.0 %. The predominant fatty acids were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), and C14:0 2-OH. A polar lipid profile revealed phosphatidylethanolamine, two unidentified phospholipids, and three aminoglycophospholipids as major compounds. The major respiratory quinone was ubiquinone Q-10. Genotypic, chemotaxonomic, and phenotypic analyses characterized the newly identified strain IK01T, as a novel species of the genus Novosphingobium, for which we propose the name Novosphingobium pituita sp. nov. The type strain is IK01T (NBRC 116408T = DSM 116658T).

Refractory degradable dissolved organic matter (R-DOM) driving nitrogen removal by the electric field coupled iron‑carbon biofilter (E-ICBF): Performance and microbial mechanisms

Researches on the advanced nitrogen (N) removal of municipal tailwater always overlooked the value of refractory degradable dissolved organic matter (R-DOM). In this study, a novel electric field coupled iron‑carbon biofilter (E-ICBF) was utilized to explore the performance and microbial changes with polyethylene glycol (PEG) as the representative R-DOM. Results demonstrated that the removal efficiencies of E-ICBF for nitrate nitrogen (NO3--N), ammonia nitrogen (NH4+-N), and total nitrogen (TN) improved by 28.76 %, 12.96 %, and 28.45 %, compared to quartz sand biofilter (SBF). Moreover, removal efficiencies of NO3--N and TN in E-ICBF with R-DOM went up by 12.11 % and 14.02 % compared to methanol. Additionally, both PEG and the electric field reduced the microbial richness and diversity. However, PEG promoted the increase of denitrifying bacteria abundance including unclassified_f_Comamonadaceae, Thauera, and unclassified_f_Gallionellaceae. The electric field improved the abundances of genes related to N removal (hao, nasC, nasA, nifH, nifD, nifK) and PEG further enhanced the effect. The abundances of key enzymes [EC:1.7.5.1], [EC:1.7.2.1], [EC:1.7.2.4], and [EC:1.7.2.5] decreased due to the addition of PEG and the electric field mitigated the negative influence. Additionally, the electric field changed relationships between microorganisms and pollutant removal, and improved interspecific relationships between denitrifying bacterial genera and other genera in E-ICBF.

Novosphingobium cyanobacteriorum sp. nov., isolated from a eutrophic reservoir during the Microcystis bloom period

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain, HBC54T, was isolated from periphyton during a Microcystis bloom. Based on the results of the 16S rRNA gene sequence analysis, strain HBC54T was closely related to Novosphingobium aerophilum 4Y4T (98.36 %), Novosphingobium aromaticivorans DSM 12444T (98.08 %), Novosphingobium huizhouense c7T (97.94 %), Novosphingobium percolationis c1T (97.65 %), Novosphingobium subterraneum DSM 12447T (97.58 %), Novosphingobium olei TW-4T (97.58 %) and Novosphingobium flavum UCT-28T (97.37 %). The average nucleotide identity and digital DNA-DNA hybridization values between HBC54T and its related type stains were below 78.97 and 23.7 %, which are lower than the threshold values for species delineation. The major fatty acids (>10.0 %) were identified as C14 : 0 2-OH, summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c) and summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c) and the respiratory quinone was ubiquinone Q-10. The main polar lipids detected in the strain were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol and three unidentified phospholipids. The genomic DNA G+C content was 64.8 mol%. Strain HBC54T is considered to represent a novel species within the genus Novosphingobium, for which the name Novosphingobium cyanobacteriorum sp. nov. is proposed. The type strain is HBC54T (=KCTC 92033T=LMG 32427T).

pH-dependent microbial niches succession and antibiotic resistance genes distribution in an oxygen-based membrane biofilm reactor treating greywater

System pH is found to crucially affect biofilm growth and microorganisms' activity in the biofilm-based wastewater treatment system. This study investigated the pH-dependent pollutants removal, microbial niches succession and antibiotic resistance genes (ARGs) accumulation in an oxygen-based membrane biofilm reactor treating greywater. Results indicated that neutral conditions achieved the highest biofilm concentration and living cells, which enabled the highest pollutants removal rates; multifarious functional groups in biofilm enabled pollutants adsorption, which favored its continuous bio-removal. Microbial communities under acidic condition (pH = 5.0) were significantly different with that under other conditions (p < 0.05). The neutral and alkaline niches (pH = 7.0 and 9.0) were predominant by organics biodegradation and nitrogen reduction bacteria (e.g. Sphingobacteriales, Pseudomonas, Flavobacterium and Phenylobacterium), but which were significantly dropped under acidic conditions, leading to the declined reactor performance. ARGs in biofilm (predominant by korB, intI-1, sul1 and sul2) were much higher than that in the cell-free liquid and the target ARGs accumulation (korB, intI-1, bla_CTX-M, qnrS) had nearly linear positive relationships (R² > 0.95, P < 0.01) with biofilm-attached linear alkylbenzene sulfonate (LAS). LAS stimulate ARGs proliferation in functional microorganisms (korB, sul-1 and intI-1 were significantly associated with related microbial genus) and biofilm played a key role in ARGs dissemination. The relatively low ARGs in both biofilm and effluent under neutral conditions suggested that pH controlling can be an effective strategy to inhibit ARGs dissemination and proliferation in the system.